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 – http://IEQUDUD.exampro.net Higher Questions - http://EEVOIUD.exampro.net

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

Standard Demand – http://2c4c41d4.exampro.net/ Higher Demand – http://256d0a5b.exampro.net/

B3.2 Transport systems in animals and plants

Standard Demand – http://256d0a5b.exampro.net/ Higher Demand – http://ec1bccae.exampro.net/

B3.3 Homeostasis

Standard Demand – http://cbccf77c.exampro.net/ Higher Demand – http://ccdd9b74.exampro.net/

B3.4 Humans and the environment

Standard Demand – http://de69a60a.exampro.net/ Higher Demand – http://6e89ca3f.exampro.net/

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.

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.

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

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.

B3.1.2 GASEOUS EXCHANGE Q21 Label these structures.

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.

Q27 Describe what mechanical ventilators are. Explain how the two types of

ventilators/machines are used.

A27 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.

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.

Describe the passage of blood through the heart. (6 marks)

A38 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.

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 anti-

blood 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.

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.

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.

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.

Q69 Evaluate the advantages and disadvantages of treating kidney failure by dialysis or

kidney transplant.

A69

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

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.

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

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.

Explain why greenhouse gas levels are increasing. (6 marks)

A92 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.

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

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.

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. QuornTM.

- 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.

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

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%

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)

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,

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

Keeping internal conditions constant (Q) 1. If your muscles respire anaerobically which waste product do they produce? 2. How is the waste product of anaerobic respiration harmful if it isn’t removed? 3. What is the process called where waste products are removed from the body 4. Name five internal conditions that must be kept constant 5. What does ammonia react with to make urea? 6. How is urea harmful to the body? 7. Why must temperature be regulated? 8. Why must blood sugar be regulated? Keeping internal conditions constant (A) 1. Lactic acid 2. Increases blood pH which can prevent enzymatic reactions 3. Excretion 4. pH, Water, ion content, temperature, blood sugar levels 5. carbon dioxide 6. makes the blood alkaline which affects the enzymes 7. Proteins and cell membranes would become damaged above or below 36 – 37.50C 8. Needed for respiration. Too little – tired and faint. Too much and water would leave the cells by osmosis The kidney (Q) 1. How is urea made in the body? 2. Which organ removes urea? 3. How is urea transported from the liver to the kidneys? 4. Why is the glucose that is filtered from the kidneys reabsorbed? 5. Apart from urea what else does the kidney regulate? 6. How would a high protein diet affect the levels of urea? 7. How would the water content of your urine change if the weather was hot but you didn’t drink any water 8. How would your urine change if you ate a very salty meal? The kidney (A) 1. Proteins digested into amino acids. Excess amino acids are carried by the blood to your liver and are converted to ammonia. This reacts with carbon dioxide and it becomes urea. 2. The kidneys 3. Via blood 4. Glucose is useful for respiration 5. Excess salt ions and water 6. Increase the amount of urea 7. Urine would be very concentrated, little water 8. The urine would become very salty.

Renal Dialysis (Q) 1. What is renal failure? 2. Explain the difference between acute and chronic renal failure 3. Why does the renal dialysis fluid have to be sterile? 4. Why is the dialysis fluid at body temperature? 5. Why is heparin added to the patients blood before the blood enters the dialysis machine? 6. Why does the dialysis fluid contain glucose at the same concentration as a healthy human? 7. Why does the renal dialysis fluid have to be changed after a dialysis session? 8. Why do you think people with renal dialysis get swollen ankles, feet, face and legs? Renal Dialysis (A) 1. Condition where the kidneys don’t function properly 2. Acute – sudden, but treatable. Usually caused by an infection or drugs. Chronic – long lasting and patients will not recover. Could be genetic or due to diabetes. Symptoms include sickness, paralysis, back pain, anaemia, swollen limbs 3. To prevent infections 4. To prevent the patient loosing or gaining heat 5. It is an anticoagulant which prevents the blood from clotting 6. So that the concentration of glucose will not change – it won't diffuse through the membrane 7. The dialysis fluid will contain the patients excess salt and water 8. Renal failure disrupts the ion concentration in the cells and so cells may take up extra water to balance the concentration inside the cells which contain excess ions Kidney transplants (Q) 1. What are the advantages of having a kidney transplant compared with renal dialysis? 2. What precautions do medical teams take to reduce the risk of rejection when transplanting a kidney? 3. Why are transplant patients more at risk of infection? 4. Explain why a recipient may reject a transplanted kidney? Kidney transplants (A) 1. improved quality of life (no more dialysis 4 times per week, can go on holiday) / Cheaper for NHS to transplant 2. Tissue type the patient and the donor, match blood types closely 3. They have to take immunosuppressant drugs to prevent the immune system attacking the transplanted organ 4. The recipients immune system can recognize that the antigens on the transplanted kidney are not their own. The white blood cells would then attack and destroy the organ

