Chemical Reactions:

Year 10 Science Yearly Notes /School Certificate

Chemical Reactions:

Reactants: Reactants are the starting substances in the chemical reaction

Products: Products are the substances produced in a chemical reaction

Conservation of Mass: Chemical equations show that atoms are conserved in the reaction; this is known as the conservation of mass o Total mass of products = Total mass of reactants

In a chemical reaction, no atoms are destroyed or created

Acids

Properties of Acids: Acids have certain properties which distinguish it from bases: o Taste sour o Corrosive o React with solid substances

Bases

Properties of Bases: Bases have certain properties which distinguish it from acids: o Taste Bitter o React with the hydrogen in acids

Indicators

Indicators are substances that can be used to tell whether a substance is an acid or base.

Types of Indicators

An example of an indicator is litmus paper o Acid turns blue litmus paper red o Acids do not change the colour of red litmus paper

Another example of an indicator used for acids is the metal test o Acids wear away metals o Hydrogen gas is given off while the metal is changing

Universal Indicator & pH:

pH is a measure of the acidity or basicity of a solution o The lower the pH the more acidic the solution o Strongly acidic solutions have pH around 0 to 2 o The higher the pH the more basic the solution o Strongly basic solutions have pH around 12 to 14

Chemical Reactions:

- A chemical reaction is when substances combine to form new substances. o Indicated by change in colour odour, o Exothermic (gives off heat) o Endothermic (heat is absorbed) o Gas is given off

A Chemical equation: chemical equation summarises the events of a chemical reaction.

Types of chemical reactions:

Metal/acid Reaction: acid+metal  salt+hydrogen gas

To test for the presence of hydrogen gas, you bring a lit taper next to the gas and it should pop. The name of the salt changed depending on the name of the acid and metal.

I.E: Hydrochloric +Magnesium  Magnesium Chloride + hydrogen

1


Neutralisation (ACID/BASE reaction) : acid + base  salt +water

I.E: Sulfuric acid + calcium Hydroxide  calcium + water

-

Acid/carbonate Reaction: acid+carbonate  salt +carbon dioxide +water

In another words, acid carbonate reaction is when limewater goes from visible to cloudy/turbid.

Nitric Acid + calcium carbonate  calcium nitrate + Co2 +H2o

Types of chemical reactions:

-

Combustion: Burning- it is a self-sustaining chemical reaction that occurs at temperatures higher than the surroundings.

Corrosion: is the eating away of metal so that it loses strength and become unable to do its intended purpose.

Precipitation: the formation of a solid from 2 solutions.

Neutralisation: the reaction between an acid and a base

-

Decomposition: the breaking of a compound into more simple substances.

The Arrangement of the Periodic Table

The elements are arranged in the periodic table according to their increasing atomic number

The elements are arranged in rows and columns o Rows are called periods o Columns are called groups

Recognising the Elements on the Periodic Table

Each element is represented in a separate box on the periodic table

Each box has four different characters: o 1. the atomic number o 2. the symbol of the element o 3. the atomic weight o 4. the name of the element

Structure of an atom:

The atoms of all matter are electrical and are made up of three small subatomic particles:



Electrons: which carry negative charges



Protons, which carry positive charges



Neutrons, which carry no charge.

Atoms are held together by a strong attraction between protons and electrons.

Particles with opposite charges attract one another. E.g.: opposite poles of a magnet.

Definitions:

Atom: an atom is the smallest unit in an element that can exist by itself.

Molecule: a molecule is 2 or more atoms joined together.

Element: Element is made from one type of atoms only.

Compound: A compound is made up from many molecules joined together.

2


Attractions between ions:

The attraction of the ions forms new compounds.

More electrons than electrons is negative.

More protons than electrons is positive.

The electrons and protons keep the compound together.

The chemical bond is called Ionic bond.

The difference in charge keeps them together.

A compound stays together because they share electrons and protons from each other.

3


Structure of an Atom:

The atoms of all matter are electrical and are made up of three small subatomic particles:



Electrons: which carry positive charges.



Protons: which carry positive charges.



Neutrons: which carry no charge.

Protons and neutrons make up the very dense nucleus of the atom and the tiny electrons are arranged in shells of different energy levels and orbit around the nucleus.

The maximum number of electrons in the first shell is always two, the second is eight and the third is eight. Electrons fill the inside shells first.

Attractions: o Atoms are held together by a strong attraction between the protons and electrons. o Particles with opposite charges attract one another, like opposite poles of a magnet. o The attractions of the ions form new compounds. o More electrons then protons are negative. o More neutrons than electrons is positive. o The protons and electrons keeps the compound together.

4


Life cycle of a star

Sun is the nearest star to earth.

The sun is a bright yellow dwarf star” o Sun is about 4.6 billion years. o The sun belongs to a galaxy called Milky Way. o Only 8.5 light-minutes away from Earth. o Sun contains 98% of all the mass of the solar system. o It is composed of Hydrogen and a smaller amount of helium. o Inside the sun, hundreds of huge nuclear explosions occur each second.

Stars can’t be seen during the day because the sun blinds us from seeing them.

Distance in space is measured in light years.

Galaxies are a huge collection of stars.

Globular clusters:

o Globular clusters are small and very old stars packed together, they are found outside galaxies. o Omega Centauri is a name of a globular cluster.

Inside the stars:

o The atomic reaction in a star occurs in the core. o It takes over 100 000 years for the light and heat produced by the atomic reaction to reach the surface of the star. o The energy leaves a star in the form of heat light. ULTRA VIOLET.

