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Short Review Science Checkpoint

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BIOLOGY • Microscope – Parts •
Microscope – How to use 1. Turn the revolving turret (2) so that the lowest power objective lens (eg. 4x) is clicked into position. 2. Place the microscope slide on the stage (6) and fasten it with the stage clips. 3. Look at the objective lens (3) and the stage from the side and turn the focus knob (4) so the stage moves upward. Move it up as far as it will go without letting the objective touch the coverslip. 4. Look through the eyepiece (1) and move the focus knob until the image comes into focus. 5. Adjust the condenser (7) and light intensity for the greatest amount of light. 6. Move the microscope slide around until the sample is in the centre of the field of view (what you see). 7. Use the focus knob (4) to place the sample into focus and readjust the condenser (7) and light intensity for the clearest image (with low power objectives you might need to reduce the light intensity or shut the condenser). 8. When you have a clear image of your sample with the lowest power objective, you can change to the next objective lenses. You might need to readjust the sample into focus and/or readjust the condenser and light intensity. If you cannot focus on your specimen, repeat steps 3 through 5 with the higher power objective lens in place. Do not let the objective lens touch the slide! 9. When finished, lower the stage, click the low power lens into position and remove the slide. NOTES: • Do not touch the glass part of the lenses with your fingers. Use only special lens paper to clean the lenses. • Always keep your microscope covered when not in use. • Always carry a microscope with both hands. Grasp the arm with one hand and place the other hand under the base for support. 1 •
Microscope – Make slide Your microscope slide should be prepared with a coverslip over the sample to protect the objective lenses if they touch the slide. •
Animal vs Plant Cells Cell structure and Organization -­‐ All living things are made of cells. -­‐ All typical cells (Animal and Plant) have: a. Cell membrane: differentially or partially permeable to allow certain substances to enter and leave the cell. b. Cytoplasm: where chemical reactions take place c. Nucleus: contains DNA and controls the cell d. Mitochondria: organelle where aerobic respiration happens e. Ribosome: makes protein and can be found floating within the cytoplasm -­‐ Only plant cells have as well: Vacuole: stores food & water & helps to maintain shape of cell Cell wall: rigid to keep shape of cell Chloroplasts: contain chlorophyll, which absorbs light energy for photosynthesis •
Balanced Diet Balanced Diet: getting all the right nutrients in correct proportions Diet should be related to age/sex/activity. -­‐ Children Below 12: Require more calcium -­‐ Teenagers: Highest calorie Intake -­‐ Adults: Balanced meal with less calories -­‐ Pregnant Women: more iron, calcium and folic acid -­‐ Males: Generally, require more energy •
Digestive System – Enzymes 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. 2 Digestion: The break-­‐down of large, insoluble food molecules into small, water soluble molecules using mechanical and chemical processes •
Mouth: contains teeth used for mechanical digestion, area where food is mixed with salivary amylase & where ingestion takes place •
Salivary glands: produce saliva which contains amylase and helps food slide down oesophagus •
Oesophagus: tubeshaped organ which uses peristalsis to transport food from mouth to stomach. •
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 parts the: • Duodenum: fats are emulsified by bile, and digested by pancreatic lipase to form fatty acids and glycerol. • Ileum: Maltase breaks down maltose to glucose. This is where absorption takes place; adapted by having villi and microvilli. • Pancreas: produces pancreatic juice which contains amylase, trypsin and lipase and ydrogencarbonate. • Liver: produces bile, stores glucose as glycogen, interconverting them to keep glucose concentration constant. Also carries out interconversion of amino acids (transamination), deamination and removal of old red blood cells and storage of their iron. Also site of breakdown of alcohol and other toxins. • Gall bladder: stores bile from liver • Bile: produced by liver and stored in gall bladder, its role is to emulsify fats, to increase surface area for the action of enzymes. 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: Denaturing enzymes in harmful microorganisms in food Giving the optimum pH for pepsin activity 3 •
Lungs •
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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 creates 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 BREATHING IN BREATHING OUT External intercostal External intercostal muscles contract – pulls muscles relax – rib cage rib cage upwards and falls downwards and outwards inwards ·∙ Diaphragm muscles ·∙ Diaphragm muscles relax contract – diaphragm – returns to dome shape moves upwards ·∙ Lung volume decreases – ·∙ Lung volume increases – and pressure increases and pressure falls ·∙ Air is forced out ·∙ Air rushes in to equalise pressure 4 •
Respiration -­‐ O2 & Glucose -­‐ Making Energy -­‐
