TABLE OF CONTENTS 2 CHAPTER 1 4 CHAPTER 2 6 CHAPTER 3 10 CHAPTER 4 12 CHAPTER 5 Data Representation Communication & Internet Technologies Hardware & Software Security Ethics CIE IGCSE COMPUTER SCIENCE//0478 1. DATA REPRESENTATION 1.1 Binary Systems The binary system is based on the number 2 Made up of 1s and 0s Use of binary numbers in computer systems Converting Binary to Denary To calculate a binary number like, 10101000, place it in columns of base 2 numbers Then add all the base 2 numbers 128 64 32 16 8 4 2 1 1 0 1 0 1 0 0 0 128 + 32 + 8 = 𝟏𝟔𝟖 Converting Denary to Binary To calculate a denary number like, 84, set up the columns of base 2 numbers 128 64 32 16 8 4 2 1 0 1 0 1 0 1 0 0 𝟎𝟏𝟎𝟏𝟎𝟏𝟎𝟎 1.2 Measurement of the Size of Computer Memories A binary digit is referred to as a BIT, 8 bits is a byte Byte is used to measure memory size NAME OF NO. OF EQUIVALENT DENARY VALUE MEMORY SIZE BITS 1 kilobyte (1KB) 210 1 024 bytes 2 megabyte (1MB) 220 1 048 576 bytes 1 gigabyte (1GB) 230 1 073 741 824 bytes 1 terabyte (1TB) 240 1 099 511 627 776 bytes 1 petabyte (1PB) 250 1 125 899 906 842 624 bytes Example use of binary A register is a group of bits, often depicted as: o 𝟏𝟎𝟎𝟏𝟎𝟏𝟏𝟏 Robotics Digital instruments Counting systems HEXADECIMAL DENARY VALUE VALUE 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 A 10 B 11 C 12 D 13 E 14 F 15 Converting Binary to Hexadecimal To convert binary number 01100001 o Separate into two nibbles (4 bits) o Convert nibbles to denary o Change denary numbers to hex if needed (e.g. 10 = A) 8 4 2 1 8 4 2 1 0 1 1 0 0 0 0 1 =6 =1 ℎ𝑒𝑥 𝑣𝑎𝑙𝑢𝑒 𝟔𝟏 Converting Hexadecimal to Binary To convert hex value 6C o Change hex value to denary numbers (e.g. 12 = C) o Separate hex value and convert to 4 bit binary value o Put the two nibbles together to form an 8 bit binary ℎ𝑒𝑥 𝑣𝑎𝑙𝑢𝑒 6 𝑡𝑜 𝑏𝑖𝑛𝑎𝑟𝑦 8 0 4 1 2 1 ℎ𝑒𝑥 𝑣𝑎𝑙𝑢𝑒 𝐶 (12) 𝑡𝑜 𝑏𝑖𝑛𝑎𝑟𝑦 1 8 0 1 𝟎𝟏𝟏𝟎𝟏𝟏𝟎𝟎 4 1 2 0 Converting Denary to Hexadecimal To convert denary number 98 1.3 Hexadecimal o Convert to binary Closely related to the binary system o Split the binary (8bits) into nibbles (4bits) Hexadecimal is a base 16 system o Find the values separately Numbers 0 to 9 and letters A to Fare used to represent 128 64 32 16 8 4 2 each hexadecimal digit 0 1 1 0 0 0 1 A =10, B = 11, C = 12, D = 13, E = 14, F = 15 8 4 2 1 8 4 2 =𝟔 =𝟐 PAGE 2 OF 12 1 0 1 0 1 CIE IGCSE COMPUTER SCIENCE//0478 Converting Hexadecimal to Denary To convert hex value 2B o Split the hex value into two o Convert each number to binary o Put the two binary numbers together o Convert to denary ℎ𝑒𝑥 𝑣𝑎𝑙𝑢𝑒 𝐵 (11) 𝑡𝑜 𝑏𝑖𝑛𝑎𝑟𝑦 ℎ𝑒𝑥 𝑣𝑎𝑙𝑢𝑒 2 𝑡𝑜 𝑏𝑖𝑛𝑎𝑟𝑦 8 0 128 0 4 0 64 0 2 1 32 1 Automatic Repeat Request (ARQ) ARQ is another method to check if data has been transmitted correctly It uses and acknowledgement (message sent by the receiver indicating that data has been received correctly) 1 0 16 0 8 1 8 1 4 0 4 0 2 1 2 1 1 1 1 1 Checksum Checksum is another way to see if data has been transmitted correctly Data is sent in blocks and an additional value sent at the end of the block = 𝟒𝟑 Echo check When data is sent to another device, this data is sent back again to the sender The sender compares the two sets to check if any errors occurred Not reliable 1.4 Use of the Hexadecimal System Examples: o defining colours in Hypertext Markup Language (HTML) o Media Access Control (MAC) addresses o Assembly languages and machine code o Debugging 1.6 File types Memory Dumps Hexadecimal is used when developing new software or when trying to trace errors Memory dump is when the memory contents are output to a printer, monitor. Assembly code and machine code (low level languages) Computer memory is machine code/ assembly code Using hexadecimal makes it easier, faster, less error prone to write code compared to binary. Using machine code (binary) takes a long time to key in values and prone to errors 1.5 Error Checking Parity Checking Parity checking is used to check weather data has been changed or corrupted following transmission from one device to another A byte of data is allocated a parity bit o Systems that use even parity have an even number of 1-bits o Systems that use odd parity have an even number of 1-bits Musical Instrument Digital Format (MIDI) Storage of music files Communications protocol that allows electronic musical instruments to interact with each other Stored as a series of demands but no actual music notes Uses 8-bit serial transmission (asynchronous) Each MIDI command has a sequence of bytes: o First byte is the status byte – informs the MIDI device what function to preform o Encoded in the status byte is the MIDI channel (operates on 16 different channels) Examples of MIDI commands: o Note on/off: indicates that a key has been pressed o Key pressure: indicates how hard it has been pressed (loudness of music) Needs a lot of memory storage MP3 Uses technology known as Audio Compression to convert music and other sounds into an MP3 file format This compression reduces the normal file size by 90% o Done using file compression algorithms which use Perceptual Music Shaping o Removes sounds that human ear cannot hear properly o Certain sounds are removed without affecting the quality too much PAGE 3 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 CD files are converted using File Compression Software Use lossy format as the original file is lost following the compression algorithm MP4 This format allows the storage of multimedia files rather than just sound Music, videos, photos and animations can be stored Videos, could be streamed without losing any real discernible quality Joint Photographic Experts Group (JPEG) JPEG is a file formats used to reduce photographic file sizes Reducing picture resolution is changing the number of pixels per centimetre When photographic file undergoes compression, file size is reduced JPEG will reduce the raw bitmap image by a factor between 5 and 15 2.2 Serial & Parallel Transmission Serial data transmission is when data is sent one bit at a time over a single wire o Works well over long distances o Data transmitted at a slower rate (USB) Parallel data transmission is when data several bits (1 byte) are sent down several wires at the same time o Works well over short distance o Faster method (internal components use parallel for high speed) 2.3 Simplex, Half-duplex and Full-duplex Simplex data transmission is in one direction only (e.g. computer to printer) Half-duplex data transmission is in both directions but not at the same time (e.g. phone conversation where only one person speaks) Full-duplex data transmission is in both directions simultaneously (e.g. broadband connection on phone line) 2.4 Universal Serial Bus (USB) 1.7 Lossless and Lossy File Compression Lossless File Compression All the data bits from the original file are reconstructed when the file again is uncompressed Important for files where loss of data would be disastrous (spreadsheet) Lossy File Compression The file compression algorithm eliminates unnecessary bits of data like MP3 and JPEG formats Impossible to get original file back once compressed 2. COMMUNICATION & INTERNET TECHNOLOGIES USB is an asynchronous serial data transmission method USB consists of: o Four-wire shielded cable o Two wires used for power and earth o Two wires used in data transmission ADVANTAGES Automatically detected Only fit one way, prevents incorrect connections Different data transmission rates DISADVANTAGES Maximum cable length is about 5 metres Transmission rate is less than 500 mb/sec 2.1 Transmission of Data Asynchronous data transmission refers to data being transmitted in an agreed bit pattern o Data bits are grouped together & sent with control bits o This means the receiver of the data knows when the data starts and ends, prevents data getting mixed up Synchronous data transmission is a continuous stream of data (not in discrete groups like asynchronous) o Ensures that the sender and receiver are synchronised with each other o Faster method 2.5 Security Aspects Hacking The act of gaining illegal access to a computer system Effect: o Leads to identity theft, gaining personal information o Data can be deleted, changed or corrupted To remove risk: o Firewalls o Strong passwords/ user IDs o Use of anti-hacking software PAGE 4 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 Difference between hacking and cracking o Hacking breaks into computer system to steal data o Cracking is where someone edits a program code, malicious Viruses: Program that can replicate itself with the intention of deleting or corrupting files, cause computer malfunction Effect: o Can cause computer to crash o Can delete or corrupt files/data To remove risk: o Install anti-virus software o Don’t use software from unknown sources o Be careful when opening emails from unknown Wardriving: The act of locating and using wireless internet connections illegally Effects: o Possible to steal internet time o Possible to hack into wireless network and steal user’s password To remove risk: o Use complex passwords o Firewalls Spyware: Software that gathers info by monitoring key presses on the user’s keyboard and info is sent back Effects: o Access to all data entered o Software is able to install other spyware, read cookie data To remove risk: o Use of anti-spyware software o Use a mouse to select characters from passwords rather than typing them 2.6 Internet Principles of Operation Internet Service Protocol: These are companies that provide user with access to the internet Internet Protocol (IP) Address Each device on the internet is given a unique address known as the IP address 32-bit number written in the form: 109.108.158.1 IP address gives the location of a device on the internet whereas the MAC address identifies the device connected to the internet IP address changes, MAC address remains unchanged HTML (HyperText Mark-up Language) Used when writing and developing pages Mark-up language is used in the processing Html use <tags> to bracket piece of codes Different intensity of colours is determined by its hexadecimal value Media Access Control (MAC) MAC address refers to a number which uniquely identifies a device on the internet Refers to the network interface card (NIC) which is part of the device Usually made up of 48 bits shown as six groups of hexadecimal digits NN:NN:NN:DD:DD:DD o (NN:NN:NN) first half is the identity number of the manufacturer of the device o (DD:DD:DD) second half is the serial number of the device Types of MAC Address: o Universally Administrated MAC Address (UAA) o Locally Administrated MAC Address (LAA) o UAA is the most common type set by the manufacturer Reasons to change MAC address using LAA o To ensure they follow the correct formula o To bypass MAC address filter on a router or a firewall o To get past certain types of network restrictions Web addresses Each character on the keyboard has its own ASCII code Can be represented using hexadecimal or decimal values Hexadecimal addresses are used in the address of files or webpages as a security figure Takes longer to type in URL but advantage is that you are unlikely to fall into the trap of copying a fake website Cookies A packet of information sent by a web server to a web browser Generated each time the user visits the website PAGE 5 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 Every time a user visits a website, cookies will have collected some key information about the user They are able to carry out user tracking and maintain user preferences Cookies are pieces of data Information gathered by cookies doesn’t contain personal information 3. HARDWARE & SOFTWARE 3.1 Logic Gates Logic Gates: use one or more inputs and produces a single logical output AND gate: If both inputs high, output is high 𝐴. 𝐵 A B Output 0 0 1 1 OR gate: If either inputs high, output is high 𝐴+𝐵 0 1 0 1 A 0 0 1 1 B 0 1 0 1 0 0 0 1 Output 0 1 1 1 NOT gate: an inverter 𝐴̅ A 1 0 Output 0 1 NAND gate: ̅̅̅̅̅ 𝐴. 𝐵 A 0 0 1 1 B 0 1 0 1 A 0 0 1 1 B 0 1 0 1 NOR gate: ̅̅̅̅̅̅̅̅ 𝐴+𝐵 XOR gate: ̅̅̅̅̅̅̅̅ 𝐴⨁𝐵 A 0 0 1 1 B 0 1 0 1 Output 0 1 1 0 3.2 Computer Architecture & Fetch-Execute Cycle Computer Architecture Address bus – unidirectional Data bus – bi-directional Control bus – unidirectional and bi-directional Processor: The processor contains the Arithmetic and Logic Unit (ALU) Control Unit: The control unit controls the operation of the memory, processor and input/output devices The Fetch-Execute Cycle 1. PC contains address of the next instruction to be fetched 2. This address is copied to the MAR via the address bus 3. The instruction of the address is copied into the MDR temporarily 4. The instruction in the MDR is then placed in the CIR 5. The value in the PC is incremented by 1, pointing the next instruction to be fetched 6. The instruction is finally decoded and then executed 3.3 Input Devices SCANNERS: Two-dimensional Scanners: Used to input hard-copy documents The image is converted into an electronic form which Output 1 can be stored in the computer 1 o Document is placed on a glass panel 1 o A bright light illuminates the document 0 o A scan head moves across the document until the whole page is scanned. And image of the document is produced and sent to a lens using a series of mirrors Output o The lens focuses the document image 1 o The focused image now falls onto a charge couple 0 device (CCD) which consists of a numbers of integrated 0 circuits 0 o Software produces a digital image from the electronic form PAGE 6 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 Optical Character Recognition (OCR) is a software which converts scanned documents into a text file format If the original document was a photo/image, then the scanned image forms an image file such as JPEG Three-dimensional Scanners 3D scanners can scan solid objects and produce a threedimensional image Scanners take images at several points, x, y and z (lasers, magnetic, white light) The scanned images can be used in Computer Aided Design (CAD) or to a 3D printer to produce a working model Application of 2D Scanners at an Airport: Make use of (OCR) to produce digital images which represent the passport pages Text can be stored in ASCII format The 2D photograph in the passport is also scanned and stored as jpeg image The passenger’s face is also photographed using a digital camera and compared using face recognition software Key parts of the face are compared (distance between eyes, width of nose) Barcode readers/scanners A barcode is a series of dark and light parallel lines of varying thicknesses The numbers 0 -9 are each represented by a unique series of lines The left and right hand sides of the barcode are separate using guard bars Allows barcode to be scanned in any direction o Barcode is read by a red laser or red LED o Light is reflected back off the barcode; dark areas reflect little light which allows the bars to be read o Reflected light is read by sensors (photoelectric cells) o Pattern is generated which is converted to digital Quick Response (QR) Codes Another type of barcode is the QR codes Made up of a matrix of filled in dark squares on a light background Can hold more storage (7000 digits) Advantages of QR codes: o No need for the user to write down website address o QR codes can store website addresses Digital Cameras Controlled by microprocessor which automatically adjusts the shutter speed, focus the image, etc. Photo is captured when light passes through the lens onto a light sensitive cell Cell is made up of pixels Number of pixels determines size of the file Keyboards Connected to computer with a USB connection or by wireless connection Each character has an ASCII value and is converted into a digital signal Slow method Prone to errors Pointing devices Mouse/trackball o Traditional; mechanical ball, connected by USB port Modern type; red LEDs to detect movement Microphones Used to input sound to a computer When a microphone picks up sound, a diaphragm vibrates producing an electric signal The signal goes to a sound card and is converted into digital values and stored in computer Voice recognition, voice is detected and converted into digital Touchscreens Capacitive (medium cost tech) o Made up of many layers of glass o Creating electric fields between glass plates in layers o When top layer of glass is touched, electric current changes o Co-ordinates where the screen was touched is determined by an on-board microprocessor Infra-red heat (expensive) o Use glass as the screen material o Needs warm object to carry an input operation Infra-red optical (expensive) o Uses glass as screen material o Uses an array of sensors (grid form) o Point of contact is based on which grid co-ordinate is touched PAGE 7 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 Resistive (inexpensive) o Upper layer of polyester, bottom layer of glass o When the top polyester is touched, the top layer and bottom layer complete a circuit o Signals are then sent out which are interpreted by a microprocessor, determine where screen was touched Sensors Devices which read or measure physical properties Data needs to be converted to digital Analogue to Digital Converter (ADC) converts physical values into digital Control of Street Lighting Light sensor sends data to the ADC Digitises data and sent to the microprocessor Microprocessor samples data every minute If data from sensor < value stored in memory: o Signal sent from microprocessor to street lamp o Lamp switched on 3D Printers Used for models of cars Produce solid objects that work Built up layer by layer, using powdered resin, ceramic powder A design is made using Computer-aided Design (CAD) 3.4 Output Devices PRINTERS: Inkjet Printers Used to print one-off pictures and documents 1. Data from document sent to printer driver 2. Printer driver ensures data is in correct format 3. Check made by printer driver that chosen printer is available 4. Data is sent to printer, stored in a temporary memory (printer buffer) 5. Sheet of paper is fed; sensor detects if paper is available in paper tray 6. Print head moves across paper printing text/image, four ink colours sprayed in exact amount 7. Paper is advanced so next line is printed 8. Repeated until buffer is empty 9. Once it is done, printer send an interrupt to the processor (request for more data to be sent) Laser Printers Used to print flyers, high quality Use dry powder ink (toner) and static electricity to produce text and images Prints the whole page in one go 1. (steps 1-4 same as inkjet) 2. Printing drum is given a positive charge; as the drum rotates, a laser beam is scanned across it removing the positive charge leaves negatively charged areas which match the text/image 3. Drum is then coated with positively charged toner, it only sticks to negatively charged parts of the drum 4. A negatively charged sheet is rolled over the drum 5. Toner on the drum now sticks to the paper to produce copy of page 6. Paper finally goes through a fuser (set of heated rollers); heat melts the ink so it is permanent 7. Discharge lamp removes all electric charge from the drum, ready to print next page 2D and 3D Cutters 3D cutters can recognise objects in x, y, z direction 3D laser cutters can cut; glass, crystal, metal, wood Actuators Used in many control applications involving sensors and devices (ADC and DAC) Loudspeakers/Headphones Sound is produced by passing the digital data through a DAC then through amplifier and then emerges from loudspeaker Produced by voltage differences vibrating a cone in the speaker at different frequencies LCD and LED Monitors Front layer of monitor is made up of Liquid Crystal Display (LCD), these tiny diodes are grouped together in threes as pixels (LCD doesn’t emit any light) LCD monitors are back lit using Light Emitting Diode (LED) because: o LEDs reach their maximum brightness immediately o LEDs sharpens image (higher resolution), CCFL has yellow tint o LEDs improve colour image PAGE 8 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 o Monitors using LED are much thinner than CCFL o LEDs consume very little power Before LEDs, LCD monitors were backlit using CCFL CCFL uses two fluorescent tubes behind the LCD screen which supplies the light source LIGHT PROJECTORS: Two common types of light projectors: o Digital Light Projector (DLP) o LCD Projector Projectors are used to project computer output onto larger screens/interactive whiteboards Digital Light Projectors (DLP) Uses millions of micro mirrors the number of micro mirrors and the way they are arranged on the DLP chip determines the resolution of the image When the micro mirrors tilt towards the light source they are on When the micro mirrors tilt away from the light source they are off This creates a light or dark pixel on the projection screen A bright white light source passes through a colour filter on its way to the DLP chip White light splits into primary colours LCD Projectors Older technology than DLP A powerful beam of white light is generated from a bulb This beam of light is then sent to a group of chromaticcoated mirrors; these reflect the light back at different wavelengths When the white light hits the mirrors, the reflected light has wavelengths corresponding to red, green and blue These three different light pass through three LCD screens; these screens show the image to be projected as millions of pixels in grayscale When the coloured light passes through the LCD screens, a red, green and blue version of the grey image emerges Finally, the image passes through the projector lens onto the screen 3.5 Memory, Storage Devices & Media PRIMARY MEMORY: Random Access Memory (RAM) Features of RAM o Volatile/temporary memory (contents lost if RAM is turned off) o Used to store; data, files o It can be written to or read from and the contents from the memory can be changed Larger the size of the RAM, faster the computer will operate RAM never runs out of memory, continues to run slow As RAM becomes full, the processor has to continually access the hard drive to overwrite old data on RAM with new data Read Only Memory (ROM) Features of ROM o Non-volatile/permanent memories (contents remain even when ROM is turned off) o Used to store start up instruction (basic input/output systems) o Data/contents of a ROM chip can only be read, cannot be changed SECONDARY STORAGE: Hard Disk Drives (HDD) Data is stored in a digital format on the magnetic surface of the disks (platter) Number of read/write heads can access all of the surfaces of the disk Each platter will have two surfaces which can be used to store the data Data is stored on the surfaces in sectors and tracks HDD have very slow data access compared to RAM Solid-State Storage (SDD) No moving parts and all data is received at the same time (not like HDD) Store data by controlling the movement of electrons within NAND chips, as 1s and 0s Non-volatile rewritable memory Benefits of using SDD rather than HDD: o More reliable (no moving parts) o Considerably lighter (suitable for laptops) o Lower power consumption PAGE 9 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 o Run much cooler than HDDs o Very thin o Data access if faster than HDD Drawback – questionable longevity (20GB per day) OFF-LINE STORAGE CD/DVD Disks Laser (red) light is used to read and write data in the surface of the disk Use a thin layer of metal alloy to store data Both systems use a single, spiral track which runs from the centre of the disk to the edge DVD uses Dual-Layering which increases the storage capacity (two individual recoding layers) Blu-ray Disks Uses blue laser to carry out read and write operations Wavelength of laser light is less than CD and DVD (stores up to five times more data than DVD) Automatically come with secure encryption (prevent piracy and copyright infringement) Used as back-up systems USB Flash Memories Very small, lightweight suitable from transferring files Small back-up devices for photo, music Solid state so need to be treated with care 3.6 High- & Low-Level Languages High-Level Languages Easier to read and understand as the language is closer to human language Easier to write in shorter time Easier to debug at the development stage Easier to maintain once in use Low-Level Languages Refer to machine code Binary instructions that computer understands TRANSLATORS: A program must be translated into binary before a computer can use it Types of translators; Compiler, Interpreter and Assembler Compiler Translates a program written in high-level language into machine code Used without compiler Executable file of machine code produced One high-level language translated into several machine code instructions Used for general use Interpreter Executes a high-language program a statement at a time No executable file of machine code produced One high-level language program statement may require several machine code instructions to be executed Cannot be used without interpreter Used when program is being developed Assembler Translates a low-level language program into machine code Executable file of machine code produced One low-level language translated into one machine code instructions Can be used without assembler Used for general use Syntax Errors: When program is being compiled, if any syntax errors are found no translated program is produced Instead, a list of all errors in program is produced Programmer corrects program and recompiles When a program is being interpreted, the interpreter preforms the action until syntax error is found The programmer is the alerted to the place in the program where error was found The error is corrected and interpretation continues 4. SECURITY Need to keep data safe from accidental damage, including corruption and human errors Need to keep data safe from malicious actions, including unauthorised viewing, deleting, copying and corruption PAGE 10 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 4.1 Firewalls & Proxy Servers 4.3 Encryption A firewall sits between the user’s computer and an external network (internet) and filter information in and out of the computer Tasks carried out by firewall: o Examining ‘traffic’ o Checking weather incoming or outgoing data meets criteria o If data fails the criteria, the firewall blocks ‘traffic’ o Firewall can keep a list of all undesirable IP addresses o Helping to prevent viruses or hackers entering the user’s computer Proxy servers act as an intermediary between the user and a web server Functions of proxy servers: o Allowing the internet ‘traffic’ to be filtered o By using cache, they can speed up access to information from a website o Keeping the user’s IP address secret Acting as a firewall Used to protect data in case it has been hacked Doesn’t prevent hacking, makes data meaningless 4.2 Security Protocols Secure Sockets Layer (SSL) Type of protocol that allows data to be sent and received securely over the internet When a user logs onto a website, SSL encrypts the data https or padlock in the status bar When user wants to access a secure website: o User’s web browser sends a message so it can connect with required website which is secured by SSL o Web browser requests that the web server identifies itself o Web server responds by sending a copy of its SSL certificate o Web browser checks if certificate is authentic o Sends signal back to web browser o Starts to transmit data once connection is established o If not secure, browser will display an open padlock Symmetric Encryption A secret key which can be a combination of characters If this key is applied to a message, its contents is changed One key is needed to encrypt a message and another key is needed to decrypt a message Increasing the length of the key increases the strength of the encryption Plain text and Cypher Text Plain text is the normal representation of data before it goes through an encryption algorithm Cypher text is the output from an encryption algorithm Authentication Authentication is used to verify that data come from a trusted source Works with encryption to strengthen internet security Passwords: usually a user id/name and password are used to log on to systems Digital Signatures: public key encryption; ensure an electronic document is authentic Biometrics: relies on the unique characteristics of human beings (fingerprint scans, retina scans) 4.4 Phishing, Pharming & DoS Phishing: Creator sends out a legitimate-looking email; as soon as recipient clicks on link, user is sent to a fake website Effect: o Creator of email can gain personal data; bank account o Can lead to fraud To remove risk: o Many ISPs filter out phishing emails o User should be cautious Pharming Malicious code installed on a user’s hard drive or on the web server, code will redirect the user to a fake website Effect: o Creator of malicious code can gain personal data; bank account o Can lead to fraud or identity theft Transport Layer Security (TLS) Form of protocol that ensures the security and privacy of data between devices and users when communicating over the internet Designed to provide encryption, authentication and data integrity in a more effective way than SSL Possible to extend TLS by adding new authentication methods PAGE 11 OF 12 CIE IGCSE COMPUTER SCIENCE//0478 To remove risk: o Some anti-spyware can identify and remove pharming code from hard drive o User should be alert Denial of Service Attacks (DoS) An attempt at preventing users from accessing part of a network Usually temporary but may be damaging Attacker me be able to prevent user from: o Accessing their emails o Accessing websites o Accessing online services Shareware All the features of the full version of software are not made available; full version needs to be purchased first Subject to all copyright laws Permission needs to be obtained before software is copied and given to friends or family 4.5 Applications Ways bank protect their costumers from online fraud o Banks use 10/12-digit code unique to the costumer o May be asked to input three random numbers from a four-digit PIN o Some use a hand-held device into which a customer inserts their card. Device will generate an eight-digit code which the customer types into web page o Some ask to key in parts of their passwords using drop-down boxes (using a mouse) 5. ETHICS A set of principles set out to regulate the use of computers Plagiarism is when a person takes another person’s idea/work and claims it as their own 5.1 Types of Softwares Free Software Software source code can be freely accessed and modified as required Run, copy, change or adapt free software (e.g. Scribus, Abiword) Possible to distribute modified versions of software to friends and family Freeware A software a user can download from the internet free of charge Once it has been downloaded, there are no fees associated (e.g. Adobe, Skype) Subject to all copyright laws User is not allowed to study, modify code PAGE 12 OF 12 TABLE OF CONTENTS 2 CHAPTER 1 3 CHAPTER 2 Algorithm Design & Problem Solving Programming 4 Databases CHAPTER 3 CIE IGCSE COMPUTER SCIENCE//0478 • Functions are sub-routines that return a single value 1. ALGORITHM DESIGN & PROBLEM-SOLVING • Trace Tables: A technique used to test algorithms, in order to make sure that no logical errors occur whilst the algorithm is being processed. 1.1 Problem-solving & Design • Every computer system is made up of sub-systems, which are in turn made up of further sub-systems. • Top-down Design – The breaking down of a computer system into sub-systems, then breaking each sub-system into smaller sub-systems, until each one only performs a single action. A structure diagram diagrammatically represents top-down design. Example below. • Test data – All the items of data required to work through a solution. It is inputted into the program and compared with the expected results. Examples are for a school grade o Normal – 28; 64; 98 - Accept o Erroneous/Abnormal – eleven; -12; 158 - Reject o Extreme – 0; 100 – Accept o Boundary – 0; -1 – Accept; Reject • Validation – Automated checking by a program that data is reasonable before it is accepted as an input. o Range – Accepts numbers within a specified range o Length – Accepts data with an exact number of characters OR has a reasonable amount of characters o Type – Accepts data with a certain data type o Character – Accepts data without invalid characters o Format – Accepts data that conforms to a specified patter/format o Presence – Requires data to be inputted • Verification – Checking that data has been accurately copied onto the computer or transferred from one part of a computer system to another. o Double entry – Data is entered twice and compared o Visual/Screen – Manual check compared by the user 1.2 Pseudocode & Flowcharts • Pseudocode - Verbal representation of an algorithm (a process or set of steps) and flowcharts are a diagrammatic representation. • Sub-rountine - Block of code that can be called and accessed by a main program. PAGE 2 OF 5 CIE IGCSE COMPUTER SCIENCE//0478 • Flowcharts o CASE…OF…OTHERWISE…ENDCASE – Multiple conditions and corresponding consequences CASE OF [VARIABLE] OPTION: [CONSEQUENCE] OTHERWISE: [CONSEQUENCE] ENDCASE CASE OF GRADE GRADE>80: OUTPUT “A” GRADE>70: OUTPUT “B” GRADE>60: OUTPUT “C” OTHERWISE: OUTPUT “FAIL” ENDCASE • Input & Output (READ & PRINT) – Used to receive and display data to the user respectively FOR [VARIABLE] [VALUE] TO [VALUE] [CODE] NEXT OUTPUT “ENTER NAME” INPUT NAME OUTPUT “HELLO”, NAME (ALTERNATIVELY) PRINT “ENTER NAME” READ NAME PRINT “HELLO”, NAME o REPEAT… UNTIL – Will run at least once till condition is satisfied; Verification is done after running code • Assignment - Each variable is assigned using a left arrow. [VARIABLE] [VALUE] GRADE 98 • Conditional Statements: o IF…THEN…ELSE…ENDIF – 1 condition IF [CONDITION] THEN [CONSEQUENCE] ELSE [CONSEQUENCE] ENDIF IF GRADE > 100 THEN OUTPUT “INVALID” ELSE OUTPUT “VALID” ENDIF • Loop Structures: o FOR…TO…NEXT- Will run for a determined/known amount of times REPEAT [CODE] UNTIL [CONDITION] o WHILE…DO…ENDWHILE – May not ever run; Verification is done before running code WHILE [CONDITION] DO [CODE] ENDWHILE 2. PROGRAMMING 2.1 Programming Concepts • Declaration & Usage of Variables & Constants o Variable – Store of data which changes during execution of the program (due to user input) o Constant – Store of data that remains the same during the execution of the program PAGE 3 OF 5 CIE IGCSE COMPUTER SCIENCE//0478 • Basic Data Types o Integer – Whole Number e.g. 2; 8; 100 o Real – Decimal Number e.g. 7.00; 5.64 o Char – Single Character e.g. a; Y o String – Multiple Characters (Text) e.g. ZNotes; COOL o Boolean – Only 2 Values e.g. True/False; Yes/No; 0/1 3.2 Primary Key • It is a field that uniquely identifies each record. E.g. Student code will be the primary key in a school database. DECLARE [VAR/CONST] AS [DATA TYPE] [VALUE] • IMPORTANT CONCEPTS o Sequence – Statements are executed in order. E.g. Variables must first be declared, and then used. o Selection – Allows data items to be picked according to given criteria. E.g. Finding the highest/smallest value o Repetition – Causes statements to be repeated (loops) o Totaling – Used with repetition, to keep the total updated. E.g. BillTotal BillTotal + ProductCost o Counting – Used with repetition to increment the counter by 1, each time the loop is repeated. E.g. NumItems NumItems + 1 3.3 Query-By-Example (QBE) 2.2 Data Structures; Arrays • Declaration DECLARE [NAME][1:n] AS [DATA TYPE] DECLARE GRADE [1:18] AS REAL • Use of FOR Loop to Read & Write DECLARE GRADE [1:18] AS INTEGER FOR I 1 To 18 OUTPUT “GRADE OF STUDENT”, I INPUT/OUTPUT GRADE [I] NEXT • Field: Field Name • Table: Table Name • Sort: Ascending (A-Z) or Descending (Z-A) • Show: Checked (Present) or Empty (Absent) • Criteria: TEXT Criteria Name Written As Function 3. DATABASES Contains 3.1 Data types Does Not Contain Like (“*x*”) Not like (“*x*”) Begins With Like (“x*”) Values beginning with x Ends With Like (“*x”) Values ending with x Comes After >= “x” Values that come before x in alphabetical order Comes Before <= “x” Values that come after x in alphabetical order • The data type names are different in Access: o Real – Number o String – Text o Boolean – Yes/No PAGE 4 OF 5 Values that contain x Values that do not contain x CIE IGCSE COMPUTER SCIENCE//0478 Criteria Name Between Less Than Less Than or Equal To Greater Than Greater Than or Equal To Criteria Name Between NUMBERS Written As Function Between Values in the range “x” and “y” between x and y <x Values smaller than x Values smaller than or <=x equal to x >x Values larger than x Values larger than or equal >=x to x DATES Written As Between “#mm/dd/yyyy#” and “#mm/dd/yyyy#” Before < “#mm/dd/yyyy#” After > “#mm/dd/yyyy#” Today =Date() x Days Before Today <=Date()-x Function Dates between the specified dates Dates before a certain date Dates after a certain date Records containing today’s date Records containing dates x or more days in the past PAGE 5 OF 5 CIE IGCSE BUSINESS STUDIES//0450 TABLE OF CONTENTS 2 CHAPTER 1 7 CHAPTER 2 13 CHAPTER 3 20 CHAPTER 4 24 CHAPTER 5 27 CHAPTER 6 Understanding business activity People in business Marketing Operations management Financial information and decisions External influences on business activity Page 1 of 30 CIE IGCSE BUSINESS STUDIES//0450 1. UNDERSTANDING BUSINESS ACTIVITY 1.1 Nature of Business Activity • Needs: goods or services that we need in order to live • Wants: goods or services which people would like to have. But are not essential for living. • People’s wants are unlimited (you will always want something) • There are unlimited wants but there are limited resources to produce them • Resources include: Land, Labour, Capital & Enterprise • This creates scarcity. • Scarcity: there are not enough products to fulfil the wants of the population • Since there are limited resources, we have to make choices on what we want. This means that we will be giving something up, this is the opportunity cost • Opportunity cost: the thing we give up by choosing another item. The next best alternative. 