B3 Revision Pack (Please keep this pack with you)

Transcription

1 Name: B3 Revision Pack (Please keep this pack with you) Follow all the steps below... 1) Practice all the maths and working scientifically questions PRACTICE ALL THESE QUESTIONS! Maths and Science Skills Questions Standard Questions Higher Questions - 2) Practice Quiz short answer questions (included in this pack) 3) Practice QWC questions long answer questions (included in this pack) 4) Practice all the Popplet questions B3.1 Movement of molecules into and out of cells B3.2 Transport systems in animals and plants B3.3 Homeostasis B3.4 Humans and the environment Standard Demand Higher Demand Standard Demand Higher Demand Standard Demand Higher Demand Standard Demand Higher Demand Our Predictions: Experiments and graphs are a BIG part of this paper - Practice the maths and working scientifically questions above! o Don t forget to reference the data when describing/explaining graphs o Identify changes in graph look at how many marks and use this as guidance for how much detail you need to give Deforestation Farming methods, e.g. problems and new technology Drugs and peoples help, e.g. treatment and new technology Cells and movement of substances into and out of them, e.g. factors affecting rate of movement. Homeostasis (last year water came up but nothing on any other types of homeostasis!) Organ systems, e.g. medical advances related to organ systems and ethical implications Revise everything in detail as they are likely to throw something new at you and you will have to apply your knowledge to it.

2 PRACTICE QUIZ GCSE Biology Unit 3 Summary questions and answers B3.1.1 DISSOLVED SUBSTANCES Q1 Explain what diffusion is. A1 - Diffusion is the process by which particles of a substance spread out from each other, moving from a region where they are in high concentration to a region of low concentration. Q2 Explain what active transport is. A2 - Active transport is a transport process which is used to move dissolved molecules from low concentration to high concentration, against a concentration gradient. - This process requires energy from respiration in order to take place. Q3 Explain what osmosis is. A3 - The movement of water molecules from a dilute solution (with a high proportion of water molecules) to a more concentrated solution (with a low proportion of water molecules) across a partially permeable membrane. Q4 What would happen if animal cells that are placed in a solution have a higher solute concentration than the cytoplasm? A4 - Water will leave the cell by osmosis, until it shrinks and dies. Q5 What would happen if animal cells that are placed in a solution have a lower solute concentration than the cytoplasm? A5 - Water will enter the cell by osmosis until it bursts. Q6 What would happen if plant cells that are placed in a solution have a higher solute concentration than the cytoplasm? A6 - Water will leave the cell by osmosis. - The cell membrane separates from the cell wall. - This will cause a plant to wilt. Q7 What would happen if plant cells that are placed in a solution have a lower solute concentration than the cytoplasm? A7 - Water will enter the cell by osmosis until it is fully turgid. - The cell wall would prevent any more water entering. - This is important in enabling plants to remain upright. Q8 What three substances do most soft drinks contain? A8 - Most soft drinks contain water, sugar and ions.

3 Q9 Why do sports drinks contain these substances? A9 - Water and ions replace the water and ions lost during sweating. - Sugar can replace the sugar that is used up by muscles during exercise. Q10 What happens if the water and ions are not replaced? A10 - If water and ions are not replaced, the ion / water balance of the body is disturbed and the cells do not work as efficiently. Q11 (a) What do energy drinks contain? (b) What does this enable? A11 (a) Contain the same concentration of ions as the body fluids, and a high concentration of glucose. (b) This enables rapid uptake of glucose. Q12 (a) What do rehydrating drinks contain? (b) What does this enable? A12 (a) These contain lower concentration of ions than in body fluids. (b) This enables rapid uptake of water by osmosis. These drinks enable people to become quickly rehydrated after exercise. Q13 Evaluate the claims of manufacturers about sports drinks. A13 - Sports drinks manufacturers often make claims about the performance benefits of using their branded sports drinks, but it is important that these claims are evaluated based on valid data from controlled trials of a large sample of athletes. - Different manufacturers put slightly different amounts of sugar and mineral ions in their sports drinks, and therefore each brand will potentially have differing effects on an athlete s performance. Q14 Explain the process of active transport. A14 - Active transport is carried out by a series of protein carriers within the cell membrane. - These have a binding site, allowing a specific dissolved substance to bind to the side of the membrane where it is at a lower concentration. - Energy from respiration then changes the shape of the protein so that it releases the substance onto the other side of the membrane. Q15 Describe what substances are absorbed via the process of active transport: (a) Root hair cells (b) Villi A15 (a) Root hair cells in plant roots use active transport to absorb mineral ions (such as nitrates) from the soil. (b) Small intestine villi cells use active transport alongside diffusion to maximise the absorption of glucose and other substances, e.g. minerals. Q16 Explain the common features of exchange surfaces. A16 - Having a large surface area for greater exchange achieved by having a folded surface. - Having a thin exchange surface for a short diffusion distance. Q17 Explain how animals can further maximise the efficiency of exchange. A17 - Having a good blood supply due to an extensive capillary network in exchange organs this distributes the exchanged materials to all cells of the body and can help to maintain a concentration gradient. - Maintaining ventilation of the surface (at gas exchange surfaces) through breathing - this always ensures that a concentration gradient is maintained. Q18 Fill in the blanks: The and of an organism increases the difficulty of exchanging materials. A18 - size - complexity