Types of stars:

o The outer planet of our solar system are made of gas same as the stars. o There are 4 types of stars:

1Red Dwarf ( Smallest star 0.2 solar mass)

2Yellow Dwarf ( solar mass)

3White Dwarf ( 10 solar mass)

4Blue dwarf ( 40 solar mass) Largest star o The temperature of the star depends on the size of it. o The size of a star determines its fate, which means the bigger the star, the longer its life will be. o The smaller the star, the shorter the life.

Big Bang:

o The big bang occurred around 15 billion years ago, there was a giant explosion in space. o During the BIG BANG:

1Everything was compressed to about the size of an atom

2There was a huge explosion that produced quantities of hydrogen, helium & small amount of lithium.

5

Year 10 Science Yearly Notes /School Certificate o The spiral arms of galaxies grow by collecting gas from space, they form clouds then stars are born there.

- Stars are born in Stella nurseries in the clouds of gases.

How is a star born?

1Gases fall into the centre of a cloud

2A protostar is formed but it is not yet hot.

3Gases spin to form a rotating disc. Planets form in this disc.

4The protostar in the middle of the disc collects more hydrogen.

5The squeezing air together (compression) of gases causes the gases in the protostar to heat up.

6When the temperature is hot enough the hydrogen gas is squeezed together to form an atomic fusion reaction.

7A star is born.

Features of universe:

o Galaxy:

- Collection of billions of stars and matter held together by gravity.

- Galaxies are spread over thousands of light years.

- The Milky Way which the sun belongs to is an example of a galaxy. o Nebula:

- Is a contracting, swirling cloud of dust, ice and gas that forms a concentric series of rings from which the planets were formed. o Black hole:

- A region containing a huge amount of compacted mass.

- It makes its pull of gravity so strong that nothing, not even light, can escape from it. o Neutron stars:

- Dense objects

- They form after a supernova occurs. o Pulsars:

- Special types of neutron stars that emit beams of radio waves, and also spin. o Nuclear fusion occurs when hydrogen nuclei fuse together and release energy.

Hydrogen  (Nuclear fusion)  Helium + Energy.

6


Electromagnetic waves:

- There are two types of waves: o Electromagnetic waves and o Mechanical waves.

- Electromagnetic waves are composed of electric and magnetic fields and do not need particles to transfer energy, that is, they can travel through a vacuum. The electromagnetic

Radio Waves:

Microwaves:

Infrared waves:

Transmit radio and TV Signals, radar in air traffic control

Cooking, radar speed guns used by police

Given off by hot objects, used to take temperature pictures and find people in collapsed buildings.

Visible Light:

UV Rays

Seeing, photosynthesis, photography

Fluorescent lamps, sterilising

X Rays Radiography, treating cancer, finding faults in metals, examining crystals.

Measure thickness of metals, sterilise medical equipment. Gamma Rays spectrum contains several types of electromagnetic waves:

- Electromagnetic waves travel through space at the speed of light.

- There are 2 types of Electromagnetic waves: o Transverse waves and o Longitudinal waves.

- Transverse waves: in transverse waves the particles vibrate at right angles to the direction of the wave. I.e.: Vibrates Up and down. The wavelength of a transverse wave is the distance from one crest to the next.

- Longitudinal waves do not look wavy; they can be seen as a pulse along a stretched spring.

The wavelength of a longitudinal wave is the distance between two compressions.

Wave Sample:

Note: As the wave transmits energy, the trough becomes the crest and the crest becomes the trough because the wave is moving up and down.

7


Parts of wave:

- Crest: Crest is the top part of a wave.

-Trough: The trough is the bottom part of a wave.

-Wave Length: Wave length is the distance between each group.

-Amplitude: is the distance from the imaginary line to the crest or the imaginary line to the trough.

-Frequency: the number of waves produced per second, measured in Hertz (Hz)

-Wave Speed (m/s) = Frequency (Hz) x wavelength (m)

Electromagnetic Waves: o All waves transfer energy without moving material in the direction that they are moving. They may be vibrations that go up and down, or back and forth.

1.

The lower the frequency in a wave, the longer the wave length.

2.

The higher the frequency, the shorter the wave length.

Lights:

- An object that lights is called a Luminous Object, eg: Sun, switched on light bulbs, and burning wood.

- An object that light shines upon is called an illuminated object, eg: the moon, in fact most things are illuminated.

- A small luminous body is called a point source.

- A light that spreads out greatly is called an extended light source.

- Light travels in a straight line, it moves along 300 000 km/s, light doesn’t ned any medium in order to travel.

- When light strikes matter, 3 things happen, it can be: absorbed, reflected or transmitted.

1.

When light is absorbed, it’s taken in by the matter it strikes. Substances like wood and metal do not transmit light they only absorb, we can’t see through them at all.

They are called opaque.

2.

When light is reflected, it bounces off the substance it strikes. A mirror is a common example. Light that is transmitted passes through the matter it strikes. Transparent substances transmit light eg: window glass, water and air.

3.

Substances that scatter the light are called TRANSLUCENT, because we can see the light through them but we cannot see any details, eg: waxed paper and frosted glass.

Reflection:

o Angle of reflection is the angle between the normal and the reflected ray. o Angle of incidence is the angle between the normal and the incident ray. o Angle of incidence and angle of reflection are always equal. o The normal is an imaginary line between the angle of reflection and angle of incidence; it bisects the angle in half.

8


Refraction:



Refraction is the bending of light as it passes from one medium to another.



When light passes through a glass slab, the light is transmitted and bent.



This bending of light is called refraction.



Air is less dense than glass.



Light bent when the medium changed.