1.2 Specialisation • Specialisation: when people and businesses focus on what they are best at. • Using specialised machinery, work is more efficient • Being efficient keeps costs low, good for competition • A specialised worker has higher living standards • Division of labour is when production is split in different tasks and each worker performs one of these tasks Advantages Disadvantages Workers specialized in Workers become bored of certain task, increases doing the same job. efficiency Efficiency might fall Less time is wasted from If a worker is absent, no one workbench to other worker can do the another, more efficiency job. Efficiency might fall 1.3 Purpose of Business Activity: • Businesses combine scarce factors of production to produce goods or services to satisfy people’s wants • Factors of production: o Land – all resources provided by nature (oil, metal) o Labour – the no. of people to make the products o Capital – the finance and equipment (machinery) needed to make products • Enterprise – the skill of the person who brings other factors of production together to make goods • A business also employs people as worker and pays them wages to allow them to consume products as well 1.4 Added Value • Added value is how much more a business sells a product for than the total cost of materials Added Value = selling price – total cost • It is NOT the profit because added value does not include the price to pay for labour, transport etc. • To increase added value, a business can either: o Increase the selling price of product, while keeping the total cost of material the same o Decrease the total cost of materials, while keeping the selling price of the product the same. 1.5 Classification of Businesses • Businesses can be put into three sectors: • In developing countries, the primary sector employs most of the work-force. This is because most people live in rural areas and there is low demand for services • In more developed countries, the secondary and tertiary sector employ more workers • In economically developed countries, the tertiary (service) sector employs most people as they import manufactured goods from other countries (tourism) 1.6 Mixed Economy • Has both a private sector and a public sector. Stage What it does Example Extracts and uses the Farming, Primary natural resources to mining, forestry produce raw materials Takes the raw materials Manufacturing Secondary and converts them into (car, food, etc.) manufactured goods Providing services to Retail shops, Tertiary consumers and other hotels, hospitals sectors • Private Sector: Businesses NOT owned by government, will make own decisions on what and how to produce. • Public Sector: Owned by the government. Government will make decisions on what and how to produce (i.e. healthcare, education, defence, public transport) Page 2 of 30 CIE IGCSE BUSINESS STUDIES//0450 1.7 Enterprise, Business Growth & Size • An entrepreneur is a person who organises, operates and takes risk to make the business better • Characteristics of entrepreneurs: o Hard Working o Optimistic o Risk Takers o Self-Confident o Creative o Innovative o Effective Communicators o Independent Advantages Independent, able to choose how to use time and money Able to put own ideas into practice May become successful and very profitable if business grows Able to make use of personal interests and skills Disadvantages entrepreneurs will have to put their own money into the business. many entrepreneur’s businesses fail (risky) Lack of knowledge and experience in starting and operating a business Lost income from not being employee for another business (Opportunity cost) 1.8 Business Plans • A business plan contains business objectives, important details about the operations, finance, and the owners • Business plans assist entrepreneurs because: o It helps gain finance. banks will ask for a business plan before agreeing to a loan or overdraft for the business o It forces the entrepreneur to plan ahead carefully, which reduces risk of the business failing. • The main parts of a business plan include: name, type of organization, business aim and forecast profit 1.9 Government Support for Start-Ups • Governments encourage entrepreneurs to set up a business because start-ups: o Reduce unemployment, new businesses create jobs o Increase competition, gives consumers more choice o Increase output, economy benefits from increased output of goods and services o Can grow further and become large and important businesses which pay government more taxes • Governments may give support to entrepreneurs by: o Business ideas & help, they set up support sessions held by experienced business people o Finance, they may lend loans at low interest rates or grants if business starts up in places with high unemployment rates. o Governments provide grants for training employees to make them more efficient and productive o Governments allow entrepreneurs to use research facilities in universities 1.10 Business Size • There are several different measurements of business size and they all have limitations: Measurements Limitations Some businesses employ The number of people few people but produce employed in the business high output values The value of output of the high level of output does business not mean business is big different businesses sell The value of sales different products (expensive and cheap) The total value of capital some companies may use (money) invested into the cheap labor giving low business (capital output with low-cost employed) equipment 1.11 Business Growth • Some businesses want to grow because: o Higher profits o More status for owners and managers o can benefit from Economies of Scale (lower costs) o Larger share of its market, ‘big names' 1.12 Economies of Scale • Economies of scale are the factors that lead to a reduction in average costs as a business grows. • Purchasing - when businesses buy in ‘bulk’ so they get cheaper prices • Marketing - targeting a larger audience, business advertises its own product rather than having another company doing it • Financial - bigger businesses get better interest rates from banks as they are less risk Page 3 of 30 CIE IGCSE BUSINESS STUDIES//0450 • Managerial: Big businesses can afford specialist managers • Technical - Big businesses can afford specialist machines to do more efficient work with less staff • Businesses can either grow by: o Internal Growth o External Growth • Internal Growth is when the business expands its existing operations • External Growth is when the business takes over or merges with another business. • There are three types of External Growth: • Horizontal Integration – firm taking over/merging with another firm in the same industry o i.e. a paper company taking over another paper company • Vertical Integration – firm taking over/merging with another firm in same industry but different stage of production (there is forwards and backwards) o i.e. paper manufacturing company taking over paper selling company • Conglomerate Merger - firm merging/taking over another firm in a different industry. (also known as ‘diversification’) o i.e. paper company taking over a food company 1.13 Problems with business growth (Diseconomies of Scale) • Diseconomies of scale are factors that lead to increase of average costs as a business grows above a point. • Poor communication - Bigger businesses are hard to send and receive messages. • Low Morale - Big businesses employ many people, some workers feel unimportant as they cannot grow in business, efficiency lowers. • Slow decision making - Bigger businesses take longer to make decisions to satisfy all of the audience • Some businesses stay small because: o Market size is small o Owner’s objectives o Type of industry 1.14 Why Businesses Fail • Poor management – from lack of experience, poor choice of managers (family business), bad decisions • Failure to plan for change – businesses need to adapt everchanging business environment. Must take risks. • Poor money management – lack of money to pay workers, suppliers, landlords, etc. • Over-expansion – (diseconomies of scale), management problems and finance • Competition with other businesses – new businesses are at more risk of failing than existing businesses. • This is because start-ups have lack of money, resources, poor planning & don’t have much research 1.15 Sole Trader • A business owned by just one person. It’s the smallest type of business. Can employ other people however. o Useful for people who are setting up new business o Do not need much capital to get business running o Will be dealing mainly with the public Advantages Disadvantages Easy to set up, do not Capital is usually provided require a lot of money to by owner, hard to get set up capital to expand firm They are their own boss, They have unlimited has the freedom to choose liability (responsible for their own holidays, work any debts of the business, hours, prices, who to bank can take away employ possessions to pay back) Close relationship with Business is likely to remain customers small Does not have to share No one to discuss business profits matters with Does not have to give They are unincorporated information about the (business has same business identity as the owner). So, business ends when owner dies Page 4 of 30 CIE IGCSE BUSINESS STUDIES//0450 1.16 Partnerships • A business in which 2 to 20 people agree to own it. Usually small businesses but bigger than sole traders. o Useful for people who want to form a business but don’t want the legal complications o Industries such as medicine or law where you are not allowed to form a company o Partners that know each other very well • Requires a Partnership Agreement Advantages Disadvantages Easy to set up, do not Capital is usually provided require a lot of money by partners More capital invested Partners have unlimited (more expansion) liability Partners are motivated Partners can disagree on because any losses are decisions. If one of the shared by the partners partners is inefficient, they all lose money Responsibilities are shared They are unincorporated. (focused on different parts If one of the partner dies, of business) the partnership ends • Contents of Partnership Agreement: o Amount of capital invested by all partners o Tasks to be done by each partner o The way profits are shared out o How long partnership will last o Arrangements for absence, retirement and how partners could be let known o Rules for shareholder meetings o List of directors and their jobs o Voting rights of shareholders o Details of how accounts are recorded • Memorandum of Association – must contain important information about the company: o Company name, address o What the business does o Number of shares to be sold Advantages Disadvantages Shares can be sold to lots Difficult to set up (legal of people. More capital to formalities). expand Owners are able to keep Shares are difficult control of company as transfer. Requires other long as they don’t sell too shareholders to agree many shares All shareholders have Accounts are less secret limited liability (bank can than other forms of only take amount of business money invested) Company continues after Company cannot offer it a shareholder dies shares to the public • Private Limited Companies are useful for family businesses or businesses/partnerships where owners want to expand more (as you can sell shares) 1.18 Public Limited Company (PLC) 1.17 Private Limited Company (LTD) • An LTD is different from the other because it can sell shares and it is an incorporated business. • Company must be owned by at least 2 shareholders o A shareholder buys shares of an LTD company which represent part ownership of the company o Dividend is the amount of profit each shareholder gets • Shares are sold privately to friends and family • Has separate identity from owners, incorporated, so company accounts are separate from the owners’ • Must have: Articles of Association and Memorandum of Association • Article of Association – must contain the RULES in which the company will be managed. Contains: • A PLC is similar to LTD only the shares can be sold to the public. It is the biggest type of business. • Shareholders of PLCs may attend an Annual General Meeting where they may vote for the board directors Advantages (in addition Disadvantages to those in LTDs) Opportunity to raise high Difficult to set up (legal capital sums formalities) & accounts are even more public No restriction of buying, Danger of business being selling or transferring taken over due to public shares shares Selling shares to public is expensive • DON’T GET CONFUSED, Public Limited Companies are NOT in the PUBLIC sector, they are in PRIVATE sector Page 5 of 30 CIE IGCSE BUSINESS STUDIES//0450 1.19 Joint Venture • A joint venture is when two or more businesses start a project together sharing capital risks, and profits Advantages Disadvantages Costs are shared, good for Profits have to be shared if expensive projects project is successful Shared knowledge of two Might have disagreements businesses over important decisions Risks are shared Different methods of running business • Usually these businesses have been nationalized (used to be private sector but government bought it) • Capital comes from taxes, by tax payer 1.23 Business Objectives • A franchise is an agreement of a business based upon an existing brand/business • The franchisor is the main business/brand • The franchisee is the individual to start up franchise • In a franchise, the franchisor allows the franchisee to trade under its name and see its products for a fee • The franchisee pays an original fee to franchisor and a percentage of its profit for the privilege • Franchisor provides support, such as: o Advertising o Employee training o Legal advice o Financial advice • Franchise agreements last 5 – 20 years, if franchisee cancels the agreement early there may be large fines • Business objectives are aims or targets a business works towards • Business objectives give clear target to managers and employees and boosts the workers’ motivation • Private sector business objectives: o Business Survival - Adjust to business environment, change price of products if necessary o Generating profit – pay a return to owners or provide finance to invest further in business o Returns to shareholders - discourage shareholders from selling their shares. Can be increased by increasing profit or increasing the share price o Growth of business – increase salaries, economies of scale. only achieved if customers are satisfied with the product o Market Share – the proportion of the total market sales by one business, gives good publicity, more influence over suppliers and customers o Service to community – provide jobs, support disadvantaged groups in society, protect environment 1.21 Risk, Ownership & Limited Liability 1.24 Stakeholder objectives • Risk - the uncertainty of profits or danger of loss, events that could cause business to fail • Ownership – who owns the business (partnership = partners, LTDs and PLCs = the shareholders) • The people with risk are usually the owners • Liability – how much the shareholders of a company are liable for the debts in the business o Limited Liability – liability of shareholders is limited to the amount of money they invested (PLC & LTD) o Unlimited liability – owners of business are held responsible for all the debts of the business (not just their investment) (Sole trader & partnerships) • A stakeholder is any person with a direct interest in the performance of a business • There are two types of stakeholder groups: o Internal Stakeholders work/own the company o External Stakeholders are outside of the business Internal Stakeholders External Stakeholders Owners Consumers Managers Government Workers Banks • Each stakeholder group has different objectives for the performance of the business • Internal Stakeholder’s objectives are payments or profits, they want business growth so value of investment increases or they get higher status/power • Customers objectives are reliable products, value for money, good quality, good design and good service 1.20 Franchise 1.22 Public Sector • The public sector includes every business owned by the government. • Businesses in the public sector are public services, i.e. education, transport, hospitals, education and police Page 6 of 30 CIE IGCSE BUSINESS STUDIES//0450 • Government objectives include: money from taxes, will employ more people, increase country’s output • Banks objectives are to make profit out of loans • Since different stakeholders have different objectives, it may cause conflict, to try to please all the stakeholders • For example: customers want cheap products but workers want higher salaries. • Therefore, managers have to compromise to decide which objectives are best for the company 2. PEOPLE IN BUSINESS • It is very important for a business to have a wellmotivated workforce The main reasons why people work: o Money: to pay for the basic needs for life and some wants o Security: to know that you are safe (financially) o Affiliation (Social needs): to feel part of a group, meet people, make friends o Self-importance (esteem): to feel that you are important and that the job you do is important o Job Satisfaction: to feel pleasure that you have done a good job • Motivation – the feeling that makes employees want to work hard and effectively in a business 2.1.1 Key Motivational Theories • • • • • 2.1 Motivating Workers • • ‘Maslow’s Hierarchy of Needs’ – a pyramid showing the different types of needs and how some are more important than others Safe/security Needs – protection against danger & poverty. Having fair treatment (fulfilled by having job security) Social Needs – friendship, belonging in a group (fulfilled by having colleagues at work) Esteem Needs – having status and recognition (fulfilled by being recognised for good work) Self-actualisation – achieving your full potential, feeling that you have done a good job (fulfilled by being promoted & being given more responsibility) Maslow’s theory also suggests that each level in the hierarchy (starting from Physiological needs) needs to be achieved before moving on to the next • F.W Taylor’s theory - “All individuals are motivated by personal gain” • This means that if the workers are paid more, they will work more effectively By breaking down worker’s jobs into simple tasks, you could calculate how much output they could do in a day Taylor’s theory focused mainly on factory workers, since it is easy to work out their output done Taylor’s idea was that if the workers produced this target output, they would be paid more money This idea led to big productivity gains in companies that adopted this theory Herzberg’s theory – humans have two sets of needs: o Basic animal needs (called ‘Hygiene’) o To be able to grow physiologically (called ‘Motivator’ needs) • • • • • ‘Motivator’ Factors • • • • Achievement Recognition Personal Growth Advancement/ Promotion • Work itself • Physiological Needs – food, rest, shelter (fulfilled by receiving wages) • ‘Hygiene’ Factors • • • • Status Security Work Conditions Relationship with boss & subordinates • Salary Herzberg’s theory claims that the ‘Hygiene’ factors must be satisfied, if not, it will demotivate workers • Only after they are satisfied, can the ‘Motivator’ factors can act as motivators for employees Page 7 of 30 CIE IGCSE BUSINESS STUDIES//0450 • 2.1.2 Methods of Motivation • • • There are 3 Factors that motivate employees: o Financial Rewards o Non-Financial Rewards o Job Satisfaction Financial Rewards/Motivators include: o Wages (payment for work, usually weekly) o Time Rate (payment per hour, i.e. 10$/hour) o Piece Rate (where workers are paid depending on the quantity of products made). Has also BONUS system for employees who produce more than the set target. o Salaries (payment for work, usually monthly) Financial Rewards/Motivators include: o Company Car o Discounts of products o Health care o Children’s school paid for o House is paid for o Free trips abroad (holidays) • • • The benefits of an organisational chart are that it shows how everybody is linked together in the organisation, they know who to reach and how. Each employee can also see their own position, who’s authority they are under and who they have authority over It gives everyone a sense of belonging, motivates them to move up the chain of command There are two types of organisational structures of a business: o You can have a ‘tall’ structure, with a long chain of command: o 2.2 Organisation and Management • • • • • Organisational structure – the levels of management and division of responsibilities within a company Organisational structures show the chain of command in a company this is usually in the form of an Organisational Chart Organisational Charts show a clear structure of the business and make it easy to see which part of the company does what Example of Organisational Chart: • • • • • • You can have a ‘wide’ structure, with a short chain of command: Chain of command – the structure in a business that allows instructions to be passed down from a person to another, below them in the command. Subordinate – someone who is lower in rank, under authority of a superior (manager) Span of control – how many subordinates work directly under a manager Authority – someone that has recognised power to make decisions and to delegate tasks Delegation – the process of giving authority to a subordinate to perform a task (instructions) The advantages to have a short (and wide) structure is that: o Communication is faster and more accurate o Top managers are more in touch with subordinates because there are less levels o wider span of control means employees feel trusted and take more decisions by themselves Page 8 of 30 CIE IGCSE BUSINESS STUDIES//0450 • • • • In organisational charts, it is usually arranged in department (finance, operations, etc) Sometimes there is conflict between departments (i.e. marketing wants to buy something but finance does not think it is necessary) The supervisors working in these departments are Line managers – they have direct responsibility over people below them in the organisational chart You also have Staff Managers – which are specialists in certain areas to provide support and information to line managers • • • • • • o makes employees feel trusted and important However, some managers do not delegate tasks They might be afraid the subordinates will fail and manager wants to control everything Manager might also feel threatened that subordinate will do a better job than them Delegation means that once the task is completed, the manager will have less direct control This means the trust for the workers is increased by the manager Therefore, there needs to be more trust in workers in order to reduce control over them 2.2.3 Leadership Styles • • 2.2.2 Role of Management • • • • • All organisations have managers. Leaders, director, executive are all different names, but they are all managers The functions of managers include: o Planning – setting aims or targets o Organising – delegating tasks. organising people and resources effectively o Co-ordinating – making sure departments work well with each other and have good communication o Commanding – making sure the workers are keeping to targets and deadlines. By guiding and delegating tasks o Controlling – measuring and evaluating work of employees and verify they are on target Managers often delegate tasks to employees, giving them authority to complete that task. However, if the employee does a bad job, the manager must accept the responsibility for it Delegation is important because: o Managers cannot do every job by themselves o managers can then measure the success of the employees o work becomes more interesting for subordinate, increases their motivation Leadership styles are the different approaches to deal with people when with authority There are THREE TYPES OF leadership styles: o Autocratic Leader: where the manager expects to be in charge of the business and expects to have their orders followed with no questions asked o Democratic Leader: where the manager allows the subordinates to be involved in the decisionmaking process o Laissez-Faire Leader: Where the manager makes broad/general objectives for the employees and leaves them to make their own decisions. 2.2.4 Trade Unions • • • • Trade union – a group of workers that join together to protect their interests A trade union is a pressure group Employees usually have the same interests (i.e. good wages, pleasant work environment, etc) If an employee wants to join a trade union, they must pay a yearly subscription for the benefits Page 9 of 30 CIE IGCSE BUSINESS STUDIES//0450 • Benefits from a trade union usually include: o Improved conditions of employment (such as wages, holidays, hours of work) o Improved work environment (health & safety, heating, noise) o Advice/support if member thinks they have been unfairly fired, mistreated, etc • • • 2.3 Recruitment • • • • • • Recruitment – the process from identifying that a business needs to employ someone, to the point where applications have arrived at the business Recruitment is one of the roles of the Human Resources department Recruiting usually happens when an employee leaves a job, a business is starting up, or it wants to expand Recruitment process (for external recruitment): 1. A job analysis is done to identify the tasks and responsibilities to be carried out by the new employee 2. Once the details of the job are gathered, a job description will be made, outlining these duties. 3. From the job description, a job specification is created, which outlines the requirements, qualifications and expertise for the job 4. Then the job is advertised in the appropriate media (i.e. if it is a finance related job, it might be advertised in finance magazine) 5. Candidates start sending their application forms and the company does a short-list for interviews (because they cannot interview all) 6. The candidate is chosen after the interviews by the company, job is filled There are two types of recruitment: o External Recruitment – job is filled by someone who is not an existing employee o Internal Recruitment – job is filled by an existing employee of the company. Internal recruitment is good because it saves money for business. The person already has knowledge about the business & position and it motivates other workers to get a promotion. however, it doesn’t bring in new ideas & experience. • There are also two types of employment: o Part-time employment o Full-time employment Part time employment is normally between 1 and 35 hours a week Advantages: o Work hours are flexible. Fits with employees that have kids to take care of o Business can extend the opening/closing hours o Employees can just work at busy times o Cheaper for the employer than employing a fulltime worker Disadvantages: o Employees are less likely to be trained because they might see it as temporary and don’t want a promotion o Takes longer to recruit many part-time workers than a couple full-time workers o Might be less committed to the company 2.3.2 Training • Training is important for a business because: o It helps employees become more comfortable with new processes or equipment o Improves the efficiency of the workers o Makes employees more valuable to the company because they become more skilled o Reduces the amount of supervision needed by the workers o Reduces the amount of accidents • There are three types of training: 1. Induction Training – where the employee is given an introduction on the company’s procedures and customs, and is introduced to their co-workers Advantages • Employees settle into their job quickly • Workers make fewer mistakes • May be a legal requirement Page 10 of 30 Disadvantages • Time consuming • Worker is being paid while not doing work • Delays the start of work for the employee CIE IGCSE BUSINESS STUDIES//0450 2. On-the-job Training – where the employee does the job while being supervised by a more experienced worker, giving tips, suggestions and help Advantages • Employee does not need to be sent away So cheaper than off-thejob training • There is still production from worker while training • Employee is trained exactly how the company want Disadvantages • Trainer won’t be as productive because they are teaching employee • Trainer might have bad habits and pass on to employee • Not recognised training qualifications outside the business 3. Off-the-job training – where the employee is trained away from the workplace, normally by specialised trainers. • • • • • • • Advantages Lots of skills are taught trainings are sometimes off-work hours, worker will still work Employees become versatile (can be moved around company and know what to do) Employees are taught by expert trainers. Up-todate knowledge Disadvantages • Expensive to send employees off to expert trainings • Workers are being paid but not doing any work • Professional training gives employees additional qualifications, makes it easier for employee to find another job Sometimes, a company might need to reduce the size of the workforce, possibly because of: o Automation (robots replacing human jobs) o Less demand for products or services o Business might have relocated abroad o Business being taken over/merged and now there are too many workers doing same job Companies need to think ahead on the future and establish how many employees they will need and their skills, this is called workforce planning When a business needs to reduce the number of employees, they can either dismiss the employee or make them redundant • • Dismissal – when the worker is told to leave the job due to poor work or poor behaviour (i.e. if employee is always late for work after being given warnings, when employee is caught stealing, etc) It is more commonly known as being ‘fired’ Redundancy – when a business no longer needs an employee. Even though the employee did nothing wrong. Usually happens during period of falling sales or due to an economic recession (when no one is buying anything) 2.3.4 Legal Controls over employment issues • • • • There are many laws in countries, that ensure that everyone has equal employment opportunities regardless of race, gender, religion, age etc. This means that businesses need to be careful when advertising a job. They cannot advertise for just a single type of person. Companies must treat all applicants for the job equally, if not, they will be fined and prosecuted Employees of a business have legal right that must be protected, which includes: o Unfair discrimination at work/when applying: i.e. when employers discriminate unfairly against employees or applicants due to their race, gender, religion or colour. o Health and safety: there are laws that make sure that employees are protected from dangerous machinery, that they are provided safety equipment & clothing, hygiene conditions, suitable temperatures, provide breaks. o Unfair dismissal: when the worker is dismissed unfairly (i.e. from joining a trade union, being pregnant, or when given no warnings before being dismissed), the worker can take their case to an industrial tribunal to see both sides of argument. o Wage protection: an employee in a business should have a contract of employment, where it should contain the wage rate, frequency of wages and what deductions are made from the wages (from tax). In some countries businesses pay whatever they want because unemployment is high, so they offer very low wages. Page 11 of 30 CIE IGCSE BUSINESS STUDIES//0450 • Message is reinforced by the speaker’s body language Governments take action by creating a legal minimum wage. 2.4 Internal & External Communication • • • • • • • • • • • • • Effective communication is important so that the information sent in the message is received, understood and acted upon as it should It is important to businesses because if it is not understood, it can lead to serious consequences There are two types of communication in businesses: Internal Communication – communication between employees of the same business External Communication – communication between the business and other businesses and individuals External communication has to be especially efficient because it establishes the image and the efficiency of a business i.e. if a company communicates inefficiently with their suppliers, they might receive the incorrect materials Effective communication involves: 1. The transmitter/sender sending a message to pass on information 2. A medium of communication – the method for sending message (i.e. e-mail, phone, etc) 3. The message being sent to the receiver 4. The receiver confirming that the message has been received and responds to it (feedback) There are two types of communication: o One-way communication – where the receiver cannot reply to the message (i.e. posters) o Two-way communication – where the receiver can respond to the message, could be just confirmation that message was received (e-mail) The methods of communication include: Verbal methods – sender speaks to the receiver (i.e. meetings, telephone, video conference) Advantages Disadvantages Information given out • If talking to many people, quickly &Efficient way it’s hard to tell whether to communicate with everyone got the many people message Opportunity for • Not good for accurate immediate feedback messages and if a • • • • • • permanent record of the message is needed Written methods – sender creates e-mails, memos or letters, including the use of Information Technology Advantages Disadvantages Message can be • Might lead to too many referred to in the future e-mails and ‘information “hard evidence” overload’ Easy to explain • Two-way communication complicated messages is difficult Can be copied and re• Hard to check if message sent to many people has been received Quick and cheap • No body language to emphasize message Visual methods – sender uses diagrams, charts, videos, PowerPoints Advantages Disadvantages • Information presented • No feedback and needs in more appealing way, other methods of people will be more communication to go interested to look at it with it • Can be used to make • Graphs and charts may written messages be difficult for people to clearer, to illustrate the understand, message point may be misunderstood 2.4.2 Communication Barriers • • • • • Communication Barriers – things that prevent efficient communication Problems with the sender: when language is too difficult, speaks too quickly/not clearly, communicates wrong message Overcome by: using understandable language, making sure message is a clear as possible by asking questions to make sure message was understood Problems with the medium: message may be lost/not seen by receiver, wrong medium used (i.e. important message on noticeboard), if message is being passed along – it might get distorted Overcome by: sender asking for feedback/receiver always sending feedback that message is received, selecting the appropriate channel to send message Page 12 of 30 CIE IGCSE BUSINESS STUDIES//0450 • • Problems with the receiver: not listening/paying attention, receiver doesn’t trust the sender/doesn’t want to do it Overcome by: emphasizing importance of message, ask for feedback to ensure it was understood, using direct communication 3. MARKETING 3.1. Marketing, Competition & Customer • Marketing – Identifying customer needs and satisfying them • There are many departments within the Marketing sector of a business • The role of the marketing is to: o Identify customer needs – this will be done via ‘Market Research’. It will influence the development of a product, its price, and the sales technique ▪ A good marketing department should also be able to anticipate (predict before happening) changes of customer needs (i.e. due to advancement in technology) ▪ Find new trends or gaps in market with potential o Satisfy customer needs – selling the exact product customers want, for a price they are willing to pay o Maintaining customer loyalty – building customer relationships and make sure that existing customers will continue to buy from them and to attract new customers ▪ Maintaining customer loyalty will be achieved by always satisfying customer needs • Markets don’t stay the same forever, businesses need to adapt to market changes in order to stay competitive • Some markets change very often (i.e. phones) while some don’t change quickly (i.e. jewelry or cereals) • Markets change because consumer spending patterns change, this might be due to: o Trends and fashions change – for a period of time it might be fashionable to have a specific product (i.e. Fidget Spinner) but a month later no one buys them o Advancement in technology – new products provide the latest technology so older versions (i.e. iPads or computers) don’t have high sales o Unemployment/Wages – Economies with high unemployment rates/low wages will not have high sales of expensive products o Ageing population – different ages are interested in different products (i.e. anti-ageing creams) • Changing customer needs are important to businesses. They must identify these changes and respond in order to stay successful • Market Share – the percentage of the total sales of a market held by a single business (i.e. if Company A has $50 Million in sales out of a $200 Million market, then Company A has (50/200 =) 25% market share • Some markets have become more competitive because: o Globalization – products are sold all over the world o Transportation – it is cheaper, quicker and easier to send products around the world now o Internet – customers can now search for products or services and buy from somewhere else around world • For a business to stay competitive, it must: o Maintain good customer relationships o Keep improving its existing products o Bring out new products to keep customer’s interest o Keep costs low 3.1.3 Market • Market – the total number of customers, potential customers and other sellers of a product/service • There are two types of market: o Mass market – where there is a very large number of sales of a product type o Niche market – a SMALL (usually specialized) segment (part) of a mass market • For example, the tie industry is a mass market, but a business that makes ties out of crocodile skin is a niche market MASS Market: Advantages Disadvantages • Sales are very high • Lots of competition • Can benefit from • High costs of economies of scale advertisement • Opportunities for growth • Many similar products (large sales) so it may not meet specific needs of all • There are many customers variations of products so risk is spread Page 13 of 30 CIE IGCSE BUSINESS STUDIES//0450 NICHE Market: Advantages • Avoid competition with big businesses • Specific needs of customers are focused. Advantage over mass market Disadvantages • Small – limited number of sales • Usually specialize in just one product, if product has low demand, it will fail 3.1.4 Market Segmentation • Market segments – a sub-group of a market in which the consumers have similar characteristics or preferences • A market can be segmented by: o According to age o SOCIO-ECONOMIC group – grouping people according to how much they are paid o Location – where people live (people that live in wet areas will buy more waterproof clothing than those who live in dry areas) o Gender – men and women products differ o Lifestyle – how many children a person has, religion, habits, etc. • Benefits of market segmentation: o Business aims all of its marketing efforts to the specific segment, making marketing costs efficient o Since less money is spent on marketing, more profit o Identify a market segment whose needs are not being fully met and fill the gap (first in market) 3.2 Market Research • There are 2 types of businesses: o Product-oriented business – a business that focuses mainly on the product itself o Market-oriented business – a business that focuses on market research and find out what the customer wants BEFORE a product is developed • Market research is important because a business needs to know how many people would be willing to buy the product, this is to see how profitable it would be • Market Research – gathering information about consumers' needs or preferences in a market • There are 2 main types of market research: o PRIMARY RESEARCH (field research) o SECONDARY RESEARCH (desk research) • Primary Research - Gathering of ORIGINAL data by talking directly with customers/potential customers • Primary research includes: o Questionnaires/surveys o Interviews – person will interview other person and ask questions o Samples – A group of people who are selected (randomly) to answer (i.e. questionnaire) o Quota Sample – when people are selected based on certain characteristics (age, income) o Focus Groups – a group of people who represent the target market. They test out product/service and explain what they like or don’t like about it o Observations – many methods, i.e. Seeing which television channels are being watched or watching people and their habits or seeing which products have sold well in a store Benefits Limitations • Detailed information • If questions in can be gathered about questionnaires aren’t the product (can even thought out answers be carried online won’t be useful to the business • Customer/potential customer’s opinions • Can take lots of time can be gathered and it and therefore, is detailed expensive • Most of these ways are • Interviewer may lead inexpensive and gather the interviewee to lots of useful data answer in a certain way (inaccurate) • Secondary Research – information that has already been collected and is available for others • This information can be obtained either from INTERNAL SOURCES or EXTERNAL SOURCES. • Internal Sources – within the firm’s own records: sales departments, customer records, finance department and CUSTOMER SERVICE department Page 14 of 30 CIE IGCSE BUSINESS STUDIES//0450 • External Sources – outside the business: government statistics (i.e. population, ages), Newspapers, Market research agencies, INTERNET Benefits • cheaper than primary as research has already been done by others • There is some information (i.e. economic forecasts or population size) that can’t be obtained by primary research Limitations • You do not get specific results for a certain product or service, you get broad results • data may be outdated or incorrect as it was collected by others • Might not have the specific information • Regardless on which type of research a business chooses to use, the accuracy of the research data depends on: o How carefully the sample was drawn up o How the questions in questionnaires/interviews were written to make sure honest answers were given o The sample itself and its size. By using quota sampling you might get more reliable results o The bias – some secondary research will be biased (i.e. articles on newspapers) which means the information might be unreliable o Age of the data – older data might be inaccurate 3.3 Marketing Mix • Marketing Mix – all of the activities that are involved when marketing a product or service • The marketing mix can be summed up as the 4 Ps: o Product o Price o Place o Promotion You should always mention the 4 Ps when answering question about Marketing Mix! 3.3.1 Product • The product itself is part of the marketing mix, it has to ensure it is the right product for the market. • This includes the quality and the design of the product (including its packaging) • Marketers must ask themselves “what can I do to make this product better than my competitors’ products” • Unique Selling Point (USP) – the special feature of a product that makes it different from other products • When businesses are developing new products there are several benefits, but also many costs/implications: Benefits Costs • Since the product has • Carrying out new market its USP, the business research & analysis is will be the first into the expensive market with the new • Producing prototypes & product cost of wasted materials • Diversification for the • Lack of sales if the target business – more range market is wrong of products to sell, • Deterioration of brand more customers image if the new product • Allows business to fails to meet consumer needs. expand into new (or existing) markets • Now-a-days products are sent straight to a retail store. There is no seller to persuade the potential customer to buy the brand’s product over competitors • This has to be done through brand image of the product • Brand image – the identity of a product which separates it from competitor products • The product brand is advertised to inform all the qualities about the product and encourage consumers • Businesses want to encourage existing and new/potential customers to buy from them and create Brand Loyalty • If a business has a bad brand image due to poor quality or bad service, then consumers will not buy from them and there won’t be brand loyalty. Page 15 of 30 CIE IGCSE BUSINESS STUDIES//0450 • The other very important aspect of the product is the packaging. It has 2 functions: o To be easy to put the product in, protect it, allow it to be used easily, and to be easily transported from factory o To promote the product: it must appeal to the customer (colour & shape) and must emphasize the brand image (i.e. a luxury product’s packaging might be gold colour) • Product Life-Cycle – the stages a product will go through all the way from development until decline (stop selling) 1. Development of product – market research carried out and product is tested, before launching (no sales) 2. Product introduced to market – Sales growing slowly because customers don’t know it exists yet (no profit) 3. Growth - Sales grow quickly – advertising is changed to encourage customer loyalty 4. Maturity - Sales still increase, but slowly, competition is high so prices are changed (profits are at highest) 5. Saturation – competition is very high, profits start to fall as sales reached maximum point. Price reduced 6. Sales decline – new products are made or trend is gone. Prices are so low it is unprofitable to make it. Advertisement is stopped • As you can see different stages can influence marketing decisions (i.e. pricing & promotion) 3.3.2 Pricing: • There are 5 main types of pricing methods: o Cost Plus – the cost of manufacturing plus a profit. it will cover costs and make sure profit will be made o Competitive – priced just below the competitors’ prices to get more market share and increase sales o Penetration – priced lower than competitors’ prices to enter new market (consumers will try out cheaper product and see if they like it) o Price Skimming – a high price is set for a new product on the market. (used for new inventions or development of an old product) high profits to cover the research o Promotional – priced very low for a short period of time to increase sales. when there is lots of stock but no one is buying. don’t make much (if any) profit Method Benefits Limitations • It is easy to • You could lose create and apply sales if price is Cost Plus too high compared to competitors • Lots of sales • You have to do because the research to see price is what reasonable competitors’ Competitive prices are. Time & • Product is not Money under- or overpriced • Prices are low so not much profit • Sales are • Product is sold at guaranteed and low price so profit Penetration the new product will be low enters a market • Establishes • Price is so high product as good that may put off Price quality potential Skimming customers off • Make quite a lot of profit • Gets rid of • there will not be unwanted stock much/if any that won’t sell profit made – because sales • renews Promotional revenue is lower consumer’s interest in business if sales are falling • Price Elasticity – a measurement of how responsive the market is when there is a change in price of a product • In other words, how much you can increase the price before sales fall enough that you make less money • A product either has price-elastic demand or price inelastic demand. • Price-Elastic Demand is when the % of the loss in demand is GREATER than the % of the increase in price • i.e. prices increase by 5% but then sales decrease by 10%. Therefore, there is falling revenue for the business • Price-Inelastic Demand is when the % of the loss in demand is LESS than the % of the change in price Page 16 of 30 CIE IGCSE BUSINESS STUDIES//0450 • This means you can increase the price of the product a lot without the demand changing (i.e. oil & petrol because people have to buy it) 3.3.3 Place – Distribution Channels • Where a product is sold will affect how well it will sell • Distribution Channel - the method a business will use to send a product from the factory to customer/retailer There are 4 main distribution channels: 1. Manufacturer sells products directly to consumer (i.e. car components to car factory) Advantages Disadvantages • Reduces storage costs for • More expensive to small retailers because buy from wholesaler small quantities are sold than from manufacturer • Small quantities so transport costs are low • Wholesaler might not have all the products • Wholesaler can give a retailer wants feedback on what sells well to producer • Takes longer to get to consumer 2. a manufacturer hires an agent (person or business) Advantages Disadvantages that will sell products on behalf or manufacturer • Very simple • Impractical because Advantages Disadvantages • Suitable for products that consumers don’t usually • Agents know the most • Manufacturer loses live near factories are sold straight out of profitable places & prices lots of control on factories • Not good for products that to sell in other markets the way the product can’t be sent easily by post • There is a lower price for that manufacturers may is sold to customers (may be expensive to ship consumer (cuts retailer) not know it) • Producer sells to retailers which sell to consumers: 3.3.4 Promotion (i.e. farms selling food to big supermarkets) • Promotion – publicizing a product/brand to increase • Advantages • Disadvantages customer awareness or increase sales • Manufacturer sells lots • There is no direct • The aims of promotion include: of stock to retailer contact with o To create a brand image for a product customers which • Cheaper transportation o To introduce a new product into a market makes It hard to costs because all o To increase competition in a market create customer products go to one o To improve the company’s image loyalty place o To increase the sales of a product • There are many types of promotion methods a business may choose to use. • There are 2 types of advertisements: o Informative Advertisement – where the promotion of a product focuses on giving information about a • Producers sell to wholesalers – which buy in bulk and product (i.e. the benefits of the product) then divide their stock into smaller quantities and sell o Persuasive Advertisement – where the promotion of a them to retailers product focuses on persuading the consumer that they really need the product and they should buy it • A business must also choose the most suitable advertising media to use to promote a product/brand • Advertising media include: Page 17 of 30 CIE IGCSE BUSINESS STUDIES//0450 o Television – suitable for products sold to most people (food, cars, household products). it is very expensive but millions of people will see it o Radio – cheaper than TV but there’s no visual message o Newspapers – suitable for local products. Cheap to advertise and can be select to target specific group o Magazines – niche/specialist products can be promoted in specific magazines (bike magazines, technology) o Billboards – suitable for mass products/local events. Reasonably cheap and are seen by many people. But many people miss it. And no detailed info can be put o Internet (social media) – suitable for products people already know (clothes, books, electronics). Quite cheap and through algorithms, websites can direct ads to a target audience, and orders can be made online. However, there is lots of competition (i.e. top on google) • Another way a business can promote a product/brand is through Sales Promotions – when incentives (i.e. special offers/sales) are used to increase sales (short term) • The main sales production methods include: o Sales (price reductions) o Gifts (i.e. little toys in cereals) o “Buy one get one free” o Competitions (I.e. raffles, a chance to win something) o Free samples • When a marketing department of a business is deciding which type of promotion it should use, it must take into account the marketing budget – the financial plan for marketing product/brand for a period of time • i.e. if the budget is small, a business cannot afford to advertise on television • It must plan out perfectly in order to have cost effectiveness, while reaching target audience • This is where small business struggle compared to big businesses, because their budget is so much smaller. 