4 Q19 Explain how villi are adapted to maximise the absorption of digested food molecules. A19 - The folded villi greatly increase the surface area of the intestine so that digested food is absorbed quickly into the blood. - The villi are made of a single layer of thin cells. - Beneath the villi is an extensive blood capillary network to distribute the absorbed food molecules. Q20 Describe how alveoli are adapted to maximise the diffusion of oxygen and carbon dioxide. A20 - They are folded, providing a much greater surface area for gas exchange to occur. - The walls of the alveoli are only one cell thick. This makes the exchange surface very thin - shortening the diffusion distance across which gases have to move. - Each alveolus is surrounded by blood capillaries which ensure a good blood supply. This is important as the blood is constantly taking oxygen away and bringing in more carbon dioxide - which helps to maintain the maximum concentration gradient between the blood and the air in the alveoli. - Each alveolus is ventilated, removing waste carbon dioxide and replenishing oxygen levels in the alveolar air. This also helps to maintain the maximum concentration gradient between the blood and the air in the alveoli. Q21 Label these structures. B3.1.2 GASEOUS EXCHANGE A21 1- thorax, 2- abdomen, 3- trachea, 4- bronchi/bronchus, 5- intercostal muscles, 6- diaphragm Q22 What does the breathing system do? A22 - The breathing system takes air into and out of the body so that oxygen from the air can diffuse into the bloodstream and carbon dioxide can diffuse out of the bloodstream into the air. Q23 What is meant by the term ventilation? A23 - The movement of air into and out of the lungs is known as ventilation. Q24 Describe the mechanism by which ventilation takes place. A24 Inhalation - The intercostal muscles contract, expanding the ribcage outwards and upwards. - The diaphragm contracts, pulling downwards to increase the volume of the chest. - Pressure inside the chest is lowered and air is sucked into the lungs. Exhalation - The intercostal muscles relax, the ribcage drops inwards and downwards. - The diaphragm relaxes, moving back upwards, decreasing the volume of the chest. - Pressure inside the chest increases and air is forced out. Q25 What are artificial ventilators? A25 Artificial ventilation may be used when someone is unable breathe themselves. Q26 Describe what manual ventilators are and how they re used. A26 - Often used for first aid to help someone breathe. - A mask attached to a bag is placed over the mouth and nose. - The bag can be squeezed, pushing air into the lungs.

5 Q27 A27 Describe what mechanical ventilators are. Explain how the two types of ventilators/machines are used. Machines can be used that enable air to move into and out of the lungs: Negative pressure machines/ventilators - Often referred to as iron lungs. - These are used in cases of paralysis, for example, due to polio. - The patient s thorax is contained inside a metal box that can create a very low pressure outside the lungs. - This causes the thorax to expand so air enters the lungs. Positive pressure machines/ventilators - These attach by a tube and mask to the mouth and nose. - They are used during surgery or when a patient is unconscious. - Air enters the lungs under high pressure. B3.1.3 EXCHANGE SYSTEMS IN PLANTS Q28 Explain the role of the roots. A28 - The role of the roots is to absorb water from the soil by osmosis and dissolve mineral ions from the soil by active transport. - The mineral ions are transported around the plant where they serve a variety of functions, whilst the water is transported to be used as a reactant in photosynthesis, as well as to cool the leaves by evaporation and support the leaves and shoots by keeping cells rigid. Q29 Explain how root hair cells are adapted. A29 Root hair cells have several adaptations: - The tube-like protrusion provides a greater surface area across which water and mineral ions can be exchanged. - The tube-like protrusion can penetrate between soil particles, reducing the distance across which water and mineral ions must move. - The root hair cell contains lots of mitochondria, which release energy from glucose during respiration in order to provide the energy needed for active transport. Q30 Explain how leaves are adapted to maximising the absorption of carbon dioxide and sunlight. A30 Q31 Complete this table. A31 Q32 In which conditions does evaporation take place the quickest? A32 - Evaporation is more rapid in hot, dry and windy conditions.

6 Q33 Describe what happens if plants lose water faster than it is replaced by the roots. A33 - If plants lose water faster than it is replaced by the roots, the stomata can close to prevent wilting. B3.2.1 THE BLOOD SYSTEM Q34 What does the circulatory system do? A34 The circulatory system transports substances around the body. Q35 Explain what the circulatory system consists of. A35 - the heart - which is the muscular pump that keeps the blood moving around the body - the blood - which carries the substances around the body - the arteries - which carry blood away from the heart - the veins - which return blood to the heart - the capillaries - which are tiny blood vessels that are close to the body s cells where exchanges can happen Q36 Explain why the circulatory system is often regarded as a double circulation. A36 - Humans have a double circulation, in which the heart acts as a double pump - The right side pumps blood at low pressure to the lungs to release carbon dioxide and pick up oxygen - The left side pumps blood at high pressure to the body to release oxygen and pick up carbon dioxide. Q37 What are valves? A37 Valves in the heart ensure that blood flows in the correct direction. Q38 In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. A38 Describe the passage of blood through the heart. (6 marks) Deoxygenated blood arrives at the left-hand side of the heart: 1. It enters the heart through the vena cava. 2. Blood flows into the right atrium. 3. Blood is pumped into the right ventricle. 4. Blood is pumped out of the heart, along the pulmonary artery, to the lungs. Oxygenated blood arrives at the right-hand side of the heart: 1. It enters the heart through the pulmonary vein. 2. Blood flows into the left atrium. 3. Blood is pumped into the left ventricle. 4. Blood is pumped out of the heart, along the aorta, to the rest of the body.