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Respiration: Chemical reactions that break down nutrient molecules in living cells to release energy. Respiration involves the action of enzymes in cells 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. 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 Anaerobic Respiration: 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 → 2 C2H5OH + CO2 Disadvantages of anaerobic respiration: Only produces 1/20 of the energy per glucose molecule that aerobic respiration would Produces poisonous lactic acid Lactic acid: Transported in blood to heart, liver and kidneys, which oxidize it. The heart, liver and kidneys need extra oxygen to do this which causes you to continue breathing heavily after exercise. The extra oxygen is called the oxygen debt. 5 Circulatory System – Heart -­‐ Name 4 Chambers •
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Right atrium: collect deoxygenated blood & pump it to right ventricle Right ventricle: pumps deoxygenated blood to lungs Left atrium: collect oxygenated blood and pump it to left ventricle Left ventricle: pumps oxygenated blood to the body via the aorta Circulatory System – Heart – Blood vessels •
VESSEL FUNCTION ARTERY Transport high pressure blood away from heart. VEIN Transport low pressure blood to the heart. CAPILLARY Allow substances to diffuse into cells. STRUCTURE ·∙ Elastic walls expand and relax as blood is forced out; causes pulse ·∙ Thick walls withstand high pressure ·∙ Rings of muscle narrow or widen artery to control blood flow. ·∙ Valves prevent backflow of blood. ·∙ Blood is at low pressure, but nearby muscles squeeze veins and help push blood to the heart. ·∙ Large diameter and thin walls reduce resistance to flow of blood ·∙ One cell thick walls for easy diffusion ·∙ Highly branched; large surface area ·∙ Capillary beds constantly supplied with fresh blood, so diffusion occurs 6 CHEMISTRY •
State of Matter – Changing State 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 Heating Curve 7 •
State of Matter – Particle Diagram -­‐
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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 vapour, the particles move in rapid random motion. This movement is due to collision of vapour particles with air particles. Element – Compound – Mixture 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. 8 •
Separating Mixtures Filtration: − Mixture goes in a funnel with filter paper, into a flask. − Residue is insoluble and stays at top. − Filtrate goes through Crystallization: − 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. 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. 9 Choosing a Suitable Method Method Of Separation Filtration Evaporation Crystallization Simple Distillation Fractional Distillation Chromatography 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 •
Atomic Structure – Neutrons, Protons and Electrons. Atomic Structure and the Periodic Table Particle Proton Neutron Electron Relative Charge Mass +1 0 -­‐1 (Atomic Mass) 1 1 1⁄1837 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: The proton number increases by 1 when you go to the right When you go one element down, you increase proton number by 8 in the first 3 periods (transition elements not included) PHYSICS •
Units of measurement Measurement Length Time Mass Weight Force Speed Acceleration Power Current Voltage Energy Unit m (metre) s (seconds) Kg (kilograms) N (Newtons) N (Newtons) m/s (metre per second) m/s2 (metre per second square) W (Watts) A (Amps) v (Volts) J (Joules) 10 •
Energy – Types −
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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 KINETIC GRAVITATIONAL CHEMICAL STRAIN NUCLEAR INTERNAL ELECTRICAL LIGHT SOUND •
What It Is Due to motion From potential to fall In chemical bonds Compress/stretch Atoms rearranged/split Motion of molecules Carried by electrons Carried in light waves Carried in sound waves Example Car moving Book on shelf Bonds in starch (food) Stretched elastic band Released in nuclear plant In a glass of water Battery to bulb From sun From speaker Energy – Renewable Energy vs. Fossil Fuels −
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Renewable sources are not exhaustible. Non-­‐renewable sources of energy are exhaustible. Type Fuel: burnt to make termal energy, makes steam, turns turbine Wave energy: generators driven by up and down motion of waves at sea. Tidal energy: dam built where river meets sea, lake fills when tides comes in & empties when tide goes out; water flow runs generator. Hydroelectric: river & rain fill up lake behind dam, water released, turns turbine \ generator Geothermal: water pumped down to hot rocks rising as steam Nuclear fission: uranium atoms split by shooting neutrons at them Solar cells: made of materials that deliver electrical current when it absorbs light Advantages ·∙ Cheap ·∙ Plentiful ·∙ Low-­‐tech No greenhouse gases produced Disadvantages Harmful wastes: -­‐ Greenhouse/ pollutant gas -­‐ Radiation Difficult to build No greenhouse gases produced Expensive Can’t be built everywhere Low impact on environment Few areas of the world suitable Energy produced at constant rate No CO2 produced Produces a lot of energy with very little resources No CO2 produced 11 Deep drilling difficult and expensive Produces radioactive waste Variable amount of sunshine in some countries −
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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. •
Energy – Kinetic vs. Gravitational Potential Energy −
Example of conversion of energy: A book on a shelf has Gravitational Potential Energy (g.p.e) , if it falls of the shelf it will have Kinetic Energy (k.e) 𝐾𝑖𝑛𝑒𝑡𝑖𝑐 𝑒𝑛𝑒𝑟𝑔𝑦 = 1⁄2 × 𝑀𝑎𝑠𝑠 × 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦2 𝐺𝑟𝑎𝑣𝑖𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑃𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝐸𝑛𝑒𝑟𝑔y = 𝑀𝑎𝑠𝑠 × 𝐺𝑟𝑎𝑣𝑖𝑡𝑦 × 𝐻𝑒𝑖𝑔ℎ𝑡 •
Heat and Temperature – Difference −
Measurement of Temperature A physical property that varies with temperature may be used for measurement of temperatura Liquid-­‐in-­‐glass thermometer: −