Refraction occurs when light passes from one medium to another,



When light travels from a less dense medium to a denser medium the lights travel towards the normal.



When light travels from a denser medium to a less dense medium the lights travels away from the normal.



Always Speed depends on density.



Different substances have different densities. For example water is denser than air.

Laws of Refraction:

1.

Light that moves at an angle from a ales dense medium to a more dense medium bends towards the normal.

2.

Light that moves straight on from one medium to another does not bend. It is not refracted.

3.

Light that moves at an angle from a denser medium to a less dense medium bends away from the normal.

9


Reproduction:

Reproduction is a life function, it means creating new life.

Asexual Reproduction:

Asexual reproduction occurs when there is only on parent. It occurs in less complex organisms such as unicellular organisms.

Sexual Reproduction:

Sexual reproduction involves 2 parents, a male and female. It occurs in more complex living organisms.

Mitosis:

Mitosis is the type of cell division that leads to the growth and development of an organism. Mitosis occurs in all cells except for sex cells. Human cells have 46 chromosomes’.

Types of Cells Mitosis Produces:

Cells needed to make an adult organism from a fertilised egg.

Cells needed to heal cuts, wounds and broken bones

Cells that replace dead skin cells.

Process of Mitosis

Step One: o Cell becomes larger o Chromosomes become visible

Step Two: o Chromosomes double by splitting into two and pair up

Step Three: o Double chromosomes line up across the equator of the cell o Membrane of nucleus disappears

Step Four: o Doubles separate o Chromosomes move on the spindle form to go to opposite poles (ends) of the cell

Step Five: o Membrane divides the cell into two o Each new cell have the same number of chromosomes as the original

Step Six: o Chromosomes form nucleuses of the new cells

Meiosis:

Meiosis is the divion of cells to create sex cells. Sex cells only have 23 chromosomes.

Process of Meiosis

Step One: o Cell becomes larger o Chromosomes become visible

Step Two: o Chromosomes double by splitting into two and pair up

Step Three: o Membrane divides the cell into four o Each new sex cell has half the number of chromosomes as the original

Step Four: o Chromosomes form nucleuses of the new cells

10


Genetics

Genetics refers to the study of hereditary and inherited characteristics.

Chromosomes

Long thin threads

Contains chemicals which control what the cell does

Human cells have 46 chromosomes except for sex cells which have 23 chromosomes

Chromosomes hold DNA as a compact coil…

DNA

Deoxyribonucleic Acid

Stores the coded information that determines human characteristics

DNA consists of nucleotides…

Nucleotides

Building blocks of DNA arranged to form a genetic language or code

Four different nitrogenous bases o Adenine (A) o Thymine (T) o Cytosine (C) o Guanine (G)

Base Pairing Rule > A is chemically attracted to T

> C is chemically attracted to G

Nucleotides make up genes…

Genes

Sections of DNA which contain complete messages or sets or particular instructions

Locus > the position occupied by the gene on the chromosome

Genome > Same set of genes in each cell of an organism

The message in the gene is the coded formula needed to produce protein…

Protein

Instructions in the gene code for the production of protein which are essential to the cell

The life processes inside your body are carried out by a group of proteins called enzymes

Before the instruction can be carried out it must be copied so that the master plan remains in the cell

RNA

Copy of the DNA sequence

Passes through the pores of the nuclear membrane into the cytoplasm to the ribosomes where proteins are manufactured

Code for the production of the protein is carried in messenger RNA

Genotype : Genotype is a person’s genetic coding.

Phenotype : Phenotype is how living things appear and function. This is caused by the combined effect of their genotype and their environment.

11


DNA Mutation: o Mutations are the continual source of variation on which natural selection can act. o Cancers are due to a genetic change in a single cell. o Mutations that occur in body cells are known as somatic mutations. o Mutations are a source of new alleles in an organism.

Types of Mutations: o Aneuploidy: When an individual has an abnormal chromosome number. o Polyploidy: When an individual has one or more extra sets of chromosomes.

Changes in DNA sequence: o Most mutations involve changes in the DNA sequence. o Large changes may alter the structure of chromosomes and be visible when looking at chromosomes under the microscope. o When groups no longer share a pool of common genes, they are likely to become separate species over time.

12


DNA Structure

Scientists responsible for discovering the DNA? o The structure of DNA was worked out in 1953 by James Watson and Francis Crick, in what became one of the famous scientific discoveries of modern science.

DNA STRUCTURE: o DNA: Deoxyribonucleic acid o The molecule of DNA contains millions of atoms and is found in the cell nucleus. o It is made up of 2 strands, which twist around each other to form a shape called a double helix. o The strands are held together by the bases. o The exact sequence of these bases forms genetic information that varies from one living thing to another. o Bases always pair up precisely, these are called base pairs. o Adenine always pairs with thymine, and cytosine always pairs with guanine. o This precise pairing of bases provides a complementary copy of the first helix strand.

Replication: o When a cell divides, its DNA molecules copy themselves, or replicate, in order to pass on a set of instructions to each new cell. o During replication, each DNA molecule ‘unzips’ itself, so that its strands separate. o The two strands then from complementary copies of themselves. o Two new DNA molecules are produced, each with one old strand and one new strand.

13


Nucleic Acids:



Nucleic acids are organic compounds made up of small molecules called nucleotides.



There are 2 types of nucleic acid- DNA and RNA.



DNA carries genetic information and is stored inside the nucleus.



RNA acts as a shuttle service, copying the DNA’s information and carrying it to where it is put into action.

Types of Cells:



A homozygous cell is a cell that has identical alleles that control its particular features. They are either both dominant or recessive.