3.3.5 Technology & Marketing Mix • Now-a-days most things are sold on the internet, when you buy or sell goods/services on the internet it is called E-Commerce • Not every product/service is suitable for e-commerce, products that are handmade (i.e. suits) or businesses that like a personal approach with customers • The opportunities and threats of e-commerce to a BUSINESS include: Opportunities Threats • Low-cost promotion: • Competition is very high websites are cheap to run because competitors also and can promote worldhave websites to sell wide • Website design must be • Everything can be easy to use and attractive, automated (orders are this costs money received and sent to • Transport costs per warehouse to dispatch) product sold are higher • Businesses can buy from than sending all to retailer other businesses • No direct contact with (materials/supplies) customers – less feedback • Opportunities & threats of e-commerce to consumers: Opportunities Threats • Don’t need to leave house • Need access to internet to buy products, shipped (poorer countries don’t straight home have good access to web) • Easy to compare different • slow servers or websites prices from different or computer failures can stores and buy cheapest frustrate customers • Payment is very easy • products cannot be through credit/debit card seen/touched/tried on (i.e. shoes) and returning • Can view and buy products is inconvenient products from abroad, would be impossible • Some people are worried without about identity theft or credit card fraud by • Competition of eentering their details onto commerce makes prices a website much cheaper for consumers Page 18 of 30 CIE IGCSE BUSINESS STUDIES//0450 3.4 Marketing Strategy • Marketing Strategy is the plan of action to promote and sell a product or service • This includes combining the 4 elements of the marketing mix (Product, Place, Price, Promotion) to achieve a marketing objective, which could include: o Increasing the sales: ▪ Of existing products (i.e. by selling in new market) ▪ Of a new product o Increase market share/maintain market share • The different elements of the marketing mix are very important to influence customer decisions. • For example: A product is made, priced reasonably, and meets the consumer needs, but there is no promotional element. No one will buy it because people don’t know about its existence • Or if a product is made that doesn’t meet consumer needs, so it won’t sell regardless of the price set • It is crucial to have all elements working together in order to influence consumer decisions (buying the product) 3.4.2 Legal Controls in Marketing • There are many laws in different countries to protect consumers from businesses taking advantage of their lack of knowledge or lack product information • These legal controls include (in the U.K.): o Businesses are not allowed to sell products that weigh less than they should, or if weighing equipment is inaccurate o ‘Trade Descriptions’ - Businesses are not allowed to give consumers misleading information on purpose (i.e. saying that a shirt is made out of silk when it is made out of cotton) o ‘Sale of Goods’ - Businesses are not allowed to sell products that have less-than-satisfactory quality – that don’t fit for the purpose intended (i.e. waterproof shoes that aren’t waterproof) o A service must be provided with at-least satisfactory skill and care o Businesses cannot have misleading pricing claims (i.e. 50% off today, when yesterday it was the same price) o A business is responsible for any damage/harm that a faulty (or dangerous) product might do to a consumer o Customers have 7 days in which they can change their minds about purchasing a good or service. This applies to any transaction made over distance (i.e. online) 3.4.3 Entering New Markets Abroad • The globalization of businesses has been increasing over the years, there are opportunities & problems to this: Opportunities Problems • Growth potential in other • Lack of knowledge of countries: countries are competitors or consumer developing and population habits incomes are increasing • Cultural differences: for • Markets in original country example, alcohol won’t might be saturated (sales sell well in middle east are low) • Exchange rates: in some • Can produce products in countries their currency abroad and learn about its isn’t stable so price of market to increase sales importing goods increase • Trade barriers are lowered • Transport costs are more in most countries so it is expensive cheaper to enter markets • However, there are many methods to reduce and overcome the problems of entering a new market: Problem Method to overcome Joint-Ventures: by working together/merging with local businesses Lack of in the same market, a business will gain knowledge a lot of important knowledge about the (& Cultural culture & market Differences) Franchising: letting people from the market abroad which have local knowledge to choose location of shop Licensing: the business gives permission Transport for a local business to sell goods under costs are its name, so they do not have to expensive physically import all the products Localizing Existing Brands: where a business still has the same brand image Cultural but adapts it to the market it is in (i.e. Differences McDonalds cooking vegetarian meals in India) Page 19 of 30 CIE IGCSE BUSINESS STUDIES//0450 4. OPERATIONS MANAGEMENT 4.1 Production of Goods and Services o More output compared to inputs o Lower costs per unit (AKA Average cost) o If there is more output, maybe less workers needed, less people to pay wages o If there are less people working, raising their wages will increase motivation and so productivity • Businesses hold inventories/Stock to ensure that there are always enough products to satisfy demand of customers • If a business doesn’t have enough stock of a product it might lead to lower sales • When the inventories get to the ‘reorder point’, they will be reordered to get stock back up to maximum point. • Types of waste that occur in production: o Overproduction → leads to high storage costs and possible damage to goods while in storage o When nothing is happening to the goods (not being processed or moving) this is Waste o Transportation – when the goods are being moved unnecessarily → fuel price, may get damaged o Motion – any action made by an employee that does not relate with the production of goods wastes time o Over-processing – when sophisticated machines are being used to do simple tasks o Defects – when goods have faults/defects that require them being inspected/fixed wastes time • Lean Production – the techniques used by businesses to reduce waste, therefore increasing efficiency. • 3 Types of Lean Production: o Kaizen o Just-In-Time inventory (JIT) o Cell Production • Kaizen – Japanese Term. Means “continuous improvement” by focusing on constantly reducing waste • The Kaizen technique involves workers meeting regularly to discuss problems and to find solutions • Just-In-Time – a production method that virtually eliminated the need of having inventories of raw materials for production and of finished products • JIT method involves an efficient system to time specifically when the raw materials should arrive at a factory, for production, and when a truck should arrive to carry the finished products to the next stage of production. (used by Volkswagen) • Production – the making of a product or service to satisfy consumer wants and needs • A business combines the inputs/economic resources/factors of production to produce a more valuable output (this could be a good or a service) • The ‘inputs’ include: o Land – For factories or for materials o Labour – Employees o Capital – Money/finance o Enterprise – Managers • Businesses want to combine all of these inputs efficiently to keep costs low to increase profits • Labour-Intensive Production – where lots of workers are used rather than machines to make goods. Usually done in countries with low wages so that it is more efficient. • Capital-Intensive Production – where businesses use machines/robots rather than workers. Usually done in developed countries where the wages are high. • Productivity – the output (goods) measured against the inputs (resources) to create it Productivity = Quantity of Output / Quantity of Inputs • The difference between Production and Productivity is that Production is the process of creating the product/service from inputs. And the Productivity measures the efficiency of the Production • Businesses usually measure the productivity by measuring one of the factors of production against the outputs (usually Labour) Labour Productivity = Output / No. of employees • Efficiency is increased by either: o Using fewer input to produce the same output o Using the same inputs to produce higher output • How to increase productivity/efficiency: o Improving the layout of machines to reduce wasted time moving from one workspace to another o Improving the labour skills of workers so they use more productive techniques (more efficient) o improving employee motivation o Introducing new technology (i.e. automation) o Improved quality control (check if product is not faulty) to reduce wasted time checking • Benefits of increasing efficiency: Page 20 of 30 CIE IGCSE BUSINESS STUDIES//0450 • Just-in-time system reduces costs by not holding any inventory. Because components and materials arrive just-in-time when needed. • Cell Production – where production is divided into separate units (cells) each making a part of the finished product. Rather than having a flow or mass production. • Cell Production improves employee morale so they work harder and more efficient. 4.1.2 Methods of Production • 3 main methods of production: o Job Production – products made one at a time o Batch Production – a quantity (batch) of a product is made, then a batch of another product is made o Flow Production (mass) –large quantity of products made in a continuous process • Job Production: Features Products are made specifically to order Each order is different i.e. bridges, ships, cinema films, suits • Batch Production: Features Similar products are made in batches i.e. bakery: makes one type of bread, then one type cake. Furniture, clothing Benefits good for “oneoff” products meets exact requirements of customer varied work increases employee motivation Benefits Flexible work, can change products easily Gives some variety to worker’s jobs More variety = more consumer choice Limitations Often labor intensive, + cost Production takes longer Any errors are expensive to fix, (made to order) Materials are more expensive Limitations Machines must be reset to do diff. batches Semi-finished products may need to be transported around (+ cost) Need space for stocks of raw material • Flow Production: Features Large quantities of a product are produced Ingredients start at one end & flow to the other end, ready to be sold Cars, drinks, electronics, any mass-made products are made this way Benefits High output, capital intensive more efficient Costs are low Benefits from economies of scale Works 24/7, no need for labor No need for moving goods around (all made in the same place) Limitations Very boring for employees High cost of inventory of output & raw materials Costs of setting up are very high If machine breaks down, whole production stops • Automation – when equipment in factory is controlled by a computer to do mechanical processes (i.e. painting car). Only workers are to ensure it runs smoothly • Mechanisation – when production is done by machines but operated by people. Used to do difficult, precise or dangerous tasks. Work 24/7. • Computer Aided Design (CAD) – software that helps design or re-style products quickly, allows technical sketches to be very detailed • Computer Aided Manufacture (CAM) – when computers monitor production and control machines/robots • Computer Integrated Manufacturing (CIM) – wen software that designs the products is integrated with the machines that produce (CAM + CAD) 4.2 Costs and Scale of Production • Fixed (overhead) Costs – Costs that do not change with the number of items sold/produced. • Fixed costs must be paid regardless if the business is making a profit or not. • Examples of Fixed Costs: o Rent of factory: even if you produce lots of products, the rent price will be the same o Insurance: you set the insurance cost before-hand o Bank fees: bank fees are a set price, they don’t change depending on the products produced o Management Salaries: they are set regardless of production o Staff cost (Security) Page 21 of 30 CIE IGCSE BUSINESS STUDIES//0450 • Variable Costs – costs that are directly proportional with the number of items sold/produced. • The more items produced, the higher the variable cost • Examples of Variable Cost: o Raw materials: the more you produce, the more materials you need o Electricity & Gas: Energy is paid by use. if you are producing more, more electricity is being used o Shipping cost: Making more products means you have to ship more items and shipping is paid by weight • Total Cost – Fixed and variable costs combined • Average Cost (Per Unit) – total cost of production divided by the total output. Referred to as Unit Cost • Large businesses can benefit from Economies of scale and therefore getting lower average costs. 4.2.3 Break-Even Charts • Break even charts show how costs and revenues of a business change with sales. They show the level of sales the business must make in order to break even • The break-even point is where: total cost = sales revenue Where the revenue line intersects the total cost • Sales revenue is the income of a business from sales of goods or services in a period of time. • To draw a break-even chart, you must include: o Fixed Costs line o Variable Costs line o Total Costs line o Sales Revenue line • Anything before the break-even (BE) point is loss • Anything after the break-even (BE) point is profit • ‘y’ axis measures money amounts (cost & revenue) • ‘x’ axis shows the number of units produced or sold • Total cost is variable cost line starting from fixed cost • If the total cost increases, then the BE point increases and total cost’s line becomes steeper • If revenue increases, then revenue line becomes steeper and so the break-even point decreases • Benefits of break-even charts: o Managers can read of the graph if the company expects profit or loss, and can see how much profit/loss the will have at any level of output o They can attempt different scenarios and see the impact it will have on the profit or loss of the business. It lets managers try out different possibilities to find out which one is the best. (i.e. increasing the selling price, increasing production) o It can be used to show the SAFETY MARGIN – the amount by which sales exceed the break-even point. For example: if a business’ break-even point is at 400 units and they’re producing 600 units, their safety margin is 600 – 400 = 200. • Limitations of break-even charts: o Break-even charts assume that all products made will be sold. It does not show the possibility that inventories may build up if they are not sold o Fixed costs only stay the same if the scale of production stays the same (doubling the output will also increase the fixed cost because they must need bigger factory, more machinery, labour, etc) o Break even charts assume that costs and revenues can be drawn with straight lines, which doesn’t happen in real life. • To calculate the break-even point: Break Even = Fixed cost / contribution (per unit) • Contribution – the selling price of a product (unit cost) subtracted by the variable cost (per unit): Contribution = unit cost – variable cost (per unit) Variable cost (per unit) = Variable cost / units produced Page 22 of 30 CIE IGCSE BUSINESS STUDIES//0450 4.3 Achieving Quality Production o o Fewer customer complaints Reduced costs if products don’t have to be scrapped or reworked or service repeated • Drawbacks of Quality Assurance: o Expensive to train employees to check products o Relies on employees following instructions of the standards set by company • Total Quality Management (TQM) – the continuous improvement of products and processes by focusing on quality at each stage of production • Total quality management is used by many companies • It tries to “get it right the first time” and have no defects • It focuses on ensuring 100% that the customer is always satisfied. Customer is not just the final user, it also includes other people and departments within the business • This means that quality needs to be maintained throughout the business and no faults should occur. • Advantages of total quality management: o Quality is built into each part of the production. It becomes a habit for the employees o Eliminates virtually all faults/errors before the customers receives. o No customer complaints so brand image is improved o Waste is removed and efficiency increases which means less money is wasted (higher profits) • Drawbacks of total quality management o very expensive to train employees to check the product or service at every stage of production o relies on employees following the ideology of TQM • Quality – to produce a good or a service which meets customer expectations • Quality is important for businesses because: o It establishes brand image o It builds brand loyalty o It maintains a good reputation o It will help to increase sales o Attracts more and new customers • If quality is not maintained, businesses will: o Lose customers to other brands / competitors o Have to replace faulty products or repeat poor service which raises costs for business o Have a bad reputation because people who had bad experiences will tell other people, etc. Leads to lower sales & revenue • Quality Control – Checking for quality at the end of the production process, whether it is a product or a service. • Quality control is a traditional way to make sure that products leave the factories with no defects • The jobs of people in quality control departments are to take samples at regular intervals to check for errors. • If errors are found, the whole batch of production might have to be redone. • Their job is also to prevent any production errors before they happen during production, which will lead to money loss • Sometimes, businesses bring a mystery customer to test out the service to check if the quality is as expected • Advantages of Quality Control: o Eliminates faults/errors before customer receives product or service 4.4 Location Decisions o Less training is required for the workers • Factors that influence the choice of location of a • Drawbacks of Quality Control: business: o Expensive, as employees need to be paid to check o Labour (cost & skills) – how many employees and if the product or service they rely on special labour skills o Identifies the fault but not how and why it occurred o Cost of land/premises –big manufacturing so it is difficult to remove the problem companies need lots of cheap land to build o Increased costs if products have to be scrapped or o Transport links (supplies & distribution) – being reworked or service repeated close to transport links (i.e. rail road) means that • Quality Assurance –checking for the quality standards products can be easily and quickly transported throughout the production process which reduces time wasted. and if business imports • Advantages of Quality Assurance: lots of components it will be cheaper if they easy o Eliminates faults/errors before customer receives transported product or service Page 23 of 30 CIE IGCSE BUSINESS STUDIES//0450 o Sales technique – if a company does online or phone sales, then the company doesn’t need to be in the centre of the city. If it relies on personal visits buy customers, like retail, it should. o What the business does – manufacturing businesses are usually in the outskirts of a city where land is cheaper because they don’t rely on customer visits. A retail company would be near customers o Number / location of competitors – having competitors nearby is not always a bad thing. If there are many clothes shops right next to each other, it encourages people to visit area because there is lots of choice, increases business. • Some businesses may decide to locate their operations in another country, to expand operations. the business then becomes a TNC – Trans National Company. • Factors influencing decision of which country to locate operations in: o New market overseas - when a business sees an increase in sales overseas, it may decide to move/relocate there, instead of transporting products there o Cheaper Source of material – if the raw material runs out, the business must either bring in alternative supplies from somewhere else or relocate to new country with these raw materials, it also might be cheaper than transporting it o Difficulties with the labour force and wage costs – if business is located in country where wages keep rising, business may decide it is more profitable to relocate to country where wages are lower o Rents/taxes considerations – if other costs such as rent or taxes increase, this might cause business to relocate to countries where it is lower 5. FINANCIAL INFORMATION AND DECISIONS 5.1. Needs of Capital Finance = Capital = Money • Main reasons why businesses need finance: o To start up a business: the money needed to buy the essential assets to start trading is the start-up capital o To expand the business o To increase working capital • Working capital - money needed to pay day-to-day costs • There are 2 types of finance needs: o Short-Term Finance Needs: Finance needs to pay things that last less than a year, (working capital) - includes wages, rent o Long-term Finance Needs: long term investments (that last more than 1 year). Money to buy Fixed Assets (i.e. buildings) 5.1.2 Sources of capital • The main sources of capital include: o Internal Sources – Obtained by business itself o External Sources – Obtained from outside business Examples: Internal sources External sources Retained profit Issue of shares (if it’s LTD/PLC) Sales of assets Bank loans/Micro-finance Grants • Micro-Finance - providing smaller loans to poorer people to start up their own business. • Micro finance is very important in developing countries • There are also short-Term and long-term sources (don’t get confused with short/long term finance needs) o Short Term Sources – money that must be paid back in less than a year o Long Term Sources – money that can be paid back in longer than one year Short-Term Sources Long-Term Sources Overdrafts – when the Bank loans bank allows a business to Issuing shares spend more money than Owner’s savings they have in their account Hire Purchase – When a (i.e. to pay employees) business buys a fixed Trade Credit – delay paying asset in monthly suppliers to be in better payments (which cash position include interest) • The main factors considered in making financial choice: o Size of business & Legal Form (type of business): Public limited companies have larger choice of sources of finance because they pay less interest (less risk) o Amount of capital required: if you need just a little money you won’t issue new shares o Purpose of capital & time period: The general rule is that the finance source should match the finance need: Page 24 of 30 CIE IGCSE BUSINESS STUDIES//0450 5.3 Income Statements ▪ If use of capital is long-term, source should be long-term (same with short term) o Existing Loans: if a business already took out lots of loans, banks will think it is too risky to finance 5.2 Cash-Flow Forecasting & Working Capital • Cash is a Liquid Asset – it can be immediately available to spend on goods & services • Cash Flow – the cash inflows (money received by business) & outflows (money paid) over a period of time • Cash-Flow Forecast – an estimate of future cash inflows and outflows. • A cash-flow forecast shows the expected cash balance at the end of each month: • Cash flow forecasts are just little charts with values comparing 2 different time periods (months/years etc.) • Net Cash Flow – The difference between the cash inflow and outflow (inflow – outflow) • Cash flow forecasts are useful because: o They show how much cash is available to pay liabilities of to buy assets o They show how much money a business might need to borrow from a bank o They show whether the business is holding too much cash which could be reinvested back into business • To complete a cash-flow forecast, just rearrange and use the equation (net flow = inflow – outflow) • Short-term cash-flow problems can be solved by gathering short-term sources of finance Working Capital • Working capital is the money needed to pay day-to-day costs Working Capital = Current Assets – Current Liabilities • A business cannot run without enough working capital • You can measure the success of a business by seeing how much working capital it has • Working capital should be handled properly because it shows investors & banks how efficient a business is and its financial strength • For most business, profit is the main objective • Profit is the money left over after total costs have been subtracted from the sales revenue. The simple equation for profit: Profit = Sales revenue – total costs • Profit can be made by: o Increasing the sales revenue, so that it is higher than the production costs o Reducing the production costs • Profit is very important, especially for the private sector companies (not owned by government) o Profit is a reward for risk taking: investors & entrepreneurs take lots of risks when investing money o Profit is a reward for enterprise: entrepreneurs and workers put lots of effort to make business succeed o Profit can be re-invested back into business: the retained profits can be put onto business to expand o Profit indicates that the market might be successful: a market where most businesses are making profit would be a good market for an entrepreneur to start their own Profit ≠ Cash • Profit can be in the form of cash, but it can also be in the form of credit (customers will pay later) • If a company makes $40,000 in sales, but only $20,000 is in cash and the other $20k is in credit. The business only has $20,000 in cash to pay costs. • Credits can vary from a week to a year, it is ‘promised’ cash but not physical, and can’t pay for costs. • So, in this case, if the business makes $40,000, and the costs are $15,000 it will make $25,000 in gross profit (theoretical profit), but only $5,000 in net profit • Income Statement – A business account that records all the incomes of a business and all the cost payed over a year – to see if it is making profit. • It will be used by managers, banks and other investors to see if a business is making profit: o to compare with previous years - if it is greater than the year before o To see if it is higher than competitors • The main features of an income statement include: o Revenue o Costs Page 25 of 30 CIE IGCSE BUSINESS STUDIES//0450 o Gross Profit – the profit made after costs of goods sold are taken away from sales revenue o Net Profit (AKA ‘Profit’) – the profit made after taking away all expenses and overhead costs (other expenses) o Retained Profit – the net profit after taking away taxes and payments to owners – which is reinvested back into the business Profit Type Equation Gross Profit Sales Revenue - Costs of goods sold Gross Profit – Overhead Costs Net Profit (wages, electricity, rent, marketing) Retained Net Profit – (tax + dividends) Profit • Income statements are very important in decision making in a business • If a business is thinking to relocate a factory, they will make a forecast income statement in both locations and compare 5.4 Balance Sheets: • Balance Sheet – a document that shows the value of the business’ assets and liabilities in a point in time • A balance sheet • Assets – Items of value owned by a business • Liabilities – Debts owed by business • There are 2 types of assets: o Current Assets – (Short-term Assets) Items owned by business for less than 1 year i.e. Raw material, cash o Non-Current Assets – (Long-term Assets) Items owned by business for more than 1 year i.e. Buildings, land, company cars • There are also 2 types of liabilities: o Current Liabilities – (Short Term Liabilities) Debts owed by business for less than 1 year i.e. Bank overdrafts, wages o Non-Current Liabilities – (Long Term Liabilities) Debts owed by business for more than 1 year i.e. Long-term bank loans, creditors (money that business owes to suppliers) • the Total Equity (AKA Shareholders’ funds) is how much a business is worth. (only for Limited companies) Shareholders’ Funds = Total Assets – Total Liabilities • The shareholders’ funds is the total amount of money invested in a business by the shareholders/owners • If the total equity of a business has increased/fallen, the shareholder’s stake of the company will be worth more/less, respectively From a balance sheet, you can calculate the Working Capital = Current Assets - Current Liabilities You can also calculate the Capital Employed – the longterm capital invested in a business Capital Employed = Non-Current Assets + Total Equity Total Equity = Shareholders’ funds 5.5 Analysis of Accounts • Using all of the documents and information from cash flow forecasts, balance sheets and income statements you can rate the performance of a business • Analysis of accounts is interpreting these accounts/documents to see how a business is doing • To rate a company’s performance, you can use 5 ratios • There are 2 types of ratios: o Profitability Ratios – how profitable a business is o Liquidity Ratios – how able a business is to pay its short-term debts (current liabilities) • Profitability Ratios: o Gross Profit Margin (%) – how good a company is at converting sales into gross profit. A percentage GPM (%) = 100 × Gross Profit / Sales Revenue o Net Profit Margin (%) – how good a company is at converting sales into net profit. A percentage NPM (%) = 100 × Net Profit / Sales Revenue o Return on capital employed – how profitable a company is compared to the amount of money used RoCE (%) = 100 × Net Profit / Capital Employed • One profitability ratio isn’t useful by itself. You need to use all the profitability ratios and compare it with previous years of the business. • Liquidity Ratios: o Current Ratio – how good a company is to pay off its current liabilities with its current assets Current Ratio = Current Assets / Current Liabilities Page 26 of 30 CIE IGCSE BUSINESS STUDIES//0450 o Acid Test Ratio – measures the ability of a company to pay off its liabilities without depending on the sales of inventory Acid Test Ratio = Current Assets – Inventories (Stock) Current Liabilities • The acid test ratio is used to measure if a business is likely to survive in the future • The good and bad values of these ratios: Gross Profit Margin No exact value, you must compare with: (%) • Competitor businesses Net Profit Margin • Previous years (%) • The targets set by the ROCE (%) business Current Ratio Should be above 1.5 to be safe Should be above 1, unless you are dealing with cash sales in Acid Test Ratio which it can be above 0.75 (cash is liquid - pays of liabilities easily) • Liquidity – Ability for a business to pay off it short term debts • If a business’ assets can’t be easily converted to cash, then they are Illiquid • Current Assets are liquid. • Having lots of stock may mean that the company might be illiquid because inventories are hard to convert to cash easily • Liquidity is very important for a business: o If they can’t convert their assets into cash, they won’t be able to pay their suppliers (current liabilities) o Not paying suppliers will force them to stop trading to pay back their debts 5.5.3 Why and how accounts are used: • Limited companies must publish their accounts for the public to see. IT is used for ratio analysis. • All types of stakeholders will be interest in seeing these accounts to see how well the business is doing. i.e.: o Managers: to keep an eye on the performance of the business. Compare ratios with competitors & previous years to make decisions. o Shareholders & potential investors: They will see how profitable a business is using the ratios to see if it is worth investing in it. See how much business is worth o Banks: see if business is performing well to calculate the risk on whether to give out a loan or not. o Employees: to see how safe the business (and their jobs) are. 6. EXTERNAL INFLUENCES ON BUSINESS ACTIVITY 6.1 Government Economic Policies & Objectives • Inflation – The increase of average prices of goods & services • Governments want 3 main economic objectives: o Low Inflation: Low prices of goods & services, so people will buy more, more money in economy o Low Unemployment: High % of people working so that they don’t rely on government funds o Economic Growth: growth of the GDP (Gross Domestic Product) of a country – more goods and services being produced and sold o Balance of payment (of Imports & Exports): the difference between the imports and the exports of a country balance out (BoP = Exports – Imports) • Exports are goods/services sold from one country to another – and they bring money into a country • Imports are the opposite • An economy does not grow steadily, there are bumps where the economy does not grow at all • Recession – A period of falling GDP • Economies go through the ‘Business Cycle’: 1. Growth: GDP is rising, unemployment falling, businesses succeeding & higher living standards 2. Boom: Higher living standards so people start spending more money, so prices increase – business costs will also rise 3. Recession: people become uncertain about their jobs so they don’t spend money. Many workers lose their jobs because of lack of demand & profit in a business 4. Slump – A long-term, serious recession: Unemployment will be very high, GDP has decreased a lot and many businesses will not survive and go bankrupt Page 27 of 30 CIE IGCSE BUSINESS STUDIES//0450 6.1.1 Government Economic Policies Interest Rates • There are 3 main ways governments can influence the economy (AKA economic policies): o Government expenditure Fiscal Policy o Changing tax rates o Interest Rates • Government Expenditure is how the government spends the money made from taxes. It is usually spent on education, defense, healthcare, public transport, etc.