As temperature rises or falls, the liquid (mercury or alcohol) expands or contracts. Amount of expansion can be matched to temperatura on a scale. Thermistor thermometer: −
The probe contains a thermistor The thermistor is a material that becomes a better electrical conductor when the temperature rises (semi-­‐conductor) So when temperature increases, a higher current flows from a battery, causing a higher reading on the meter 12 BASIS FOR COMPARISON HEAT TEMPERATURE Meaning Heat is the amount of energy in a body. Temperature is the measure of the intensity of heat. Measures Total kinetic and potential energy contained by molecules in an object. Average kinetic energy of molecules in a substance. Property Flows from hotter object to cooler object. Rises when heated and falls when cooled. Unit of measurement Joules Kelvin Device Calorimeter Thermometer Labelled as Q T •
How to find density – Formula 𝑫𝒆𝒏𝒔𝒊𝒕𝒚 = 𝑴𝒂𝒔𝒔 divided by 𝑽𝒐𝒍𝒖𝒎𝒆
− How to calculate: Density of a liquid: 1. Place measuring cylinder on a balance. 2. Fill measuring cylinder with the liquid. 3. The change in mass is mass of liquid and volume is shown on the scale. 4. Then use formula. Density of solid: 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. Finding the mass: weigh object on a scale and use formula 13 •
Mass, density and 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. •
Forces – Types of forces 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 Type of Forces: − Contact Forces: Force exerted between two objects when they are touching. − Non-­‐Contact Forces: The push or pull acting between objects that are not physically touching when they interact. Contact Forces Non-­‐Contact Forces Frictional Force Gravitational Force Tension Force Electrical Force Normal Force Magnetic Force Air Resistance Force Applied Force Spring Force Type of Force Description of Force Applied Force Force that is applied to an object by a person or another object. If a person is pushing a desk across the room, then there is an applied force acting upon the object. Gravity Force (also known as Weight) Force with which the earth or moon attracts another object towards itself. This is the weight of the object. Normal Force The normal force is the support force exerted upon an object that is in contact with another stable object. For example, if a book is resting upon a surface, then the surface is exerting an upward force upon the book in order to support the weight of the book. Friction Force The friction force is the force exerted by a surface as an object moves across it or makes an effort to move across it. Air Resistance Force The air resistance is a special type of frictional force that acts upon objects as they travel through the air. The force of air resistance is often observed to oppose the motion of an object.. 14 Tension Force The tension force is the force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends. Spring Force The spring force is the force exerted by a compressed or stretched spring upon any object that is attached to it. •
Forces – Newton’s Law Newton's First Law: An object remains in the same state of motion unless a resultant force acts on it. If the resultant force on an object is zero, this means: − a stationary object stays stationary − a moving object continues to move at the same velocity (at the same speed and in the same direction) Newton's Second Law: Force, mass and acceleration Newton's Second Law of motion can be described by this equation: Resultant force = mass × acceleration F = m x a This is when: -­‐ force (F) is measured in newtons (N) -­‐ mass (m) is measured in kilograms (kg) -­‐ acceleration (a) is measured in metres per second squared (m/s²) The equation shows that the acceleration of an object is: -­‐ proportional to the resultant force on the object -­‐ inversely proportional to the mass of the object In other words, the acceleration of an object increases if the resultant force on it increases, and decreases if the mass of the object increases. Newton's Third Law: whenever two objects interact, they exert equal and opposite forces on each other. − This is often worded as 'every action has an equal and opposite reaction'. However, it is important to remember that the forces act on two different objects at the same time. − Newton's Third Law can be applied to examples of equilibrium situation. − Examples of force pairs: Car tyre on a road There are contact forces between the tyre and the road: -­‐ the tyre pushes the road backwards -­‐ the road pushes the tyre forwards •
Resultant Forces Resultant Force: When two or more forces act on an object, the resultant force can be found by adding up the individual forces. Example: A box on a table: If the weight of the box (acting downwards) is 50 N and the normal reaction force (acting upwards) is 50 N, the forces are balanced. The resultant force is zero. 15 •
Forces – Hooke´s Law −
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Springs extend in proportion to load, as long as they are under their proportional limit. 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 = 𝒌 x 𝒆) Forces -­‐ Moment of a Force − 𝑴𝒐𝒎𝒆𝒏𝒕(𝑵𝒎) = 𝑭𝒐𝒓𝒄𝒆(𝑵) × 𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝒇𝒓𝒐𝒎 𝑷𝒊𝒗𝒐𝒕(𝒎) −
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In equilibrium, clockwise moment = anticlockwise moment. Increasing force or distance from the pivot increases the moment of a force Levers are force magnifiers Turning a bolt is far easier with a wrench because distance from pivot is massively increased, and so is the turning effect 16 
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