A heterozygous cell is a cell that has one dominant and one recessive allele for its characteristics. o During sexual reproduction genes are shuffled like cards in a pack. o Alleles that are close to each other on the same chromosome often stay together.

Alleles:







Allele: one of two or more forms of the same gene.

A dominant allele is the allele that will most likely express itself. Dominant characteristics are written as capital letters.

A recessive allele is partnered by a dominant allele, is usually masked by the dominant one. It is part of the genotype and can be passed on to the next generation. Recessive characteristics are notated with lower case letters.

Genetic Engineering:





In genetic engineering, scientists deliberately change genotypes by moving genes from one organism to another.

Genetic engineering can therefore give an organism characteristic that it does not normally have.

14


Reproductive Systems

Female Reproductive System

Ovaries

Two ovaries

Circular in shape

Produce female sex cells > eggs or ova

Produce female hormone > oestrogen

Fallopian Tubes

Also known as oviducts

Provide a passageway between ovaries and uterus for the eggs to travel

Fertilisation occurs in fallopian tubes

Uterus

Also known as the womb

Where the fertilised egg implants itself, grows and develops from a zygote to an embryo to a foetus

Wall of the uterus provides nutrients for embryo

Cervix

Interface between the uterus and the vagina

Supports baby during pregnancy

Vagina

Also known as vaginal canal/birth canal

Where the sperm enters the female reproductive system

Male Reproductive System

Testes

Two testes

Circular in shape

Produce male sex cells > sperm

Produce male hormone > testosterone

Scrotum

Skin sac which holds the testes outside the male body

Vas Deferens

Also known as sperm duct

Tube which connects the testes to the urethra, providing pathway for the sperm

Urethra

Starts at the vas deferens to the external environment

Primary job: carry urine

Secondary job: transport sperm

Seminal Vesicle

Produces fluid to nourish sperm

Glans Penis

Transfers sperm from the male to the female

15


Control and Coordination: Nervous System

-The nervous system is divided into 2 parts: o The Central Nervous System and o The Peripheral Nervous System.

The Central Nervous System is divided into 2 parts: The brain and the spinal cord.

CNS represents the largest part of the nervous system.

- The spinal cord carries out 2 main functions: o Connects large parts of the peripheral nervous system to the brain. o The spinal cord also acts as a minor coordinating centre responsible for some simple reflexes like the withdrawal reflex.

The brain: o The brain is part of the nervous system. o Made up from the forebrain, midbrain and hindbrain. o Cerebrum, Medulla and cerebellum. o It receives nerve impulses from the spinal cord and 12 pairs of cranial nerves. o Analyses and stores data, directs the action to the body. o The brain and spinal cord are made up of 2 types of cells:

1.

NEURONS: Send messages in the CNS

2.

Glial cells: supports neurons in the CNS

Stimulus Response:

A stimulus is what causes an organism to react.

- A response is a reaction to the stimulus.

- There are various nerves in the body which detect stimuli:

1.

When a stimulus is detected, your brain sends the message to your muscles.

2.

A bad smell is a stimulus for the receptors in your nose.

3.

Moving your hand from hot water Is a response to a stimuli.

 The path of stimulus:

Stimulus  Sense Organ  Sensory Neuron  into the neurons  Motor

Neurons  Effectors Muscle.

The nervous system process:

1.

Stimuli from the sense organs change to electrical signals.

2.

These electrical signals do not stay in the sense organs. Nerves carry the signals to the brain and spinal cord.

3.

The brain decides what each stimulus is. The brain also decides how to respond to each stimulus.

4.

Nerves carry *what to do * messages away from the brain. The messages go to the part of the body that will answer or respond to the stimuli.

5.

Most what to do messages go to muscles. Some, however, go to glands. Most responses are carried out by muscles.

16


Nerves/ Nerve cells:

Nerves are part of the nervous system.

What do they do? o Nerves carry electric pulses backwards and forwards from the brain, spinal cord and muscles. o Nerves are located through the body. o Nerve cells work together to coordinate our body. o Nerve cells are the longest cells in the body. o They have the special name of neuron or neurone. o Neurons have the shape and features to allow them to carry messages. o Nerves are bundles of neurons.

Reflex:

A reflex is when you accidentally touch a hot stove and you pull your hand away quickly, so quickly that your brain does not know about it.

The normal action is for a stimulus to be received in a sense organ, and then detected by a sensory neuron. The impulse is transmitted to the interneuron.

Then it will be sent down several motor neurons to an effector organ, such as a muscle to produce a movement. Whereas in a reflex action the message in the sensory neuron is passed directly to a motor neuron in the spinal column. The effector muscle receives the message to move sooner.

Reflex pathway:

1.

Stimulus detected by heat receptors in skin.

2.

Sensory neuron carries impulse.

3.

Spinal column relays impulse.

4.

Motor neuron carries impulse.

5.

Effector organ pulls hand away.

Receptors: o Receptors are highly specialised cells that are able to pick up a stimulus. o Types of receptors:

1.

Light receptors

2.

Taste receptors

3.

Smell receptors

4.

Sound receptors

5.

Touch receptors

6.

Temperature receptors

7.

Pressure receptors

Effectors: o Effectors are the parts of the body that respond to a stimulus when it is sent to them.

Endocrine System:

17


Endocrine system helps the body to adjust to the changeas outside and inside the body

What does the Endocrine System do?

1.

It produces hormones (Chemical messages)

2.

Helps control chemical reactions

3.

Hormones move through ducts and they do not empty directly into the blood stream, where the hormones are used.

4.

Ducts are tubes.