… • Companies that are involved in these markets/sectors above will benefit. i.e. a bus manufacturing company will benefit if government spends more on public transport • Spending more on these markets will boost economy in a country (more jobs created, more demand) • There are 2 types of taxes: o Direct Taxes – taxes paid directly from incomes (of individuals as wages or as business as revenue) o Indirect Taxes – VAT, taxes added to prices of goods • Out of these 2 types, there are 4 common taxes that affect business activity: • The interest rate is the amount charged for borrowing money from a bank • In most countries, the interest rates are fixed by the government • the % of the interest rate is called the monetary policy • The effects to business activity due to having higher interest rates include: o Less profit for companies that already took out a loan less/slower expansion of a business. o Entrepreneurs thinking of starting business might not be able to afford to take out a loan o If consumer loans (i.e. mortgages) increase, people will have less disposable income – less demand for goods o Higher exchange rates of currency Tax Income tax (direct tax) Profits Tax (direct tax) Indirect Tax (VAT) Import Tariffs & Quotas (indirect) What it is Tax on people’s incomes – You can either have a set tax (i.e. 20% of income) or Progressive income tax, where richer people pay higher taxes. Tax on profits made by businesses (a set • percentage) • Tax added to prices of goods & services (varies within types of products) Tax on imported goods • from other countries. Import Quota is a physical limit to the amount of • products that can be imported. How it affects business activity People have less disposable income (money after tax). They would have less money to spend on goods or services. Businesses have less revenue. If tax rates increase: Harder for a business to expand (less profit) less money to reinvest back into business. Fewer people will start their own business Prices of goods will increase so less people will buy them – Less demand for a business Local businesses will have more demand because there less imported goods Importing raw materials from abroad will be much more expensive – products will be more expensive – sell less • Businesses might respond to all of these policies by: Policy Business Response Higher • Lowering production costs to be able to income tax sell goods for lower prices Higher • Focusing on the domestic market tariffs (on • Buying materials from local companies imports) rather than from companies abroad Higher • Reduce investment for business growth interest • Lower prices of goods for consumers rates • Sell assets for cash to reduce loans 6.2 Environmental & Ethical Issues • Business activity can impact the environment in many different ways, including: o Air pollution made by factories & transportation o Water & land pollution from improper waste disposal o Increase carbon emissions – global warming • Most business decisions lead to benefits and costs. There are private and external benefits and costs • Private costs & benefits are costs that a business pays for, and the benefits the business gains • External Costs – costs paid by society, rather than the business (as a result of business decision) • External Benefits – gains to society, rather than the business (as a result of business decision) Page 28 of 30 CIE IGCSE BUSINESS STUDIES//0450 • The possible external costs and benefits of a business decision might include: External Costs External Benefits • Environment is harmed • Jobs are created, from waste products economy is boosted • pollution may damage • Other companies might the health of people move in, more services • less energy • better infrastructure • traffic • better quality of life • these externalities change depending on the decision. • Sustainable development – development that does not compromise the living standards of future generations • Businesses can contribute to sustainable development by doing 4 main things: 1. Using renewable energy (wind, solar) 2. Recycling & reusing their waste 3. Using less natural resources (lean production) 4. Developing environmentally friendly products & packaging (i.e. biodegradable packaging) • People & consumers pressure companies to think more environmentally. There are many reasons and ways businesses give the environment a higher priority: • Pressure groups - a group of people who want to change policies/decisions of businesses or the government. • Pressure groups acting on unethical decisions made by a business will lead to a consumer boycott - consumers not buying their products • Environmentally friendly businesses can use the fact that they are environmental as a marketing advantage Type of pressure What it is How and why it responds • Governments sell ‘permits’ to companies that allow it to pollute the environment up to a certain level • Firms that pollute less than the government allows, can sell their permit to companies that pollute more • This motivates businesses to pollute less, to earn money • Ethics – “doing the right thing” - the moral principles • Most businesses have to face many ethical decisions, they have to decide whether to act ethically or have higher profits • Ethical decisions include: o Employing child workers, even though it might not be illegal in some countries o Buying supplies that lead to damage of the environment o Paying managers large bonuses while having their workers in minimum wage & poor conditions o Offering bribes to people to gain information • Different companies have different ethical standards because people have different moral codes • Businesses may respond to ethical issues by following their moral code and “doing the right thing” • These decisions have benefits and disadvantages: Benefits Disadvantages • Consumers appreciate • Higher costs of the efforts made by the production company and so they • Higher prices – might buy more from them lead to less demand • Creates good publicity • In some places families • Less risk of lawsuits depend on their children to earn money • Easier to find workers They lead to consumer boycotts - consumers not buying their products 6.3 Business and the International Economy • Lots of public support • Globalization –the world becoming more interconnected • Very bad brand leading to increasing worldwide trade & people moving image & • The reasons for globalization include: reputation o More Free-Trade Agreements – imports/exports • Loss in sales Laws passed by Government Government making certain activities illegal (i.e. dumping waste) • It is more expensive to manufacture Fines If a business produces more pollution than the government allows, they pay heavy fines. • Costs of business increase Pressure group a group of people who want to change policies / decisions of businesses between countries that pay no tariffs o Easier, cheaper and faster transportation between countries o E-commerce allows products to be bought from all over the world o Industrializing countries (i.e. India & China) can produce products at very low prices Page 29 of 30 CIE IGCSE BUSINESS STUDIES//0450 • The opportunities and threats of globalization to a business include: • • • • Opportunities Businesses can sell abroad, increasing sales Opening factories or offices abroad – can be cheaper to produce, but it is expensive to set up Importing materials from abroad – can be cheaper but transport costs can be too high Importing goods from abroad and selling it in home country Threats • Increasing foreign competitors importing their products, leading to less sales (& profit) • Workers in home country might leave for higher wages in other countries • More foreign companies set up operations in the home country of the business, more competition • Sometimes governments introduce import tariffs and quotas to protect local businesses – this is called Protectionism • They believe that by reducing the number of foreign competitors and goods (that would have much lower prices), there will be less unemployment and higher incomes • However, by doing this, it is harder for local businesses to import materials and export their goods abroad 6.3.2 Multinational Companies (MNCs) • Multinational Company = Transnational Company • A multinational company is a company that has factories or service operations in more than one country • It is not just selling products abroad, it is having operations abroad • The benefits of a business becoming international: Benefits to the business Producing goods at lower costs Closer to resources (i.e. oil) Closer to market Avoid expensive taxes of import of goods (i.e. Korean cars (KIA) being produced in EU to benefit from free trade) • Spread risks (if there are low sales in one country and high sales in another) • • • • Benefits to the country • Jobs are created • Investments in development of infrastructure in country • More exports • Tax – more money to government • increased product choice for consumers • However, there are potential drawbacks to the country: o Less sales for local businesses, might go bankrupt o ‘Repatriation of profits’ – profits are sent back to home country and doesn’t benefit country located o Business has lots of influence on government – they can threaten to leave the country o They can use up scarce resources in the country 6.3.3 Exchange Rates • Exchange Rate – the price of one currency in terms of another currency • For example, 1 Euro is equivalent to 1.2 Dollars • Currency Appreciation – when the value of a currency increases (i.e. 1€ = 1.2$ → 1€ = 1.7$) • Currency Depreciation – when the value of a currency increases (i.e. 1€ = 1.2$ → 1€ = 1.1$) – it can buy less of another currency • The exchange rate of a currency is influenced by 2 things: o Demand for the currency: if many people want to buy the currency the price will increase because there is a ‘limited’ number of currency (appreciate) o Supply of currency: if the central bank prints more money, the supply increases but the demand is still the same so the value is lower (depreciation) • Exchange rates can affect businesses by: If it Appreciates: • Import prices fall: since your currency can buy more of the other currency • Export prices rise: your currency is worth more so it is more expensive for other currencies to buy it If it Depreciates: • Import prices rise: your currency is worth less so you need more to buy other currencies • Export prices fall: it is worth less so other currencies can buy your currency for les of theirs • This means that if the currency Appreciates: o The product’s price in other countries will increase o Business will make more profit o Business can lower the price and still make the same amount of money as before – it is more competitive • If the currency depreciates: o The products price in other countries will decrease o less profit will be made o Business needs to raise the price to make the same amount of money as before – less competitive Page 30 of 30 TABLE OF CONTENTS 3 CHAPTER 1 3 CHAPTER 2 3 CHAPTER 3 4 CHAPTER 4 4 CHAPTER 5 5 CHAPTER 6 5 CHAPTER 7 6 CHAPTER 8 6 CHAPTER 9 6 CHAPTER 10 Length & Time Motion Mass & Weight Density Forces Momentum Energy, Work & Power Pressure Simple Kinetic Molecular Model of Matter Thermal Properties 7 CHAPTER 11 7 CHAPTER 12 10 CHAPTER 13 10 CHAPTER 14 12 CHAPTER 15 13 CHAPTER 16 13 CHAPTER 17 15 CHAPTER 18 17 CHAPTER 19 17 CHAPTER 20 Transfer of Thermal Energy General Wave Properties Light Sound Simple Phenomena of Magnetism Electrical Quantities Electrical Circuits Dangers of Electricity Electromagnetic Effects Radioactivity CIE IGCSE PHYSICS//0625 1. LENGTH AND TIME 2. MOTION 1.1 Length 2.1 Speed A rule (ruler) is used to measure length for distances between 1mm and 1meter SI unit for length is the meter (m) To find out volume of regular object, use mathematical formula To find out volume of irregular object, put object into measuring cylinder with water. When object added, it displaces water, making water level rise. Measure this rise. This is the volume. Speed is the distance an object moves in a time frame. It is measured in meters/second (m/s) or kilometers/hour (km/h). 𝑻𝒐𝒕𝒂𝒍 𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝑺𝒑𝒆𝒆𝒅 = 𝑻𝒐𝒕𝒂𝒍 𝑻𝒊𝒎𝒆 Speed is a scalar quantity 2.2 Speed/Time Graphs 1.2 Micrometer Screw Gauge Used to measure very small distances Determination of the diameter 'd' of a wire Area under the line equals to the distance travelled 𝐺𝑟𝑎𝑑𝑖𝑒𝑛𝑡 = 𝑦2 −𝑦1 𝑥2 −𝑥1 = =Acceleration (m/s)2 2.3 Distance/Time Graphs Place the wire between the anvil and spindle end as indicated in the diagram. Rotate the thimble until the wire is firmly held between the anvil and the spindle. The ratchet is provided to avoid excessive pressure on the wire. It prevents the spindle from further movement - squashing the wire To take a reading: o First look at the main scale. This has a linear scale reading on it. The long lines are every millimetre the shorter ones denote half a millimetre in between. o On the diagram this reading is 2.5 mm o Now look at the rotating scale. That denotes 46 divisions - each division is 0.01mm so we have 0.46mm from this scale. o The diameter of the wire is the sum of these readings: o 2.5 + 0.46 = 2.96 mm 1.3 Time 𝒚 −𝒚 𝑮𝒓𝒂𝒅𝒊𝒆𝒏𝒕 = 𝒙𝟐 −𝒙𝟏= Speed (m/s) 𝟐 𝟏 2.4 Distance Calculating distance travelled: o With constant speed: 𝑆𝑝𝑒𝑒𝑑 × 𝑇𝑖𝑚𝑒 𝑆𝑝𝑒𝑒𝑑 o With constant acceleration: 𝐹𝑖𝑛𝑎𝑙 𝑆𝑝𝑒𝑒𝑑+𝐼𝑛𝑖𝑡𝑖𝑎𝑙 × 𝑇𝑖𝑚𝑒 2 2.5 Acceleration 𝑭𝒊𝒏𝒂𝒍 𝑺𝒑𝒆𝒆𝒅 − 𝑰𝒏𝒊𝒕𝒊𝒂𝒍 𝑺𝒑𝒆𝒆𝒅 𝑻𝒊𝒎𝒆 𝑻𝒂𝒌𝒆𝒏 Acceleration is the rate of change in velocity per unit of time, measured in meters per second, or m/s2 Acceleration is a vector quantity Positive acceleration means the velocity of a body is increasing Deceleration or negative acceleration means the velocity of a body is decreasing If acceleration is not constant, the speed/time graph will be curved. The downwards acceleration of an object is caused by gravity. This happens most when an object is in free. 𝑨𝒄𝒄𝒆𝒍𝒆𝒓𝒂𝒕𝒊𝒐𝒏 = Interval of time is measured using clocks SI unit for time is the second(s) To find the amount of time it takes a pendulum to make a spin, time ~25 circles and then divide by the same number as the number of circles. PAGE 3 OF 20 CIE IGCSE PHYSICS//0625 Objects are slowed down by air resistance. Once air resistance is equal to the force of gravity, the object has reached terminal velocity. This means that it will stay at a constant velocity. acceleration of free fall for a body near to the Earth is constant (G=10m/s) 3. MASS AND WEIGHT Mass: amount of matter an object contains, and is a property that ‘resists’ change in motion Weight is the force of gravity acting on an object, measured in Newtons, and given by the formula: 𝑾𝒆𝒊𝒈𝒉𝒕 = 𝑴𝒂𝒔𝒔 × 𝑮𝒓𝒂𝒗𝒊𝒕𝒚 Weights (and hence masses) may be compared using a balance 5. FORCES 5.1 Effects of Forces A force may produce a change in size and shape of a body, give an acceleration or deceleration or a change in direction depending on the direction of the force. If there is no resultant force acting on a body, it either remains at rest or continues at constant speed in a straight line 5.2 Friction Friction: the force between two surfaces which impedes motion and results in heating Air resistance is a form of friction 5.3 Hooke’s Law 4. DENSITY 𝑴𝒂𝒔𝒔 𝑫𝒆𝒏𝒔𝒊𝒕𝒚 = 𝑽𝒐𝒍𝒖𝒎𝒆 Density of a liquid: place measuring cylinder on a balance, fill measuring cylinder with the liquid. The change in mass is mass of liquid and volume is shown on the scale, then use formula. Density of solid: o Finding the volume: To find out volume of a regular object, use mathematical formula. To find out volume of an irregular object, put object into a measuring cylinder with water and the rise of water is the volume of the object o Finding the mass: weigh object on a scale and use formula 4.1 Flotation The density of water is 1g/cm3, if an object has a greater density than that, then it will sink in water, and if the object’s density is less than that, then it will float in water. Example: an orange with its peel has a density of 0.84g/cm3, we can predict that it will float because it is less than 1 g/cm3. We can also say, that an orange without its peel, which has a density of 1.16g/cm3, will sink because it is greater than 1g/cm3. Springs extend in proportion to load, as long as they are under their proportional limit. point at Limit of proportionality: which load and extension are no longer proportional Elastic limit: point at which the spring will not return to its original shape after being stretched 𝐿𝑜𝑎𝑑(𝑁) = 𝑆𝑝𝑟𝑖𝑛𝑔 𝐶𝑜𝑛𝑠𝑡𝑎𝑛𝑡 × 𝑒𝑥𝑡𝑒𝑛𝑠𝑖𝑜𝑛 𝑭 = 𝒌𝒆 5.4 Forces Forces measured in Newtons 𝑭𝒐𝒓𝒄𝒆 = 𝑴𝒂𝒔𝒔 × 𝑨𝒄𝒄𝒆𝒍𝒆𝒓𝒂𝒕𝒊𝒐𝒏 1 Newton is the amount of force needed to give 1kg an acceleration of 1m/s2 5.5 Circular Motion An object at steady speed in circular orbit is always accelerating as its direction is changing, but it gets no closer to the center Centripetal force is the force acting towards the center of a circle. It is a force that is needed, not caused, by circular motion, For example, when you swing a ball on a string round in a circle, the tension of the string is the centripetal force. If the string is cut then the ball will travel in a straight line at a tangent to the circle at the point where the string was cut. PAGE 4 OF 20 CIE IGCSE PHYSICS//0625 Centrifugal force is the force acting away from the center of a circle. This is what makes a slingshot go outwards as you spin it. The centrifugal force is the reaction to the centripetal force. It has the same magnitude but opposite direction to centripetal force. 𝒎𝒗𝟐 𝑭= 𝒓 5.10 Scalars and Vectors A scalar is a quantity that only has a magnitude (so it can only be positive) for example speed. A vector quantity has a direction as well as a magnitude, for example velocity, which can be negative. 5.6 Newton’s Laws First law of motion: If no external for is acting on it, an object will, if stationary, remain stationary, and if moving, keep moving at a steady speed in the same straight line Second law of motion: 𝑭 = 𝒎𝒂 Third law of motion: if object A exerts a force on object B, then object B will exert an equal but opposite force on object A 5.7 Moment 𝑴𝒐𝒎𝒆𝒏𝒕(𝑵𝒎) = 𝑭𝒐𝒓𝒄𝒆(𝑵) × 𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝒇𝒓𝒐𝒎 𝑷𝒊𝒗𝒐𝒕(𝒎) In equilibrium, clockwise moment = anticlockwise moment. Increasing force or distance from the pivot increases the moment of a force Levers are force magnifiers o Turning a bolt is far easier with a wrench because distance from pivot is massively increased, and so is the turning effect 5.8 Centre of Mass Centre of mass: imaginary point in a body where total mass of body seems to be acting Working out the center of mass: o Mark three points on the edge of the card o Make a hole using a pin on each point o Hang it on a cork board and make a line when it is stable o Do this for all three points o Where all three lines intersect, this is the center of mass 5.9 Stability 6. MOMENTUM Linear momentum: product of mass and velocity 𝒑 = 𝒎𝒗 Principle of conservation of linear momentum: when bodies in a system interact, total momentum remains constant provided no external force acts on the system. 𝒎𝑨 𝒖𝑨 + 𝒎𝑩 𝒖𝑩 = 𝒎𝑨 𝒗𝑨 + 𝒎𝑩 𝒗𝑩 Impulse: product of force and time for which it acts 𝑭𝒕 = 𝒎𝒗 – 𝒎𝒖 7. ENERGY, WORK, AND POWER 7.1 Energy Energy: amount of work and its measured in Joules (J) An object may have energy due to its motion or its position Conservation of energy: energy cannot be created or destroyed, when work is done, energy is changed from one form to another Energy can be stored ENERGY TYPE WHAT IT IS EXAMPLE KINETIC Due to motion Car moving GRAVITATIONAL From potential to fall Book on shelf Bonds in starch CHEMICAL In chemical bonds (food) Stretched elastic STRAIN Compress/stretch band Atoms Released in NUCLEAR rearranged/split nuclear plant In a glass of INTERNAL Motion of molecules water ELECTRICAL Carried by electrons Battery to bulb LIGHT Carried in light waves From sun Carried in sound SOUND From speaker waves An object will be in stable equilibrium when it returns to its original position given a small displacement For an object to start rotating it needs to have an unbalanced moment acting on it PAGE 5 OF 20 CIE IGCSE PHYSICS//0625 𝐾𝑖𝑛𝑒𝑡𝑖𝑐 𝑒𝑛𝑒𝑟𝑔𝑦 = 1⁄2 × 𝑀𝑎𝑠𝑠 × 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 2 𝑲. 𝑬. = 𝟏⁄𝟐 𝒎𝒗𝟐 𝐺𝑟𝑎𝑣𝑖𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑃𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝐸𝑛𝑒𝑟𝑔𝑦 = 𝑀𝑎𝑠𝑠 × 𝐺𝑟𝑎𝑣𝑖𝑡𝑦 × 𝐻𝑒𝑖𝑔ℎ𝑡 𝑮. 𝑷. 𝑬. = 𝒎𝒈𝒉 Example of conversion of energy: A book on a shelf has g.p.e , if it falls of the shelf it will have k.e 7.2 Energy Resources Renewable sources are not exhaustible Non-renewable sources of energy are exhaustible TYPE ADVANTAGES DISADVANTAGES Fuel: burnt to Harmful wastes: Cheap make thermal o Greenhouse/ energy, makes Plentiful pollutant gas steam, turns Low-tech o Radiation turbine Wave energy: generators driven No greenhouse by up and down Difficult to build gases produced motion of waves at sea. Tidal energy: dam built where river meets sea, lake fills when tides Expensive No greenhouse comes in & Can’t be built gases produced empties when everywhere tide goes out; water flow runs generator Hydroelectric: river & rain fill up Low impact on lake behind dam, environment Few areas of the water released, Energy produced world suitable at constant rate turns turbine generator Geothermal: Deep drilling water pumped No CO2 difficult and down to hot rocks produced expensive rising as steam Nuclear fission: Produces a lot of uranium atoms Produces energy with very split by shooting radioactive waste little resources neutrons at them Solar cells: made of materials that deliver electrical current when it Variable amount No CO2 absorbs light of sunshine in produced some countries Solar panels: absorbs energy and use it to heat water The sun is the source of energy for all our energy resources except geothermal, nuclear and tidal In the sun, energy is created through a process called nuclear fusion: hydrogen nuclei are pushed together to form helium. Efficiency: how much useful work is done with energy supplied 𝑼𝒔𝒆𝒇𝒖𝒍 𝒆𝒏𝒆𝒓𝒈𝒚 𝒐𝒖𝒕𝒑𝒖𝒕 × 𝟏𝟎𝟎% 𝑬𝒏𝒆𝒓𝒈𝒚 𝒊𝒏𝒑𝒖𝒕 𝑼𝒔𝒆𝒇𝒖𝒍 𝒑𝒐𝒘𝒆𝒓 𝒐𝒖𝒕𝒑𝒖𝒕 𝑬𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒄𝒚 = × 𝟏𝟎𝟎% 𝑷𝒐𝒘𝒆𝒓 𝒊𝒏𝒑𝒖𝒕 𝑬𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒄𝒚 = 7.3 Work Work is done whenever a force makes something move. The unit for work is the Joule (J). 1 joule of work = force of 1 Newton moves an object by 1 meter 𝑾𝒐𝒓𝒌 𝒅𝒐𝒏𝒆 (𝑱) = 𝑭𝒐𝒓𝒄𝒆 (𝑵) × 𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆 (𝒎) 𝑾 = 𝑭𝑫 7.4 Power Power is the rate of work The unit for power is Watts (W) 1W = 1J/s 𝑷𝒐𝒘𝒆𝒓 (𝑾) = 𝑾𝒐𝒓𝒌 𝑫𝒐𝒏𝒆 (𝑱) 𝑻𝒊𝒎𝒆 𝑻𝒂𝒌𝒆𝒏 (𝒔) 8. PRESSURE 8.1 Pressure in Solids 𝑷𝒓𝒆𝒔𝒔𝒖𝒓𝒆 (𝑷𝒂) = 𝑷= Unit: Pascals (Pa) = N/m2 PAGE 6 OF 20 𝑭 𝑨 𝑭𝒐𝒓𝒄𝒆 (𝑵) 𝑨𝒓𝒆𝒂 (𝒎𝟐 ) CIE IGCSE PHYSICS//0625 8.2 Pressure in Liquids 𝑷𝒓𝒆𝒔𝒔𝒖𝒓𝒆(𝑷𝒂) = 𝑫𝒆𝒏𝒔𝒊𝒕𝒚(𝒌𝒈/𝒎𝟑 ) × 𝑮𝒓𝒂𝒗𝒊𝒕𝒚(𝒎/𝒔𝟐 ) × 𝑯𝒆𝒊𝒈𝒉𝒕(𝒎) 𝑷 = 𝒉𝝆𝒈 At a depth of 10m in water, the pressure is always 100,000 Pa (1bar) and is constant for each further 10m. 8.3 Atmospheric Pressure 1 atm = 101.325 X 103 Pa = 101 KPa MANOMETER BAROMETER Atoms vibrate No fixed pattern, Particles far but can’t change liquids take apart, and move position ∴ fixed shape of their quickly volume and container Collide with each shape Particles slide other and past each other. bounce in all directions 9.2 Pressure in Gases The pressure gases exert on a container is due to the particles colliding on the container walls. If the volume is constant, then increasing the temperature will increase the pressure. 9.3 Brownian Motion A manometer measures the pressure difference. The height difference shows the excess pressure in addition to the atmospheric pressure. Tube with vacuum at the top and mercury filling the rest. Pressure of the air pushes down on reservoir, forcing mercury up the tube. Measure height of mercury ~760 mm of mercury is 1 atm. 9. SIMPLE KINETIC MOLECULAR MODEL OF MATTER 9.1 States of Matter SOLID LIQUID GAS Fixed shape and Fixed volume but No fixed shape volume changes shape or volume, gases Strong forces of depending on its fill up containers attraction container Almost no between Weaker intermolecular particles attractive forces forces Fixed pattern than solids (lattice) Gas molecules move at a random motion This is because of repeated collisions with other gas molecules Small molecules move much faster and have higher energy than larger molecules The small particles can help move the larger particles Brownian motion can be seen visually in smoke 9.4 Evaporation It is the escape of more energetic particles and occurs constantly on surface of liquids. If more energetic particles escape, liquid contains few high energy particles and more low energy particles so average temperature decreases. Evaporation can be accelerated by: o Increasing temperature: more particles have energy to escape o Increasing surface area: more molecules are close to the surface o Reduce humidity level in air: if the air is less humid, fewer particles are condensing. o Blow air across the surface: removes molecules before they can return to liquid 9.5 Pressure Changes 𝑷𝟏 𝑽𝟏 = 𝑷𝟐 𝑽𝟐 10. THERMAL PROPERTIES & TEMPERATURE 10.1 Thermal Expansion of Solids, Liquids & Gases Solids, liquids and gasses expand when they are heated as atoms vibrate more and this causes them to become further apart, taking up a greater volume. PAGE 7 OF 20 CIE IGCSE PHYSICS//0625 Due to differences in molecular structure of the different states of matter, expansion is greatest in gases, less so in liquids and lowest in solids Applications and consequences of thermal expansion: o Overhead cables have to be slack so that on cold days, when they contract, they don’t snap or detach. o Gaps have to be left in bridge to allow for expansion o Bimetal thermostat: when temperature gets too high, bimetal strip bends, to make contacts separate until temperature falls enough, then metal strip will become straight again and contacts touch, to maintain a steady temperature For a fixed mass of gas at constant pressure, the volume is directly proportional to the Kelvin temperature 10.2 Measurement of Temperature A physical property that varies with temperature may be used for measurement of temperature Liquid-in-glass thermometer: o As temperature rises or falls, the liquid (mercury or alcohol) expands or contracts. o Amount of expansion can be matched to temperature on a scale. Thermistor thermometer: o The probe contains a thermistor o The thermistor is a material that becomes a better electrical conductor when the temperature rises (semi-conductor) o So when temperature increases, a higher current flows from a battery, causing a higher reading on the meter Thermocouple thermometer: o The probe contains 2 different metals joined metals to form 2 junctions. o The temperature difference causes a tiny voltage which makes a current flow. o A greater temp. difference gives a greater current. o Thermocouple thermometers are used for high temperatures which change rapidly and have a large range (-200C° to 1100°C) Fixed points are definite temperatures at which something happens and are used to calibrate a thermometer. For example, melting and boiling point of water Calibrating a thermometer: o Place thermometer in melting ice, this is 0 °C. o Place thermometer in boiling water, this is 100 °C. Sensitivity: change in length or volume per degree To increase sensitivity: o Thinner capillary o Less dense liquid o Bigger bulb Range: change the upper and lower fixed points Linearity: change the distance between intervals o Responsiveness: how long it takes for the thermometer to react to a change in temperature 10.3 Melting This is when a solid turns into a liquid. Temperature increases thus kinetic energy in solid increases and particles vibrate more rapidly but there is no increase in temperature of the substance when melting because thermal energy supplied is instead being used to break bonds between particles of the solid thus making it into a liquid. Boiling point is the temp. at which a substance boils 10.4 Boiling This is when a liquid turns into a gas Temperature increases thus kinetic energy in liquid increases and particles vibrate more rapidly but there is no increase in temperature of the substance when boiling because thermal energy supplied is instead being used to break bonds between particles of the liquid thus making it into a gas. PAGE 8 OF 20 CIE IGCSE PHYSICS//0625 Melting point is the temp. at which a substance melts The difference between boiling and evaporation is that: o Boiling occurs at a fixed temperature and throughout the liquid o Evaporation occurs at any temperature and only on the surface 10.5 Latent Heat The latent heat of fusion is the amount of energy needed to melt 1Kg of a substance. The latent heat of vaporization is the amount of energy needed to boil 1Kg of a substance 𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑜𝑓 𝐹𝑢𝑠𝑖𝑜𝑛/𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 = 𝑳𝒇 /𝑳𝒗 = 𝑬 𝒎 𝐸𝑛𝑒𝑟𝑔𝑦 𝑇𝑟𝑎𝑛𝑠𝑓𝑒𝑟𝑟𝑒𝑑 𝑀𝑎𝑠𝑠 11.3 Convection Convection is the flow of heat through a fluid from places of higher temperature in places of lower temperature by movement of the fluid itself. As a fluid (liquid or gas) warms up, the particles which are warmer become less dense and rise. They then cool and fall back to the heat source, creating a cycle called convection current. As particles circulate they transfer energy to other particles. If a cooling object is above a fluid it will create a convection current 11.4 Radiation 10.6 Condensation and Solidification Condensation is when a gas turns back into a liquid. When a gas is cooled, the particles lose energy. They move more and more slowly. When they bump into each other, they do not have enough energy to bounce away again so they stay close together, and a liquid forms. When a liquid cools, the particles slow down even more. Eventually they stop moving except for vibrations and a solid forms. 11. THERMAL PROCESSES 11.1 Conductors Good conductors are used whenever heat is required to travel quickly through something Bad conductors (insulators) are used to reduce the amount of heat lost to the surroundings 11.2 Conduction Conduction is the flow of heat through matter from places of higher temperature to places of lower temperature without movement of the matter as a whole In non-metals - when heat is supplied to something, its atoms vibrate faster and pass on their vibrations to the adjacent atoms. In metals – conduction happens in the previous way and in a quicker way –electrons are free to move, they travel randomly in the metal and collide with atoms and pass on the vibrations. Radiation is the flow of heat from one place to another by means of electromagnetic waves Thermal radiation is mainly infra-red waves, but very hot objects also give out light waves. Infra-red radiation is part of the electromagnetic spectrum. MATT BLACK WHITE SILVER EMITTER Best Worst REFLECTOR Worst Best ABSORBER Best Worst An emitter sends out thermal radiation. A reflector reflects thermal radiation, therefore is a bad absorber. An emitter will cool down quickly, an absorber will heat up more quickly and a reflector will not heat up quickly 11.5 Application of Energy Transfer Solar panel: the sun’s thermal radiation is absorbed by a matt black surface and warms up the pipes containing water Refrigerator: the freezer compartment is located at the top of the refrigerator. It cools down the air which then sinks. Any warm air rises to the top and then is cooled. This creates a convection current which maintains a cold temperature. Metals used in cooking pans because they conduct heat well 11.6 Consequences of Energy Transfer Metal spoon in a hot drink will warm up because it conducts heat PAGE 9 OF 20 CIE IGCSE PHYSICS//0625 Convection currents create sea breezes. During the day the land is warmer and acts as heat source. During the night the sea acts as the heat source. A black saucepan cools better than a white one, white houses stay cooler than dark ones. When wave is slowed down, it is refracted towards normal (i > r) When wave is sped up, it is refracted away from normal (i < r) Deep water is denser than shallow water 12. GENERAL WAVE PROPERTIES Waves transfer energy without transferring matter Frequency: the number of waves passing any point per second measured in hertz (Hz) 𝟏 𝑭𝒓𝒆𝒒𝒖𝒆𝒏𝒄𝒚 = 𝑷𝒆𝒓𝒊𝒐𝒅 Period: time taken for one oscillation in seconds Wavefront: the peak of a transverse wave or the compression of a longitudinal wave Speed: how fast the wave travels measured in m/s Wavelength: distance between a point on one wave to the equivalent point on the next wave in meters Amplitude: maximum distance a wave moves from its rest position when a wave passes When water wave travels from deep to shallow; speed decreases, wavelength decreases and frequency remains constant When water waves travel from shallow to deep; speed increases wavelength increases and frequency remains constant 12.2 Reflection Waves bounce away from surface at same angle they strike it Angle of incidence = angle of reflection Speed, wavelength and frequency are unchanged by reflection 12.3 Diffraction TRANSVERSE WAVES LONGITUDINAL WAVES Travelling waves in Travelling waves in which oscillation is which oscillation is parallel to direction of perpendicular to travel. direction of travel Has compressions and Has crests and troughs rarefactions For example, light, water For example, sound waves and vibrating waves string 𝑆𝑝𝑒𝑒𝑑 (𝑚/𝑠) = 𝐹𝑟𝑒𝑞𝑢𝑛𝑐𝑦(𝐻𝑧) × 𝑊𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡ℎ(𝑚) 𝑽 = 𝑭𝝀 12.1 Refraction Speed and wave length is reduced but frequency stays the same and the wave changes direction Waves slow down when they pass from a less to a more dense material and vice versa Waves bend round the sides of an obstacle, or spread out as they pass through a gap. Wider gaps produce less diffraction. When the gap size is equal to the wavelength, maximum diffraction occurs 13. LIGHT 13.1 Reflection of Light Plane (flat) mirrors produce a reflection. Rays from an object reflect off the mirror into our eyes, but we see them behind the mirror. The image has these properties: o Image is the same size as the object o Image is the same distance from the mirror as object o A line joining equivalent points of the image and object meet the mirror at a right angle o Image is virtual: no rays actually pass through the image and the image cannot be formed on a screen PAGE 10 OF 20 CIE IGCSE PHYSICS//0625 Laws of reflection: Angle of incidence = angle of reflection The incident ray, reflected ray and normal are always on the same plane (side of mirror) 13.2 Refraction of Light Refraction is the bending when light travels from one medium to another 13.3 Experimental Demonstration – Ray Box Using the ray box, pass a ray through a glass slab on a white sheet of paper. Mark two points on the incident ray, refracted ray, emergent ray and draw an outline of the glass slab with a pencil on paper Then by connecting the dots you can produce a diagram like the one below, a protractor is used to find the angles. When a ray passes through a parallel sided transparent material its passage will look like this: 𝐬𝐢𝐧 𝒊 𝐬𝐢𝐧 𝒓 𝑪𝒓𝒊𝒕𝒊𝒄𝒂𝒍 𝒂𝒏𝒈𝒍𝒆 = 𝐬𝐢𝐧−𝟏 𝟏⁄𝒏 𝑹𝒆𝒇𝒓𝒂𝒄𝒕𝒊𝒗𝒆 𝑰𝒏𝒅𝒆𝒙 = 13.5 Optical Fibres Light put in at one end is totally internally reflected until it comes out the other end. Used in communications: signals are coded and sent along the fiber as pulses of laser light Used in medicine: an endoscope, an instrument used by surgeons to look inside the body; contains a long bundle of optic fibers. 13.6 Thin Converging Lens Principal focus: the point where rays parallel to the principal axis converge with a converging lens. Focal length: distance from principle focus and the optical center. Principal axis: line that goes through optical center, and the 2 foci. Optical center: the center of the lens Real: image can be caught on a screen Virtual: image cannot be caught on a screen Real Image When object is further away from the optical centre than F’ is Note: the emergent ray is parallel to the incident ray 13.4 Critical Angle Angle at which refracted ray is parallel to the surface of material. If angle of incidence is greater than the critical angle there is no refracted ray, there is total internal reflection. If angle of incidence is less than the critical angle the incidence ray will split into a refracted ray and a weaker reflected ray. 𝑹𝒆𝒇𝒓𝒂𝒄𝒕𝒊𝒗𝒆 𝑰𝒏𝒅𝒆𝒙 = A) A ray through centre of the lens passes straight through the lens. B) A ray parallel to the principal axis passes through the focus on the other side of the lens C) A ray through F’ will leave the lens parallel to the principal axis Virtual Image When the object is closer to the optical centre than F’ is 𝑺𝒑𝒆𝒆𝒅 𝒐𝒇 𝒍𝒊𝒈𝒉𝒕 𝒊𝒏 𝒗𝒂𝒄𝒖𝒖𝒎 𝑺𝒑𝒆𝒆𝒅 𝒐𝒇 𝒍𝒖𝒈𝒉𝒕 𝒊𝒏 𝒂 𝒎𝒆𝒅𝒊𝒖𝒎 PAGE 11 OF 20 CIE IGCSE PHYSICS//0625 Magnifying glass: when a convex lens is used like this an object is closer to a convex (converging) lens than the principal focus (like the diagram above), the rays never converge. Instead, they appear to come from a position behind the lens. The image is upright and magnified, it is a virtual image. 13.7 Dispersion of Light Refraction by a prism: When light is refracted by a prism, the incidence ray is not parallel to the emergent ray, since the prism’s sides are not parallel. If a beam of white light is passed through a prism it is dispersed into a spectrum. White light is a mixture of colors, and the prism refracts each color by a different amount – red is deviated least & violet most 13.8 Light Spectrum 13.9 Electromagnetic Spectrum All electromagnetic waves: Travel at the speed of light: 3 × 108m/s Don’t need a medium to travel through (travel through a vacuum) Can transfer energy Are produced by particles oscillating or losing energy in some way Are transverse waves 13.10 Uses Radio waves: radio and television communications Microwaves: satellite television and telephones o Safety issue: cause internal heating of body tissues Infrared: electrical appliances (radiant heaters and grills), remote controllers for televisions and intruder alarms X-rays: medicine (x-ray photography and killing cancer cells) and security o Safety issue: is a mutagen, it cause cancer (mutations) Monochromatic: light of a single wavelength and color (used in lasers) 14. SOUND 14.1 Production Sound waves come from a vibrating source e.g. loudspeaker As the loudspeaker cone vibrates, it moves forwards and backwards, which squashes & stretches the air in front. As a result, a series of compressions (squashes) and rarefactions (stretches) travel out through the air, these are sound waves 14.2 Properties Sound waves are longitudinal: they have compressions and rarefactions and oscillate backwards and forwards. Humans can hear frequencies between 20 and 20 000Hz. Sound waves need a medium to travel through. Ultrasound Waves: high frequency sound waves, medically used to look at structures and organs inside the human body, i.e. to form an image of a fetus in a pregnancy Compression: high pressure section of the wave Rarefaction: low pressure section of the wave The higher the frequency, the higher the pitch. The higher the amplitude, the louder the sound 14.3 Speed of Sound MEDIUM STATE CONCRETE Solid PURE WATER Liquid AIR Gas 𝑉 𝑮𝒂𝒔 < 𝑽 𝑳𝒊𝒒𝒖𝒊𝒅 < 𝑽 𝑺𝒐𝒍𝒊𝒅 PAGE 12 OF 20 SPEED 5000 m/s 1400 m/s 330 m/s CIE IGCSE PHYSICS//0625 14.4 Experiment: Finding Speed of Sound When sound reflects off of a wall, it will come back to you; echo If you know the distance between you and the wall, and measure how long it takes for the echo to sound, you can figure out the speed of sound in air. Remember to take into account that sound has gone there & back 15. SIMPLE PHENOMENA OF MAGNETISM 15.1 Properties of Magnets Has a magnetic field around it Has 2 opposite poles (North and South) which exert forces on other magnets. Like poles repel and unlike poles attract. Will attract magnetic materials by inducing (permanent or temporary) magnetism in them. Will exert little or no force on a non-magnetic material The direction of an electric field at a point is the direction of the force on a positive charge at that point 15.2 Induced Magnetism Magnets attract materials by inducing magnetism in them; the material becomes a magnet as well. The side of the material facing the magnet will become the opposite pole as the magnet. FERROUS NON-FERROUS Magnetic materials Non-magnetic materials IRON NICKEL COBALT 15.3 Magnetisation Methods A piece of steel becomes permanently magnetized when placed near a magnet, but its magnetism is usually weak. It can be magnetized more strongly by stroking it with one end of a magnet Most effective method: place it in a solenoid and pass a large, direct current (d.c.) through the coil. 15.4 Demagnetisation Methods If a magnet is hammered, its atomic magnets are thrown out of line and it becomes demagnetized. Heating a magnet to a high temperature also demagnetize it. Most efficient method: place magnet inside a solenoid connected to an alternating current (a.c.) supply. 15.5 Experiment: Field Lines Around Bar Magnet The magnetic field lines can be traced on a paper by a compass needle (a tiny magnetic needle). The compass needle is first placed near the north pole of magnet. The position of poles of needle are marked on paper. Then needle is moved to new position such that position of its south pole coincides with previous position of its north pole. This process is continued until the needle reaches South Pole. By joining these points we get to magnetic line of force. Then it is placed at some other position near North Pole and above procedure id repeated. 15.6 Magnetic Properties of Iron and Steel IRON Gets magnetized faster but loses its magnetism as soon as inducing magnet is removed. High susceptibility but low retentivity Use: core in the transformer STEEL Slow to be magnetized but retains acquired magnetism for a long time. Low susceptibility but high retentivity. Use: making magnets. 15.7 Permanent Magnets & Electromagnets PERMANENT MAGNET Design: hard magnetic material Use: for applications where magnetism is needed over long periods – fridge doors ELECTROMAGNET Design: Uses a solenoid to create magnetic field Use: For applications where magnetic field needs to be turned on & off - scrap metal moving 16. ELECTRICAL QUANTITIES 16.1 Electric Charge You can detect an electrostatic charge using a leaf electroscope. o If a charged object is placed near the cap, charges are induced. o The metal cap gets one type of charge (positive or negative) and the metal stem and gold leaf get the other type of charge so they repel each other. PAGE 13 OF 20 CIE IGCSE PHYSICS//0625 The conventional current is the opposite of what actually happens. Red=conventional current Green=actual current There are 2 types of charges: positive and negative. Unlike charges attract and like charges repel. Electric field: region in which electric charge experiences a force Conductors: materials that let electrons pass through them. o Metals are the best electrical conductors as they have free electrons. Insulators: materials that hardly conduct at all. o Their electrons are tightly held to atoms and hardly move, but they can be transferred by rubbing The SI unit of charge is the Coulomb (C). 16.2 Electric Field Lines Parallel plates Point charge +ve and -ve +ve and +ve 1𝑒̅ = 1.6 × 10−19 𝐶 1𝐶 = 6.25 × 1018 𝑒̅ 16.5 Electromotive Force (EMF) The maximum voltage a cell can produce is called the electromotive force (EMF), measured in volts. When a current is being supplied, the voltage is lower because of the energy wastage inside the cell. A cell produces its maximum PD when not in a circuit and not supplying current. 16.6 Potential Difference (P.D) Potential difference, or PD for short, is also known as voltage. Voltage is the amount of energy the cell gives the electrons it pushes out. Voltage is measured in volts (V) and is measured by a voltmeter (connected in parallel). If a cell has 1 Volt, it delivers 1 Joule of energy to each coulomb of charge (J/C). 𝑬𝒏𝒆𝒓𝒈𝒚 𝑪𝒉𝒂𝒓𝒈𝒆 𝑬 𝑽= 𝑪 𝑽𝒐𝒍𝒕𝒂𝒈𝒆 = 16.3 Induced Charge A charge that “appears” on an uncharged object because of a charged object nearby For example if a positively charged rod is brought near a small piece of aluminum foil, electrons in foil are pulled towards rod, which leaves the bottom of the foil with a net positive charge. The attraction is stronger than repulsion because the attracting charges are closer than the repelling ones. 16.4 Current Current: a flow of charge, the SI unit is the Ampere (A). An ammeter measures the current in a circuit and is connected in series Current is a rate of flow of charge. 𝐶ℎ𝑎𝑟𝑔𝑒 (𝐶) = 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 (𝐴) × 𝑇𝑖𝑚𝑒 (𝑠) 𝑄 = 𝐼𝑡 Current follows path of least resistance 16.7 Resistance 𝑹𝒆𝒔𝒊𝒔𝒕𝒂𝒏𝒄𝒆 (Ω) = Factors affecting resistance: Length o𝑅∝𝐿 Cross-sectional area 1 o𝑅∝𝐴 𝑽𝒐𝒍𝒕𝒂𝒈𝒆 𝑽 = 𝑪𝒖𝒓𝒓𝒆𝒏𝒕 𝑰 Material o Better conductor = less resistance Temperature o For metal conductors higher temperature = more resistance o For semi-metal conductors higher temperature PAGE 14 OF 20 CIE IGCSE PHYSICS//0625 16.8 V-I Characteristics of a Resistor Lightdependent resistors Ohm’s law states that voltage across a resistor is directly proportional to the current through it. This is only true if the temperature of the resistor remains constant 16.9 Electrical Energy Lamp Ammeter Measure current Voltmeter Measure voltage Galvanometers Type of sensitive ammeter; instrument for detecting electric current. 