7 Q39 Explain how arteries are adapted to carrying blood under high pressure. A39 - thick walls - to resist the high pressure of the blood - a thick layer of elastic fibres to allow the artery to stretch when a surge of blood passes through it, and then recoil in between heart beats to maintain blood pressure - a thick layer of muscle within the wall to allow blood to be diverted to where it is needed in the body Q40 Explain how veins are adapted to carrying blood under low pressure. A40 - thin walls as they have blood with a lower pressure flowing through them - one-way valves in them to prevent blood flowing back in the opposite direction - larger lumen than arteries to maximise blood flow despite the lower pressure Q41 What are artificial hearts? A41 - Artificial hearts are devices made of plastic or other man-made materials that can replace the ventricles and valves. Q42 Evaluate the use of artificial hearts. A42 Advantages - They are not rejected by the body s immune system. This is because they re made from metals or plastics, so the body doesn t recognise them as foreign and attack in the same way as it does with living tissue. - Many artificial hearts can be made. Disadvantages - Surgery to fit an artificial heart can lead to bleeding and infection. - Artificial hearts don t work as well as healthy natural hearts parts of the heart could wear out or the electrical motor could fail. - Blood doesn t flow through artificial hearts as smoothly, which can cause blood clots and lead to strokes. - The patient has to take drugs to thin their blood and ensure this doesn t happen, causing problems with bleeding if they are hurt in an accident. - They are very expensive and not readily available. Q43 Evaluate the use of heart valves. A43 Biological valves Advantages Disadvantages - Do not damage red blood cells as they pass through the open valves - Prone to becoming hardened over the course of several years - For patients with long life expectancy, there is a higher chance of further operations to replace the valves (any operation carries risks) Mechanical valves Advantages Disadvantages - Very strong and durable - able to last a lifetime - Damage red blood cells as they pass through the open valves - Require the patient to take antiblood clotting drugs for the rest of their life - Some people say they can hear the valves opening and closing Q44 What is coronary heart disease? A44 - Arteries that supply the blood to the muscle of the heart get blocked by fatty deposits. - This causes the arteries to become narrow and blood flow is restricted this can result in a heart attack.

8 Q45 What are stents? A45 - Stents are metal grids which can be inserted into an artery to maintain blood flow by keeping the artery open. Q46 Explain how stents are inserted inside the arteries. A46 - To insert a stent, a catheter with a balloon attached to it is inserted into a blood vessel in the leg. - The balloon has the metal stent on it. - The catheter is directed to the coronary artery. - When the narrowed section of artery is found, the balloon is inflated which causes the stent to expand, and it becomes lodged in the artery. Q47 Why are capillaries so small? A47 - To slow the blood and allow exchange of nutrients and oxygen. Q48 Explain how the capillaries are adapted to exchange substances. A48 - Walls are one cell thick. This increases the rate of diffusion by decreasing the distance over which it occurs. - They have permeable walls, so substances can diffuse in and out. B3.2.2 THE BLOOD Q49 Name the four components of the blood and state the function of each. A49 - Red blood cells - transport oxygen - White blood cells form part of body s defence system - Platelets help blood to clot at the site of a wound - Plasma transports dissolved substances Q50 Explain what the plasma does. A50 Blood plasma transports: - carbon dioxide from the organs to the lungs - soluble products of digestion from the small intestine to other organs - urea from the liver to the kidneys Q51 Explain how red blood cells are adapted to carry oxygen. A51 - Red blood cells have no nucleus. - They are packed with a red pigment called haemoglobin. - In the lungs: o Oxygen diffuses into the red blood cells. o Haemoglobin combines with oxygen to form oxyhaemoglobin. - In the other organs: - Oxyhaemoglobin splits up into haemoglobin and oxygen. - Oxygen diffuses out of the red blood cell. o They have a biconcave shape. o This increases their surface area to increase rate of diffusion across the cell membrane. Q52 Evaluate the use of stents. A52 - Stents are good alternatives to more risky operations, like by-pass surgery, providing the patient s heart disease is not too serious. - However, fatty deposits may build up on the stent over time - meaning that blood flow to the heart muscle may be reduced again. B3.2.3 TRANSPORT SYSTEMS IN PLANTS Q53 What is the function of xylem tissue? A53 - To transport water and dissolved minerals from the roots to other parts of the plant. Q54 What is the function of phloem tissue? A54 - Phloem tissue carries dissolved sugars from the leaves to the rest of the plant, including the growing regions and the storage organs.