Parts of the Endocrine System:

Functions Glands Location Hormones

Produced

1- The Thyroid gland Attached to windpipe Thyroxine

2- Adrenal Glands

3- Ovaries

On top of the kidney Adrenalin

Reproductive system Oestrogen

Controls the speed of chemical reactions in cells.

Prepares your body for action

Gives girls their female

4- Pituitary glands

5- The pancreas

Under the brain

Below the stomach

Makes many hormones

Insulin feature such as breasts, soft skin, and a feminine voice.

Control growth.

In females it controls the release of eggs from ovaries

& the birth of a baby.

Insulin controls the amount of glucose in the blood

6- Testes Reproductive system Testosterone Give boys their male features such as deeper voices and more body hair than females.

18


Transmission of Diseases:

A disease is a condition that prevents or stops the body or any of its parts from working well.

Diseases are divided according to whether they are infectious or non-infectious.

Infectious diseases: o Infectious diseases are those that can be spread or transferred from one person to another. o Infectious disease is triggered by an infection or the growth of pathogen.

Pathogen o A disease producing organism o Pathogenic bacteria damage the cells of animals and plants causing disease. o Sometimes they produce poisonous wastes or toxins. o A pimple is caused when a bacteria gets into you sweat glands.

Microbe: o A microbe is usually just a single cell and so cannot be seen without a microscope. o Microbes are used to make bread and cheese.

Bacteria: o Bacteria are one-celled organisms; they are among the smallest and simplest living things. o They carry out all the life functions. o Bacteria cells don’t have a definite nuc leus. o Most bacteria can’t move by themselves, they are carried by air or moving water.

Diseases caused by bacteria:

Disease

Tonsillitis

What it does

Headache, sore throat, raised temperature.

How it spreads

Sneezing, coughing, spitting.

Whooping cough

Salmonella food poisoning

Tuberculosis

Bad cough, raised temperature

Diarrhoea, feeling sick

Very ill, a bad cough

Sneezing, touching, spitting

Eating infected food

Water droplets in the air

Viruses: o Viruses are bundles of genetic material that attack cells and take chemicals from them. o They cannot exist on their own. o Some viruses are easier to catch than others and sometimes you don’t catch them again after you have had them once.

19


Examples of viruses:

Disease What it does

Influenza Aches, pains, runny nose, high temperature

Measles

Mumps

AIDS

Small red spots and a skin rash

Chicken pox Raised itchy spots on skin

Swollen cheeks and neck

Destroys some of the cells of the immune system

Fatigue and high temperature

How it spreads

Water droplets in the air

Close contact

Close contact

Close contact

Sexual contact or blood

Ross river fever

Blood-sucking insects

Parasites: o A parasite Is an organism that benefits at the expense of the host. o Vectors carry parasites and pathogens from one host to another.

Diseases caused by parasites:

Disease

Malaria

Typhus

Amoebic dysentery

What it does

Severe recurring fever

Fever, muscle pain, rash

Diarrhoea, blood in the faeces

Rash, cough, diarrhoea

How it spreads

Mosquito

Lice, mites, ticks, fleas

Protozoan in food and water

Water snail Bilharzia

Antibodies: o They are special proteins that are produced by cells of the immune system and circulate in the blood. o Antibodies attack pathogens when they enter the body, the immune response makes the invader harmless. o The immune system produces substances that are specifically selected to attack a particular invading pathogen.

20


Organisation of organs in human body:

Organs: o An organ is a structure that contains at least two different types of tissue functioning together for a common purpose. o There are many different organs in the body: the liver, kidneys, heart, even the skin is an organ.

Organ Systems: o Organ systems are composed of two or more different organs that work together to provide a common function. There are 10 major organ systems in the human body.

1-Skeletal system: The main role of the skeletal system is to provide support for the body, to protect delicate internal organs and to provide attachment sites for the organs.

Major organs: Bones, cartilage, tendons and ligaments.

2-Muscular system: The main role of the muscular system is to provide movement.

Muscles work in pairs to move limbs and provide the organism with mobility. Muscles also control the movement of materials through some organs, such as the stomach and intestine, and the heart and circulatory system.

Major organs: Skeletal muscles and smooth muscles throughout the body.

3-Circulatory system: The main role of the circulatory system is to transport nutrients, gases (such as oxygen and CO

2

), hormones and wastes through the body.

Major organs: Heart, blood vessels and blood.

4-Nervous system: The main role of the nervous system is to relay electrical signals through the body. The nervous system directs behaviour and movement and, along with the endocrine system, controls physiological processes such as digestion, circulation, etc.

Major organs: Brain, spinal cord and peripheral nerves.

5-Respiratory system: The main role of the respiratory system is to provide gas exchange between the blood and the environment. Primarily, oxygen is absorbed from the atmosphere into the body and carbon dioxide is expelled from the body.

Major organs: Nose, trachea and lungs.

6-Digestive system: The main role of the digestive system is to breakdown and absorb nutrients that are necessary for growth and maintenance.

- Major organ: Mouth, esophagus, stomach, small and large intestines.

7- Excretory system: The main role of the excretory system is to filter out cellular wastes, toxins and excess water or nutrients from the circulatory system.

- Major organs: Kidneys, ureters, bladder and urethra.

8- Endocrine System: The main role of the endocrine system is to relay chemical messages through the body. In conjunction with the nervous system, these chemical messages help control physiological processes such as nutrient absorption, growth, etc.

- Major organs: Many glands exist in the body that secrete endocrine hormones. Among these are the hypothalamus, pituitary, thyroid, pancreas and adrenal glands.

21


9- Reproductive system: The main role of the reproductive system is to manufacture cells that allow reproduction. In the male, sperm are created to inseminate egg cells produced in the female.