1 Watt is 1J/s 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝑝𝑜𝑤𝑒𝑟 = 𝑉𝑜𝑙𝑡𝑎𝑔𝑒 (𝑉) × 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 (𝐴) 𝑷 = 𝑽𝑰 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 = 𝑉𝑜𝑙𝑡𝑎𝑔𝑒 (𝑉) × 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑬 = 𝑽𝑰𝒕 17. ELECTRICAL CIRCUITS 17.1 Circuit Diagrams COMPONENT Cell Battery DC Supply AC Supply Switch Fixed resistor Variable resistor SYMBOL Bell Fuse Flows in one direction Flows in both direction Allows current only to flow when the switch is closed Restrict the flow of current. Used to control current (by varying the resistance) Heaters Thermistor Magnetizing Coil Transformer FUNCTION Supplies electrical energy. Larger terminal (left) is positive (+). Supplies electrical energy. A battery is more than one cell. Larger terminal (left) is positive (+). Resistor whose resistance varies with temperature Resistor whose resistance varies with light intensity Transducer which converts electrical energy to light Relay Two coils of wire linked by an iron core. Transformers are used to increase and decrease AC voltages. Transducer which converts electrical energy to sound A safety device which will 'blow' (melt) if current flowing through it exceeds specified value, breaking circuit An electrically operated switch, e.g. a 9V battery circuit connected to the coil can switch a 230V AC mains circuit (the electromagnet is used to pull away the contacts and vice versa) 17.2 Series and Parallel Circuits The current at any point in a series circuit is the same The current splits at each branch in a parallel circuit so the total current is always greater than the current in one branch PAGE 15 OF 20 CIE IGCSE PHYSICS//0625 Combining resistors o In Series: 𝑹𝑻𝒐𝒕𝒂𝒍 = 𝑹𝟏 + 𝑹𝟐 𝟏 o In Parallel: 𝑹𝑻𝒐𝒕𝒂𝒍 = 𝟏 𝟏 NORMAL CLOSED RELAY NORMALLY OPEN RELAY ⁄𝑹 + ⁄𝑹 𝟏 𝟐 o The combined resistance of 2 resistors in parallel is less than that of either resistor by itself Advantages of putting lamps in parallel are: o If one lamp breaks, the other still works o Each lamp gets maximum PD In series: PD across the supply = PD across all the components combined In parallel: Current across the source = sum of currents in the separate branches 17.3 Potential Divider A potential divider divides the voltage into smaller parts. To find the voltage (at VOUT) we use the following formula: 𝑹𝟐 𝑽𝑶𝑼𝑻 = 𝑽𝑰𝑵 × ( ) 𝑹𝑻𝒐𝒕𝒂𝒍 A variable potential divider (potentiometer) is the same as the one above but using a variable resistor; it acts like a potential divider, but you can change output voltage. 17.4 Input Transducer Thermistor: input sensor and a transducer. It is a temperature-dependent resistor. At higher temperature there is less resistance. Light dependent resistor (LDR): input sensor and a transducer. When light intensity increases, resistance decreases. When coil not energized, switch is closed, completing circuit When coil energized, switch is closed, completing circuit 17.6 Diode A device that has an extremely high resistance in one direction and a low resistance in the other, therefore it effectively only allows current to flow in one direction Forward bias is when the diode is pointing in the direction of the conventional current and reverse bias is the opposite It can be used in a rectifier; turns AC current into DC current. 17.7 Digital Electronics Analogue uses a whole range of continuous variations to transmit a signal. Digital signals use only 2 states, on and off. Logic gates are processors that are circuits containing transistors and other components. 17.5 Relay A switch operated by an electromagnet PAGE 16 OF 20 CIE IGCSE PHYSICS//0625 18. DANGERS OF ELECTRICITY 19. ELECTROMAGNETIC EFFECTS 18.1 Hazards 19.1 Electromagnetic Induction Damaged insulation: contact with the wire (live wire especially) due to gap in the insulation causes electric shock which can cause serious injury or shock. Overheating of cables: when long extension leads are coiled up, they may overheat. The current warms the wire, but the heat has less area to escape from a tight bundle. This might cause a fire. Damp conditions: water can conduct a current, so if electrical equipment is wet someone might get electrocuted FUSE CIRCUIT BREAKER Wire passed across a magnetic field: If a wire is passed across a magnetic field, a small EMF is induced, If the wire forms part of a complete circuit, the EMF makes a current flow and this can be detected using a galvanometer. The EMF induced in a conductor is proportional to the rate at which the magnetic field lines are cut by the conductor. The induced EMF can be increased by: o moving the wire faster o using a stronger magnet o Increasing length of wire in magnetic field, e.g. looping the wire through the field several times. The current and EMF direction can be reversed by: o moving the wire in the opposite direction o turning the magnet round so that the field direction is reversed Fleming’s right-hand rule gives the current direction: A fuse protects a circuit. An automatic switch Thin piece of wire which which if current rises over overheats and melts if a specified value, the current is too high. It is electromagnet pulls the placed on the live wire contacts apart, breaking before the switch. This the circuit. The reset prevents overheating and button is to rest catching fire. A fuse will everything. It works like a have a specific current fuse but is better because value (e.g. 13a) so when it can be reset. choosing a suitable fuse you must use the one above minimum value but less than maxiumum value Benefits of Earthing a Metal Case: o Many electrical appliances, have metal cases, the earth wire creates a safe route for current to flow through, if live wire touches casing o Earth terminal connected to metal casing, so the current goes through earth wire instead of causing an electric shock. o A strong current surges through earth wire because it has very low resistance o This breaks the fuse and disconnects the appliance Bar magnet pushed into coil The induced EMF (and current) can be increased by: o moving the magnet faster o using a stronger magnet o increasing the number of turns in the coil If the magnet is pulled away, the direction of the induced EMF (and current) is reversed PAGE 17 OF 20 CIE IGCSE PHYSICS//0625 Using South pole instead of North pole reverses direction of induced EMF (and current) If the magnet is held still, there is no EMF An induced current always flows in a direction such that it opposes the change which produced it. When a magnet is moved towards a coil the pole of the coil and magnet next to each other are the same. When the magnet is moved away the poles are opposite (opposite poles attract). The pole-type (north or south) is controlled by the direction in which the current is induced. The direction of the current is given by the right-hand grip rule: 19.3 Transformers AC currents can be increased or decreased by using a transformer. Consists of a primary coil, a secondary coil and an iron core. The iron core gets magnetized by the incoming current and this magnetism then creates a current in the leaving wire. The power is the same on both sides (assume= 100% efficiency). You can figure out number of coils and the voltage with: 𝑶𝒖𝒕𝒑𝒖𝒕 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 𝑻𝒖𝒓𝒏𝒔 𝒐𝒏 𝒐𝒖𝒕𝒑𝒖𝒕 𝒄𝒐𝒊𝒍 = 𝑰𝒏𝒑𝒖𝒕 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 𝑻𝒖𝒓𝒏𝒔 𝒐𝒏 𝒊𝒏𝒑𝒖𝒕 𝒄𝒐𝒊𝒍 𝑽𝑷 𝑽𝑺 = 𝑵𝑷 𝑵𝑺 𝑰𝒏𝒑𝒖𝒕 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 × 𝒊𝒏𝒑𝒖𝒕 𝒄𝒖𝒓𝒓𝒆𝒏𝒕 = 𝒐𝒖𝒕𝒑𝒖𝒕 𝒗𝒐𝒍𝒕𝒂𝒈𝒆 × 𝒐𝒖𝒕𝒑𝒖𝒕 𝒄𝒖𝒓𝒓𝒆𝒏𝒕 The fingers point in the conventional current direction and the thumb gives the North Pole. 19.2 A.C. Generator The oil is made of insulated copper wire and is rotated by turning the shaft; the slip rings are fixed to the coil and rotate with it. The brushes are 2 contacts which rub against the slip rings and keep the coil connected to the outside part of the circuit, usually made of carbon. When the coil is rotated, it cuts magnetic field lines, so an EMF is generated, which makes a current flow. Each side of the coil travels upwards then downwards then upwards etc. so the current flows backwards then forwards then backwards etc. so it is an alternating current. The current is maximum when the coil is horizontal since field lines are being cut at the fastest rate and 0 when the coil is vertical, since it is cutting NO field lines. The EMF can be increased by: o increasing the number of turns on the coil o increasing the area of the coil o using a stronger magnet o rotating the coil faster 𝑽𝟏 × 𝑰𝟏 = 𝑽𝟐 × 𝑰𝟐 When magnetic field is changed across the primary coil by connecting it with A.C. an e.m.f. induces across the secondary coil. The iron core channels the alternating field through the secondary coil, inducing an alternating e.m.f. across it. A step-up transformer increases the voltage and a stepdown transformer decreases it. Transformers used to make high voltage AC currents. Since power lost in a resistor 𝑷 = 𝑰𝟐 × 𝑹, having a lower current will decrease the power loss. Since transmission cables are many kilometres long they have a lot of resistance, so a transformer is used to increase the voltage and decrease the current to decease power lost. The advantages of high-voltage transmission: o less power lost o thinner, light, and cheaper cables can be used since current is reduced 19.4 Electromagnetic Effect of a Current Magnetic field around a current carrying wire PAGE 18 OF 20 Magnetic field around a current carrying solenoid CIE IGCSE PHYSICS//0625 Increasing the current increases the strength of the field Increasing the number of turns of a coil increases the strength. Reversing the current direction reverses the magnetic field direction (right-hand rule). Magnetic effect of current is used in a relay and a circuit breaker 19.5 Force on a Current-Carrying Conductor If a current carrying conductor is in a magnetic field, it warps the field lines. The field lines from the magnet want to straighten out naturally. This causes a catapult like action on the wire creating a force If you reverse current, you will reverse direction of force If you reverse direction of field, you will reverse direction of force. The direction of the force, current or magnetic field is given by Fleming’s left-hand rule: 19.6 D.C. Motor When a current-carrying coil is in a magnetic field, it experiences a turning effect. A DC motor runs on a direct current. The coil is made of insulated copper wire and is free to rotate between the poles of the magnet. The commutator (split-ring) is fixed to the coil and rotates with it. When the coil overshoots the vertical, the commutator changes direction of the current through it, so the forces change direction and keep the coil turning. The brushes are two contacts which rub against the commutator and keep the coil connected to battery, usually made of carbon The max. turning effect is when the coil is horizontal. There is no force when the coil is vertical but it always overshoots this position TURNING EFFECT REVERSING ROTATION CAN INCREASED BY: BE DONE BY: Increasing the current Reversing the battery Using a stronger magnet Reversing the poles Increasing length of coils: o Increasing no. of coils o Increasing area of coil 20. RADIOACTIVITY 20.1 Direction of Radioactivity Background radiation: small amount of radiation around us all time because of radioactive materials in the environment. It mainly comes from natural sources such as soil, rocks, air, building materials, food and drink – and even space. Geiger-Müller (GM) tube (detects 𝛼, 𝛽 and 𝛾) The ‘window’ is thin enough for alpha particles to pass through. If an alpha particle enters the tube, it ionizes gas inside. This sets off a high-voltage spark across the gas and a pulse of current in the circuit. A beta particle or gamma radiation has the same effect. It can be connected to a rate meter (tells the counts per seconds) or a scaler (tells total number of particles or bursts of gamma radiation) PAGE 19 OF 20 CIE IGCSE PHYSICS//0625 20.2 Characteristics of 3 Kinds of Emissions Radioactive emissions occur randomly over space & time ALPHA (𝜶) BETA (𝜷) GAMMA (𝜸) Helium One high Electronucleus (2 NATURE speed magnetic protons and electron radiation 2 electrons) CHARGE +2 -1 none Stopped by Stopped by Only reduced PENETRATION paper aluminum by lead EFFECT FROM Very Not Deflected FIELDS deflected deflected IONIZING Very strong Weak Very weak EFFECT 1⁄ 𝑣 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 9⁄ 𝑣 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 𝑣 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡 SPEED 10 10 20.3 Radioactive Decay Radioactive decay: A radioisotope (unstable arrangement of neutrons and protons) is altered to make a more stable arrangement. The parent nucleus becomes a daughter nucleus and a particle (decay products). Alpha decay: An element with a proton number 2 lower and nucleon number 4 lower, and an alpha particle is made (2p + 2n) e.g. Radium-226 nucleus → Radon-222 + helium-4 nucleus 226 222 4 88Ra → 86Rn + 2He Beta decay: A neutron changes into a proton, an electron and an antineutrino so an element with the same nucleon number but with a proton number 1 higher e.g. e.g. iodine-131 → xenon-131 + antineutrino + beta particle 131 131 0 0 53𝐼 → 54𝑋𝑒 + −1β + 0v Gamma emission: Gamma emission by itself causes no change in mass number or atomic number; they just emit energy Some isotopes do not change in mass or atomic number however they emit energy as their particles rearrange themselves to become more stable Kept away from the body and not pointed at people Left out of its container for as short a time as possible 20.6 Atomic Model Atoms consist of: Nucleus: central part of atom made of protons (positively charged) and neutrons. These two types of particles are called nucleons. They are bound together by the strong nuclear force. Electrons: almost mass-less particles which orbit nucleus in shells 20.7 Rutherford’s Experiment Thin gold foil is bombarded with alpha particles, which are positively charged. Most passed straight through, but few were repelled so strongly that they were bounced back or deflected at large angles. Rutherford concluded that the atom must be largely empty space, with its positive charge and most of its mass concentrated in a tiny nucleus. 20.8 Nucleus The nucleus is composed of protons and neutrons. Proton number: number of protons in an atom Nucleon number: the number of nucleons (protons + neutrons) in an atom 20.9 Isotopes Isotope: atoms of the same element that have different numbers of neutrons e.g. Carbon 12 and Carbon 14. There are non-radioactive isotopes and radio-isotopes. 20.4 Half Life Radio isotopes are unstable atoms, which break down Half-life of a radioisotope: is the time taken for half the giving radiation nuclei present in any given sample to decay. Medical use: cancer treatment (radiotherapy) – rays kill Some nuclei are more stable than others cancer cells using cobalt-60 Industrial use: to check for leaks – radioisotopes 20.5 Safety Precautions (tracers) added to oil/gas. At leaks radiation is detected Radioactive material is stored in a lead container using a Geiger counter. Picked up with tongs, not bare hands Archaeological use: carbon 14 – used for carbon dating PAGE 20 OF 20 TABLE OF CONTENTS 3 CHAPTER 1 4 CHAPTER 2 5 CHAPTER 3 6 CHAPTER 4 6 CHAPTER 5 7 CHAPTER 6 9 CHAPTER 7 11 CHAPTER 8 12 CHAPTER 9 14 Characteristic & Classification of Living Organisms Organization of the Organism Movement In and Out of Cells Biological Molecules Enzymes Plant Nutrition Human Nutrition Transport in Plants Transport in Animals CHAPTER 10 Diseases & Immunity CIE IGCSE BIOLOGY//0610 15 CHAPTER 11 16 CHAPTER 12 16 CHAPTER 13 17 CHAPTER 14 Gas Exchange in Humans Respiration Excretion in Humans Coordination & Response 21 Drugs CHAPTER 15 22 CHAPTER 16 27 CHAPTER 17 Reproduction Inheritance 28 Variation & Selection CHAPTER 18 29 CHAPTER 19 Organisms & their Environment 31 Biotechnology & Genetic Engineering CHAPTER 20 33 Human Influences on Ecosystems CHAPTER 21 PAGE 2 OF 35 CIE IGCSE BIOLOGY//0610 1. CHARACTERISTICS AND CLASSIFICATION OF LIVING ORGANISMS 1.1 Characteristics of Living Organisms Movement: action by an organism or part of an organism causing a change of position or place Respiration: the chemical reactions that break down nutrient molecules in living cells to release energy Sensitivity: ability to detect or sense changes in the environment (stimuli) and to make responses Growth: permanent increase in size and dry mass by an increase in cell number or cell size or both Reproduction: processes that make more of the same kind of organism Excretion: removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements Nutrition: taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them 1.2 Concept & Use of a Classification System Organisms can be classified into groups by the features that they share Classification systems aim to reflect evolutionary relationships (change of adaptive features of a population over time, as a result of natural selection) Species: organisms which can reproduce successfully Classification is traditionally based on studies of morphology and anatomy Morphology: the overall form and shape of their bodies e.g. wings or legs Anatomy: the detailed body structure determined by dissection Binomial system: a system of naming species in which the scientific name of an organism is made up of two parts showing the genus (starting with a capitol letter) and species (starting with a lower case letter), written in italics when printed (therefore underlined when written) e.g. Homo sapiens KING PHILIP CAME OVER FOR GOOD SPAGHETTI Kingdom, Phylum, Class, Order, Family, Genus, Species Kingdom Species = Similarity increases DNA is the chemical from which chromosomes are made Each DNA molecule is made up of strings of smaller molecules containing four bases Biologists compare the sequences of the bases in the DNA of organisms from two different species The more similar the base sequence, the more closely related the species are to one another Organisms which share a more recent ancestor have base sequences in DNA that are more similar than those that share only a distant ancestor The sequences of bases in DNA and of amino acids in proteins are used as a more accurate means of classification (cladistics) 1.3 Kingdoms Animal: Multi-cellular ingestive heterotrophs (eat living organisms) Plant: Multi-cellular photosynthetic autotrophic (make their own food) organism with a cellulose cell wall. Fungi: Single celled or multi cellular heterotrophic organism with cell wall not made of cellulose, spread by spreading of spores in moist/dark/warm environment, saprotrophs (feed off dead organisms) or parasites Prokaryotes: Single celled organism with no true nucleus Protocist: Single celled organism with a nucleus 1.4 Vertebrates MR FAB Mammals o Fur/hair on skin o Can live on land and in water o 4 legs o Lungs to breathe o Give birth to live young Reptiles: o Scales on skin o Usually 4 legs o Lungs to breathe o Hard eggs Fish: o Wet scales o External fertilization and soft eggs o Gills to breathe Amphibians: o Smooth, moist skin o External fertilization and soft eggs o Gills/lungs to breathe so can live on land and in water o 4 legs PAGE 3 OF 35 CIE IGCSE BIOLOGY//0610 Birds o Feathers on body and scales on legs o Have 2 legs and 2 wings o Lungs to breathe o Hard eggs 1.7 Viruses and Bacteria VIRUS Protein coat 1.5 Arthropods (Invertebrates with Legs) CAMI Crustaceans: (e.g. crabs) o Have an exoskeleton o 1 pair of compound eyes o 2 body segment – cephalothorax and abdomen o More than four pairs of legs o 2 pairs of antennae sensitive to touch and chemicals Arachnids: (e.g. spiders) o 2 body segment – cephalothorax and abdomen o Four pairs of legs o Pair of chelicerae to hold prey o Two pedipalps for reproduction o Simple eyes Myriapods: (e.g. centipede) o Segmented body o Additional segments formed o One pair of antennae o 70+ pairs of legs – 1 or 2 pairs on each segment o Fused head and thorax and segmented abdomen o Simple eyes Insects: (e.g. bees) o 3 body segments – head, thorax and abdomen o 3 pairs of legs o 1 pair of antennae o 1 or 2 pairs of wings o Compound and simple eyes 1.6 Classifying Plants Ferns: o Do not produce flowers o They are plants with roots, stems and leaves o Have leaves called fronds o Reproduce by spores Flowering plants: o They are plants with roots, stems and leaves o Reproduce sexually by means of flowers and seeds o Seeds are produced inside the ovary in the flower Monocotyledons Dicotyledons One cotyledon Two cotyledons Parallel veins Veins netlike Fibrous root Taproot present Floral parts in 3s Floral parts in 4s or 5s COVERED BY CELL No MEMBRANE CYTOPLASM No GENETIC DNA or RNA – MATERIAL only a few genes LIVING OR Non-living unless NOT? in host Two examples of virus structure BACTERIA Cell wall Yes Yes DNA – enough for several 100 genes Living 1.8 Dichotomous Keys Dichotomous key: uses visible features to classify organisms. It is which gives you a choice of two features and you follow the one that applies: each choice leads to another choice until the organism is narrowed down to its genus and finally species. 2. ORGANIZATION OF THE ORGANISM 2.1 Cell structure and Organization All living things are made of cells. All typical cells have: o Cell membrane: differentially or partially permeable to allow certain substances to enter and leave the cell. o Cytoplasm: where chemical reactions take place o Nucleus: contains DNA and controls the cell o Mitochondria: organelle where aerobic respiration happens o Ribosome: makes protein and can be found floating within the cytoplasm A typical animal cell (e.g. the liver cell) has all above Only plant cells have: o Vacuole: stores food & water & helps to maintain shape of cell o Cell wall: rigid to keep shape of cell o Chloroplasts: contain chlorophyll, which absorbs light energy for photosynthesis PAGE 4 OF 35 CIE IGCSE BIOLOGY//0610 A typical plant cell (e.g. the palisade cell) has all the above things. 2.2 Levels of Organization CELL RED BLOOD CELL FUNCTION Transport of oxygen MUSCLE CELL Contracts to get structures closer together CILIATED CELL Move and push mucus Absorb ROOT minerals HAIR CELL and water XYLEM VESSEL Transport water and support plant PALISADE CELL Photosynthesizes ADAPTATION(S) Biconcave shape No nucleus Flexible Has haemoglobin Long Many protein fibres in cytoplasm to shorten cell when energy available Tiny hairs called cilia Elongated shape for more surface area No cytoplasm so water passes freely No cross walls so cells connect to form tube Lignin makes it strong and waterproof Regular shape so many can fit in a small space Many chloroplasts DIAGRAM Organelle: a specialized part of a cell that has its own function, e.g. the nucleus Cell: the smallest part of a living structure that can operate as an independent unit e.g. red blood cell Tissue: a group of cells with similar structures, working together to perform a shared function e.g. muscle tissue Organ: a structure made up of a group of tissues, working together to perform specific functions e.g. heart Organ system: group of organs with related functions, working together to perform body functions e.g. respiratory system 2.3 Size of Specimens 𝑀𝑎𝑔𝑛𝑖𝑓𝑖𝑐𝑎𝑡𝑖𝑜𝑛 = 𝑠𝑖𝑧𝑒 𝑜𝑓 𝑑𝑟𝑎𝑤𝑖𝑛𝑔 𝑖𝑚𝑎𝑔𝑒 𝐼 = = 𝑠𝑖𝑧𝑒 𝑜𝑓 𝑠𝑝𝑒𝑐𝑖𝑚𝑒𝑛 𝑎𝑐𝑡𝑢𝑎𝑙 𝐴 3. MOVEMENT IN AND OUT OF CELLS 3.1 Diffusion This is the movement of molecules from a region of high concentration to a region of low concentration down the concentration gradient. This results in random movement of molecules until equilibrium is reached The diffusion of gases and solutes is important as without it, molecules which are needed for life, for example glucose and oxygen for respiration, would not be able to get to the places they are needed. Water is needed as a solvent Factors influencing faster diffusion: o Larger concentration gradient o Higher temperature o Smaller surface area 3.2 Osmosis Movement of water molecules from a region of high water potential to a region of low water potential, through a partially permeable membrane Conc. of solute outside cell = conc. inside cell → no change in size Conc. of solute outside cell > conc. inside cell → cell shrinks (Plasmolysis) Conc. of solute outside cell < conc. inside cell → cell swells (Turgid) In animals: o Increasing solute concentration inside of cell can cause cell to explode as a result of it having too much water, crenation. PAGE 5 OF 35 CIE IGCSE BIOLOGY//0610 In plants: o Increasing solute concentration inside of cell causes cell to become turgid, vacuole fills up. o Decreasing solute concentration inside of cell causes cell to become flaccid, losing water and vacuole gets smaller. Cell body shrinks, pulling away from cell wall 3.3 Active Transport Movement of particles through a cell membrane, from a region of lower concentration to a region of higher concentration against a concentration gradient, using energy released during respiration Active transport is needed when an organism wants to optimize the amount of nutrients it can take up - ion uptake by root hairs and uptake of glucose by epithelial cells of villi. Two strands coiled together to form a double helix Each strand contains chemicals called bases Cross-links between strands are formed by pairs of bases The bases always pair up in the same way: o A and T o C and G 5. ENZYMES Catalyst: a substance that speeds up a chemical reaction and is not changed by the reaction Enzymes: proteins that function as biological catalysts Enzymes lowers amount of energy needed for reaction to take place Enzyme lowers the activation energy needed for reaction to take place Lock and key theory: 4. BIOLOGICAL MOLECULES Carbohydrates: made from Carbon, Hydrogen and Oxygen (CHO) Fats and oils: made from Carbon, Hydrogen and Oxygen (CHO) Proteins: made from Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulfur (CHON[S]) BASIC UNITS LARGER MOLECULES (MONOMERS) (MACROMOLECULES) Simple sugars Starch and glycogen Fatty acids and glycerol Fats and oils Amino acids Proteins 4.1 Chemical Tests Starch: Add few drops of iodine, +ve result = blue-black colour Reducing sugars: Add Benedict’s reagent, then mixture is heated in water bath for 2 to 3 minutes. +ve result = brick-red precipitate, -ve result = remains blue Proteins: Add few drops of Biuret reagent, +ve result = mauve colour Fats: Emulsion test; ethanol is added to mixture, and this is poured into a test tube with an equal amount of distilled water, +ve result = milky-white emulsion Vitamin C: Decolourisation of DCPIP shows that a vitamin C is probably present. 4.2 Structure of a DNA Chromosomes are made of a molecule called DNA Each chromosome is a very long molecule of tightly coiled DNA Substrate: the molecule(s) before they are made to react Product: the molecule(s) that are made in a reaction Catabolic reaction: molecules are broken down Anabolic reaction: molecules are combined 5.1 Effect of Temperature on Enzymes Enzymes have an optimum temperature: the temperature at which they work best giving the fastest reaction ≈ 37°C in animals When temperature increases, molecules move faster so collide with an enzyme in less time Having more energy makes them more likely to bind to active site. If temperature is too high, enzyme molecules vibrate too vigorously and enzyme is denatured; it loses its shape and will no longer bind with a substrate. When the temperature is too low there is not enough kinetic energy for the reaction so it reacts too slowly. 5.2 Effect of pH on Enzymes Enzymes are sensitive to pH Some enzymes work best in an acid and others in an alkaline Enzymes work best at their optimum pH If the pH is changed then the enzyme will denature and will no longer fit with substrate- no reaction takes place PAGE 6 OF 35 CIE IGCSE BIOLOGY//0610 5.3 Graphs for Changes in Enzyme Activity EFFECT OF TEMPERATURE EFFECT OF PH Warmed in ethanol until leaf is colourless to extract chlorophyll, which would mask observation Dipped in water briefly: to soften leaf Leaf is placed on a white tile and iodine is added. If starch is present, colour will be blue-black and if absent, it will remain orange 5.4 Enzymes and their Uses Seeds to germinate: the enzymes turn insoluble food stores to soluble. Biological washing powders: enzymes are added to washing powders to help remove stains for example: o Lipase for lipids from fatty foods and greasy fingerprints o Protease for proteins from blood stains Food industry: o Isomerase converts glucose to fructose which is sweeter, so less is needed to give a sweet taste o Pectinase helps break down cell walls in fruit juice production so it increases yield, lowers viscosity and reduces cloudiness 6.2 Light Is Necessary for Photosynthesis Destarch the plant by keeping it in darkness for 48hrs Place a stencil over part of a leaf Place the leaf in sunlight for 4-6 hours Remove the stencil and test for starch +ve result = parts which received light turn black -ve result = parts which didn’t receive light remain yellow/brown 6. PLANT NUTRITION Photosynthesis: process by which plants manufacture carbohydrates from raw materials using energy from light. 𝑙𝑖𝑔ℎ𝑡 + 𝑐ℎ𝑜𝑙𝑜𝑟𝑝ℎ𝑦𝑙𝑙 𝐶𝑎𝑟𝑏𝑜𝑛 𝐷𝑖𝑜𝑥𝑖𝑑𝑒 + 𝑊𝑎𝑡𝑒𝑟 → 𝐺𝑙𝑢𝑐𝑜𝑠𝑒 + 𝑂𝑥𝑦𝑔𝑒𝑛 𝑙𝑖𝑔ℎ𝑡 + 𝑐ℎ𝑜𝑙𝑜𝑟𝑝ℎ𝑦𝑙𝑙 6𝐶𝑂2 + 6𝐻2 𝑂 → 𝐶6 𝐻12 𝑂6 + 6𝑂2 The carbon dioxide diffuses through the open stomata of the leaf of a plant and water is taken up through roots. Chlorophyll is a dye, which traps light energy and converts it into chemical energy for the formation of carbohydrates and their subsequent storage. 6.1 Chlorophyll Is Necessary for Photosynthesis Take a potted plant with variegated (green and white) leaves. Destarch the plant by keeping it in complete darkness for about 48 hours. Expose the plant to the sunlight for a few days. Leaf boiled in water for 2 minutes to break down cell walls, denature enzymes and allow for easier penetration by ethanol. 6.3 Carbon Dioxide is Necessary for Photosynthesis Take two destarched potted plants. Cover both the plants with bell jars and label them as A and B. Inside A, keep NaHCO3 (sodium bicarbonate). It produces CO2. Inside B, keep NaOH (Sodium hydroxide). It absorbs CO2. Keep both the set-ups in the sunlight for at least 6 hours. Perform the starch test on both plants. B A The leaves of Plant A will turn black after the starch test The leaves of Plant B will remain orange/brown after starch test PAGE 7 OF 35 CIE IGCSE BIOLOGY//0610 6.4 Limiting Factors 6.6 Leaf Structure •Limiting factor: something present in the environment in such short supply that it restricts life processes. Light intensity As the amount of light increases, the rate of photosynthesis increases (a-b) The limiting factor is light Increasing the amount of light after a certain point has no effect on the rate (c) The limiting factor is now carbon dioxide or temperature Carbon dioxide concentration As the amount of carbon dioxide increases, the rate of photosynthesis increases (a-b) The limiting factor is carbon dioxide Increasing amount of carbon dioxide after a certain point has not effect on rate (c) The limiting factor is now light or temperature (warmth) Temperature As temperature increases, the rate of photosynthesis increases until it reaches optimum temperature 40°c (a) The limiting factor is the temperature Increasing the temperature above 40°c will cause the enzymes to denature (b) This will decrease rate of photosynthesis C B A C B A A B Cuticle: waxy layer that prevents water loss from top of the leaf Epidermis: transparent cell that allows sunlight to pass through to the palisade cell Palisade: found at the top of the cell and contains many chloroplasts which absorbs sunlight. Spongy mesophyll layer: irregularly shaped cells which create air spaces to allow gaseous exchange to take place; do not contain many chloroplasts Vascular Bundle: made up of xylem and phloem Xylem: vessel which transports water and dissolved minerals and has lignified walls made of cellulose Phloem: vessel which transports nutrients Stomata: little holes that opens and closes to allow gaseous exchange to take place. The stomata close to prevent water loss and open to let gases come in and out. When guard cells lose water, the stoma close (at night), while the stoma open when guard cells gain water & swell (during the day). 6.5 Glasshouse Systems To increase the crop yield, farmers control the limiting factors: CO2 enrichment: paraffin is burnt to increase CO2 concentration by three times the original amount and doubling the yield Optimum temperature: thermostatically controlled heaters make the temperature right for enzymes to work Optimum light: light has a high intensity for more photosynthesis, the correct wavelengths (red and blue not green) and duration controls production of fruit 6.7 Xylem Unidirectional vessel which transports water and dissolved minerals. Walls are made out of waterproof lignin. Water moves up due to transpiration and osmosis PAGE 8 OF 35 CIE IGCSE BIOLOGY//0610 6.8 Phloem 7.1 Malnutrition Bidirectional vessel Contains sieve elements which allow sugars to pass from one cell to next downwards Contains companion cells which provide energy for active transport of sugars all over plant. Translocation moves organic molecules (sugars, amino acids) from source to sink. Phloem vessels still have cross walls called sieve plates that contain pores. Companion cells actively load sucrose into the phloem. Water follows high solute in phloem by osmosis. A positive pressure potential develops moving mass of phloem sap forward. Phloem still contains small amount of cytoplasm along the walls but the organelle content is greatly reduced. Companion cells actively unload (ATP used) the organic molecules A condition caused by eating an unbalanced diet. Several forms: o Overnutrition: balanced diet but eating too much of everything o Undernutrition: having too little food o Eating foods in incorrect proportions 6.9 Mineral Requirements NITROGEN MAGNESIUM Needed for protein Needed for chlorophyll synthesis synthesis Deficiency: small plant, Deficiency: plant lack slow growth, top leaves chlorphyll, leaves yellow pale, bottom leaves but normal roots dead and roots slightly affected Nitrogen fertilizers: provide nitrogen in the form of nitrate ions, nitrite ions or ammonium ions. But using fertilisers can lead to eutrophication, which is when the fertiliser is transported by rain and leaches into stagnant water e.g. pond or river 7. HUMAN NUTRITION Balanced Diet: getting all the right nutrients in correct proportions Diet related to age/sex/activity: o Children Below 12: Require more calcium o Teenagers: Highest calorie Intake o Adults: Balanced meal with less calories o Pregnant Women: more iron, calcium and folic acid o Males: Generally, require more energy 7.2 Effects of Malnutrition Starvation: losing strength & finally dying because of lack of food Coronary heart disease: eating too much fats which are rich in saturated fatty acids and cholesterol, may lead to heart attack Constipation: lack of roughages in food causes constipation because roughages are indigestible and form bulks. Friction between bulks and walls of intestine stimulate the peristalsis Obesity: Eating too much fats and carbohydrates leads to their storage in storage in the body mainly in the forms of fats and causing an increase in body weight. This can cause; heart attack, stroke, joint pain, mobility impairment, high blood pressure 7.3 Uses NUTRIENT CARBOHYDRATES FATS PROTEINS VITAMIN C VITAMIN D CALCIUM IRON FIBER WATER USES Energy Source of energy, building materials, energy store, insulation, buoyancy, making hormones Energy, building materials, enzymes, haemoglobin, structural material (muscle), hormones, antibodies Protect cells from ageing, production of fibres Absorption of calcium Development and maintenance of strong bones and teeth Making haemoglobin Provides bulk for faeces, helps peristalsis Chemical reactions, solvent for transport 7.4 Deficiencies Vitamin C: Scurvy; loss of teeth, pale skin & sunken eyes Vitamin D: Rickets; weak bones and teeth Calcium: Rickets; weak bones and teeth, also poor clotting of blood, spasms PAGE 9 OF 35 CIE IGCSE BIOLOGY//0610 Iron: Anaemia: Fatigue (less iron → less haemoglobin → less oxygen transported → less respiration → less energy) 7.5 Human Alimentary Canal Large intestine: tube shaped organ composed of two parts: o Colon: organ for absorption of minerals and vitamins, and reabsorbing water from waste to maintain body’s water levels o Rectum: where faeces are temporarily stored Anus: ring of muscle which controls when faeces is released. Ingestion: taking substances (e.g. food, drink) into the body through the mouth. Egestion: passing out of food that has not been digested, as faeces, through the anus. 7.6 Diarrhoea Digestion: the break-down of large, insoluble food Diarrhoea: when not enough water is absorbed from the molecules into small, water soluble molecules using mechanical and chemical processes faeces Mouth: contains teeth used for mechanical digestion, To cure this is to give oral rehydration therapy area where food is mixed with salivary amylase & where One of these this infectious by a bacterium causing the ingestion takes place diseases cholera (spreads rapidly) Salivary glands: produce saliva The cholera bacterium produces a toxin that causes which contains amylase secretion of chloride ions into the small intestine, and helps food slide causing osmotic movement of water into the gut, down oesophagus causing diarrhoea, dehydration and loss of salts from the Oesophagus: tubeblood shaped organ which uses peristalsis to transport food 7.7 Teeth from mouth to stomach INCISOR CANINE PREMOLAR MOLAR Stomach: has sphincters to control movement into and also has pepsin (a protease) to break down proteins into peptides, it also kills bacteria with hydrochloric acid. They also have elastic walls. Small intestine: tube shaped organ composed of two Blunt Blunt for Rectangular Sharpparts the: pointed for chewing and chewing and shape, sharp o Duodenum: fats are emulsified by bile, and digested crushing. holding and crushing for cutting by pancreatic lipase to form fatty acids and glycerol. Two roots and biting cutting Pancreatic amylase and trypsin (a protease) break down starch and peptides into maltose and amino 7.8 Structure of a Tooth acids Enamel: the strongest tissue in the body made from o Ileum: Maltase breaks down maltose to glucose. This calcium salts is where absorption takes place; adapted by having Cement: helps to anchor tooth villi and microvilli. Pulp cavity: Pancreas: produces pancreatic juice which contains contains toothamylase, trypsin and lipase and hydrogencarbonate. producing cells, Liver: produces bile, stores glucose as glycogen, blood vessels, and interconverting them to keep glucose concentration nerve endings which constant. Also carries out interconversion of amino acids detect pain. (transamination), deamination and removal of old red Dentine: calcium salts blood cells and storage of their iron. Also site of deposited on a framework breakdown of alcohol and other toxins. of collagen fibres Gall bladder: stores bile from liver Neck: in between crown and root, it is the gums Bile: produced by liver and stored in gall bladder, its role is to emulsify fats, to increase surface area for the action of enzymes. PAGE 10 OF 35 CIE IGCSE BIOLOGY//0610 Vein: delivers absorbed products to liver via hepatic portal vein. Gland: produces enzymes Lacteal: absorbs fatty acid and glycerol Epithelium: only one cell thick for faster transport. The cells of the epithelium are folded to form microvilli. Small intestine and colon absorb water o The small intestine absorbs 5–10 dm3 per day o The colon absorbs 0.3–0.5 dm3 per day 7.9 Tooth Decay 8. TRANSPORT IN PLANTS 7.10 Prevention Eating food with low sugar content Regular and effective teeth brushing to remove plaque Finishing a meal with a crisp vegetable and a glass of water 7.11 Chemical Digestion Where enzymes are used to break down large insoluble substances such as proteins into smaller soluble substances like amino acids so that they can be absorbed. Amylase: breaks down starch into maltose, it is produced in the pancreas (but also in the salivary gland) Protease: breaks down proteins to peptides (done by pepsin) then into amino acids (done by trypsin). Pepsin comes from the stomach and trypsin comes from the pancreas. Lipase: breaks down lipids into fatty acids and glycerol, produced by the pancreas. Hydrochloric acid in gastric juice: o Denaturing enzymes in harmful microorganisms in food o Giving the optimum pH for pepsin activity 8.1 Xylem and Phloem Functions of xylem and phloem o To transport substances from source, where they are taken in or made, to the sinks, where they are used o To support the stem Stem Root Leaf 8.2 Root Hair Cell 7.12 Absorption Movement of digested food molecules through wall of the intestine into the blood or lymph. The small intestine is the region for absorption of digested food. The small intestine is folded into many villi which increase the surface area for absorption. One villus will have tiny folds on the cells on its outside called microvilli. More surface area means more absorption can happen Capillary: transports glucose and amino acids Function: to absorb water and minerals from the soil They have an elongated shape for more surface area which increases the rate of absorption of water by osmosis and ions by active transport PAGE 11 OF 35 CIE IGCSE BIOLOGY//0610 8.3 Pathway Taken By Water 8.7 Translocation Water enters root hair cell from moist soil via osmosis because water potential is higher in soil than in cytoplasm. Water passes through the cortex cells by osmosis but mostly by “suction”. Water and minerals are forced to cross the endodermis. Water enters xylem then leaves when it gets to mesophyll cells Movement of sucrose and amino acids in phloem; from regions of production (sources) to regions of storage or to regions of utilization in respiration or growth (sinks). Translocation in different seasons: o Spring: sucrose transported from stores in roots to leaves o Summer & early autumn: sucrose goes from photosynthesizing leaves to root stores, 9. TRANSPORT IN ANIMALS Circulatory system: system of tubes (veins, capillaries, arteries) with a pump (heart) and valves (in heart and veins) to ensure one-way flow of blood. 9.1 Transport Systems Transpiration: evaporation of water at surfaces of the mesophyll cells followed by loss of water vapour from plant leaves, through stomata. Water leaves mesophyll cells, into air spaces created by irregular shape of spongy mesophyll cells, then diffuses out of the stomata. Wilting: occurs if water loss is greater than water uptake – cells become flaccid, tissues become limp and plant no longer supported Single circulation system (fish): o Two heart chambers o Blood absorbs oxygen in gills o Released in body cells then back to heart Double circulation system: o Four heart chambers o Blood passes through heart twice o Oxygenated in lungs, to heart, to body, back to heart o Advantage: delivers greater blood flow rate to tissues around the body as the heart pumps the oxygenated blood to it from the lungs 8.5 Uptake of Water 9.2 The Heart 8.4 Transpiration Caused by water loss in leaves which lowers its water potential Water moves from xylem to leaf tissues via osmosis Water moves up the stem in the xylem due to tension (because of cohesion of water molecules to each other) caused by water loss from the leaves Ends with the gain of water through roots This upward flow of water is called the transpiration stream Bicuspid 8.6 Factors Affecting Rate of Transpiration Temperature: higher temperatures increase waterholding capacity of air and increases transpiration rate Humidity: low humidity increases water potential gradient between leaf and atmosphere increasing transpiration rate Light intensity: high light intensity causes stomata to open (to allow more photosynthesis) which causes increase in transpiration Septum Right atrium: collect deoxygenated blood & pump it to right ventricle Right ventricle: pumps deoxygenated blood to lungs PAGE 12 OF 35 CIE IGCSE BIOLOGY//0610 Pulmonary artery: carries deoxygenated blood from right ventricle to lungs Septum: separates left and right sides of the heart Pulmonary vein: carry oxygenated blood from lungs to left atrium Left atrium: collect oxygenated blood and pump it to left ventricle Left ventricle: pumps oxygenated blood to the body via the aorta Aorta: carries oxygenated blood from left ventricle to rest of body Tricuspid and bicuspid valves: prevent backflow of blood into the atria when ventricles contract (atria ventricular valves) Pulmonary and aortic valves: prevent backflow of blood from the arteries into the ventricles (semi-lunar valves) 9.3 Cardiac Cycle Cardiac diastole: all chambers are relaxed, and blood flows into the heart Atrial systole, Atrial diastole, ventricular ventricular diastole: atria systole: after atria contract, pushing relax, ventricles blood into the contract, pushing ventricles blood out of heart Physical activity makes the heart beat more quickly and more deeply, for an increased circulation of blood so that more oxygen and glucose can get to the muscles. 