9 Q55 Xylem vessels are involved in the movement of water through a plant - from its roots to its leaves via the stem. Describe what happens during this process. A55 During this process: 1. Water is absorbed from the soil through root hair cells. 2. Water moves by osmosis from root cell to root cell until it reaches the xylem. 3. It is transported through the xylem vessels up the stem to the leaves. 4. It evaporates from the leaves (transpiration). Q56 What is a transpiration stream? A56 - The movement of water from the roots through the xylem and out of the leaves is called the transpiration stream B3.3.1 REMOVAL OF WASTE AND WATER CONTROL Q57 What THREE roles do kidneys perform? A57 - Removal of urea from the blood - Adjustment of ions in the blood - Adjustment of water content of the blood Q58 Give examples of waste products that have to be removed and explain where they are excreted from the body. A58 - Carbon dioxide produced by respiration and removed via the lungs when we breathe out. - Urea produced in the liver by the breakdown of amino acids and removed by the kidneys in the urine, which is temporarily stored in the bladder. Q59 What happens if the water or ion content of the body is wrong? A59 - Too much water may move into or out of the cells and damage them. Q60 Describe how water is taken in and lost. A60 - Our bodies take in water from food and drinks. - We even get some water when we respire by burning glucose to release energy. - We lose water in sweat, faeces, urine and when we breathe out. - On a cold day you can see this water as it condenses into vapour. Q61 What can the level of water in the blood plasma depend on? A61 - External temperature - when it is hot, we sweat more and lose water, which makes the blood plasma more concentrated. - Amount of exercise - if we exercise, we get hot and increase our sweating, so we lose more water and the blood plasma becomes more concentrated. - Fluid intake - the more we drink, the more we dilute the blood plasma. The kidneys respond by producing more dilute urine to get rid of the excess water. - Salt intake - salt makes the plasma more concentrated. This makes us thirsty, and we drink more water until the excess salt has been excreted by the kidneys. Q62 What are nephrons? A62 - Each kidney contains over one million microscopic filtering units called nephrons. Q63 What do nephrons do? A63 - Each nephron is made of a tubule and is responsible for cleaning the blood by removing urea and excess water and mineral ions.

10 Q64 In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Describe, as fully as you can, how urine is produced by the kidneys. (6 marks) A64 1. Filtering the blood - Blood enters the capillaries under high pressure. - Most of the liquid leaves the blood and enters a tubule. - The cells and large molecule remain in the blood. - The blood becomes very concentrated. 2. Reabsorbing all the sugar - All of the sugar is reabsorbed from the tubule, back into the blood by active transport. - It moves against a concentration gradient. 3. Reabsorbing the dissolved ions needed by the body - Some of the ions are also reabsorbed back into the blood by active transport. - Some salt is left behind to balance what the body needs. 4. Reabsorbing as much water as the body needs - Water is reabsorbed into the blood by osmosis. - This occurs because there is a much higher solute concentration (lower water concentration) in the blood than in the tubule. - The body balances how much water it needs by changing how much water is lost in the urine. 5. Releasing urine - Urine is released from the kidney. - It contains urea, excess ions and water. - Urine is stored in the bladder, before being expelled from the body. Q65 (a) Describe what happens to the kidneys once they do not function properly. (b) Name TWO ways in which people with kidney failure can be kept alive. A65 (a) People whose kidneys do not function properly can die because toxic substances accumulate in their blood. (b) Their lives can be saved by using dialysis machines or by having a healthy kidney transplanted. Q66 Explain how a dialysis machine works. A66 - The blood vessels in the arm are connected to a dialysis machine. In the dialysis machine a person s blood flows between partially permeable membranes. The dialysis fluid contains the same concentration of useful substances as the blood. - This ensures that glucose and useful mineral ions are not lost. - There is a high concentration of urea in the person s blood, and no urea in the dialysis fluid. - There is a concentration gradient of urea between the blood and the dialysis fluid. - Urea passes out from the blood into the dialysis fluid by diffusion. - Treatment by dialysis restores the concentrations of dissolved substances in the blood to normal levels. - It has to be carried out at regular intervals. Q67 In kidney transplants, the donor kidney may be rejected from the immune system. Explain why. A67 - Antigens are proteins on the surface of cells. - The antigens on the cells of the donated kidney may be different to the recipient s antigens. - White blood cells do not recognise them as part of the recipient s body. - They produce antibodies which attack the antigens on the donor organ. Q68 What must be done to prevent rejection of the transplanted kidney? A68 - A donor kidney with a tissue-type similar to that of the recipient is used. - The recipient is treated with drugs that suppress the immune system.

11 Q69 A69 Evaluate the advantages and disadvantages of treating kidney failure by dialysis or kidney transplant. B3.3.2 TEMPERATURE CONTROL Q70 What is temperature control? A70 - Temperature control is the process of keeping the body at a constant core temperature close to 37 C. Q71 Explain how our body maintains a constant temperature. A71 - Temperature receptors in the skin detect changes in the external temperature. Sensory and relay neurones transmit this information as impulses to the thermoregulatory centre of the brain the area of the brain responsible for monitoring and controlling temperature. - The thermoregulatory centre also has temperature receptors which detect changes in the temperature of the blood flowing through the brain. Q72 (a) What glands does the skin contain? (b) Fill in the blank: Skin has network of just under the surface A72 (a) sweat glands (b) capillaries Q73 What happens to our skin if the core body temperature is too high? [H] A73 - Blood vessels supplying the skin capillaries dilate (get wider): o More blood flows through the capillaries. o More heat is lost from the skin. - Sweat glands release more sweat: o This cools the body as it evaporates. Q74 What happens to our skin if the core body temperature is too low? [H] A74 - Blood vessels supplying the skin capillaries constrict (get narrower): o This reduces the flow of blood through the capillaries. o This reduces heat loss from the skin. - Muscles may shiver. o Their contraction needs respiration, which releases some energy as heat. B3.3.3 SUGAR CONTROL Q75 What organ monitors and controls the blood glucose level? A75 - Pancreas Q76 What two hormones control blood glucose level and what do they do to the glucose? [H] A76 - Insulin - allows the glucose to move from the blood into the cells. - Glucagon - Insulin causes glucose to move from the blood into cells, where it is either used for respiration or stored in liver and muscle cells as glycogen. The effect of this is to lower the blood glucose concentration back to normal. Q77 Describe what happens when the blood glucose levels are high. A77 1. Too much glucose in the blood 2. Pancreas produces insulin which enters blood 3. Insulin allows glucose to be absorbed by body cells 4. Blood glucose is reduced