- Major organs: Female: ovaries, oviducts, uterus, vagina and mammary glands.

Male: testes, seminal vesicles and penis.

10- Lymphatic/Nervous system: The main role of the immune system is to destroy and remove invading microbes and viruses from the body. The lymphatic system also removes fat and excess fluids from the blood.

Major organs: Lymph, lymph nodes and vessels, white blood cells, T- and B- cells.

22


Component

Dry Cell

2 Dry cells

Motor

Light bulb

Switch (open )

Switch (closed)

Wire

Resistor

Variable resistor

Voltmeter

Ammeter

Electricity

Static Electricity

Static electricity is electricity that is not moving.

Laws of Static Electricity

Opposite charges attract

Like charges repel

Charged and uncharged objects attract

Current (Dynamic) Electricity: Current (dynamic) electricity is electricity that is moving. The electrons move around in a set path (circuit).

Electrical Circuits: An electrical circuit is a complete conducting pathway for the flow of electricity from one terminal of an electrical cell/battery back to the other terminal.

Parts of a Circuit

DC energy source > where the electricity is generated e.g. battery

Circuit controls > switches used to open and close the circuit

Wires > conductors that transfer the current between each component of the circuit

Resistors > materials that resist the current flow e.g. light bulbs, appliances

Measuring devices > ammeters and voltmeters

Fuses or Circuit breakers > safety feature which stops the flow of electricity when circuits overheat

Electrical Symbols

Symbol

23


Series Circuit

Electrons have only one path to follow

Open switch > electricity disconnects > circuit is incomplete

Closed switch > electricity is connected > circuit is complete

One appliance breaks down > whole circuit stops working

Appliances share electricity

Parallel Circuit

Electrons have two or more paths to follow

Each path has its own switch

When one appliance in one path breaks down all other appliances in other paths still work

Appliances do not share electricity

Electric Current

The size of electric current depends on how many electrons pass a point in a circuit every second. More electrons mean a larger current while fewer electrons mean a smaller current.

Ammeter

Device used to measure the size of an electric current

Placed in series

Amperes

The unit in which the size of an electric current is measured

Another name for electric current

Symbol > I

Force (Voltage)

Force is needed to make electricity move. Force pushes electrons in a circuit to make them move. The name for a force or pressure that pushes electrons is voltage or electromotive force (EMF).

Voltmeter

Device used to measure the strength of the EMF

Placed in parallel

Volts

Unit in which the EMF is measured

Symbol > V

Resistance

Resistance is a measure of the electrical conductivity of the conductor. Materials that are not very good conductors of electricity are said to offer resistance to current flow. The symbol for resistance is R.

24


Ohms

Unit in which the amount of resistance is measured

Symbol > Ω

Ohms Law

Ohms law shows that current, voltage and resistance are all related.

Mathematically : R = V/I

If you increase the voltage the current will also automatically increase at the same rate thus the resistance remains the same

Circuit Series: o In a circuit series, the electrons have only one path to follow, the switch is closed which makes the circuit complete.

 Advantages of circuit series:

All voltages are added up together

 Disadvantages of circuit series:

Two lamps are only half s bright as one lamp, because the electrons use their energy to light the lamp, you can make them bright by increasing the voltages, and you can only turn off both lamps together. If one lamp breaks the other breaks too.

Parallel Series: o The light globes are shining and they are bright. There are 2 paths for the electrons to follow. If one lamp is damaged the other will continue to function because they don’t share the same path of electrons.

 Advantages of parallel series:

Brightness of the globes does not change. The lamps are equally as bright; each lamp can be turned on and off, without affecting another lamp.

 Disadvantages of parallel series:

Parallel series are hard to set.

25


Environmental Impacts of producing electricity:

Types of Energy: o Non-renewable: energy sources that will eventually run out. o Renewable: energy sources that won’t run out because they are continually being replaced.

Global Warming: o Global warming refers to the average increase in the earth’s temperature as a result of a build up of greenhouse gases. E.g.: These chemicals cause changes in the climate:

 Co2,

 Methane

 Nitrous oxide o These changes have some effects on earth by making it warmer. o A warmer earth may lead to changes in rainfall patterns, a rise in sea levels, and a wide range of impacts on the environment and humans.

Electricity Production: o Modern technology uses large amounts of electrical power. This is normally generated at power plants which convert some other kind of energy into electrical power. o There are several ways to produce electricity, they are:

 Fossil Fuels: the burning of fossil fuels releases energy which has been stored as chemical energy. The burning of fossil fuels affects the atmosphere, problems such as the greenhouse effect, acid rain and smog.

 Nuclear Power: it’s fuelled by Uranium; it has problems with disposing radioactive waste left by the fission process. Accidents: Chernobyl USSR in 1896.

 Tidal power: Tides occur because of the gravity of the sun, moon and planets; water can be trapped behind a dam at high tide and used to drive a turbine when it’s out.

 Biomass: is any matter derived from biological sources, such as plants, animals (WASTE)

 Wind power: is one of the most promising of the renewable energy technologies for generating electricity.

 Geothermal power: rocks deep down in the ground can be used to change water into steam, which can be used to generate electricity.

 Solar Power: Solar energy is transformed into electrical energy in solar cells and panels.