9.4 ECG Trace The electrical activity of the heart can be monitored by the electrocardiogram, pulse rate and listening to the sounds of the valves closing Physical activity makes the heart beat more quickly and more deeply, for an increased circulation of blood so that more oxygen and glucose can get to the muscle 9.5 Coronary Heart Disease Coronary artery becomes blocked, interrupting the supply of blood to the heart muscle. The heart muscle cells are deprived of oxygen & glucose, and poisonous wastes such as lactic acid build up. Part of the heart muscle stops contracting, causing a heart attack Caused by stress, smoking, poor diet, poor lifestyle & genetically Can be prevented by not smoking, avoiding fatty food and exercising regularly Treated by aspirin and surgery (stents, angioplasty and by-pass) 9.6 Arteries, Veins and Capillaries VESSEL STRUCTURE Elastic walls expand and relax as blood is forced out; causes pulse Transport high pressure Thick walls withstand ARTERY blood away high pressure from heart Rings of muscle narrow or widen artery to control blood flow. Valves prevent backflow of blood. Blood is at low pressure, Transport but nearby muscles low pressure VEIN squeeze veins and help blood to the push blood to the heart heart Large diameter and thin walls reduce resistance to flow of blood One cell thick walls for easy diffusion Allow Highly branched; large substances to CAPILLARY surface area diffuse into Capillary beds constantly cells supplied with fresh blood, so diffusion occurs Useful substances move out of plasma of capillaries into tissue fluid (fluid in between cells in tissues) Cells need oxygen and nutrients, and produce waste products such as CO2 & useful products such as hormone Capillaries are constantly supplied with new blood, otherwise diffusion could not occur Lungs → heart Heart → Lungs = Pulmonary vein = Pulmonary artery Liver → heart Heart → Liver = Hepatic vein = Hepatic artery Kidneys → heart Heart → Kidneys = Renal vein = Renal artery PAGE 13 OF 35 FUNCTION CIE IGCSE BIOLOGY//0610 9.7 Lymphatic System Circulation of body fluids, and the production of lymphocytes. Lymph node contains many lymphocytes which filter lymph. Tissue fluid: made when plasma is squeezed out of capillaries. Substances diffuse between cells and tissue fluid. Lymph vessels collect lymph and return it to the blood. Tissue fluid returns to the capillaries by osmosis. 9.8 Blood Red blood cells: haemoglobin and oxygen transport White blood cells: phagocytosis and antibody formation Platelets: causing clotting Plasma: transport of blood cells, ions, soluble nutrients, hormones, carbon dioxide, urea and plasma proteins 9.9 Immune system PHAGOCYTE Phagocyte has lobed nucleus and vesicles containing digestive enzymes. Phagocytosis: engulf pathogen, vesicles fuse with vacuole, enzymes digest bacteria. Antigen: protein/ carbohydrate on surface of pathogen which provokes immune system LYMPHOCYTE Lymphocytes are found in blood and in lymph nodes Large nucleus and they produce antibodies, Antibodies: Y-shaped protein, bind to label pathogens. Then either destroyed by being ingested by phagocytes, or the antibodies may do it. 9.10 Blood Clotting Reduces blood loss and keeps pathogens out Fibrinogen (inactive) turns to fibrin (activated), and forms a mesh to trap red blood cells, which eventually dries to form a scab. 10. DISEASES AND IMMUNITY 10.1 Pathogens Pathogen: a disease-causing organism. Transmissible disease: a disease in which the pathogen can be passed from one host to another. The pathogen for a transmissible disease may be transmitted either: o Direct contact e.g. through blood, body fluids o Indirectly e.g. from contaminated surfaces/food, from animals, from air 10.2 Body Defences The human body has many natural defences against pathogens. Mechanical barriers: o Nostrils contain hairs that help trap dust o Skin has a thick outer layer of dead cells Chemical barriers: o Sticky mucus which can trap pathogens o In the stomach, hydrochloric acid is secreted which kills many of the bacteria in food Cells: Pathogens that manage to get through all these defences are usually destroyed by white blood cells: o Some of these cells take in and digest the pathogens by phagocytosis o Others produce antibodies that incapacitate or kill the pathogen o Vaccination against disease helps antibodies to produce very quickly 10.3 The Immune System An antibody is a protein molecule which fits into another molecule Pathogen molecules are called antigens. To destroy a pathogen, antibody molecules must be made which are exactly the right shape to fit into molecules (antigens) on the outside of the pathogen. Antibodies lock onto antigens leading to destruction of pathogen / marking of pathogens for destruction by phagocytes If a pathogen enters the body, it meets a large number of lymphocytes. One of these will recognize the pathogen and divide rapidly by mitosis These lymphocytes then secrete antibody, destroying the pathogens Active immunity: defence against a pathogen by antibody production in the body. Active immunity is gained after an infection by a pathogen or by vaccination. Vaccines immunise children against diseases caused by pathogens PAGE 14 OF 35 CIE IGCSE BIOLOGY//0610 Process of vaccination: o Harmless pathogen given which has antigens o Antigens trigger an immune response by lymphocytes which produce antibodies o Memory cells are produced that give long-term immunity In controlling the spread of disease, it is important to consider hygienic food preparation, good personal hygiene, waste disposal and sewage treatment Passive immunity: short-term defence against a pathogen by antibodies acquired from another individual, e.g. mother to infant Memory cells are not produced in passive immunity Babies get passive immunity by breast feeding. o Breast milk contains antibodies from the mother which are passed on to her baby. o Useful because a young baby’s immune system is not well developed and so the mother’s antibodies can protect it against any diseases to which she is immune for the first few months of its life Some diseases are caused by the immune system targeting and destroying body cells (Type 1 diabetes) 11. GAS EXCHANGE IN HUMANS 11.1 Gas Exchange PROPERTY OF SURFACE THIN (ONE CELL THICK) LARGE SURFACE AREA MOIST WELL VENTILATED CLOSE TO BLOOD SUPPLY REASON Short distance to diffuse Many molecules can diffuse at once Cells die if not kept moist Concentration gradients for oxygen and carbon dioxide are kept up by regular fresh supplies of air Gases can be carried to/from the cells that need/produce them 11.2 Structure Cartilage (in trachea): prevents the trachea from collapsing during absence of air and also to protect it Ribs: to protect vital organs and blood vessels and expands and contracts (and efficient breathing) Intercostal (internal & external) muscles: situated between the ribs that create and move the chest wall Diaphragm: produces volume and pressure changes in the thorax leading to the ventilation of the lungs INSPIRED AIR 21% oxygen 0.04% carbon dioxide 78% nitrogen Water vapour varies to climate EXPIRED AIR 18% oxygen 3% carbon dioxide 78% nitrogen Saturated water vapour. Test for CO2: Blow CO2 through limewater. +ve result = turn cloudy 11.3 Effect of Physical Activity on Breathing Physical activity increases the breathing rate – more breaths per minute, and the tidal volume – more air per breath This is measured with a spirometer to produce a spirogram. During exercise, tissues respire at a higher rate, the change in breathing volume and rate helps to keep CO2 concentration and pH at safe levels. PAGE 15 OF 35 CIE IGCSE BIOLOGY//0610 11.4 Breathing BREATHING IN External intercostal muscles contract – pulls rib cage upwards and outwards Diaphragm muscles contract – diaphragm moves upwards Lung volume increases – and pressure falls Air rushes in to equalise pressure 12.2 Anaerobic Respiration BREATHING OUT External intercostal muscles relax – rib cage falls downwards and inwards Diaphragm muscles relax – returns to dome shape Lung volume decreases – and pressure increases Air is forced out Release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen. In muscles: Glucose → lactic acid C6H12O6 → 2 C3H6O3 In yeast (single-cell fungi): Glucose → ethanol + carbon dioxide C6H12O6 → 2C2H5OH + CO2 Disadvantages of anaerobic respiration: o Only produces 1/20 of the energy per glucose molecule that aerobic respiration would o Produces poisonous lactic acid Lactic acid: o Transported in blood to heart, liver and kidneys, which oxidize it o The heart, liver and kidneys need extra oxygen to do this which causes you to continue breathing heavily after exercise. o The extra oxygen is called the oxygen debt. 13. EXCRETION IN HUMANS Internal intercostal muscles: are used in coughing and sneezing. Mucus & cilia: goblet cells produce sticky mucus to trap and eliminate particulate matter and microorganisms. Ciliated cells have cilia: little hairs which sweep back and forward in a coordinated way to brush mucus up the lungs into the mouth 12. RESPIRATION Chemical reactions that break down nutrient molecules in living cells to release energy. Uses of energy in the body of humans: muscle contraction, protein synthesis, cell division, active transport, growth, the passage of nerve impulses and the maintenance of a constant body temperature. Respiration involves the action of enzymes in cells Excretion: the removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements. Substances should include carbon dioxide, urea and salts. 13.1 Function of Kidney Removal of urea and excess water and the re-absorption of glucose and some salts Urea is formed in the liver from excess amino acids Alcohol, drugs & hormones are broken down in the liver 12.1 Aerobic Respiration Release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen. Glucose + oxygen → carbon dioxide + water C6H12O6 + 6O2 → 6CO2 + 6H2O Cortex: contains Bowman’s capsules and coiled tubules Ureter: carries urine from kidney to bladder Medulla: contains loops of Henlé and collecting ducts Loop of Henlé: selectively absorbs water/solutes PAGE 16 OF 35 CIE IGCSE BIOLOGY//0610 Collecting ducts: reabsorbs water into blood and store wastes until they are passed into ureter Urethra: carried urine from bladder to the outside. Bladder: stores urine Renal capsule: filters from blood: water, glucose, urea and salts. Tubule: (yellow) reabsorbs 100% of glucose, most of the water and some salts back into the blood (red), leading to concentration of urea in the urine as well as loss of excess water and salts into the tubule. Renal artery: brings wastes and water from blood Renal vein: reabsorbs water and useful molecules and leaves wastes behind 13.2 Structure of the Kidney 5. Collecting duct: the remaining substances move through the second coiled tubule (distal tubule), into the collecting duct. The permeability of this part of the nephron to water is controlled 13.3 Dialysis When a kidney machine takes a patient’s blood and cleans it, then returns the blood to circulation. This is how it works: o Blood enters machine from patient o The pump passes the blood passes the dialysis tubing which is semi-permeable therefore acting as a filter o The surrounding liquid contains some salts, glucose but no urea so waste materials pass from blood by diffusion; o The ‘cleaned' blood returns to patient's circulation/body DIALYSIS TRANSPLANT More expensive in the Less expensive in the long run long run Very disruptive (three 6- Not very disruptive (only 8 hrs sessions per week) have to take medication) Do not need to find kidney Need a kidney Need a machine & must Can go anywhere, live near one anytime Risk of rejection 14. COORDINATION AND RESPONSE 1. Ultrafiltration: blood from renal artery enters the glomerulus. Water, urea, salts and glucose are forced into the Bowman’s capsule. Blood cells and large proteins cannot pass through. 2. Selective reabsorption: in the proximal tubule two thirds of the salt and water and all the glucose moves out of the nephron, by active transport. These substances are reabsorbed back into the blood capillary. 3. Loop of Henlé: this part of the loop of Henlé is permeable to water but not salt. Water passively diffuses out of the nephron because of the low water potential of the medulla tissue fluid. 4. Loop of Henlé: this part is permeable to salt but not water. The loss of water from the filtrate in the previous stage increases the salt concentration. Some salt passively diffuses out of the loop here. 14.1 Nervous Control in Humans The nervous system consists of two parts: o Central nervous system (CNS) consisting of the brain and spinal cord, which are the areas of coordination o Peripheral nervous system (PNS) made up of nerves and neurones, which coordinate and regulate bodily functions. Involuntary actions: not under conscious control e.g. reflex action Voluntary actions: are done if we decide to carry them out 14.2 Types of Neurons Nerve impulse: an electrical signal that passes along nerve cells called neurones PAGE 17 OF 35 CIE IGCSE BIOLOGY//0610 Motor Neurone: Reflex action: means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands) Sensory Neurone: 14.4 Synapses Relay (connector) neurone: 14.3 Reflex Arc A reflex action is an involuntary, quick action to respond to a stimulus, in order to protect the body from danger E.g. quickly removing your hand from hot metal surface They involve three neurones: a sensory neurone, relay neurone and motor neurone. The gap between neurones is called a synapse. How the reflex arc works: o A stimulus affects a receptor (cell or organ that converts a stimulus into an electrical impulse) o A sensory neurone carries impulse from the receptor to the CNS o Connector/relay neurone carries impulse slowly (because it has no myelin sheath) across the spinal chord o Motor neurone carries impulse from the CNS to the effector o Effector (either a muscle or a gland) carries out the response Synapse: a junction between two neurones, consisting of a gap across which impulses pass by diffusion of a neurotransmitter Synaptic cleft: small gap between each pair of neurones Inside the neurones axom, there are 100s of tiny vacuoles (vessicles each contain a chemical called neurotransmitter) When an impulse arrives, the vessicles move to the cell membrane and empty their content into the synaptic cleft The neurotransmitter quickly diffuses across the tiny gap and attaches to receptor molecules in the cell membrane of the relay neurone This can happen because the shape of the neurotransmitter molecules is complimentary to the shape of the receptor molecule Many drugs e.g. heroin act upon synapses 14.5 Antagonistic Muscle A muscle that opposes the action of another; e.g. biceps and triceps are antagonistic muscles or circular and radial muscles in the eye Agonist: a muscle that contracts while another relaxes; e.g. when bending the elbow the biceps are the agonist Antagonist: a muscle that relaxes while another contracts; e.g. when bending the elbow the triceps are the antagonist Sense organ: groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals. PAGE 18 OF 35 CIE IGCSE BIOLOGY//0610 14.6 The Eye 14.8 Pupil Reflex The sense organ responsible for sight Adjusting for high and low light intensity LOW LIGHT INTENSITY Radial muscles (straight lines) contract and become shorter to pull the pupil (black dot) making it wider, to let more light enter, to form a clear image on retina HIGH LIGHT INTENSITY Circular muscles (circular lines) contract and become shorter to reduce the size of the pupil to protect retina from bleaching. 14.9 Rods and Cones Cornea: refracts light Iris: controls how much light enters pupil Lens: focuses light onto retina Retina: contains light receptors, some sensitive to light of different colours Optic nerve: carries impulses to the brain 14.7 Accomodation RODS Provide low detail, black & white images, good for seeing in low intensity light (at night). Packed most tightly around edge of retina so you can see things most clearly when not looking directly at them. CONES Provide detailed, coloured images; they work in high light intensity. Most tightly packed at centre of retina, so objects are seen most clearly when being directly looked at. Fovea: o Part of the retina where the receptor cells are pushed most closley together o Where light is focused when you look straight at an object Adjusting for near and distant objects. 14.10 Hormones A chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver. 14.11 Adrenaline NEAR OBJECT Ciliary muscles contract Ligaments relax Lens becomes short and fat DISTANT OBJECT Ciliary muscles relax Ligaments are tight Lens becomes long and thin A hormone secreted by the adrenal gland. It increases pulse rate, makes the glycogen in muscles get converted to glucose, and released into blood, makes you breath deeper and more rapidly, airways become wider, and makes skin become pale as blood is diverted away. Increases conc. of glucose in the blood for respiration. Adrenaline is secreted for example: while bungee jumping or riding a rollercoaster PAGE 19 OF 35 CIE IGCSE BIOLOGY//0610 GLAND ANDRENAL GLAND HORMONE Adrenaline PANCREAS Insulin TESTIS Testosterone OVARY Oestrogen FUNCTION Prepares body for vigorous action Reduces conc. of glucose in blood Causes development of male sexual characteristics Causes development of female sexual characteristics 14.15 Glucoregulation Blood glucose levels are monitored and controlled by the pancreas The pancreas produces and releases different hormones depending on the blood glucose level Insulin is released when blood glucose levels are high – the liver stores excess glucose as glycogen Glucagon is released when blood glucose levels are low – the liver converts stored glycogen into glucose and releases it into the blood 14.12 Nervous and Hormonal Systems COMPARISON SPEED OF ACTION NATURE OF MESSAGE NERVOUS SYSTEM Very rapid ENDOCRINE SYSTEM Can be slow Electrical impulses, travelling along nerves Chemical messenger (hormones) travelling in bloodstream DURATION OF Usually within May take years RESPONSE seconds (puberty) AREA OF Localized Widespread RESPONSE response (only response (in one area usually) many organs) EXAMPLE OF Reflexes such as Development of PROCESS blinking reproductive CONTROLLED system Hormones are used in food production, for example oestrogen is used to boost growth rate of chickens. Advantage: chickens grow quickly meaning more profit. Disadvantages: this may cause human males to develop feminine characteristics, and it is unnatural. 14.13 Homeostasis The maintenance of a constant internal environment. Homeostasis is the control of internal conditions within set limits 14.14 Negative Feedback Feedback controls the production of hormones – the hormones regulate their own production. A negative feedback control is when the change in hormone level acts as a signal to cancel out that change, so when blood hormone level is low, hormone production is stimulated, when it is high, it is inhibited. When the control of blood glucose does not work, a person is said to have diabetes Type 1 diabetes is caused by the death of the cells that secrete insulin o Symptom: hyperglycaemia (feel unwell, dry mouth, blurred vision and feel thirsty) or hypoglycaemia (tired, show confusion and irrational behaviour) o Treatment: eating little and often and avoiding large amount of carbohydrates, injecting insulin to reduce blood glucose concentration 14.16 Thermoregulation Constant body temperature is maintained by: Insulation: provided by fatty tissue retains heat. Hairs become erect to trap warm air by contracting erector muscles and vice versa. Vasodilatation: when it is hot, arterioles, which supply blood to the skinsurface capillaries, dilate (become wider) to allow more blood near to skin surface to increase heat loss (face redder) Vasoconstriction: when it is cold, arterioles, which supply blood to the skin-surface capillaries, constrict (become smaller) to allow less blood near to skin surface to decrease heat loss PAGE 20 OF 35 CIE IGCSE BIOLOGY//0610 Sweating: the water evaporates giving a cooling effect Skin receptors: sense heat and sensory neurons send impulses to the hypothalamus Shivering: muscular activity generates heat Thermoregulatory centre: in the hypothalamus, it controls the use of corrective mechanisms (e.g. sweating and shivering). Phototropism: a response in which a plant grows towards (positive) or away (negative) from the direction from which light is coming. Auxins’ role in phototropism: o If sun shines on right side of a plant’s shoot, auxins will accumulate on dark opposite left side. o Auxins accumulating makes cells on left side grow faster than cells on right side. o When left side of shoot starts growing faster than right side, shoot will start to bend to right side towards sunlight. Hormones can be used as weed killers: spraying with high concentrations of hormone (2,4-D) upsets normal growth patterns. It affects different species differently so might only kill one species not the other (this is good). 15. DRUGS 14.17 Homeostatic Organs 15.1 Drugs Cells: change composition of blood as they remove nutrients and O2 and add wastes and CO2 Heart: keeps blood pressure constant to deliver oxygen and nutrients around body Skin: to maintain heat exchange with external environment Kidneys: regulate water and salt levels (osmoregulation) and the removal of wastes like urea (excretion) Lungs: regulate gas exchange Intestines: supply soluble nutrients and water to blood Liver: regulates blood solutes and removes toxins Any substance taken into the body that modifies or affects chemical reactions in the body. 14.18 Tropic Responses Auxin: o Plant hormones or growth substances o Controls tropisms o It is produced by cells at the tip of roots and shoots of plants Gravitropism: a response in which a plant grows towards (positive) or away (negative) from gravity. Auxins’ role in gravitropism: o Tend to settle at the bottom end of the root. o However, this does not make the cells of the tip of the root grow longer; auxins prevent cells at bottom tip of root from growing, making cells at top of root grow faster. o When cells of top of the root grow faster, they push root deeper into soil and root gets longer. o The root grows in direction of the gravitational pull. 15.2 Antibiotics Antibiotics work by stopping a metabolic practice performed by the bacteria you are trying to get rid of, but not performed by human cells. Some bacteria are resistant to antibiotics which reduces the effectiveness of antibiotics Development of resistant bacteria such as MRSA can be minimised by limiting use of antibiotics only when essential and ensuring treatment is completed Antibiotics don’t work on viruses because they are not really living and they make the host cell perform the tasks for them. 15.3 Heroin Effects of the abuse of heroin: a powerful depressant Problems of addiction Severe withdrawal symptoms (vomiting, restlessness) Malnourishment as drug depresses appetite Financial problems – stealing, loss of job Infection from sharing needles e.g. HIV/AIDS Heroin affects the nervous system by its effect on the function of synapses PAGE 21 OF 35 CIE IGCSE BIOLOGY//0610 16 REPRODUCTION 15.4 Alcohol Effects of excessive consumption of alcohol –a depressant: Causes coronary heart diseases Reduced self-control Depression Effect on reaction times Damage to liver – cirrhosis 15.5 Smoking Some effects of tobacco smoke: Drying effect and heat irritate lungs – destroys cilia Nicotine is addictive, it is also a stimulant, it increases pulse rate and narrows blood vessels which can cause damage Tobacco smoking can cause chronic obstructive pulmonary disease (COPD), lung cancer and coronary heart disease Tar causes cancer, and is an irritant so causes coughing. There are other irritants in tobacco smoke including: smoke particles, ammonia, and sulphur dioxide Emphysema: walls between alveoli break making large sacs, reducing surface area massively and making you breathless after a couple of steps Loss of limbs due to poor circulation, CHD and lower sperm-count Carbon monoxide irreversibly bonds with haemoglobin which can lead to oxygen starvation Cancer of the stomach, pancreas and bladder etc. Liver is the site of breakdown of alcohol and other toxins 15.6 Hormones and Sports Hormones: can be used to improve sporting performance Testosterone o Improved hand- eye coordination o Improved body-fat composition o Increased muscle mass Anabolic Androgenic Steroids o Affects limbic system Mood swings Impaired judgement High blood pressure Kidney failure o Increased risks of prostate cancer (male) o Inconsistencies of menstrual cycle (female) o Changes in blood cholesterol 16.1 Asexual Reporudction The process resulting in the production of genetically identical offspring from one parent. Bacteria: o Reproduce by binary fission, each bacterium divides into two. o The generation time is the time taken for a cell to divide into 2. Fungi: o Single-celled yeast reproduces by binary fission. o All other fungi produce via spores. o When the sporangium bursts it spreads the spores. o Spores land and grow mycelium (roots) for example mushrooms Potatoes: o The shoot from a potato goes back underground and the stem swells to form a new genetically identical potato. o The swollen stem acts as a storage organ. ADVANTAGES DISADVANTAGES Fast: no need to find No variation mate, fertilise etc. Harmful genes Good characteristics are transferred kept Overcrowding- fighting for food 16.2 Sexual Reproduction Sexual reproduction: process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other Fertilisation: the fusion of gamete nuclei Nuclei of gametes are haploid and that the nucleus of a zygote is diploid ADVANTAGES Produces genetically different offspring; don’t all die from change in the environment PAGE 22 OF 35 DISADAVNATGES Takes lots of time and energy Good characteristics can be lost Energy on improving appearances or pollen volume for pollination (plants) CIE IGCSE BIOLOGY//0610 Anther & stigma inside flower Stick stigma Flowers have stripes which act as guide-lines for insects 16.3 Sexual Reproduction in Plants Insect pollinated, dicotyledonous flowering plant: foxglove Anther & stigma hangs out Stigma hairy Pollen tube: pollen grain lands on stigma and creates a tunnel down the style, through the micropyle, to the ovules. Structure of non-endospermic seed: Wind pollinated flower structure: grass 16.4 Functions Sepal: protect the flower bud. Petal: brightly coloured and scented and may have nectarines which are all used to attract insects, petals in wind pollinated flowers are tiny, and used for pushing the bracts (leaf-like structures) apart to expose stamens and stigma Anther: has pollen sacs with pollen grains which contain the male nucleus (male gamete). Stigma: platform on which pollen grains land Ovary: hollow chamber, ovules grow from the walls. 16.5 Pollination Pollination: transfer of pollen grains from the male part of the plant (anther of stamen) to the female part of the plant (stigma). Agents of pollination: insects, birds, mammals, water and wind INSECT POLLINATED WIND POLLINATED Large colourful petals – Dull petals attract No scent Sweetly scented No nectaries Nectaries Huge amount of pollen Moderate amount of Pollen round and pollen smooth Pollen is spiky/sticky Formation of a seed: the zygote divides many times by mitosis to form and embryo. The cotyledon is the food store. The testa stops drying out of embryo. Wind and animal dispersal are used by plants to colonise new areas; done because new areas have less competition for light, space and nutrients, so seeds are more likely to develop. WIND DISPERSED SEED Dandelion Sycamore SELF POLLINATION Pollen is transferred from the anther to the stigma of the same flower. Implications: O Very efficient O No genetic variation PAGE 23 OF 35 ANIMAL DISPERSED SEED Apple (internal) Bur (external) CROSS POLLINATION Pollen transfer from anther to stigma of another flower of the same species. Implications o Risky: pollen might not reach other flower o Chance for genetic variation CIE IGCSE BIOLOGY//0610 16.6 Germination A process controlled by enzymes Water: activates enzymes to turn insoluble food stores into soluble substances, and makes tissues swell so that the testa splits Oxygen: enters through the gaps in the testa (along with water), and is used in aerobic respiration. Temperature: must be suitable for enzymes to work (at optimum temperature). o Ovary: contains follicles which develop into the ova and produces progesterone and oestrogen o Oviduct (fallopian tube): carries the ovum to uterus o Uterus (womb): where the fetus develops. o Cervix: neck of uterus: a strong rigid muscle, moist by mucus with a small opening o Vagina: receives penis during intercourse, and way out for baby at birth. Moist tube of muscle, flexible and secretes mucus 16.8 Menstrual Cycle 16.7 Sexual Reproduction In Humans Male reproductive system: o Testes: have many coiled tubes which produce sperm, and the cells between tubes produce testosterone. o Scrotum: holds testicles o Sperm duct: carries sperm from testicles to urethra. o Prostate gland: makes seminal fluid o Urethra: carries semen from sperm duct to tip of penis o Penis: male sex organ, used to transfer semen to the female. Female reproductive system: Day 1 to 5: o In the ovary, FSH secreted by the Pituitary Gland to stimulate the maturation of ONE follicle in the ovary. o In the uterus: the endometrium breaks down; menstruation Day 5 to 12: o In the ovary the follicle keeps maturing o In the uterus, oestrogen is secreted by follicle and the ovarian tissues to prepare the endometrium Day 13/14/15: o In the ovary, LH is also secreted by the Pituitary Gland to trigger the release of the egg from follicle into the fallopian tube Day 15 to 28: o In the ovary, LH triggers formation of Corpus Luteum o In the uterus: progesterone is secreted by Corpus Luteum to keep endometrium thick, waiting for possible embryo implant. PAGE 24 OF 35 CIE IGCSE BIOLOGY//0610 Day 28 – Scenario 1: Egg not fertilized o No implantation takes place, the Corpus Luteum degenerates, causing a lack of progesterone. o This means that endometrium is no longer thick, back to Day 1 Day 28 – Scenario 2: Egg is fertilized o Implantation occurs. o This makes the hormones to keep the Corpus Luteum maintained which means that progesterone is high. o This keeps the Endometrium thick for pregnancy 16.9 Hormones in Menstrual Cycle Oestrogen is secreted by the ovaries. It stops FSH being produced - so that only one egg matures in a cycle and it stimulates the pituitary gland to release hormone LH. Progesterone is a hormone secreted by ovaries. It maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy. Follicle stimulating hormone (FSH) is secreted by the pituitary gland. It causes an egg to mature in an ovary and it stimulates ovaries to release hormone oestrogen Luteinizing hormone (LH): is also secreted by pituitary gland and causes mature egg to be released from ovary. 16.10 Sexual Intercourse Penis fills with blood and becomes erect Vagina walls secrete a lubricant. Rubbing of the glans (end of penis) against the vagina wall sets of a reflex action, causes sperm to be released from the testes, and is transported by peristalsis along sperm ducts and urethra, where seminal fluid is added to make semen. The exit of semen from the penis is called ejaculation. Sperm then swim through the cervix and oviducts to the first third of the oviduct (from the ovary) where one combines with the egg. 16.11 Fertilization The fusion of an ovum and a sperm to form a zygote. Development of zygote: o One sperm penetrates o Ovum membrane alters to form barrier against sperm o Head of sperm (male nucleus) approaches and then fuses with the nucleus of the ovum. o Zygote divides over and over, to make a ball of cells called an embryo. o It implants itself in the wall of the nucleus (implantation) which is followed by conception Development of foetus: zygote is changed through growth (mitosis) and development (organization of cells into tissues and organs) Umbilical cord: contains umbilical artery which carries deoxygenated blood and waste products from foetus to placenta and umbilical vein which carries oxygenated blood and soluble food from placenta to foetus. (Contains foetus’ blood) Placenta: organ for exchange of soluble materials such as foods, wastes and oxygen between mother and foetus; physical attachment between uterus and foetus. (Contains mother’s blood) Amniotic sac: membrane which encloses amniotic fluid, broken at birth. Amniotic fluid: protects foetus against mechanical shock, drying out and temperature fluctuations 16.12 Antenatal Care: Change in diet: o More proteins → growth of foetus o Slightly more fat → the new cells’ cell membrane o More vitamin C and D → blood vessel walls and bones o Iron → haemoglobin o Calcium → growth of bones and teeth Guidance on motherhood Checks on foetus and mother including: weight check, blood tests, urine tests, blood pressure checks, ultrasound scanning etc. 16.13 Labour and Birth Labour: The uterine muscular wall contract and cervix tries to relax, then contractions get more frequent. Contractions cause amniotic membrane to break and release amniotic fluid. Expulsion: Powerful Contraction pushes baby out. Afterbirth: Placenta is expulsed out. All contraction & pain gone GAMETE SIZE MOBILITY NUMBER SPERM Smaller Very Many more mobile – (300,000,000) use its tail EGG Larger Immobile – Fewer and moved by limited peristalsis PAGE 25 OF 35 CIE IGCSE BIOLOGY//0610 DISADVANTAGES ADVANTAGES BREAST FEEDING Has antibodies – no bacteria Nutrients- correct proportion Correct temp. No additives /preservatives Builds mother-child bond No cost/preparation Causes decline in uterus size BOTTLED MILK Less painful Other people can feed baby May contain supplement vitamins and minerals o Diaphragm: used by woman, prevent sperm entering uterus, reliable, must stay in place 6 hours after sex, needs a correct size o Femidom: closed end, has a ring which gets pushed through cervix and open end’s ring lies against the labia o IUD: plastic-coated copper coil, can be left inside for months or even years, has a string which is used to remove it out of the vagina, reliable, it irritates uterus wall preventing implantation Surgical: o Vasectomy: sperm ducts are cut and tied o Female sterilization: oviducts are cut and tied 16.16 Artificial Insemination May be painful Mother must be present Damage beauty More likely to develop illness Risk of wrong mixture Expensive 16.14 Sex Hormones At puberty, the pituitary gland starts to stimulate the primary sex organs; the testes in males and the ovaries in females. Sex hormones – testosterone in males and oestrogen in females are released into the bloodstream. They only affect the target organs which have receptors which can recognize them. Causes secondary sexual characteristics such as the growth of pubic hair and maturation of sexual organs. 16.15 Methods of Birth Control Natural: o Abstinence: don’t have sex o Rhythm method: don’t have sex during the fertile period, only during the safe period Chemical: o Progesterone-only pill: pill which affects the uterus and makes implantation difficult o Spermicide: a chemical applied as a gel, cream or foam which kills sperm. It is very unreliable on its own but makes barrier methods of contraception more effective. Mechanical: o Condom: thin rubber covering over penis, it protects from impregnation and STDs, used by man By donor: man’s sperm has a problem, making impregnation impossible, so a donor gives his sperm. In vitro fertilization: an ovum is fertilized outside a woman’s body. The fertilized ovum is implanted into the uterus. Fertility drugs: drugs which enhance reproductive fertility. For women, fertility medication is used to stimulate follicle development of the ovary. The side effect is multiple pregnancies. They contain varying amount of FSH and LH. 16.17 Gonorrhoea A bacterial infection caused by penetrative sex through the mouth, vagina or anus Symptoms/signs: o Pain or burning when passing urine o Greenish/yellow discharge from the penis or vagina o Inflammation of the testicles Effects: o In men the urethra becomes infected, in woman it is the cervix. o If left untreated, the disease can travel through reproductive tract causing sterility Treatment: o Can be cured with penicillin however no immunity 16.18 Human Immunodeficiency Virus (HIV) Transmission: Intercourse, blood transfusion, organ transplant or sharing needle with infected person Prevention: o Avoid intercourse with many partners o Use a condom o Don’t come in contact with other people’s blood PAGE 26 OF 35 CIE IGCSE BIOLOGY//0610 How it affects the immune system: o Infects and destroys lymphocytes o Decreases efficiency of immune system o Body becomes liable to infection by other pathogens 17. INHERITANCE The transmission of genetic information from generation to generation 17.1 Chromosome Chromosome: a thread of DNA, made up of a string of genes Gene: a length of DNA that is the unit of heredity and codes for a specific protein. A gene may be copied and passed on to the next generation Allele: any of two or more alternative forms of a gene Haploid nucleus: a nucleus containing a single set of unpaired chromosomes (e.g. sperm and egg) Diploid nucleus: a nucleus containing two sets of chromosomes (e.g. in body cells) Inheritance of gender in humans: woman’s gamete can only carry an “X” chromosome, and a male gamete can carry either an “X” or “Y” chromosome; females are “XX” while males are “XY”. There is always a 50% chance of getting a boy and vice versa. 17.2 DNA & Protein Synthesis DNA: control cell functions by controlling production of proteins, antibodies and receptors for neurotransmitters DNA has 2 long strands and 4 nucleotides, AT and CG How proteins are made: o Made from long chains of amino acids (20) o DNA bases are read as triplets o DNA is found in the nucleus o Protein synthesis happens on ribosome in cytoplasm o mRNA carries information from DNA to ribosome o When a protein is made, mRNA is made in the nucleus, copying the base sequence o mRNA moves out of the nucleus into the cytoplasm and attaches to the ribosome o ribosome assembles amino acids into protein molecules o the specific order of amino acids is determined by the sequence of bases in the mRNA All body cells in an organism contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs 17.3 Mitosis The nuclear division giving rise to genetically identical cells in which the chromosome number is maintained by the exact duplication of chromosomes. Mitosis is needed for: o Growth: in animals each tissue provides its own new cells when they are needed. o Repair of damaged tissues: for example when you cut your skin, mitosis provides new cells to cover up cut. o Replacement of worn out cells o Asexual reproduction: in plants Stem cells: unspecialized cells that divide by mitosis to produce daughter cells that can become specialized for specific functions 17.4 Meiosis Reduction division in which the chromosome number is halved from diploid to haploid Gametes are the result of meiosis Meiosis results in genetic variation so the cells produced are not all genetically identical. 17.5 Monohybrid Inheritance Genotype: genetic makeup of an organism in terms of the alleles present (e.g. Tt or GG) Phenotype: physical or other features of an organism due to both its genotype and its environment (e.g. tall plant or green seed) genotype + environment + random variation → phenotype Homozygous: having two identical alleles of a particular gene (e.g. TT or gg). Two identical homozygous individuals that breed together will be pure-breeding Heterozygous: having two different alleles of a particular gene (e.g. Tt or Gg), not pure-breeding Dominant: an allele that is expressed if it is present (e.g. T or G) Recessive: an allele that is only expressed when there is no dominant allele of the gene present (e.g. t or g) Pedigree diagrams: PAGE 27 OF 35 CIE IGCSE BIOLOGY//0610 Genetic diagrams: 1:1 Monohybrid Crosses 3:1 Monohybrid Crosses Discontinuous variation is caused by genes alone and results in a limited number of distinct phenotypes (e.g. you are either blood group O, A, B or AB, nothing else) Mutation: genetic change Gene mutation: a change in the base sequence of DNA Mutation is the way in which new alleles are formed Ionising radiation and some chemicals increase the rate of mutation Mutation is a source of variation e.g. in Down’s syndrome, where a parent’s chromosomes are unevenly distributed in meiosis. In fertilisation, a zygote with a number of chromosomes that is not 46 is created (e.g. 23 + 24). Characteristics: broad forehead, short neck, downward-sloping eyes, short nose and mental retardation. 