12 Q78 Describe what happens when the blood glucose levels are low. A78 1. Too little glucose in the blood 2. Pancreas produces glucagon (and not insulin) which enters blood 3. Less glucose absorbed by body cells 4. Blood glucose is increased Q79 What is type 1 diabetes? A79 - Type 1 diabetes is a disease in which a person s pancreas does not produce enough of the hormone insulin. - The result is that a person s blood glucose can rise to a level that can kill them if it s not controlled. Q80 Explain how type 1 diabetes can be controlled. A80 - Carefully controlling your diet by avoiding foods high in sugar and exercising due to increased respiration in the muscles - Injecting insulin into the blood at regular intervals this makes the liver remove the glucose as soon as it enter the blood from the gut, when the food is being digested. Q81 Compare the past and present on how insulin is obtained/produced. A81 - Insulin was extracted from pigs and cows - Insulin is now produced using micro-organisms that have been genetically engineered to contain the human insulin gene. This modern insulin is chemically identical to human insulin. Q82 Evaluate the use of the having a pancreas transplant. A82 - There are not enough dead donors to supply all the people who need them. - Organ transplants are not always successful as the body might reject the tissue immunosuppressive drugs which are expensive must be taken, but often can have serious side-effects. - No need to inject themselves with insulin again. Q83 Explain what may happen in the future to cure diabetes and describe the views this may have. A83 - In the future, stem cells may be used to cure diabetes. - However, this requires the use of human embryos, which many people disagree with. - Organ rejection would not occur.

13 B3.4.1 WASTE FROM HUMAN ACTIVITY Q84 Why is the human population increasing so rapidly? A84 - Human population is increasing because of an increase in the standard of living. o Land availability for farming is limited, so it will become more and more difficult to feed the population. o Also, in less developed countries, where the population is rapidly increasing, the availability of clean water is limited. o Using modern medicine means that there are higher births than deaths. Q85 Rapid growth in the human population and an increase in the standard of living also mean that increasingly more waste is produced. Explain what waste can pollute. A85 Waste may pollute: - Water, with sewage, fertiliser or toxic chemicals. - Air, with smoke and gases such as sulphur dioxide which contributes to acid rain. - Land, with toxic chemicals such as pesticides and herbicides, which may be washed from the land into waterways. Q86 Describe how humans reduce the amount of land available for other animals and plants. A86 - Building - Quarrying - Farming - Dumping Waste B3.4.2 DEFORESTATION AND THE DESTRUCTION OF AREAS OF PEAT Q87 Why are large areas of tropical forests cut down? A87 - To provide timber to use as building material. - To provide land for agriculture, important to provide more food or to grow crops from which biofuels based on ethanol can be produced. Q88 What is deforestation? A88 - cutting down of forests

14 Q89 In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Explain the consequences that deforestation can cause. (6 marks) A89 - It reduces the rate at which carbon dioxide is absorbed and locked away in the plant biomass by photosynthesis, as there are fewer trees. - As timber is burnt to clear space, it increases the release of carbon dioxide into the atmosphere. The remaining parts of the tree (eg the roots) are then decomposed by microorganisms. This adds further carbon dioxide to the atmosphere and so contributes to global warming. - Forest habitats are destroyed and biodiversity is reduced. - Cattle are often reared on the land, producing methane. Methane, a greenhouse gas, contributes more to global warming than carbon dioxide. - Rice fields - created to satisfy the need for food production due to the growing population - are grown on previously deforested land and also produce methane when the crop rots. Q90 Explain what peat is and why we should not destroy areas of peat. A90 - Peat bogs form in areas where plants grow in waterlogged conditions, and when the plants die they do not fully decompose. - Therefore, lots of which carbon is locked up in these bogs. - Peat can be as compost used in agriculture to improve the nutrient content of soil. - Consequently, many peat bogs are being destroyed. - The destruction of peat bogs and other areas of peat release carbon dioxide into the atmosphere. - People should be encouraged to use peat-free compost. B3.4.3 BIOFUELS Q91 Explain what the greenhouse effect is. A91 - The presence of certain greenhouse gases in our atmosphere naturally results in the Earth being warmer than it should be, as the gases trap some of the Sun s heat and prevent it escaping from our atmosphere. Q92 In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. A92 Explain why greenhouse gas levels are increasing. (6 marks) Carbon dioxide levels are increasing because: - Humans are burning more fossil fuels to provide energy. - Humans are cutting down forests - reducing the number of trees that can absorb carbon dioxide. - Humans are destroying peat bogs and the process of destroying them releases carbon dioxide. Methane levels are increasing because: - Humans are rearing more cattle to supply food. During their digestive process, cows produce a lot of methane. - Humans are planting more rice paddy fields to supply food. These grow in water, creating anaerobic conditions - and therefore as plants rot, methane is produced. - Humans are producing more waste - which produces methane as it decays anaerobically.