26


Energy Efficiency:

Ecological sustainability means that the needs of the present population can be met without endangering the ability of future generations to meet their needs o Don’t use electric blanket, when not needed. Or replace it with a couple of warm blankets to keep you warm. o Take showers instead of baths. o Wash only full load of clothes and use hot water only for dirty clothes. o Try to avoid opening the refrigerator and freezer to browse, because each time we do, cold air escapes and the energy costs increase. o Use the microwave instead of an oven for cooking meals, to save energy. o Open your curtains in winter, so light will come in and warm your room. o Unplug all electronic devices that are not in use e.g.: DVDs, televisions, microwave etc, because they still use energy when they’re plugged in even though they’re switched off.

27


Pollution

Pollution is the spoiling or poisoning of the environment through human activity.



Pollution is usually a result of contamination by unwanted substances.



Industrialisation in the last 150 years has had a major impact on air and water quality and produced large quantities of toxic wastes.

Air Pollution:

Major Pollutants: o Smoke, dust, sulphur dioxide, carbon monoxide and lead. o Low concentrations may harm living organisms, including humans, and high concentrations may kill them.

Water Pollution:

Major pollutants: o Industrial wastes, oil and pesticides may be toxic to living organisms; the addition of sewage and run-off from fertilised soils reduced the oxygen level and the number of organisms which can be supported. o Suspended solids, washed into waterways as a result of soil erosion, reduce light levels and may cause silting, changing an aquatic ecosystem completely.

Dumping wastes:

Major pollutants: o Waste materials from urban and industrial areas may be deposited untreated and in bulk in other ecosystems. Sewage, toxic metals and waste from industry and tonnes of household garbage are disposed of everyday on to the land or into the water. o Some of these materials may be toxic to living things. o Plastic, may be non-biodegradable.

28


Simple Machines

Simple Machines: o A machine is a device that makes a physical task easier; it can change speed, make force stronger or change direction, used in every day life. o A machine can change a weak force into a strong force. o The number of times a machine multiplies a force is called its mechanical advantage. o A machine divides a big job into smaller, easier jobs. o The smaller jobs are spread out over a longer distance.

Types of simple machines and examples:



Lever: a simple machine that is uses the turning effect of a force to make a task easier. E.g.: Can opener, scissors, tongs, spanners, hammers, brooms, tennis racket.



Inclined planes



Wheels



Pulleys



Axles



Gears

Advantages: o Makes a physical task easier. o Helps us to do our jobs, but it still needs the same force. o Machines divide work into smaller work.

Disadvantages: o A machine does not multiply a force without charging a price. o When a machine multiplies a force, it also increases the effort distance. o There is a definite relationship between the effort distance and the resistance distance.

29


Rev Heads (Newton’s laws)

1.

Newton’s First law: INERTIA

Inertia is an object’s resistance to change in motion, depending on its mass. The greater the mass the greater the inertia.

An object will remain at rest, or will not change its speed direction unless it is acted upon by an outside, unbalanced force.

2- Newton’s second law:

Describes how much mass of an object affects the way that it moves when acted upon by one or more forces.

 Force: is a push or pull or a twist acting on an object. Forces can make things change shape, direction and speed. The effect that a force has on an object depends on its mass and the size of the force.

Forces can be a contact force eg: frictional, stretching, air resistance.



Non-contact force eg: contact-gravitational magnetic, the forces that act between objects that do not touch each other are called non-contact forces.

The 6 types of Forces: o Gravity or weight always acting straight downwards. o Reaction force from a surface, usually acting straight upwards. o Thrust or push or pull due to an engine or rocket speeding something up. o Drag or air resistance or friction which is slowing the thing down. o Lift due to an aero plane wing. o Tension in a force or cable.

Force= mass x acceleration, there’s a relationship betw een mass and force, because if the force goes up the mass goes up.

3- Newton’s Third law:

For every action there is an equal and opposite reaction.

Mass and weight:

Mass is the measure of the amount of matter in an object. The unit used to describe mass is Kilograms.

The larger an object’s mass, the more force is needed to start it moving and to stop it moving. o Mass = force / acceleration

The more force is needed to change its direction when it is moving.

The larger is the force of attraction it exerts on another object.

The force of attraction between objects or masses is called gravitational force or gravity.

Gravitational forces hold the earth in orbit around the sun and the moon around the earth. The gravitational force on an object is called its weight.

Weight: o Is the downward force of gravity (N) o Is a measured in newtons like all other forces. o Weight (N) =mass (Kg) x acceleration due to gravity (N/Kg) w=m x g

30


Acceleration and deceleration: o Acceleration is a measure of the rate at which it changes speed, or when an object moves in a straight line. o To calculate the acceleration: average acceleration = Change in speed

Time taken o The more the friction the less the acceleration. o 2 things that affect acceleration: - Mass & forces (friction) o Deceleration is the decrease in speed.

Speed/time and distance relationship: o Speed= Distance/time o Distance= speed x time o Time = Distance/speed

31


Theory of Plate tectonics/Stratigraphy:

Our continent: o The continents that exist today developed from one giant continent called Pangaea. o The edges of tectonic plates are sites of intense geological activity such as earthquakes, volcanoes and mountain formation.

The theory of Plate tectonics: o The theory of global dynamics in which the crust is broken up into plates that move over the mantle. The margins of the plates are sites of considerable geologic activity. o The plates move around very slowly on top of the mantle. o Continents ride on a number of the plates. o The interactions between plates at their boundaries results in earthquakes, volcanoes, folding and faulting. o Earthquakes and volcanoes eruptions occur at weak points in the earths crust. o The Eurasian and the North American plates are spreading.

The movement of earth: o There are 3 main locations of plate activities:

1Constructive boundaries: when two plates move away from each other, they leave a gap out through which magma, from the Earth’s mantle, oozes.

2Destructive boundaries: sometimes plates push against each other and one is forced down under the other. The old ocean crust is being dragged back into the mantle. This is called subduct ion.