18.2 Sickle Cell Anaemia Co-dominance: when neither of two alleles is dominant to each other. There are three alleles for blood group given by the symbols IA, IB and IO. IA and IB are co-dominant giving blood group AB or IAIB, and both dominant to IO. Sex-linked characteristic: a characteristic in which the gene responsible is located on a sex chromosome and that this makes it more common in one sex than in the other o Colour blindness as an example of sex linkage Disease in which the red blood cell has a sickle shape instead of a round biconcave shape, controlled by a recessive allele, which causes weakness, aching joints and poor circulation. The fact that it is recessive means that a heterozygous person can be a carrier: they have the allele but it is not expressed. Being a carrier of sickle cell anaemia makes you resistant to malaria In equatorial Africa, being sickle cell anaemic causes death, malaria causes death, but the carriers have immunity to malaria and have some symptoms of anaemia, in severe cases they are very weak. 18.3 Adaptive Features Adaptive feature: o inherited feature that helps an organism to survive and reproduce in its environment o the inherited functional features of an organism that increase its fitness 18. VARIATION & SELECTION Fitness: the probability of an organism surviving and reproducing in the environment in which it is found 18.1 Variation Xerophytes: live in deserts where water is scarce and Variation: differences between individuals of the same evaporation is rapid, or in windy habitats. Their features species Phenotypic variation is caused by both genetic and are: environmental factors o Deep roots to reach water far underground Continuous variation is influenced by genes and o Leaves reduced spines with minimum surface area for environment, resulting in a range of phenotypes transpiration between two extremes, e.g. height in humans o Shallow spreading roots to collect occasional rain o Rolled leaves, leaf hairs and stomata sunk in pits to trap moist air PAGE 28 OF 35 CIE IGCSE BIOLOGY//0610 o Waxy leaf cuticle, impermeable water o Stomata opening at night and closed at midday when evaporation is highest o E.g. cactus and marram grass Hydrophytes: live in wholly or partly submerged in water. Their features are: o Leaves are highly divided to create large surface area for absorption and photosynthesis o Very little cuticle formation o Lack of xylem tubes, no stomata underside of leaves o Stomata is in the upper surface, has a thick waxy layer to repel water and to keep the stomata open and clear o Roots are often reduced and root hairs are often absent 18.4 Natural Selection The greater chance of passing on of genes by the best adapted organisms. Variation is natural or random changes in all living organisms. Variation leads to survival of the fittest since the variations in certain organisms allow that organism to have an advantage over the others in its species in that area The surviving organisms reproduce, since they don’t get eaten up, so variation has caused the species to evolve. Evolution is caused by natural selection which is caused by a change in the environment 18.5 Artificial Selection Is breeding organisms with valued characteristics together in order to try to produce offspring which shares those useful characteristics (selective breeding). Can be used to produce organisms which are more economically valued For example: cows that produce more milk, wheat that is easier to separate from grain, dogs which have better appearance Selective breeding: o Selecting by humans of individuals with desirable features o Crossing three individuals to produce the next generation 18.6 Resistant Antibiotic Strains of antibiotic-resistant bacteria are developing as the use of antibiotics is increasing. In a group of many bacteria, one might mutate to be resistant to the antibiotic, as a result it reproduces and the others die making a new strain of bacteria, which is resistant to antibiotics. The susceptible (weak) bacteria are killed first Only resistant (strong) bacteria are left 19. ORGANISMS AND THEIR ENVIRONMENT 19.1 Food Chains and Food Webs The sun is the principal source of energy input to biological systems. Energy flow is not a cycle; it starts from the sun and then that energy is harnessed by plants which are eaten by animals which are eaten by other animals. At each step, energy is lost to the environment. Food chain: a chart showing the flow of energy (food) from one organism to the next beginning with a producer, for example: Mahogany tree → caterpillar → song bird → hawk Food web: showing the transfer of energy from one organism to the next, beginning with a producer o Energy is transferred between organisms in a food chain by ingestion Producer: an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis Consumer: an organism that gets its energy by feeding on other organisms Herbivore: an animal that gets its energy by eating plants Carnivore: an animal that gets its energy by eating other animals Decomposer: an organism that gets its energy from dead or waste organic matter (i.e. a saprotroph) Ecosystem: a unit containing all of the organisms and their environment, interacting together, in a given area e.g. decomposing log or a lake Trophic level: position of an organism in a food chain, food web or pyramid of biomass, numbers or energy o Primary consumer: eat vegetables o Secondary consumer: eat meat/drink milk o Tertiary consumer: eat a predatory fish, salmon PAGE 29 OF 35 CIE IGCSE BIOLOGY//0610 Food chains usually have fewer than five trophic levels, because energy transfer is inefficient: Sun produces light, less than 1% of the energy falls onto leaves. Producers ‘fix’ only about 5-8% of that energy, because of: transmission, reflection and incorrect wavelength. Primary consumer only gets between 5-10% because some parts are indigestible (e.g. cellulose) and not eating the whole plant. Secondary consumer gets between 10-20% because animal matter is more digestible & has higher energy value At each level heat is lost by respiration. Humans eating plants is more efficient than humans eating animals because… We need only a couple of vegetables to have one meal, but to have meat we must feed the animal a lot of plant material in order to get far less meat. In the process of raising an animal, plants lose energy to environment, then animal loses energy to environment and does not use up all the plant material so it is very inefficient. PYRAMID OF NUMBERS PYRAMID OF BIOMASS Shows number of each organism in a food chain When moving up pyramid, number of individuals’ decreases 19.2 Carbon Cycle Pyramid which shows the biomass (number of individuals × their individual mass) 19.3 Nitrogen Cycle Nitrogen-fixing bacteria provide usable nitrogen for plants, these may exist in the root nodules where they live in symbiosis with the plants (nitrogen fixation), or this can happen because of lightning, or microorganisms provide them through decomposition. Nitrifying bacteria convert nitrogen-containing substances into better nitrogen-containing substances for the plants (nitrification). Plants absorb these substances and convert them into proteins Primary consumers eat the plants and can make their own proteins, secondary consumers eat primary consumers and so on. Death and decay happens at each trophic level leading to stage one Denitrifying bacteria carry out denitrification: they convert nitrogen-containing substances into atmospheric nitrogen 19.4 Water Cycle PAGE 30 OF 35 CIE IGCSE BIOLOGY//0610 DEFORESTATION COMBUSTION OF FOSSIL FUELS O2 CONC. IN CO2 CONC. AIR IN AIR Decreases Decreases WHY? Increases Burning uses up oxygen, and produces carbon dioxide Increases Fewer trees means less photosynthesis Trees are usually burnt (combustion) Decomposition of tree trunks (respiration) 19.5 Population Population: a group of organisms of one species, living in the same area at the same time Community: all of the populations of different species in an ecosystem Ecosystem: a unit containing the community of organisms and their environment, interacting together, e.g. a decomposing log, or a lake 19.6 Factors Affecting Rate of Population Growth Food supply: quantity and quality, for example snails need calcium to reproduce to make a shell (food quality). Predation: if predator population falls, the prey population will rise Disease: causes organisms to die so a high death rate partly cancels out birth rate meaning less population growth, especially if the organism dies before giving birth, or even population decline Log phase: exponential growth occurs, the conditions are ideal and maximum growth rate is reached. Limiting factors do not limit growth much. Stationary phase: limiting factors slow growth as population has reached “carrying capacity” of its environment; mortality rate = birth rate; curve levels off and fluctuates around this maximum population size. 19.8 Human Population Growth FACTORS FAVOURING GROWTH: Lower infant mortality, higher life expectancy, better nutrition, better housing, better sanitation, medicine, vaccination FACTORS CONTROLLING GROWTH: Disease, famine, war The human population is becoming stable (stagnation) due to: o better education (particularly for women), so they work instead of getting married and having children o better living conditions, fewer people die, fewer births needed o cities, reduced need for physical labour on farms o family planning but overall the population in still increasing. Social implications of human growth: o demands for roads as there is an increases number of cars o greater expectation for a variety of foods all year round o smaller families increase demand for housing o greater demand for leisure and recreation space 20. BIOTECHNOLOGY & GENETIC ENGINEERING Bacteria are useful in biotechnology and genetic engineering due to their rapid reproduction rate and their ability to make complex molecules Why are microorganisms used: o Bacteria and fungi are small and easy to grow in a lab o They reproduce quickly and don’t take up much space o No ethical issues involved o Genetic code is the same for bacteria as it is for human o Bacteria have loops of DNA called plasmids which are easy to transfer from one cell to another 19.7 Sigmoid Curve Lag phase: number of mature, reproducing individuals is low and they may be widely dispersed PAGE 31 OF 35 CIE IGCSE BIOLOGY//0610 20.1 Making Biofuel Use plants to make sugars which yeast then breaks down to make ethanol Ethanol can then be used as a fuel o Maize is treated with amylase enzyme (starch to glucose) o Add yeast (glucose used in respiration) and make it respire anaerobically o Ethanol that is produced is extracted by distillation o Mixed with gasoline to increase energy and can be used in cars 20.2 Bread Making Flour, sugar, water and salt are mixed with yeast to make the dough. Amylase breaks down some starch to make maltose and glucose. This is used by yeast in respiration The dough is kept in a warm, moist environment (28°c). Yeast ferments sugar making carbon dioxide which creates bubbles, so bread rises Cooking (at 180°c) – kills yeast, evaporates alcohol and hardens outer surface. 20.3 Uses of Enzymes Pectinase: Fruit juices are extracted using pectinase (breaks down pectin) Pectin helps plant walls stick together If pectin is broke down, it’s easier to squeeze juice from the fruit Extraction of juice from fruit, making juice clear not cloudy Washing powders: Biological washing powders and liquids contain enzyme that help remove stain The enzymes are coated with a special wax that melts in the wash releasing the enzyme Once the stains have been broken down, they are easier for detergents to remove Proteases break down proteins in stains e.g. grass, blood Lipases break down stains containing fats and oil Carbohydrases break down carbohydrate-based stains, such as starch Lactase: Enzyme that breaks down lactose (sugar found in milk) People can stop making lactase naturally, therefore can’t digest lactose Milk can be treated with lactase to break down lactose before a person drinks it Also produces glucose & galactose, used in sweets 20.4 Making Penicillin Penicillin: an antibiotic produced by a fungus called penicillium. Stainless steel fermentation vessel is filled with medium containing sugars and ammonium salts. Penicillium is added to produce penicillin. They use sugar for respiration and ammonium salts to make protein and nucleic acids The fermentation vessel consists of PAWS o Probes monitor temperature and pH o Air provides oxygen for aerobic respiration in fungus o Water-cooled jacket removes heat to maintain temperature of 24C. o Stirrer keeps the microorganism suspended (allowing access to nutrients and oxygen) while maintaining an even temperature. Filtered to remove fungus and then can be crystallized to make capsules. 20.5 Genetic Engineering Genetic engineering: changing the genetic material of an organism by removing, changing or inserting individual genes Examples of genetic engineering: o the insertion of human genes into bacteria to produce human insulin o the insertion of genes into crop plants to confer resistance to herbicides o the insertion of genes into crop plants to confer resistance to insect pests o the insertion of genes into crop plants to provide additional vitamins PAGE 32 OF 35 CIE IGCSE BIOLOGY//0610 Human Insulin in Bacteria Isolation of the DNA making up a human gene using restriction enzymes, forming sticky ends Cutting of bacterial plasmid DNA with the same restriction enzymes, forming complementary sticky ends Insertion of human DNA into bacterial plasmid DNA using DNA ligase to form a recombinant plasmid – insertion of plasmid into bacteria Replication of bacteria containing recombinant plasmids which make human protein as they express the gene 20.6 Genetically Modified Crops ADVANTAGES Uniform in shape – easy to transport/ appeal consumers Growing season shorter Drought resistant – less water Higher yields DISADVANTAGES Natural species may die Tastse often not as good Lead to development of super weeds – stronger than GM No one knows long term effect on humans 21. HUMAN INFLUENCES ON ECOSYSTEMS 21.1 Food Supply Food production has increased because: Improved machinery means less labor is needed Fertilizers help crops to grow better Insecticides: a type of pesticide that kills insects Herbicides: a type of pesticide that kills weeds Artificial selection and genetic modification means that yields are improved: cows produce more milk, cows are more muscular giving more meat, plant crops can resist insects and cold weather World Food Supplies Not enough food available in a country to feed its people because: o Fast increase in population o Increasing use of crops for fuel o Decrease of farming = Climate change/Urbanization Famine: Wide spread scarcity of food The main causes of famine: o The rapid rate of population increase o Long term climatic change o Soil erosion and desertification o Economic pressure o Unequal distribution of food o Drought o Flood Monoculture is the continuous production of one type of crop that is often genetically uniform. Negative Impacts of Monoculture o If a natural disaster were to occur, the whole crop could be wiped out. o If pests & disease attacked crop, it could harm it easily o Using large fields and pesticides reduces the variety of species. This hinders biodiversity. Negative Impacts of Intensive Livestock Production o Welfare issues for the livestock o Diseases can spread easily among them o Waste can pollute land and waterways nearby 21.2 Habitat Destruction Reason for habitat destruction o Increased area for food crop growth, livestock production and housing o Extraction of natural resources o Marine pollution Through altering food webs, and food chains, humans can have a negative impact on habitats Effects of deforestation o Reduced biodiversity/destroys habitats/extinction o Loss of CO2 fixation, thus increase in CO2, thus global warming o Soil erosion: tree roots cannot retain soil, goes into rivers making the water dirty & causes blockages, soil becomes less fertile o Flooding: usually 75% of water is absorbed by foliage, root systems or evaporates. After deforestation water, accumulates in valleys 21.3 Pollution Water and air pollution: Chemical waste and sewage in rivers results in water not being drinkable and eutrophication can occur Sulphur dioxide dissolves in rain, causing acid rain which increases acidity of lakes and leaches aluminium out of the soil causing: o The fishes’ gills are damaged, eventually killing them. This is fixed by adding calcium hydroxide (slaked lime) o Destroys top of trees and aluminium damages tree roots = dead tree, important nutrients leached away o SO2 poses health hazards for humans (asthma sufferers) o Damages limestone buildings and sculptures o Fewer crops can be grown on an acidic field (fixed by adding lime) PAGE 33 OF 35 CIE IGCSE BIOLOGY//0610 Pollution due to pesticides: Insecticides (kill insects): meant to kill insects which eat crops, but can kill other, useful insects such as bees which are pollinators, or by bioaccumulation (the increase in dose of toxin from one level of the food chain to the next) Herbicides (kill weeds): can be harmful to animals which eat the plants Nuclear fall-out: Radioactive particles are sprayed into the atmosphere in a nuclear accident or bombing; These particle “rain” back to earth from clouds, sometimes far from the accident site; The radioactivity damages DNA and causes cancer and radiation illness at every level of the food chain. Non-biodegradable plastics: Choke birds, fish and other animals Fill up the animals’ stomachs so that they can’t eat food Collect in rivers, and get in the way of fish Acid rain: Caused by sulphur dioxide (burning fossil fuels) and nitrogen oxides (nitrogen reacting hot engines), as they dissolve and cause acid rain Damages trees and plants, and kills fish and other river life Prevention: catalytic converters, in factories slaked lime neutralizes these acidic oxides and use of flue-gas desulfurization Global Warming: Increase in average temperature of the Earth Started at the same time as humans began burning fossil fuels Scientists believe fossil fuels are causing this – not proven yet Increase in carbon dioxide and methane concentrations in the atmosphere cause an enhanced greenhouse effect the leads to climate change Negative impact of female contraceptive hormones in water courses: Reduced sperm count in men and feminisation of aquatic organisms Eutrophication: when water plants receive too many nutrients. Fertilisers put in soil by farmers Fertilisers with nitrates / detergents with phosphates leach into rivers and lakes after rain Water plants grow more than usual They block sunlight and kill plants underneath They die and sink to bottom Bacteria/fungi decompose remains using the O2 and decreasing the O2 concentration Fish and other creatures die from oxygen starvation 21.4 Conservation Sustainable resource: one which is produced as rapidly as it is removed from the environment so that it does not run out Sustainable development: development providing for the needs of an increasing human population without harming the environment Sustainable development requires: o Management of conflicting demands o Planning and co-operation at local, national and international levels Some resources can be maintained, limited to forests and fish stocks. They can be sustained using: o Education o Legal quotas o Re-stocking Natural resources: Water: used to grow food, keep clean, provide power, control fires and to drink. We get water constantly through rainfall but we are using up planet’s fresh water faster than it can be replenished. Fossil fuels: need to be conserved as they will soon run out, they should be therefore replaced with green forms of energy. PAGE 34 OF 35 CIE IGCSE BIOLOGY//0610 Recycling: Water: water from sewage can be returned to environment for human use by sanitation and sewage treatment Paper: sent to special centres where it is pulped to make raw materials for industry Plastic: fossil fuels, bottles → fleece clothing Metal: mining takes a lot of energy so recycling saves energy Species and habitats: need to be conserved because: Organisms have value in themselves (ethical value) Value to medicine (new molecules from exotic plants = new drugs) Genetic resources are useful to humans as well and are lost when species disappear (DNA for genetic engineering) Each species has its role in its ecosystem; if it is removed, then the whole ecosystem could collapse Endangered species: How they become endangered: climate change, habitat destruction, hunting, pollution and introduced species If the population size drops, variation decreases Endangered species can be conserved by: monitoring and protecting species and habitats, education, captive breeding programmes and seed banks Conservation programmes include: o reducing extinction o protecting vulnerable environments o maintaining ecosystem functions, by nutrient cycling and resource provision, e.g. food, drugs, fuel and genes PAGE 35 OF 35 TABLE OF CONTENTS 3 CHAPTER 1 4 CHAPTER 2 5 CHAPTER 3 7 CHAPTER 4 The Particulate Nature of Matter Experimental Techniques Atoms, Elements and Compounds Stoichiometry 8 Electricity and Chemistry CHAPTER 5 9 CHAPTER 6 10 CHAPTER 7 12 CHAPTER 8 14 CHAPTER 9 15 Chemical Energetics Chemical Reactions Acids, Bases and Salts The Periodic Table CHAPTER 10 Metals 16 CHAPTER 11 18 CHAPTER 12 18 CHAPTER 13 19 CHAPTER 14 Air and Water Sulfur Carbonates Organic Chemistry CIE IGCSE CHEMISTRY//9093 1. THE PARTICULATE NATURE OF MATTER 1.1 Kinetic Particle Theory HeatINCREASES increases HEAT When a solid is heated, particles vibrate faster about a fixed point causing particles to move further apart and so solid expands When particles gain sufficient energy to overcome strong forces of attraction, they move out of their fixed position and can slide over each other in a continuous random motion – solid has melted. Particles in liquid have energy to move around but are still close to each other and do not have enough energy to overcome the forces that hold them close to each other. If more heat’s supplied, particles move faster until they have enough energy to overcome the forces of attraction. Particles escape the liquids surface and move around in continuous rapid motion – the liquid has boiled In the vapor, the particles move in rapid random motion. This movement is due to collision of vapor particles with air particles. 1.2 States of Matter SOLID Strong forces of attraction between particles Fixed pattern (lattice) Atoms vibrate but can’t change position ∴ fixed volume and shape LIQUID Weaker attractive forces than solids No fixed pattern, liquids take up the shape of their container Particles slide past each other. GAS Almost no intermolecular forces Particles far apart, and move quickly Collide with each other and bounce in all directions PROCESS Melting Boiling Condensing Freezing Sublimation Reverse sublimation HEAT ENERGY Gained Gained Lost Lost Gained EXO/ENDOTHERMIC Endothermic Endothermic Exothermic Exothermic Endothermic Lost Exothermic 1.3 Heating Curve 1.4 Diffusion Diffusion is the spreading of one substance through another from a region of high concentration to a region of low concentration due to the continuous random motion of particles. Evidence for diffusion: In liquids: potassium manganate (VII) in a beaker of water In gases: a gas jar of air and a gas jar of bromine connected Factors that affect the rate of diffusion: Temperature increases → rate of diffusion increases Lower density gas → rate of diffusion is higher PAGE 3 OF 22 CIE IGCSE CHEMISTRY//9093 Interpreting simple chromatograms: o Number of rings/dots = number of substances o If two dots travel the same distance up the paper they are the same substance. o You can calculate the Rf value to identify a substance, given by the formula: 2. EXPERIMENTAL TECHNIQUES 2.1 Measurement VARIABLE Time APPARATUS Stopwatch or Clock Thermomemeter (liquid in glass, Temperature thermistor or thermocouple) Mass Balance 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑚𝑜𝑣𝑒𝑑 𝑏𝑦 𝑠𝑜𝑙𝑢𝑡𝑒 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑚𝑜𝑣𝑒𝑑 𝑏𝑦 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 To make colourless substances visible, use a locating agent: o Dry paper in oven o Spray it with locating agent o Heat it for 10 minutes in oven Assesing purity from m.p./b.p: o Pure substances have a definite, sharp m.p./b.p. o Substance+impurity has lower m.p. and higher b.p. o More impurity means bigger change 𝑅𝑓 𝑉𝑎𝑙𝑢𝑒 = Measuring Volume: 2.3 Filtration Beaker Burette Pippette Measuring Cylinder Gas Syringe Mixture goes in a funnel with filter paper, into a flask. Residue is insoluble and stays at top. Filtrate goes through 2.2 Critertia of Purity Paper chromatography: o Drop substance to center of filter paper and allow it to dry o Drop water on substance, one drop at a time o Paper + rings = chromatogram. o Principle: Difference in solubility separates different pigments o Substances travel across paper at different rates which is why they separate into rings o Method works because different substances travel at different levels of attraction to it 2.4 Crystallization Stationary phase is material on which separation takes place Mobile phase consists of the mixture you want to separate, dissolved in a solvent. Some water in the solution is evaporated so solution becomes more concentrated. A drop is placed on a slide to check if crystals are forming. Solution is left to cool and crystallise. Crystals are filtered to remove solvent. PAGE 4 OF 22 CIE IGCSE CHEMISTRY//9093 2.5 Simple Distillation Impure liquid is heated It boils, and steam rises into the condenser Impurities are left behind Condenser is cold so steam condenses to the pure liquid and it drops into the beaker If one solid is magnetic, can use a magnet e.g. sand and iron fillings SOLVENT IT DISSOLVES… Water Some salts, sugar White spirit Gloss paint Propanone Grease, nail polish Ethanol Glues, printing inks, scented substances 2.8 Choosing a Suitable Method METHOD OF SEPARATION Filtration Evaporation Crystallization Simple Distillation Fractional Distillation Chromatography 2.6 Fractional Distillation Removes a liquid from a mixture of liquids, because liquids have different b.p.s Mixture is heated to evaporate substance with lowest b.p. some of the other liquid(s) will evaporate too. A mixture of gases condense on the beads in the fractional column. So the beads are heated to the boiling point of the lowest substance, so that substance being removed cannot condense on the beads. The other substances continue to condense and will drip back into the flask. The beaker can be changed after every fraction 2.7 Seperating Mixture of Two Solids Can be done by dissolving one in an appropriate solvent Then filter one and extract other from solution by evaporation USED TO SEPARATE A solid from a liquid A solid from a solution A solid from a solution A solvent from a solution Liquids from each other Different substances from a solution 3. ATOMS, ELEMENTS AND COMPOUNDS 3.1 Atomic Structure and the Periodic Table PARTICLE RELATIVE CHARGE MASS (ATOMIC MASS ) 1 1 1⁄1837 Proton +1 Neutron 0 Electron -1 Proton number: number of protons in an atom (and number of electrons in an atom) Nucleon number: number of protons + neutrons in an atom. In the periodic table o The proton number increases by 1 when you go to the right o When you go one element down, you increase proton number by 8 in the first 3 periods (transition elements not included) Isotopes: atoms of same element with different no. of neutrons o E.g. Carbon 12 and Carbon 14. o Two types: non-radioactive isotopes and radioactiveisotopes which are unstable atoms that break down giving radiations o Medical use: cancer treatment (radiotherapy) – rays kill cancer cells using cobalt-60 o Industrial use: to check for leaks – radioisotopes (tracers) added to oil/gas. At leaks radiation is detected using a Geiger counter. PAGE 5 OF 22 CIE IGCSE CHEMISTRY//9093 Electrons are arranged in electron shells. Atoms want to have full outer shells (full set of valency electrons), this is why they react. Noble gases have full outer shells so they have no need to react. Electron shell structure: 2, 8, 8, 18. More reactive elements have a greater desire to have a full outer shell, so also form more stable compounds. 3.2 Bonding: the Structure of Matter Element: substance that cannot be split into anything simpler, in a chemical reaction. Each element has a unique proton number. Mixture: two or more elements mixed together but not chemically combined Compound: substance in which two or more different elements are chemically combined METALS NON-METALS Strong Brittle Poor conductors of heat & Good conductors of heat electricity (except & electricity graphite) Lower m.p. and b.p. than High m.p. and b.p. metals High density Low density Forms basic oxides Forms acidic oxides Forms cations in reactions Forms anions in reactions Malleable and ductile Sonorous Some are magnetic PROPERTY Form giant lattice High m.p. and b.p. Don’t conduct electricity when solid Conduct electricity when molten/aqueous Usually soluble in water REASON Cations and anions attract Strong bonds between ions Ions can’t move Ions can move Not required 3.4 Molecules and Covalent Bonds When atoms share 𝑒̅s to obtain a noble gas electron structure Covalent bonding takes place between non-metals only SINGLE BOND DOUBLE BOND TRIPLE BOND 2𝑒̅s shared (1 from each atom) 4𝑒̅s shared (2 from each atom) 6𝑒̅s shared (3 from each atom) PROPERTY Low m.p. and b.p. Usually liquid, gas or low m.p solid Don’t conduct electricity Usually insoluble in water Example: REASON Weak intermolecular forces of attraction between molecules No mobile ions/electrons Not required Alloy: Mixture of two or more metals or mixture of one or more metal with a non-metal, to improve its properties 3.5 Macromolecules 3.3 Ions and Ionic Bonds Chemical bond formed by transfer of 𝑒̅s from one atom to another Metals lose 𝑒̅s to form cations, non-metals gain 𝑒̅s to form anions Positive cations & negative anions attract to each other Strong electrostatic force of attraction between positive cations and negative anions is called ionic bonding DIAMOND GRAPHITE SILICON DIOXIDE Four bonds Three bonds Makes up sand High m.p. Made of flat Each Si is bonded to 4 oxygen atoms, Doesn’t conduct sheets and each oxygen is Used for cutting Held together by bonded to 2 silicon weak forces so is as is srongest atoms known soft used as a it has a high m.p. substance lubricant Conducts electricity and is hard, like as it has one free e- diamond PAGE 6 OF 22 CIE IGCSE CHEMISTRY//9093 Melting point: high - structure made up of strong covalent bonds Electrical: don’t conduct electricity - have no mobile ions or electrons, except for graphite Strength: hard - exists in tetrahedral structure but graphite is soft 3.6 Metallic Bonding 4.4 Masses Relative atomic mass (Ar): mass of one atom of an element relative to one twelfth of the mass of one atom of Carbon-12 Relative molecular mass (Mr): sum of relative atomic masses of all the atoms in one molecule of the compound 4.5 The Mole Concept A mole of a substance is the amount that contains the same number of units as the number of carbon atoms in 12 grams of carbon-12 A mole is the Ar or Mr expressed in grams e.g. 1 mole of Carbon-12 is equal to 12 grams. It is equal to 6.02 × 1023 atoms, this number is called Avogadro’s constant. 4.6 Number of Moles 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑀𝑜𝑙𝑒𝑠 = Positive ions held together by electrons – acts like glue 4. STOICHIOMETRY 4.7 Moles in Gases Balancing equations: a chemical equation is balanced when there are equal number of atoms and charges on both sides of the equation State symbols: o (s) = solid o (l) = liquid o (g) = gas o (aq) = aqueous solution 𝑉𝑜𝑙𝑢𝑚𝑒 = 𝑁𝑜. 𝑜𝑓 𝑀𝑜𝑙𝑒𝑠 × 24𝑑𝑚3 4.8 Concentration 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 = Moles per dm3 o 1mol/dm3 = 1M Grams per dm3, g/dm3 𝑛𝑜. 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑣𝑜𝑙𝑢𝑚𝑒 4.9 Molecular Formulae 4.1 Valency Table NAME Nitrate Hydroxide Acetate/ ethanoate Carbonate Sulphate Silicate Phosphate 𝑚𝑎𝑠𝑠 𝑚𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 FORMULA NO3OHCH3COO- VALENCY 1 1 1 CO32SO42SiO32PO43- 2 2 2 3 4.3 Ending of Names Compound ending with -ide only contain two different elements Compound ending with -ate contain oxygen The formula using the actual number of atoms in a molecule 4.10 Empirical Formulae This is the simplest ratio of the atoms in a compound For example: o Molecular formula of ethanol = C2H5OH o Empirical formula of ethanol = C2H6O To find out the empirical formula you: o Make the percent ratio into the simplest whole number ratio (NOTE: if given %s, use them as grams) o Divide the coefficients of each element symbol by the lowest coefficient 4.11 Percentages 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑝𝑟𝑜𝑑𝑢𝑐𝑡 (𝑝𝑢𝑟𝑒) 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑 (𝑖𝑚𝑝𝑢𝑟𝑒) 𝑎𝑐𝑡𝑢𝑎𝑙 𝑚𝑎𝑠𝑠 𝑜𝑏𝑡𝑎𝑖𝑛𝑒𝑑 × 100 𝑐𝑎𝑙𝑐𝑢𝑙𝑎𝑡𝑒𝑑 𝑚𝑎𝑠𝑠 𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑝𝑢𝑟𝑖𝑡𝑦 = 𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑦𝑖𝑒𝑙𝑑 = PAGE 7 OF 22 × 100 CIE IGCSE CHEMISTRY//9093 5. ELECTRICITY AND CHEMISTRY 5.3 Electroplating Decomposition of an electrolyte with the help of electric current Electrolyte: o Aq. solution of ionic substance or molten ionic salt o Conducts electricity due to the presence of mobile ions Electrodes: o Rods which help current enter the electrolyte o Inert electrodes: do not take part in the reaction o Reactive electrodes: take part in the reaction Coating one metallic object with another metal using electrolysis For electroplating, you need: o Anode made of metal you want to electroplate object with o Ions of same metal as anode in solution o Object to be plated at cathode Used to: o Make things look better o Prevent corrosion 5.4 Uses ALUMINUM Used for Used in electricity cables electrical wires because: as it is: o Light o A very good o Nonconductor corrosive (not best) o Good o Ductile conductor o Cheaper than copper Cables have steel core, for strength 5.1 Principle At the cathode Metal At the anode Non-metal Molten Electrolyte At the cathode Higher in reactivity then H+ H2 formed Lower in reactivity then H+ Metal formed Aqueous Electrolyte Halide present At the anode Concentrated Halogen fomed Dilute Oxygen formed Halide not present This is purifying impure metals Rules: o Cathode: thin strip of pure metal o Anode: impure metal o Electrolyte: Aqueous Salt Solution of metal Example: Oxygen Formed Molten lead(II) bromide Concentrated hydrochloric acid Concentrated aqueous sodium chloride AT CATHODE Lead Hydrogen Hydrogen PLASTIC & CERAMICS Used as insulators because they: o Don’t conduct electricity o Conduct heat poorly Plastic used for casing in plugs Ceramics used to support cables in electricity pylons 5.6 Refining Metals 5.2 Examples ELECTROLYTE COPPER AT ANODE Bromine Chlorine Chlorine PAGE 8 OF 22 CIE IGCSE CHEMISTRY//9093 AT THE ANODE Made of titanium Chlorine gas evolved Unreacted ions (Na+, H+ and OH-) move through porous membrane due to difference in liquid pressure Net flow to the right AT THE CATHODE Made of steel Hydrogen cations reduced to H2 molecules Left Na+ and OH- which is aqueous sodium hydroxide Reaction at Anode: Cu – 2e Cu2+ (mass decreases) Reaction at Cathode: Cu2+ + 2e Cu (mass increases) 6. CHEMICAL ENERGETICS 5.7 Basics Exothermic reaction: one that releases heat energy into the surrounding Endothermic reaction: one which absorbs heat energy from the surroundings Bond breaking is endothermic Bond making is exothermic Electrolysis is a way to decompose compounds, using electricity. Reduction of positive cations happens at the cathode Oxidation of negative anions happens at the anode For example: o At the anode: 2Cl- → Cl2 + 2eo At the cathode: 2H+ + 2e- → H2 5.8 Extraction of Aluminium The main ore of aluminium is bauxite – high m.p. Aluminium (III) oxide (alumina) is dissolved in molten cryolite (Na3AlF6) – this mixture has a lower m.p. (industrially preferred) 6.1 Energetics of a Reaction EXOTHERMIC REACTION Energy given out to the surroundings Surroundings become hot Bond making – exothermic ENDOTHERMIC REACTION Energy is taken in from the surroundings Surroundings become cold Bond breaking – endothermic 6.2 Energy Level Diagrams During electrolysis aluminium is produced at the carbon cathode and oxygen at the carbon anode. Due to the high temp. the oxygen reacts with the graphite anode to form CO2 and so anode had to be periodically replaced 5.9 Electrolysis of Brine Brine is concentrated NaCl solution Ions present: Na+, H+, Cl- and OH- 6.3 Bond Energy This is the amount of energy consumed or liberated when a bond is broken or formed in kJ/mol ∆𝐻 = 𝐵𝑜𝑛𝑑 𝐵𝑟𝑒𝑎𝑘𝑖𝑛𝑔 + 𝐵𝑜𝑛𝑑 𝐹𝑜𝑟𝑚𝑖𝑛𝑔 If overall heat energy is negative, reaction is exothermic If overall heat energy is positive, reaction is endothermic 6.4 Production of Energy A fuel is a substance which can be conveniently used as a source of energy. Burning fuels (like oil) to form oxides is an exothermic reaction. The heat from burning fuels is used in power plants to create steam from water and turn turbines. PAGE 9 OF 22 CIE IGCSE CHEMISTRY//9093 In order for any material to combust three things must be present: o Fuel o Heat o Oxygen A good fuel would: o Be cheap o Be available in large quantities o Ba a liquid at room temperature o Produce a large amount of energy when combusted o Not produce polluting gases 6.5 Hydrogen Burns explosively with oxygen, so it is used in rockets. In a fuel cell, it combines with oxygen without burning. Produced by reacting methane gas with steam ADVANTAGES Produces a lot of energy Abundant on earth (sea) Less pollutant Renewable fuel DISADVANTAGES Difficult to transport as it is a gas at room temperature Forms explosive mixture with air – very dangerous 6.6 Simple Cells A cell is a device which converts chemical energy into electrical energy and is composed of two metals of different reactivity connected by an external circuit and an electrolyte The process works due to the different reactivity of metals Consists of a negative pole (the more reactive metal) and a positive pole (less reactive metal) and an electrolyte. The greater the difference in reactivity of the two metals, the greater the voltage will be. The electrons flow because one metal is more reactive, so it has a stronger drive to give up its electrons. The atoms give up electrons and enter the solution as ions. 6.7 Radioactive Isotopes Uranium-235 can be used in nuclear power stations to produce electricity The radioactive isotope is bombarded by neutrons resulting in a lot of heat being produced Small amount of radioactive fuel produces large amount of heat Advantages: lots of energy is from a small amount and no CO2 Disadvantage: radioactive waste produced and nonrenewable 7. CHEMICAL REACTIONS 7.1 Collision Theorey Collisions are needed for a chemical reaction to take place Successful collisions have enough activation energy at moment of impact to break preexisting bonds and form new bonds 7.2 Rates of Reaction Rate of a chemical reaction is the concentration of reactant used up or product made in a given time. Unit = (mol/dm3)/s 7.3 Concentration Increasing concentration of reactants increases rate of reaction This is because there are more particles per unit volume, so the collision rate between reacting particles increases, therefore the successful collision rate increases, which results in an increased rate of reaction. 7.4 Temperature Increasing temperature increases the rate of reaction This is because average kinetic energy of particles increase which means they are moving faster & also more particles have an energy greater/equal to activation energy, therefore successful collision rate increases, resulting in increased rate of reaction PAGE 10 OF 22 CIE IGCSE CHEMISTRY//9093 For gaseous reactants, if catalyst is solid metal, the catalyst provides a surface for reaction to take place on The larger the surface are of the metal catalyst, the larger the area for reaction to take place therefore higher rate of reaction 7.5 Particle Size Decreasing the particle size (increasing surface area) increases the rate of reaction This is because there are more reactant particles exposed to collide, so the collision rate increases, therefore the successful collision rate increases, resulting in an increased rate of reaction Large surface area can mean danger. For example, flour dust and wood dust have large surface areas, and are combustible. A spark from a machine, or a lit match, can cause an explosion. This also applies to gases from mines. Enzymes are protein molecules. They are biological catalysts which speed up reactions but remain chemically unchanged at the end Enzymes function best at optimum temperature and pH level otherwise they may denature and completely stop functioning 7.8 Measuring Rates of Reaction Experimentally GAS EVOLVED MASS LOSS COLOUR CHANGE If a gas evolves, measure volume of gas produced per unit time using a gas syringe If a gas evolves, measure loss in mass per unit time by placing on a balance then putting a cotton wool on top to allow gas to pass but not to enter If a color change occurs we can measure the time taken to go cloudy 7.6 Pressure in Gaseous System Increasing the pressure in a gaseous system increases the rate of reaction The distance between particles is reduced under pressure There are more particles per unit volume, so the collision rate increases, therefore the successful collision rate increases, resulting in an increased rate of reaction. 7.7 Catalyst A catalyst is a substance (usually a transition metal) which speeds up a chemical reaction, but remains unchanged at the end Adding a catalyst increases the rate of reaction A catalyst allows the reaction to go by an alternative pathway with lower activation energy More particles will have an energy greater than or equal to the activation energy, therefore successful collision rate increases resulting in increased rate of reaction 7.9 Light Causing a Chemical Reaction A photochemical reaction is one where light causes a reaction to occur. The higher the light intensity the higher the rate of the reaction. Photosynthesis: light provides energy for the reaction and chlorophyll is a dye that absorbs light. carbon dioxide + water → (light + chlorophyll) → glucose + oxygen 6CO2 + 6H2O → (light + chlorophyll) → C6H12O6 + 6O2 PAGE 11 OF 22 CIE IGCSE CHEMISTRY//9093 Silver salts in photographic film: Silver bromide breaks down, where light strikes the film, so silver is reduced. Silver ions are reduced to silver. 