15 Q93 Explain what happening at each number on the diagram, which shows how global warming occurs. A93 Q94 Outline FIVE likely effects of an increase in global average temperatures. A94 - cause big changes in the Earth s climate and weather patterns - cause ice caps on land to melt causing a rise in sea level - resulting in flooding and low lying areas being submerged - reduce biodiversity as habitats are lost and organisms fail to adapt to the changed environment - cause changes in the migration patterns of birds and other organisms - result in changes to the distribution of species (i.e. where they are found) as some species move to cooler areas to cope with the increase in global temperatures Q95 Explain what is meant by the term sequestration. A95 - The oceans, lakes and ponds of planet Earth are important as they absorb and lock away over a quarter of the carbon dioxide that humans emit into the atmosphere. - The process by which they absorb and lock away the carbon dioxide is known as sequestration. Q96 Describe what fermentation is. A96 - Fermentation is when bacteria or yeast break sugars down by anaerobic respiration. Q97 Explain how ethanol is made. A97 - Ethanol can be made by a process called fermentation. - This converts sugar into ethanol and carbon dioxide if conditions are anaerobic. - Single-celled fungi, called yeast, contain enzymes that are natural catalysts for making this process happen: glucose ethanol + carbon dioxide + energy Q98 Because of maize containing starch rather than sugar, which enzyme must first break down the starch into sugar before the yeast can ferment it into ethanol? A98 - Amylase

16 Q99 What is done to separate ethanol from the yeast and remaining glucose? A99 - Distillation Q100 Explain how biogas is made. A100 - Biogas is a biofuel produced from the anaerobic fermentation of carbohydrates in plant material or waste (e.g. food peelings or manure) by bacteria. - Biogas is usually about 70% methane and 30% carbon dioxide. - It is made in a simple fermenter called a digester or generator. Q101 Name TWO different types of biogas generators. A101 - Batch generators - Continuous generators Q102 Describe how batch generators work. A102 - Batch generators make biogas in small batches. - They are manually loaded up with waste, which is left to digest, and the by-products are cleared away at the end of each session. Q103 Describe how continuous generators work. A103 - Continuous generators make biogas all the time. - Waste is continuously fed in, and biogas is produced at a steady rate. - Continuous generators are more suited to large-scale biogas projects. Q104 Explain the factors that need to be considered when designing a generator. A104 - Cost o Continuous generators are more expensive than batch generators because waste has to be mechanically pumped in and digested material mechanically removed all the time. - Convenience o Batch generators are less convenient because they have to be continually loaded, emptied and cleaned. - Efficiency o Gas is produced quickly at about 35 C. o If the temperature falls below this, the gas production will be slower. o Generators in some areas will need to be insulated or kept warm, e.g. by solar heaters. o The generators mustn t have any leaks or gas will be lost. - Position o The waste will smell during delivery, so generators should be sited away from homes. o The generator is also best located close to the waste source. Q105 Discuss the economic and environmental advantages of biogas production. A105 - It is a useful way to recycle waste material. - Initial set up costs are expensive, but the raw materials for biogas production are very cheap (or free). - The fuel is readily available. - This is particularly useful in developing countries. - Waste products from the process can be used as fertilisers. - It reduces the use of fossil fuels. B3.4.4 FOOD PRODUCTION Q106 Explain why the efficiency of food production can be improved by reducing the number of stages in food chains. A106 - This is because fewer energy losses occur along a shorter food chain, meaning a greater proportion of the energy that entered the food chain is available to humans and more people can be fed.

17 Q107 Explain how efficiency of food production can be improved by reducing the energy lost from animals, and how is this achieved? A107 - Preventing animals moving around too much - this conserves energy which can be used to increase biomass. - Keeping their surroundings warm - this preserves the energy which would have been used to maintain their body temperature, so that it can be used to increase biomass. Q108 Describe how efficiency of food production can be improved by developing new food sources like mycoprotein. A108 - It is used to make meat substitutes for vegetarian meals e.g. Quorn TM. - A fungus called Fusarium is the main source of mycoprotein. - The fungus is grown in fermenters, using glucose syrup as food. The glucose syrup is obtained by digesting maize starch with enzymes. - The fungus respires aerobically, so oxygen is supplied, together with nitrogen (as ammonia) and other minerals. - It is important to prevent other microorganisms growing in the fermenter. So the fermenter is initially sterilised using steam. The incoming nutrients are heat sterilised and the air supply is filtered. - The mycoprotein is then harvested and purified. Q109 Discuss the advantages and disadvantages of factory farming of animals. A109 Advantages Disadvantages - It results in more efficient food production - and therefore cheaper food. - Action is taken to prevent disease by providing animals with antibiotics. - Forcing animals to live in unnatural and uncomfortable conditions is cruel. - The crowded conditions on factory farms create a favourable environment for the spread of disease. - Animals need to be kept warm to reduce the energy they lose as heat. This often means using power from fossil fuels. Q110 Explain how distributing food causes problems. A110 - The distance that food travels from the farm where it is produced to the consumer is referred to as food miles. - The greater the distance the food has travelled, the greater the impact on the environment. - This is due to the pollution from carbon dioxide emissions, generated by the transporting vehicles. - A compromise must be found between the monetary cost to the consumer, the impact on developing economies and the environmental cost of the pollution associated with transporting food over such long distances. Q111 What is sustainable food production? A111 - Fish stocks in the oceans are declining. - It is important to maintain fish stocks at a level where breeding continues or certain species may disappear altogether in some areas.