3Intraplate hot spots: sometimes a narrow section of magma burns through the crust creating a hot spot. This section remains stationary while the plate moves over it.

The theory of Continental drift: o The theory that the continents have moved in relation to one another.

Stratigraphy:

The study or origins, composition, and development of rock strata.

The earth is made up of a central core surrounded by the mantle and an outer layer called the crust.

Fossils: o Remains of plants and animals. o They are usually found in sedimentary rocks. o They are important because they tell us what happened millions of years ago. o They help us to learn more about the earth’s history and climate, geology and environment. o Most fossils are excavated from sedimentary rocks.

32


How are fossils preserved?

1.

When plants and animals die, they generally rot or are eaten away. This happens quickly in a matter of days or months.

2.

The hardest parts (wood, teeth and bone) are the last to decay.

3.

If they become buried in sediment such as gravel, sand, silt and especially mud, they are most likely to be fossilised.

4.

Fossilisation often involves shell, bone and wood being slowly replaced by minerals.

33


Evolution due to natural selection: o The theory of natural selection proposes that it is the environment that selects favourable variations and eliminates harmful ones.

Evolution: o Evolution can only take place if the living things in a population are not all the same.

The 4 basic steps of evolution:

1.

There are variations in the genes carried by individuals.

2.

Environmental pressures select some individuals and reject others.

3.

The best adapted individuals have the gene that allows them to survive the environmental pressures.

4.

Genes are passed on to many generations.

Charles Darwin’s Theory on Evolution:

In any population there are variations, all the members of one species are not identical.

In any generation there are offspring that do not reach maturity and reproduce; the characteristics of these organisms are removed from the population.

Those organisms that survive and reproduce are well adapted to that environment, they have favourable variations.

Favourable variations are passed on to offspring; they become more and more common in the population.

Lamarck theory is not accepted is because Lamarck was black and

Darwin was white they only believed in white people back then

34


Biotic and abiotic features of the environment:

Ecosystem: o Ecosystem is any environment living organisms that interact with each other and with the non-living parts of the environment. o Ecosystems are largely self-sustaining, because materials and energy are exchanged between the organisms and their environment. o Energy from sunlight enters the system through photosynthesis in plants, and then flows through other living organisms via food webs. o Environments have:

- Abiotic and

- Biotic features. o The habitat of an organism is the place where it lives. o The study of the relationships living organisms have with each other and with their environment is called ecology. o In an ecosystem there is no re-use of energy: it is either used by a living thing or lost as heat. Because of this, a continual input of energy is needed to keep living

systems functioning.

Abiotic and biotic features:



Abiotic means non-living, they include physical and chemical factors such as the temperature, rainfall, type of soil, and the salinity of the water.



Biotic means living, it includes all the living organisms, how many types there are, their numbers, distribution and interactions.

35


Cycles of nature:

The water cycle: o Water in the atmosphere falls to the earth’s surface as rain or snow. o Water falling on land will evaporate back into the atmosphere, drain into the oceans via lakes or rivers, or become trapped far below the surface in artesian basins. o Water in the oceans and in all bodies of water on land such as ponds, lakes and rivers evaporate into the atmosphere, completing the cycle.

Draw water cycle:

The carbon-oxygen cycle: o Carbon dioxide is absorbed from air by land plants during photosynthesis, and incorporated into plant compounds. Oxygen is released back into the air by plants. o Respiration by living organisms uses oxygen and returns some carbon dioxide to the atmosphere. o When living things die, their bodies are broken down by decomposers and more carbon dioxide is released. o A large amount of carbon is stored in coal, oil and natural gas deposits. o Burning these fuels returns carbon dioxide to the atmosphere. o Volcanoes also emit carbon dioxide when they erupt. o Carbon cycles very quickly though ecosystems.

The carbon-oxygen cycle

36


Photosynthesis:



Photosynthesis is the process by which plant cells capture energy from sunlight and use it to combine carbon dioxide and water to make sugars and oxygen.



All living things depend on photosynthesis.



The compounds plants make during photosynthesis provide nutrients and energy to organisms that consume plants.

Respiration:



Respiration is the process by which cells obtain energy.



In respiration organic molecules, particularly sugars are broken down to produce carbon dioxide and water, and energy is released.

Relationship between respiration and photosynthesis:







Respiration and photosynthesis might appear to be almost the reverse of each other.

This is not true: the sequence in one is not the reverse in the other.

The processes themselves are related because energy from the sun is incorporated into the products of photosynthesis.

37


Energy flow through a natural ecosystem:

Food chains:



The flow of energy from one living thing to another can be shown diagrammatically in a food chain:

Green plant



plant-eater

 animal-eater o Food chains begin with plants (producers). Plant eaters are herbivores.

Animal eaters are carnivores. Animals that eat both plants and animals are omnivores. Herbivores, carnivores and omnivores are all consumers. o Scavengers are consumers that eat dead animals. o Decomposers have an important role to play: they make the materials produced by decomposition available to plants.

Food webs:



Food webs are a series of interacting food chains link up to form a food web.

 It is a complex set of interacting food chains within an ecosystem.

 The feeding level of an organism is sometimes called its trophic level.

38

Chemical Reactions:

Life cycle of a star

Globular clusters:

Inside the stars:

Types of stars:

Big Bang:

How is a star born?

Features of universe:

Reflection:

Refraction:

Genetics

Lamarck theory is not accepted is because Lamarck was black and

Darwin was white they only believed in white people back then

Related documents

Add this document to collection(s)

Add this document to saved

Suggest us how to improve StudyLib