2AgBr(s) →2Ag(s)+Br2(g) 7.10 Reversible Reactions A reversible reaction is a reaction in which reactants form products and the product(s) can then react or decompose to form the reactants Example: CuSO4.5H2O (blue) ⇌ CuSO4(white) + H2O (to get anhydrous, heat it, & to get hydrated form, add water) There are two types of equilibrium: static and dynamic. At dynamic equilibrium: o Rate of forward reaction = rate of reverse reaction o Concentrations of all reactants and products remain constant o System is closed, and on large scale everything is constant 7.11 Equilibrium Potassium manganate is an oxidising agent and will go from purple to colourless To test for an oxidising agent, add a reducing agent (KI) and to test for a reducing agent, add an oxidising agent (KMnO4) 8. ACIDS, BASES AND SALTS 8.1 Properties of Acids An acid is a compound which when dissolved in water produces hydrogen ions (H+) and are described as proton donors (H+) Acids turn blue litmus indicator paper (or solution) red. Have pH 1 to 6 Acid + metal → salt + hydrogen gas Acid + base → salt + water Acid + metal carbonate → salt + carbon dioxide + water Strong acids completely ionize in water producing lots of H+ ions Weak acids partially ionize in water producing few H+ ions Le Châtelier’s Principle: if conditions of an equilibrium are changed, the position of equilibrium moves to oppose change Temperature: Temperature lowered; equilibrium moves in exothermic direction. Temperature raised; equilibrium moves in endothermic direction. Pressure: Pressure raised; equilibrium moves to side with fewest gas molecules. Pressure lowered; equilibrium moves to side with most gas molecules. Concentration: Decreasing reactant concentration or increasing product concentration; equilibrium moves to reactant side. Increasing reactant concentration or decreasing product concentration; equilibrium moves to product side. 8.2 Properties of Bases 7.12 Redox Neutral substances are pH 7. Acidity in soil: o Plants grow at a pH near 7. o If it is too acidic or alkaline they will not grow. o Acidic soil is fixed by adding lime. A redox reaction is one in which one species has been oxidized and another species has been reduced OXIDATION MEANS: REDUCTION MEANS: Loss of electrons Gain of electrons Gain of oxygen Loss of oxygen Loss of hydrogen Gain of hydrogen OIL RIG Reducing agents are oxidized and oxidizing agents are reduced Potassium iodide is a reducing agent & will go from colorless to red-brown, so is oxidized to produce I2 H2O2 + 2KI + H2SO4→I2 + K2SO4 + 2H2O Bases are insoluble substances which neutralize acids to form a salt and water only and are proton acceptors Alkalis turn red litmus indicator paper (or solution) to blue. Have pH 8 to 14. Base + acid → salt + water (+ CO2 when base is a metal carbonate) Base + ammonium salt → salt + ammonia gas + water Strong alkalis completely ionize in water producing lots of OH- ions Weak alkalis partially ionize in water producing OH- ions 8.3 Neutral pH is the concentration of H+ ions per dm3 of solution PAGE 12 OF 22 CIE IGCSE CHEMISTRY//9093 8.4 Indicators 8.9 Starting with an Insoluble Base INDICATOR COLOR IN ACID Phenolphthalein Methyl orange Methyl red Red litmus Blue litmus Colorless Pink Red Red Red COLOR IN ALKALINE Pink Yellow Yellow Blue Blue 8.5 Types of Oxides Metal oxides are basic e.g. iron oxide and magnesium oxide Non-metal oxides are acidic e.g. sulphur oxide and carbon dioxide Aluminum, zinc and lead form amphoteric oxides e.g. zinc oxide Oxides which are neither acidic or basic are neutral e.g. water and carbon monoxide 8.6 Preparation of Salts A salt is a substance formed when all the replaceable hydrogen ions of an acid are replaced by metal ions or the ammonium ion o Salts can either be soluble or insoluble SOLUBLE SALTS All sodium, potassium and ammonium salts All nitrates Chlorides Sulphates Potassium, sodium and ammonium carbonates INSOLUBLE SALTS Except silver and lead Except barium, lead and calcium All other carbonates 8.7 Type of Salts TYPE OF SALT REQUIRED Sulphate Nitrate Chloride Ethanoate ACID USED Sulphuric acid Nitric acid Hydrochloric acid Ethanoic acid Add insoluble base to acid and heat gently, it will dissolve Keep adding until no more dissolves (reaction is done) Filter out the insoluble (excess) base 8.10 Starting with an Alkali (Titration): Put a certain amount alkali in a flask Add phenolphthalein Add acid from a burette, stirring, until it goes colorless Find out how much acid you used Repeat, to be more accurate Evaporate water from neutral solution 8.11 Precipitation Mix the two soluble salts, so they react together Filter the mixture to separate the products produced (soluble and insoluble salt produced) Wash the insoluble salt on the filter paper Dry the insoluble salt in a warm oven 8.12 Test for Aqueous Cations EFFECT OF AQ. CATION NAOH White soluble ALUMINUM precipitate formed (AL3+) giving a colorless solution Ammonium gas AMMONIUM produced turns (NH4+) damp red litmus blue CALCIUM White precipitate (CA2+) formed COPPER (CU2+) IRON(II) (FE2+) IRON(III) (FE3+) 8.8 Starting with a Metal Add excess metal to an acid When bubbling (hydrogen) stops the reaction is done Filter off excess metal ZINC (ZN2+) PAGE 13 OF 22 EFFECT OF AQ. AMMONIA White precipitate formed No precipitate/ slight white precipitate Light blue soluble Light blue precipitate precipitate formed formed giving dark blue solution Green precipitate Green precipitate formed formed Red-brown Red-brown precipitate formed precipitate formed White soluble White soluble precipitate formed precipitate formed giving a colorless giving a colorless solution solution CIE IGCSE CHEMISTRY//9093 8.13 Test for Anions 9.2 Alkali Metals ANION TEST TEST RESULT CARBONATE Add dilute nitric acid Bubble gas through (CO32-) limewater–from colorless to cloudy CHLORIDE Add nitric acid, then White precipitated (CL-) aqueous silver nitrate formed BROMIDE Add nitric acid, then Cream precipitate (BR-) aq. silver nitrate formed IODIDE (I ) Add nitric acid, then Bright yellow aqueous silver nitrate precipitate formed NITRATE Add aqueous sodium Gas produced turns (NO3 ) hydroxide then add damp red litmus aluminum paper blue SULPHATE Add dilute nitric acid, White precipitate (SO42-) then add aq. barium formed nitrate Lithium, sodium and potassium 8.14 Test for Gases Patterns Reactivity, density & softness increases down the group Melting and boiling points decreases down the group. Reactivity increases as more electron shells means there is weaker attraction between nucleus & valency electron so is lost more easily. GAS Ammonia (NH3) Carbon dioxide (CO2) Chlorine (Cl2) Hydrogen (H2) Oxygen (O2) TEST AND TEST RESULT Damp red litmus paper turns blue Bubble gas through–from colorless to cloudy Bleaches red/blue litmus paper Place lighted splint, squeaky pop Place glowing splint, splint relights 9. THE PERIODIC TABLE The Periodic table is a method of classifying elements. They are arranged in order of increasing atomic number. Made up of rows called periods and columns called groups Metals are to the left and non-metals are to the right. Elements in the same group have similar properties. Group number tells us the number of valency electrons and the period number tells us about the number of electron shells 9.1 Periodic Trends Non-metals are on the right side of the periodic table, and metals are on the left. Down a period of metals they become more reactive With non-metals, going down a period, the non-metal becomes less reactive CHEMICAL PROPERTIES Form ionic compounds React violently with chlorine Burst into flames when heated with oxygen: O A red flame for lithium O A yellow flame for sodium O A lilac flame for potassium Produce soluble white compounds. React with cold water. PHYSICAL PROPERTIES Good conductors of heat and electricity. Are soft, compared to other metals. They have low densities for metals. They have low melting and boiling points compared to most metals. 9.3 Halogens PROPERTIES PATTERNS Form colored gases, at Down the group; size, RTP: mass and density o Fluorine is a yellow gas increases o Chlorine is a green gas Down the group, color o Bromine is a red liquid darkens o Iodine is a black solid Reactivity decreases down Are poisonous the group, because it has Brittle and crumbly when to gain an electron, so the solid closer the electron is to Do not conduct electricity the positive nucleus the Form diatomic molecules more easily it will be gained, so atoms with fewer shells Will react more easily. 9.4 Transition Metals High melting points (except mercury) Malleable and ductile Good conductors of heat & electricity (silver is the best) High density Have no trend in reactivity PAGE 14 OF 22 CIE IGCSE CHEMISTRY//9093 Can be used as catalysts Form colored compounds Can form complex ions as they have variable valences 9.5 Noble Gases PROPERTIES Density increases down the group M.p. and b.p. increases down the group Don’t conduct electricity Don’t take part in chemical reactions USES Helium- filling balloons and aircrafts because it is lighter than air and will not catch fire. Argon – filling (tungsten) light bulbs to stop the filament reacting with oxygen. Neon – is used in advertising signs because it glows red. 10. METALS 10.1 Properties of Metals PHYSICAL High density Shiny when polished Malleable Ductile High m.p. And b.p. Conductor of heat & electricity CHEMICAL Form basic oxides Form positive ions An alloy is two or more metals, or a metal and non-metal which have been made molten and then mixed together Alloys are used because they have improved qualities for a particular job over the pure metals Brass MADE FROM Copper and zinc Bronze Copper and tin Stainless steel Iron, chromium and nickel 10.3 Reactivity Series K - Potassium Na - Sodium Ca – Calcium Mg – Magnesium Al – Aluminum C – Carbon Zn – Zinc Fe – Iron Pb – Lead H – Hydrogen Cu – Copper Ag – Silver Au – Gold This places metals in order of their readiness to take part in chemical reactions Everything above hydrogen can displace hydrogen from its acid, and hydrogen cannot reduce their oxides. Metals above carbon, their oxides cannot be reduced by carbon. More reactive metals will react with cold water, and less reactive will react slowly or not react with steam. Aluminum seems unreactive because it forms an oxide layer which protects it 10.4 Displacement Reactions 10.2 Alloys ALLOY Metals are often used as alloys because they have an increased range of uses and mixture of atoms gives an irregular structure which stops layers sliding over each other easily; they are stronger This is what the structure of an alloy (a) looks like, compared to a pure metal (b). SPECIAL PROPERTIES Stronger and more resistant to corrosion Harder, stronger and sonorous Does not rust USES Electrical fittings, car radiators These are reactions in which metals compete for oxygen or anions The more reactive metal will displace the less reactive metal from oxygen or an anion. If more reactive metal has oxygen or an anion, no reaction occurs The bigger the difference in reactivity between the two metals, the faster the reaction 10.5 Thermal Decomposition GROUP Statues, Group I springs, coins (except lithium) Kitchen sinks, Group II, cutlery, lithium & chemical transition plant metals PAGE 15 OF 22 METAL CARBONATE METAL METAL NITRATE HYDROXIDE Do not decompose Do not Metal nitrite and decompose oxygen Metal oxide and carbon dioxide Metal oxide, Metal oxide nitrogen dioxide and water and oxygen CIE IGCSE CHEMISTRY//9093 10.6 Extraction of Metals Reduction via electrolysis CARBON Reducing via heating with Carbon or Carbon Monoxide HYDROGEN Cu – Copper Ag – Silver Au – Gold Occur naturally More powerful/expensive method of extraction Zn – Zinc Fe – Iron Pb – Lead EXTRACTION METHOD Ores more difficult to decompose METAL K - Potassium Na - Sodium Ca – Calcium Mg – Magnesium Al – Aluminum 10.9 Extracting Zinc 10.7 Extracting Iron Ore = hematite (Fe2O3) Uses of slag o To make roads o To make cement Coke burns with air carbon + oxygen carbon dioxide Carbon dioxide reacts with coke carbon dioxide + carbon carbon monoxide Ore = Zinc Blende = Zinc Sulphide (ZnS) Zinc blende is roasted in air to convert it to zinc oxide Zinc oxide is reduced using coke to zinc and carbon monoxide in the furnace As zinc is volatile, the gaseous metal is distilled leaving less-volatile impurities behind. Zinc is condensed and liquid is run into mould. 10.10 Uses of Metal Aluminum o Airplane/Cars (Strong/Low density/resistant to corrosion) o Cans/Foil (Resistant to corrosion/malleable) o Overhead cable (Good conductor of electricity/ductile) Zinc o Galvanizes Iron = coats it to stop it rusting o Alloys – brass/bronze o Batteries o Sacrificial Protection Copper o Electrical Wiring (Good conductor of electricity/Ductile) o Cooking utensils (Malleable/good conductor of heat) o Roofs (hard wearing against weather 11. AIR AND WATER Carbon monoxide reduces Iron(III) oxide to iron 11.1 Tests for Water iron(III) oxide + carbon monoxide iron + carbon dioxide The limestone reacts with impurities to form slag calcium carbonate + silicon dioxide calcium silicate + carbon dioxide 10.8 Iron to Steel Molten iron from blast furnace is poured into an oxygen furnace. Calcium oxide is added, and a jet of oxygen is turned on. The calcium oxide neutralizes acidic impurities, forming slag that is skimmed off and oxygen burns the other impurities away. The carbon content is checked continually until it is just right then the oxygen is turned off. o Mild Steel (0.25% carbon) – Used in machinery and car bodies o Medium carbon steel (0.5%) – Used in railway lines o High carbon steel (1.5% carbon) – Used in knives and blades TEST Blue Cobalt(II) Chloride Paper Anhydrous Copper(II) Sulphate powder Test m.p. and b.p. TYPE OF TEST Chemical Chemical Physical POSITIVE RESULT Paper turns from blue to pink From white powder to blue crystals m.p. at 0°C and b.p. at 100°C 11.2 Purification of Water Water is pumped into screens, which remove solid floating debris. Aluminum sulfate is added to coagulate (stick together) small pieces of clay so that they are easily removed. The water is then filtered through coarse sand to remove larger, insoluble debris. The water encounters more flocculants (chemicals that make particles move down to bottom of tank) and is filtered again through fine sand. PAGE 16 OF 22 CIE IGCSE CHEMISTRY//9093 Chlorine gas is bubbled through the water to kill bacteria. This makes the water slightly acidic, so to reverse this appropriate amounts of sodium hydroxide (an alkali) is added. Some countries also add fluorine 11. 3 Use of Water AT HOME Drinking Cooking Washing On farms for animals & crops IN INDUSTRY Dissolve wash and cool things In power stations where steam is used to turn turbines 11.7 Catalytic Convertor 11.4 Air In the combustion engine, insufficient amounts of oxygen lead to incomplete combustion of the carbon containing fuel Gases produced: (a) carbon monoxide (b) oxides of nitrogen A catalytic convertor catalyzes the reduction of NO2 to nitrogen gas N2 and catalyzes the oxidation of CO to CO2 Clean air is composed of approximately o 79% nitrogen o 20% oxygen o Remainder: noble gases, water vapor & carbon dioxide 11.5 Pollutants in Air POLLUTANT It is compressed, causing it to heat up. Cooled by recycling cold air The cold compressed air is passed through a jet, into a larger space. It expands rapidly, making it very cold. This is repeated, cooling the air more. By -200°C it is liquid except for neon and helium. These gases are removed. They can be separated from each other by absorption on charcoal. The liquid air is pumped into the fractioning column. There it is slowly warmed up. The gases boil off one by one, and are collected in tanks or cylinders. Sources of methane: oil and natural gas, decomposition of vegetation, and waste gases from digestion in animals SOURCE PROBLEMS CAUSED Reacts with Incomplete haemoglobin, Carbon combustion of preventing it from Monoxide carbon-containing carrying oxygen; CO substances death due to oxygen starvation Irritates eyes and Sulphur From combustion of throat, causes Dioxide fossil fuels which respiratory problems SO2 contain sulfur and causes acid rain Oxides of Causes respiratory Nitrogen From car exhausts problems and forms NOx acid rain From burning of Causes damage to Lead petrol as lead is brain and nerve cells compounds added to it for better in young children performance 11.8 Rust Preventition Coating with something to prevent contact with air and moisture o Plastic, paint and grease o Electroplating with tin or chromium o Galvanising: dipping in molten zinc Sacrificial protection: attaching a piece of metal that is more reactive that iron to object, commonly magnesium or zinc. This will corrode in the place of iron. 11.9 Fertilizer NPK used in fertilizers because: o Nitrogen is needed for chlorophyll and other proteins. o Phosphorus helps roots grow and crops ripen. o Potassium helps make proteins and resist diseases. All alkalis (except ammonia) will react with ammonium compounds, removing ammonia, for example: 𝐶𝑎𝑙𝑐𝑖𝑢𝑚 ℎ𝑦𝑑𝑟𝑜𝑥𝑖𝑑𝑒 + 𝐴𝑚𝑚𝑜𝑛𝑖𝑢𝑚 𝑐ℎ𝑙𝑜𝑟𝑖𝑑𝑒 → 𝐶𝑎𝑙𝑐𝑖𝑢𝑚 𝐶ℎ𝑙𝑜𝑟𝑖𝑑𝑒 + 𝑊𝑎𝑡𝑒𝑟 + 𝐴𝑚𝑚𝑜𝑛𝑖𝑎 11.10 Greenhouse Gases 11,6 Fractional Distillation of Air Air is filtered to remove dust Water vapor and carbon dioxide removed, (because they would freeze and block the pipes): o air is cooled until water vapor condenses o then passes over absorbent beads to trap carbon dioxide The greenhouse gases are: carbon dioxide and methane. They stop heat escaping in to space. Too much greenhouse gases leads to climate change. This will cause the ice poles to melt, rising sea levels, more droughts, storms, floods and famine; global warming PAGE 17 OF 22 CIE IGCSE CHEMISTRY//9093 11.11 Formation of Carbon Dioxide 12.2 Uses Carbon dioxide is produced whenever carbon or any of its compound are completely burned in excess oxygen It is also formed as a product of respiration It is produced as product of reaction between an acid and carbon From the thermal decomposition of a carbonate 11.12 Haber Process Industrial manufacture of ammonia NH3 N2 (g) + 3H2 (g) ⇌ 2NH3 (g) Raw materials: o Nitrogen: from the air o Hydrogen: methane + steam → carbon dioxide + hydrogen Essential conditions: o Temperature: 450°C o Pressure: 200atm o Catalyst: Iron 11.13 Carbon Cycle SULFUR As a food preserver; kills bacteria As a bleach in the manufacture of wood pulp for paper In car batteries as electrolyte In manufacture of sulphuric acid (through Contact process) SULFUR DIOXIDE Manufacture of sulphuric acid To bleach wool, silk and wood pulp for making paper As a sterilising agent in making soft drinks and jam, and in drying fruit; stops growth of bacteria and moulds. 12.3 Contact Process Sulphur is first burned in air producing sulphur dioxide It is then mixed with more air and passed over four separate beds of catalyst, Vanadium (V) oxide, at 450°C to form sulphur trioxide It is then dissolved in concentrated sulphuric acid forming a thick fuming liquid called oleum It is then mixed carefully with water to form concentrated sulphuric acid. Essential conditions: o Catalyst: Vanadium (V) oxide o Temperature: 450°C o Pressure: 2atm 12.4 Properties of Sulfuric Acid Forms salts called sulphates When concentrated, it’s a dehydrating agent, and a thick oily liquid It turns blue litmus red It is a strong acid and has the properties of a typical strong acid: reacts with bases, low pH, high conductivity 13. CARBONATES 12. SULFUR 12.1 Sources Found as an element, in large underground beds Found around the rims of volcanoes. It occurs in metal ores e.g. lead sulphide Sulphur compounds also occur naturally in the fossil fuels e.g. coal Lime is manufactured by limestone by heating CaC03 + heat → CaO + CO2 PAGE 18 OF 22 CIE IGCSE CHEMISTRY//9093 Uses of quick lime: o Making steel from iron o To neutralise acidity in soil o Drying agent in industry Uses of slaked lime and lime: o Neutralise acidity in soil, and in lakes affected by acid rain, o Neutralising acidic industrial waste products, e.g. flue gas desulphurisation Uses of limestone: o Making cement: made by mixing limestone with clay, heating mixture strongly in a kiln, adding gypsum (calcium sulphate), and grinding up the final solid to give a powder o Making iron from iron ore: limestone reacts with sand) forming slag (calcium silicate), which is then used for road building. 14.4 Name of Compounds Name ending → compound-type name “ane” → alkane “ene” → alkene “ol” → alcohol “oic acid” → carboxylic acid “yl”, “oate” → ester 14.5 Alkanes General formula = CnH2n+2 METHANE (N=1) ETHANE (N=2) PROPANE (N=3) BUTANE (N=4) 14. ORGANIC CHEMISTRY 14.1 Homologous Series Homologous series: ‘family’ of similar compounds with similar properties due to the presence of the same functional group. Characteristics of a homologous series: o all the compounds fit the same general formula o the chain length increases by 1 each time o as the chain gets longer, the compounds show a gradual change in properties Structural isomers: have the same chemical formula, but different structures, they can be straight or branched 14.2 Fuels Fuels to know: o Coal o Natural gas: main constituent is methane o Petroleum: a mixture of hydrocarbons which can be separated into fractions 14.3 Uses of Petroleum Fractions Refinery gas: bottled gas for heating and cooking Gasoline fraction: fuel (petrol) in cars Naphtha fraction: making chemicals Kerosene/paraffin fraction: jet fuel, lamps Diesel oil/gas oil fraction: fuel in diesel engines Fuel oil fraction: fuel in ships and home heating systems Lubricating fraction: lubricants, waxes and polishes Bitumen: making roads Each carbon atoms in an alkene has four covalent single bonds – this makes them quite unreactive. Combustion: Complete combustion: enough oxygen supply so water and carbon dioxide form. e.g. CH4 + 2O2 → CO2 + 2H2O Incomplete: is not enough oxygen to burn them cleanly so either carbon monoxide and water or carbon and water form. e.g. 2CH4 + 3O2 → 2CO + 4H2O or e.g. CH4 + O2 → C + 2H2O Chlorine substitution: Sunlight or light is necessary A chlorine atom replaces a hydrogen atom This can happen to all hydrogen atoms if there is enough chlorine. e.g. CH4 + Cl2 → (light) → HCl + CH3Cl / CH2Cl2 / CHCl3 / CCl4 Compounds = chloromethane / di/tri/tetrachloromethane PAGE 19 OF 22 CIE IGCSE CHEMISTRY//9093 14.6 Alkenes 14.8 Alkenes’ Addition Reactions With bromine: (the test for saturation) e.g. ethene (g) + bromine (aq) → 1,2-dibromomethane (l) With steam: forms alcohols with heat, pressure and a catalyst e.g. ethene (g) + steam (g) ⇌ ethanol (l) With hydrogen: double bond breaks down to for an alkane with heat, pressure and a catalyst e.g. ethene (g) + hydrogen (g) → ethane (g) General formula = CnH2n Functional group: C=C bond (N=1) N/A ETHENE (N=2) PROPENE (N=3) BUT-1-ENE (N=4) 14.9 Alcohols Cracking: Thermal decomposition reaction, in which an alkene (and sometimes hydrogen) are produced from an alkane. Cracking always produces short chain compound with a C=C bond e.g. Cracking of ethane will give ethene and hydrogen General formula = CnH2n+1OH Functional group: OH METHANOL (N=1) ETHANOL (N=2) PROPANOL (N=3) BUTANOL (N=4) Formed by: FERMENTATION Butane → Ethane + Ethene ; C4H10 → C2H6 + C2H4 SATURATED HYDROCARBONS Have NO double bonds Do not react with aqueous bromine, so the mixture stays orange. UNSATURATED HYDROCARBONS Have double bonds React with aqueous bromine, turning the mixture from orange to colourless. 14.7 Addition Polymerisation A polymer is a compound with very long carbon chains made up of monomer units. Poly(ethene) / Polythene: is a polymer produced from ethene by addition polymerization Enzymes in yeast break down glucose to ethanol and carbon dioxide, giving out heat Can be done with substances that contain cellulose, starch or glucose Done by grinding source (e.g. grapes) and adding enzymes to break down cellulose and starch into glucose. Leave it to ferment. Fractional distillation is used to get ethanol from the mixture Double bond splits and polymer is formed PAGE 20 OF 22 CATALYTIC ADDITION OF STEAM TO ETHENE Ethene is obtained by cracking long-chain alkenes from oil. The ethene reacts with steam (reversibly) in the following conditions: o 570°C o 60-70atm o Catalyst = phosphoric acid Low temperature gives a better yield, but high temperature is used to give a better rate of reaction. 14.10 Carboxylic Acids General formula = CnH2n+1COOH Functional group: COOH METHANOIC ACID (N=1) ETHANOIC ACID (N=2) PROPANOIC ACID (N=3) BUTANOIC ACID (N=4) Properties of Ethanoic Acid: Weak acid with high pH and low dissociation Formed by: o Oxidation of ethanol o With acidified potassium mangenate (VII) Carboxylic acids react with alcohols to give esters, in a condensation reaction, for example: Ethanoic acid + ethanol ⇌ ethyl ethanoate + water (alcohol = -yl & carboxylic acid = -oate) Large molecules built up from small units (monomers). Different macromolecules have different units and/or different linkages Example of: POLYTHENE SMALL UNITS (MONOMERS) glucose amino acids fatty acids and glycerol POLYCHLOROE THANE (PVC) Oil is a non-renewable resource Lot of energy to make steam and get right conditions Lot of ethene is unreacted, (and then recycled) Ethanol burns well in oxygen, giving out plenty of heat, as well as carbon dioxide and water. Ethanol is used as a: o Solvent: to dissolve things than water cannot. Evaporates easily, so used as solvent in glues, printing inks & perfumes o Fuel: added to or instead of petrol, because it burns cleanly FROM ETHENE Fast Continuous process Pure ethanol Smaller containers 14.11 Macromolecules POLYPROPENE DISADVANATGES Lots of material needed so big tanks needed Fractional distillation is expensive Slow process Batch process POLYSTYRENE ADVANTAGES Renewable source Good use of waste organic material TEFLON FERMENTATION CIE IGCSE CHEMISTRY//9093 LINKAGES amide ester USE Plastic bags and gloves, clingfilm (low density), mugs, bowls, chairs, dustbins (high density) Water pipes, wellingtons, hoses, covering for electricity cables Crates, ropes Used as expanded polystyrene in fastfood cartons, packaging, and insulation for roofs and walls Coated on frying pans to make them nonstick, fabric protector, windscreen wipers, flooring PAGE 21 OF 22 MACROMOLECULES protein starch lipids STRUCTURE CIE IGCSE CHEMISTRY//9093 They collect in rivers, and get in the way of fish. Some river beds now contain a thick layer of plastic They blow into trees and onto beaches. So the place looks a mess. Tourists become put off. Making nylon: Uses: ropes, fishing nets and lines, tents, curtains Monomers are: 14.13 Natural Macromolecules Food’s main constituents are proteins, fats and carbohydrates. Proteins: Proteins contain the same linkages (amide links) as nylon, but with different units. Their structure is: No double bonds break, instead single bonds break, and new single bonds form. The monomers are able to join to each other by eliminating a small molecule: hydrogen chloride. This reaction continues at each the two monomers. Thousands of molecules join together, giving a macromolecule: Making terylene Uses: clothing (especially mixed with cotton), thread Monomers are: In digestion proteins are broken down into amino acids (hydrolysis). Fats: Fats are esters possessing the same linkage as Terylene (ester links) but with different units. Soap is a product of the hydrolysis of fat. It is done using sodium hydroxide (as opposed to acid, in digestion). The hydrolysis gives glycerol and the sodium salts of fatty acids. The salts are used as soaps. Carbohydrates: Complex carbohydrates: are a large number of joined sugar units (monosaccharide like glucose). The sugar units are represented like this: They join together in a condensation polymerization The monomers join by eliminating a water molecule. Thousands of molecules join up, giving a macromolecule 14.12 Pollution from Plastics Choke birds, fish and other animals that try to eat them. Or they fill up the animals’ stomachs so that they can’t eat proper food, and starve to death. They clog up drains and sewers and cause flooding. In digestion, the hydrolysis (Decomposition of a chemical compound by reaction with water) of starch happens in the mouth by the enzyme amylase to make glucose Hydrolysis: o Starch → glucose o Proteins → amino acids o Fats → fatty acids and glycerol But if hydrolysis is not complete, macromolecules are not completely broken down so you get a mixture of molecules of different sizes Identification: o Chromatography can be used to identify products & substances o However, amino acids and sugars are colourless when dissolved in water, so a locating agent is used. o Substances can be identified using Rf values or by matching them with spots which are horizontal PAGE 22 OF 22 TABLE OF CONTENTS 2 CHAPTER 1 3 CHAPTER 2 4 CHAPTER 3 6 CHAPTER 4 7 CHAPTER 5 7 CHAPTER 6 Number Algebra & Graphs Geometry Mensuration Coordinate Geometry Trigonometry 8 Matrices & Transformations CHAPTER 7 9 CHAPTER 8 9 CHAPTER 9 Probability Statistics CIE IGCSE MATHEMATICS//0580 Set representations: 1. NUMBER Natural numbers: o used for counting purposes o made up off all possible rational & irrational numbers Integer: a whole number Prime numbers: o divisible only by itself and one o 1 is not a prime number Rational numbers: can be written as a fraction Irrational numbers: cannot be written as a fraction e.g.𝜋 1.1 HCF and LCM Highest Common Factor and Lowest Common Multiple: o HCF = product of common factors of x and y o LCM = product of all items in Venn diagram Prime Factorization: finding which prime numbers o multiply together to make the original number 𝑏∈𝑋 𝐴 ∪ 𝐵 is shaded = {a, b, c, d, e} Definition of sets e.g. o 𝐴 = {𝑥: 𝑥 is a natural number} o 𝐵 = {(𝑥, 𝑦): 𝑦 = 𝑚𝑥 + 𝑐} o 𝐶 = {𝑥: 𝑎 ≤ 𝑥 ≤ 𝑏} o 𝐷 = {𝑎, 𝑏, 𝑐, … } Notation: 𝑛(𝐴) = no. of elements in A 𝐴 ⊆ 𝐵 = A is a subset of B ∈ = …is an element of… 𝐴 ⊂ 𝐵 = A is a proper ∉ = …is not an element of… subset of B 𝐴′ = compliment of set A 𝐴 ⊈ 𝐵 = A is not a subset of B Ø or { } = empty set 𝐴 ⊄ 𝐵 = A is not a proper = Universal set subset of B 𝐴 ∪ 𝐵 = union of A and B ⊂ ‘is a subset of’ A’ is shaded 1.3 Indices 𝑛(𝐴) = no. of elements in A 𝐴 ⊆ 𝐵 = A is a subset of B ∈ = …is an element of… 𝐴 ⊂ 𝐵 = A is a proper ∉ = …is not an element of… subset of B 𝐴′ = compliment of set A 𝐴 ⊈ 𝐵 = A is not a subset of B Ø or { } = empty set 𝐴 ⊄ 𝐵 = A is not a proper = Universal set subset of B 𝐴 ∪ 𝐵 = union of A and B 𝐴 ∩ 𝐵 = intersection of A and B Standard form: o 104 = 10000 o 103 = 1000 o 102 = 100 o 101 = 10 o 100 = 1 1.2 Sets 𝐴 ∩ 𝐵 = intersection of A and B 𝐴 ∩ 𝐵 is shaded 10−1 10−2 10−3 10−4 10−5 = 0.1 = 0.01 = 0.001 = 0.0001 = 0.00001 Limits of accuracy: The degree of rounding of a number o E.g. 2.1 to 1 d.p. 2.05 ≤ 𝑥 < 2.15 1.4 Ratio & Proportion Ratio: used to describe a fraction o e.g. 3 : 1 Foreign exchange: money changed from one currency to another using proportion o E.g. Convert $22.50 to Dinars $1 : 0.30KD $22.50 : 6.75KD Map scales: using proportion to work out map scales o 1km = 1000m o 1m = 100cm o 1cm = 10mm PAGE 2 OF 10 CIE IGCSE MATHEMATICS//0580 Direct variation: 𝑦 is proportional to 𝑥 𝑦∝𝑥 𝑦 = 𝑘𝑥 Inverse variation: 𝑦 is inversely proportional to 𝑥 1 𝑦∝𝑥 Trinomial: 𝑥 2 + 14𝑥 + 24 𝑥 + 12𝑥 + 2𝑥 + 24 𝑥(𝑥 + 12) + 2(𝑥 + 12) (𝑥 + 2)(𝑥 + 12) 2 𝑘 𝑦=𝑥 1.5 Percentages Percentage: o Convenient way of expressing fractions o Percent means per 100 Percentage increase or decrease: 𝐴𝑐𝑡𝑢𝑎𝑙 𝐼𝑛𝑐𝑟𝑒𝑎𝑠𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑖𝑛𝑐𝑟𝑒𝑎𝑠𝑒 = 𝑂𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝐴𝑚𝑜𝑢𝑛𝑡 Simple interest: 𝑃𝑅𝑇 𝐼= 100 𝑃 = 𝑃𝑟𝑖𝑛𝑐𝑖𝑝𝑎𝑙 𝑅 = 𝑅𝑎𝑡𝑒 𝑜𝑓 𝐼𝑛𝑡𝑒𝑟𝑒𝑠𝑡 𝑇 = 𝑃𝑒𝑟𝑖𝑜𝑑 𝑜𝑓 𝑇𝑖𝑚𝑒 Compound interest: 𝑅 = 𝑅𝑎𝑡𝑒 𝑜𝑓 𝐼𝑛𝑡𝑒𝑟𝑒𝑠𝑡 𝑛 = 𝑃𝑒𝑟𝑖𝑜𝑑 𝑜𝑓 𝑇𝑖𝑚𝑒 1.6 Speed, Distance & Time 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑇𝑖𝑚𝑒 𝑇𝑜𝑡𝑎𝑙 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑆𝑝𝑒𝑒𝑑 = 𝑇𝑜𝑡𝑎𝑙 𝑇𝑖𝑚𝑒 Units of speed: km/hr m/s Units of distance: km m Units of time: hr sec 5 𝑘𝑚/ℎ𝑟 × = 𝑚/𝑠𝑒𝑐 18 18 𝑚/𝑠𝑒𝑐 × = 𝑘𝑚/ℎ𝑟 5 𝑆𝑝𝑒𝑒𝑑 = 2. ALGEBRA & GRAPHS 2.1 Factorisation Common factors: 3𝑥 2 + 6𝑥 3𝑥(𝑥 + 2) Difference of two squares: 25 − 𝑥 2 (5 + 𝑥)(5 − 𝑥) Group factorization: 4𝑑 + 𝑎𝑐 + 𝑎𝑑 + 4𝑐 4(𝑑 + 𝑐) + 𝑎(𝑐 + 𝑑) (4 + 𝑎)(𝑐 + 𝑑) General equation: 𝑎𝑥 2 + 𝑏𝑥 + 𝑐 = 0 Solve quadratics by: o Trinomial factorization o Quadratic formula −𝑏 ± √𝑏 2 − 4𝑎𝑐 𝑥= 2𝑎 When question says “give your answer to two decimal places”, use formula! 2.3 Simultaneous Equations 𝑅 𝑛 𝐴 = 𝑃 (1 + ) 100 𝑃 = 𝑃𝑟𝑖𝑛𝑐𝑖𝑝𝑎𝑙 2.2 Quadratic Factorization Simultaneous linear equations can be solved either by substitution or elimination Simultaneous linear and non-linear equations are generally solved by substitution as follows: o Step 1: obtain an equation in one unknown and solve this equation o Step 2: substitute the results from step 1 into the linear equation to find the other unknown The points of intersection of two graphs are given by the solution of their simultaneous equations 2.4 Inequalities Solve like equations Multiplying or dividing by negative ⇒ switch sign 𝑦 ≥ −7 −3 𝑦 ≤ −7 × −3 𝑦 ≤ 21 When two inequalities present, split into two 𝑥 < 3𝑥 − 1 < 2𝑥 + 7 𝑥 < 3𝑥 − 1 3𝑥 − 1 < 2𝑥 + 7 1 𝑥 > −2 𝑥<8 2.4 Linear Programming For strict inequalities (<, >) use broken line For non-strict inequalities (≤, ≥) use solid line PAGE 3 OF 10 CIE IGCSE MATHEMATICS//0580 Steps to solve: o Interpret 𝑦 = 𝑚𝑥 + 𝑐 o Draw straight line graphs o Shade o Solve 2.5 Sequences Linear sequences: Find common difference e.g. 3 then multiply by 𝑛 and work out what needs to be added Quadratic sequences: o Format: 𝑎𝑛2 + 𝑏𝑛 + 𝑐 𝑎+𝑏+𝑐 = 3𝑎 + 𝑏 = 2𝑎 = o Work out the values and then place into formula to work out nth term formula Geometric progression: sequence where term has been multiplied by a constant to form next term 𝑛𝑡ℎ 𝑡𝑒𝑟𝑚 𝑜𝑓 𝐺. 𝑃. = 𝑎𝑟 (𝑛−1) o a = 1st term r = common difference 2.6 Distance-Time Graphs Area under a graph = distance travelled. Gradient = acceleration. If the acceleration is negative, it is called deceleration or retardation. (moving body is slowing down.) 2.8 Functions Function notation: o 𝑓: 𝑥 → 2𝑥 − 1 o Function 𝑓 such that 𝑥 maps onto 2𝑥 − 1 Composite function: Given two functions 𝑓(𝑥) and 𝑔(𝑥), the composite function of 𝑓 and 𝑔 is the function which maps 𝑥 onto 𝑓(𝑔(𝑥)) 𝑓(2) o Substitute 𝑥 = 2 and solve for 𝑓(𝑥) 𝑓𝑔(𝑥) o Substitute 𝑥 = 𝑔(𝑥) 𝑓 −1 (𝑥) o Let 𝑦 = 𝑓(𝑥) and make 𝑥 the subject 3. GEOMETRY 3.1 Triangles From O to A : Uniform speed From B to C : Uniform speed (return journey) From A to B : Stationery (speed = 0) Gradient = speed 2.7 Speed-Time Graphs From O to A : Uniform speed From A to B : Constant speed (acceleration = 0) From B to C : Uniform deceleration / retardation 3.2 Quadrilaterals Rectangle: Opposite sides parallel and equal, all angles 90°, diagonals bisect each other. Parallelogram : Opposite sides parallel and equal, opposite angles equal, diagonals bisect each other PAGE 4 OF 10 CIE IGCSE MATHEMATICS//0580 Rhombus: A parallelogram with all sides equal, opposite angles equal, diagonals bisect each other The number of times shape fits its outline during a complete revolution is called the order of rotational symmetry. Trapezium: One pair of sides parallel Kite: Two pairs of adjacent sides equal, diagonals meet at right angles bisecting one of them 3.3 Construction Constructing triangles: Perpendicular bisector: Shape Square Rectangle Parallelogram Rhombus Trapezium Kite Equilateral triangle Regular hexagon Number of Lines Rotational of Symmetry Symmetry Order 4 4 2 2 0 2 2 2 0 1 1 1 3 3 6 6 Properties of circles: o Equal chords are equidistant from the centre o The perpendicular bisector of a chord passes through the centre o Tangents from an external point are equal in length 3.5 Polygons Sum of angles at a point = 360 Angles on a straight line = 180 Sum of angles in a triangle =180 For regular polygon o External angles = Angle bisector: 360 𝑛 o Internal angles = 180 − 360 𝑛 For irregular polygon: o Sum of exterior angles =360 o Sum of interior angles =180(n-2) Vertically opposite angles Corresponding angles 3.4 Symmetry A line of symmetry divides a two-dimensional shape into two congruent (identical) shapes. A plane of symmetry divides a three-dimensional shape into two congruent solid shapes. PAGE 5 OF 10 CIE IGCSE MATHEMATICS//0580 Alternate angles 3.7 Loci The locus of points equidistant from a point is a circle Co-interior angles The locus of points equidistant between two point is a perpendicular bisector Exterior angle=sum of interior opposite ∠ 3.6 Circle Theorem The locus of points equidistant between two lines is an angle bisector Angle at centre = twice angle on circumference Angle subtended by same arc at circumference are equal The locus of points equidistant (along) from a line is a parallel line Angles in semicircle are 90° Opposite angles in a cyclic quadrilateral = 180° 4. MENSURATION 4.1 Area Parallelogram = 𝑏 × ℎ Tangents from one point are equal ∠ between tangent Alternate segment theorem and radius is 90° 1 Triangle= 2 𝑏 × ℎ 1 Trapezium= 2 (𝑎 + 2 Circle= 𝜋𝑟 𝜃 Sector= 𝜋𝑟 2 × 360 PAGE 6 OF 10 𝑏)ℎ OR 𝑎𝑏 sin 𝜃 CIE IGCSE MATHEMATICS//0580 4.2 Volume and Surface Area Cylinder o 𝐶𝑢𝑟𝑣𝑒𝑑 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 = 2𝜋𝑟ℎ o 𝑉𝑜𝑙𝑢𝑚𝑒 = 𝜋𝑟 2 ℎ Cone o 𝐶𝑢𝑟𝑣𝑒𝑑 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 = 𝜋𝑟𝑙 Equation of Line: 𝑦 = 𝑚𝑥 + 𝑐 o Find the gradient, 𝑚 o Find the 𝑦-intercept, 𝑐 1 o 𝑉𝑜𝑙𝑢𝑚𝑒 = 3 (𝜋𝑟 2 ℎ) Sphere o 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 = 4𝜋𝑟 2 4 o 𝑉𝑜𝑙𝑢𝑚𝑒 = 3 𝜋𝑟 3 Hemisphere o 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 = 2𝜋𝑟 2 Midpoint of Graph: 𝑥1 + 𝑥2 𝑦1 + 𝑦2 ( , ) 2 2 Length between two points: 2 o 𝑉𝑜𝑙𝑢𝑚𝑒 = 3 𝜋𝑟 3 4.3 Units √(𝑥1 − 𝑥2 )2 + (𝑦1 − 𝑦2 )2 Volume: 5.2 Sketching Graphs Mass: 𝑓(𝑥) = 1 𝑓(𝑥) = 𝑥 𝑓(𝑥) = 𝑥 3 𝑓(𝑥) = 𝑓(𝑥) = 𝑥 2 Capacity: Connecting volume and capacity: o 1𝑚𝑙 = 1𝑐𝑚3 o 1𝑘𝑙 = 1𝑚3 𝑀𝑎𝑠𝑠 Density = 𝑉𝑜𝑙𝑢𝑚𝑒 5. COORDINATE GEOMETRY 5.1 Graphs Gradient of a Straight Line: 𝐺𝑟𝑎𝑑𝑖𝑒𝑛𝑡 = 1 𝑥 𝑓(𝑥) = 1 𝑥2 6. TRIGONOMETRY 6.1 Bearings The bearing of a point B from another point A is: o An angle measured from the north at A. o In a clockwise direction. o Written as three-figure number (i.e. from 000 ° to 360°) e.g. The bearing of B from A is 050° 𝑦2 − 𝑦1 𝑥2 − 𝑥1 PAGE 7 OF 10 CIE IGCSE MATHEMATICS//0580 Multiplication by a scalar: o A scalar quantity has a magnitude but no direction o The negative sign reverses the direction of the vector Column vector: o Top number is the horizontal component and bottom number is the vertical component Parallel vectors: o Vectors are parallel if they have the same direction o In general the vector 𝑘(𝑎𝑏) is parallel to (𝑎𝑏) Modulus of a vector: o In general, if 𝑥 = (𝑚 ), |𝑥| = √(𝑚2 + 𝑛2 𝑛 6.2 Pythagoras Theorem To find hypotenuse o 𝑎2 + 𝑏 2 = 𝑐 2 To find one of the shorter sides o 𝑎2 = 𝑐 2 − 𝑏 2 o 𝑏 2 = 𝑐 2 − 𝑎2 Angle of elevation: o Angle above the horizontal line. Angle of depression: o Angle below the horizontal line. 7.2 Matrices Addition: 𝑝 𝑞 𝑎+𝑝 𝑏+𝑞 𝑎 𝑏 ( )+( )=( ) 𝑟 𝑠 𝑐 𝑑 𝑐+𝑟 𝑑+𝑠 Multiplication by scalar 𝑎 𝑏 𝑘𝑎 𝑘𝑏 𝑘( )=( ) 𝑐 𝑑 𝑘𝑐 𝑘𝑑 Multiplication by vector: 𝑎𝑝 + 𝑏𝑟 𝑎𝑞 + 𝑏𝑠 𝑝 𝑞 𝑎 𝑏 ( )×( )=( ) 𝑟 𝑠 𝑐𝑝 + 𝑑𝑟 𝑐𝑞 + 𝑑𝑠 𝑐 𝑑 o You can only multiply if no. of columns in left equals to no. of rows in right Determinant: o Determinant = leading diagonal – secondary diagonal 𝑎 𝑏 A =( ) |𝐴| = (𝑎𝑑) − (𝑏𝑐) 𝑐 𝑑 Inverse: o To work out inverse, switch leading diagonal, negate 1 2 Area of a triangle: 𝑎𝑏 sin 𝑐 6.3 Ratios Right angled triangles: 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 o sin 𝑥 = ℎ𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒 𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 o cos 𝑥 = ℎ𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 o tan 𝑥 = 𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 6.4 Sine & Cosine Rules Sine rule: 𝑎 𝑏 𝑐 = = sin 𝑎 sin 𝑏 sin 𝑐 o One pair of information needed Cosine rule o To find the angle given 3 sides 𝑏 2 + 𝑐 2 − 𝑎2 cos 𝑎 = 2𝑏𝑐 o To find side given angle and two sides 𝑎2 = 𝑏 2 + 𝑐 2 − 2𝑏𝑐 cos 𝑎 1 secondary diagonal, multiply by |𝑎| 𝑎 A =( 𝑐 𝑏 ) 𝑑 1 𝑑 𝐴−1 = (𝑎𝑑−𝑏𝑐) ( −𝑐 −𝑏 ) 𝑎 7.3 Transformation 7. MATRICES & TRANSFORMATION 7.1 Vector A vector quantity has both magnitude and direction. o E.g. Vectors a and b represented by the line segments can be added using the parallelogram rule or the noseto-tail method. Reflection (M): o When describing a reflection, the position of the mirror line is essential. Rotation (R): o To describe a rotation, the centre of rotation, the angle of rotation and direction of rotation are required. o A clockwise rotation is negative and an anticlockwise rotation is positive. Translation (T): o When describing a translation it is necessary to give the translation vector PAGE 8 OF 10 CIE IGCSE MATHEMATICS//0580 Enlargement (E): o To describe an enlargement, state the scale factor, K and the centre of enlargement 𝑆𝑐𝑎𝑙𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 = 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑖𝑚𝑎𝑔𝑒 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑜𝑏𝑗𝑒𝑐𝑡 2 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑖𝑚𝑎𝑔𝑒 = 𝐾 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑜𝑏𝑗𝑒𝑐𝑡 o If K > 0, both object and image lie on same side of the centre of enlargement. o If K < 0, object and image lie on opposite side of the centre of enlargement. 7.4 Transformation by Matrices Reflection: 1 0 o( ) 0 −1 −1 0 o( ) 0 1 0 1 o( ) 1 0 0 −1 o( ) −1 0 Enlargement: 𝑘 0 o( ) 0 𝑘 Rotation: 0 −1 o( ) 1 0 0 1 o( ) −1 0 −1 0 o( ) 0 −1 Independent events: Two events are independent if occurrence of one is unaffected by occurrence of other. The AND Rule: o p(A and B) = p(A) × p(B) 9. STATISTICS Reflection in the 𝑥 − 𝑎𝑥𝑖𝑠 9.1 Histograms Reflection in the 𝑦 − 𝑎𝑥𝑖𝑠 Reflection in the line 𝑦 = 𝑥 Reflection in the line 𝑦 = −𝑥 where k=scale factor and centre of enlargement = (0,0) Rotation 90° anticlockwise, centre (0,0) Rotation 90° clockwise, centre (0,0) Rotation 180° clockwise/ anticlockwise, centre (0,0) 8. PROBABILITY Probability is the study of chance, or the likelihood of an event happening. Probability of an event = 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑓𝑎𝑣𝑜𝑢𝑟𝑎𝑏𝑙𝑒 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠 𝑡𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠 If probability = 0, the event is impossible and if probability =1, the event is certain to happen All probabilities lie between 0 and 1. A histogram displays the frequency of either continuous or grouped discrete data in the form of bars. The bars are joined together. The bars can be of varying width. The frequency of the data is represented by the area of the bar and not the height. When class intervals are different it is the area of the bar which represents the frequency not the height Instead of frequency being plotted on the vertical axis, frequency density is plotted. Class width = Interval Frequency density = Height 𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 = 𝐶𝑙𝑎𝑠𝑠 𝑤𝑖𝑑𝑡ℎ × 𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 9.2 Averages 8.1 Events Mean: Exclusive events: Two events are exclusive if they cannot occur at the same time. The OR Rule: o For exclusive events A and B o p(A or B) = p(A) + p(B) 𝑆𝑢𝑚 𝑜𝑓 𝑣𝑎𝑙𝑢𝑒𝑠 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑣𝑎𝑙𝑢𝑒𝑠 Median: o The middle value when the data has been written in ascending or descending order PAGE 9 OF 10 CIE IGCSE MATHEMATICS//0580 o o 5+1 Odd no. of values 2 = 3𝑟𝑑 𝑣𝑎𝑙𝑢𝑒 6+1 Even no. of values 2 = 3.5𝑡ℎ 𝑣𝑎𝑙𝑢𝑒 (add two values divide by 2) Mode: o Most frequently occurring value Range: o Difference between highest and lowest values Estimated mean of grouped data: o Work out midpoints of each group and multiply by frequency o Divide by number of values 9.3 Cumulative Frequency Cumulative frequency is the total frequency up to a given point. Inter-quartile range = upper quartile − lower quartile PAGE 10 OF 10