18 Q112 Explain how net size and fishing quotas help to conserve fish stocks. A112 - Fishing quotas o There are limits on the number and size of fish that can be caught in certain areas. o This prevents certain species from being overfished. - Net size o Limiting mesh size of the nets. By increasing the size of the holes in nets, only mature, full-sized fish can be caught and immature fish can escape and eventually breed, allowing the population to recover. More short answer questions... Osmosis (Q) 1. Name three ways substances can move in and out of cells 2. Describe osmosis 3. What is a partially permeable membrane? 4. What happens to plant cells when they are put into a weak solution / water? 5. What can happen to animal cells when put into a very dilute solution? 6. Why do animal cells but not plant cells burst when they take up water? Osmosis (A) 1. Osmosis, diffusion, active transport 2. The movement of water from a high to low concentration down a concentration gradient across a partially permeable membrane. 3. A membrane with small holes that allows some substances (like small water molecules) to pass through but will not allow larger molecules through. 4. The pressure in the cells will increase as water will enter via osmosis. 5. Water will enter animal cell via osmosis but they can burst (called lysis) 6. Plant cells have a cell wall which prevents the cell from bursting. Animal cells do not have a cell wall Sports Drinks (Q) 1. Why do humans need water? 2. What is the recommended intake of water for adults? 3. When would you need more water? 4. What substances do you lose when you sweat? 5. Why do we sweat more when we exercise? 6. What do sports drinks contain? 7. What are the three types of sports drinks? Sports Drinks (A) 1. To prevent dehydration. Cells do not function properly without water. To protect organs, substances are dissolved in water, temperature regulation, lubricate the joints. 2. Two to three litres of water per day to remain hydrated 3. During exercise, hot day (sweat more). 4. Water and salt ions. 5. When we exercise we use energy which is released from sugars during respiration. This generates heats, so to cool your body you sweat. 6. Water hydration, carbohydrates for energy, mineral ions healthy muscles, caffeine stimulant 7. Hypotonic hydration, isotonic fuel and hydration, hypertonic - fuel

19 Active transport (Q) 1. What are the three features of active transport that makes it different from other methods? 2. What is the energy used for in active transport? 3. Give examples of where active transport may occur 4. Explain how active transport enables mineral ions to be taken up by the plant roots Active transport (A) 1. Against a concentration gradient (from low to high), requires a carrier protein to pass through the membrane, Requires ATP (energy) from respiration. 2. To change the shape of the protein carrier 3. Plant roots, the villi of the small intestine, the absorption of sugars from cells 4. Mineral ions are at low concentration in the soil, lower than in the plant cells. The minerals cannot move into the cell by diffusion. They use active transport. Exchange surfaces (Q) 1. Why does the process of exchange become inefficient in larger organisms? 2. Give examples of different exchange surfaces 3. What are the three main features of exchange surfaces? Exchange surfaces (A) 1. Their surface area to volume ratio becomes smaller so exchange in harder 2. Surface of the lungs (alveoli), the surfaces of gills, the digestive system (villi in the small intestine), the leaf (gases), plant roots. 3. Large surface area, thin surface (short distances), excellent blood supply maintains concentration gradient), Gas exchange in the lungs (Q) 1. Where does gas exchange in the lungs occur? 2. Which gases are exchanged in the lungs? 3. What causes the ribcage to move up and down during ventilation? 4. What is the role of the diaphragm when you breathe in? 5. What is the percentage of oxygen and carbon dioxide in inhaled and exhaled air? Gas exchange in the lungs (A) 1. The alveoli 2. Oxygen and carbon dioxide 3. The intercostal muscles contract, this causes the ribs to move up and expands the thorax 4. The diaphragm flattens expanding the space in the thorax decreasing the pressure so air rushes in 5. Inhaled air Oxygen 21%, carbon dioxide 0.04%. Exhaled air oxygen 17%, carbon dioxide 4%

20 Gas exchange in plants (Q) 1. By what process does water move into the plant roots? 2. Where does water enter and leave a plant? 3. State two uses of water by the plant 4. How can plants reduce water loss? 5. How do the guard cells control the water loss through the stomata? 6. What substances are exchanged through the stoma? 7. What is transpiration? Gas exchange in plants (A) 1. Osmosis 2. Enters through the roots, leaves through the stomata in the leaves 3. Water is used for photosynthesis, when water leaves the plant it cools the plant, helps to support the plant, transports dissolved minerals 4. Most stomata are on the underside of the leaf (the coolest part), the guard cells will close the stoma. 5. When there is plenty of light and water the guard cells swell and become firm by osmosis this causes them to bend and opens the stoma. When there isn t enough water the guard cells lose water via osmosis and cannot open. 6. Water vapour leaves the plant, carbon dioxide enters the leaf if the stoma are open and used for photosynthesis, oxygen leaves through the stoma produced as a byproduct of photosynthesis 7. Water flows up the stem and through the leaves before leaving the leaves by evaporation via stoma Rates of transpiration (Q) 1. What factors affects the rate of transpiration 2. What is used to measure the rates of transpiration? 3. Why do gardeners need to water their plants more in summer? 4. Why will sand dune plants loose more water than woodland plants? 5. Why do florist spray their plants will water? Rates of transpiration (A) 1. Light intensity, temperature, air movement, humidity. 2. A photometer 3. The rates of transpiration will be greater because the stomata are open allowing more gas exchange for photosynthesis 4. Sand dunes are windier and will carry the evaporated water molecules away from the leaf increasing the concentration gradient. 5. Increasing the humidity prevents plants loosing water by reducing the concentration gradient The circulatory system (Q) 1. Name three substances that blood carries to your body cells 2. Name two substances that blood carries away from your body cells 3. What are blood expanders and when might they be used? 4. What are oxygen carriers? 5. Why might the remaining haemoglobin in a trauma patients blood be enough to sustain a motionless patient but not a mobile one? 6. Give the advantages of artificial blood products The circulatory system (A) 1. Oxygen, glucose, amino acids, nutrients, 2. Urea, carbon dioxide, 3. Sterile saline solutions that maintain normal blood pressure so blood can flow if patients have lost a lot of blood. Used in emergency situations 4. If two thirds of your blood is lost you would need artificial blood that would carrier oxygen. Can be chemicals that release oxygen or can be encapsulated haemoglobin 5. Motionless patients will not need as much energy and will respire less needing less oxygen 6. Don t have to be matched to patients, useful for treating war casualties, in countries where transfusions aren t safe (not screened for disease), for trauma patients, can be stored for three years at room temp, immediately restore full oxygen carrying capacity (real blood takes 24hrs)

21 The heart (Q) 1. What are the names of the four chambers of the heart 2. Which side pumps oxygenated blood to the body? 3. What is the artery called that carries oxygenated blood to the body? 4. Which artery pumps deoxygenated blood to the lungs? 5. Which blood vessels carries deoxygenated blood towards to the heart? 6. Why are artificial heart valves made of inert materials? 7. Why would the risk of rejection be a serious problem if artificial hearts had a capillary blood supply? The heart (A) 1. The right and left ventricle, the right and left atria 2. The left side 3. The aorta 4. The pulmonary artery 5. The vena cava 6. Prevents corrosion / reaction sin the body. Smooth to prevent blood clots 7. The white blood cells would patrol the heart and attack it if the artificial heart had a capillary blood supply Arteries and Veins (Q) 1. Why is the lining of the arteries folded? 2. Why does measuring you pulse allow you to measure your heart rate? 3. Identify the features of veins 4. Identify the features of arteries 5. What is a stent? 6. Who might need a stent? Arteries and Veins (A) 1. Allows them to stretch and recoil when blood enters and is pumped under high pressure 2. Each pulse corresponds to each beat of your heart 3. Usually carry deoxygenated blood back to the heart. Large lumen, have valves to prevent backflow, smooth lining, thin walls, little muscle or elastic as the blood is under low pressure 4. Usually carry oxygenated blood away from the heart. Elastic fibres, muscle fibres, narrow lumen, folded inner lining that expands with each high pressure blood spurt. 5. A narrow mesh tube that can be inserted into blocked / narrowed artery to widen the lumen and allow the blood to flow through. 6. People at risk of a heart attack due to narrowed arteries blocked by saturated fat deposits. Capillaries (Q) 1. Describe the structure of the capillaries 2. What is the function of the capillaries? 3. What substances are carried to your cells by the capillaries? 4. What waste substances do the capillaries remove from the tissues? Capillaries (A) 1. Their wall is one cell thick for efficient exchange, blood is under low pressure so as not to damage the blood vessels, lumen diameter is wide enough to let one red blood cell through at a time. Blood flow is very slow, form vast networks at the tissues of every organ they have a large surface area. 2. To deliver blood to your tissues allowing exchange of substances 3. Oxygen for respiration, glucose for respiration, amino acids for growth and repair, other nutrients like fatty acids, water hydration and hormones. 4. Carbon dioxide, lactic acid (anaerobic respiration), urea, spent hormones, heat,

22 Blood (Q) 1. What makes blood a unique tissue? 2. Where in your body is blood made? 3. State three functions of the blood 4. Name four substances carried in your blood 5. Name four substances dissolved in plasma 6. How does your blood protect you? 7. How does your body regulate heat? 8. Why is it important to maintain a constant ph? Blood (A) 1. It is the only tissue on your body that is a fluid 2. The bone marrow 3. transport, protection, regulation of body temperature and ph 4. oxygen, carbon dioxide, glucose, amino acids, hormones, cholesterol, mineral ions, antibodies, fatty acids 5. carbon dioxide, glucose, amino acids, hormones, cholesterol, mineral ions, antibodies, fatty acids 6. Blood clots forming scabs at wounds to prevent microbes entering and stops blood loss. White blood cells fight invading pathogens 7. Distributes heat from respiring muscles to other organs and your skin 8. Enzymes require a specific ph to function or they will change shape (denature) Blood Cells (Q) 1. What is the function of red blood cells? 2. How are red blood cells adapted to their function? 3. What are the functions of white blood cells? 4. Why can t red blood cells divide? 5. Where are old red blood cells broken down? 6. What do platelets do? Blood Cells (A) 1. To carry oxygen to your tissues for respiration 2. They are biconcave large surface area, no nucleus more space for oxygen, contain haemoglobin which forms oxyhaeomoglobin when combined with oxygen. 3. Defence against pathogens. Produce antitoxins and antibodies. Some ingest foreign particles. 4. They have no nucleus 5. The liver 6. Small cell fragments no nucleus. Help the blood to clot. Made in the bone marrow. Transport in plants (Q) 1. What are the two vascular bundles of plants? 2. What do the vascular bundles do? 3. What do the xylem do? 4. What do the phloem do? 5. What is transpiration stream? 6. What is translocation? Transport in plants (A) 1. Xylem and phloem 2. Transport substances from the roots through the stem to the leaves and they provide support. 3. Dead cells stacked on top of each other forming long hollow tubes. They transport water and dissolved substances from the roots to the leaves 4. Living cells that form tubes and transport food substances in both directions 5. The continual transport of water from the roots to the leaves by xylem 6. The transport of sugars made by photosynthesis in the leaf to areas where the plant needs it for storage / growing areas by the phloem