Decreasing your body temperature (Q) 1. Why can exercise cause us to overheat? 2. Why can dehydration increase the chance of overheating? 3. How does sweating cool you? 4. Why does your skin look and feel red and hot when you are overheating? 5. Why should we drink more during hot weather? 6. Describe vasodilation 7. Where is the thermoregulatory centre? 8. How do dogs cool themselves? 9. Elephants and rabbit have large ears, how does this help them to cool? Decreasing your body temperature (A) 1. Increases respiration which produces heat as a byproduct 2. Water needed to distribute the heat in our blood between our organs and to the skin where the heat can radiate out. Water is needed for sweat 3. Sweating cools the body because the water evaporates and takes the heat away with it. 4. The blood vessels open wide to let the heat radiate from the surface 5. We sweat more so we need to replace the water 6. Nerves stimulate the blood vessels that supply the capillaries in the skin. They dilate and this allows more blood to flow to the surface. The excess heat radiates away from the body 7. The brain 8. They pant instead of sweating 9. Large surface area allows the heat to radiate away from their bodies. Increasing your body temperature (Q) 1. Why is it dangerous if your core body temperature drops below 350C 2. Why does reduced sweating prevent you from overcooling 3. State two reasons why you may overcool? 4. How does shivering warm you up? 5. What is vasoconstriction? Increasing your body temperature (A) 1. Enzymes will not work properly and chemical reactions will slow down. You will become hypothermic 2. Reduced heat loss by evaporation 3. Outside in cold weather too long, immersed in cold water, elderly, a baby (large surface area to volume ratio 4. Stimulates the skeletal muscles to contract and relax quickly which requires energy from respiration. Respiration produces heat. 5. The arterioles that supply the capillaries near the skin contrast preventing blood flowing at the skins surface. Your skin will look pale and feel cold. This conserves heat and protects internal organs from heat loss and damage. Prolonged exposure would result in frost bite

Regulating blood glucose levels (Q) 1. Explain why blood glucose level rises after you have eaten a meal? 2. Why does your blood glucose level drop when you have not eaten for several hours? 3. Explain why your blood glucose level drops after you have been swimming? 4. Which organ monitors your blood glucose levels? 5. Which hormone is released into your blood when your blood glucose level rises above normal levels? 6. Which hormone is released into your blood when your blood glucose levels are lower than normal? 7. What does insulin do? 8. Which of the are carbohydrates and which are proteins? Glucagon, glucose, glycogen, insulin Regulating blood glucose levels (A) 1. the digested carbohdrates (glucose) enters your blood via the walls of the small intestine 2. The glucose is used up during respiration 3. Exercise usues energy which is made during respiration. Glucose is needed for respiration 4. The pancreas 5. Insulin 6. Glucagon 7. Insulin promotes the uptake of glucose into cells. Takes excess glucose to the liver to be stored as insoluble glycogen 8. Carbs: Glucose, glycogen. Proteins: Glucagon, Insulin Type 1 diabetes (Q) 1. What is type 1 diabetes? 2. How is type 1 diabetes treated? 3. What would happen if people with type 1 diabetes did not get treatment? 4. What causes type 1 diabetes? 5. Why do people with diabetes urinate very frequently? Type 1 diabetes (A) 1. Where patients do not make enough insulin and so blood glucose level is not controlled. 2. Injections of insulin into blood after meals, eat regular high fiber meals, monitor blood glucose levels, avoid alcohol, take regular exercise 3. Blindness due to retina damage, poor wound healing, ulcers, increased risk of stroke, increased risk of heart attack 4. Cells of the patients immune system destroy the special cells in the pancreas which produces insulin. Could be caused by viral infection, cows milk in early life, certain antibiotics and trauma injury or pancreatic tumours. 5. When the kidneys filter the blood too much glucose is filtered out and the kidneys do not reabsorb the glucose. Glucose passes out of the urine and a lot of water goes with it. This is also why diabetics feel very thirsty Human Populations (Q) 1. Families had large numbers of children before 1900. Suggest why? 2. After 1900 there was a dramatic rise in the population. Suggest reasons why 3. Population increase has negative effects on the environment. Suggest these negative effects. 4. Describe the meaning of the term sustainable? 5. How can humans manage their use of resources? Human Populations (A) 1. Many children died young, lack of contraception 2. Diet improved, hygiene improved, healthcare improve, infant mortality fell 3. Shortage of food in some countries, more land being used for farming and building, more pollution being produced, the world’s resources are being used faster than they can be replaced 4. Sustainable means using resources for human needs without harming the environment 5. Recycle, replace resources where possible (plant new trees), avoid over use of resources if they cannot be replaced quickly eg fishing quotas. Use alternative fuels

Pollution (Q) 1. List three ways in which farming can damage the environment 2. How does sulphur dioxide produce acid rain? 3. What is the affect of carbon dioxide released from cars factories, burning wood? 4. Why are people in towns only allowed to burn smokeless fuel? 5. What are the problems with CFCs? Pollution (A) 1. Cows produce methane – greenhouse gas which contributes to global warming, the use of fertilisers can run off the soil polluting the rivers which can cause eutrophication and the use of pesticides / herbicides which can wash into waterways and build up in the food chain to toxic levels 2. The sulphur dissolves in rain to form acid rain 3. This greenhouse gas contributes to global warming 4. Smoke causes smog and the smoke particles can cause bronchitis or prevent photosynthesis 5. CFCs damage the ozone layer allowing more UV rays in Deforestation (Q) 1. State two major reasons for deforestation 2. What are the effects of deforestation? 3. What is peat? 4. What are the negative consequences of destroying and removing peat from peat bogs? 5. How do trees prevent erosion? 6. Why is the drugs industry concerned with deforestation? 7. How could humans use wood more sustainably? 8. Explain three ways in which deforestation results in carbon dioxide release Deforestation (A) 1. To provide timber for furniture, building and fuel and for creating land for farming / building 2. Increases CO2 (global warming), loss of biodiversity, soil erosion, loss of future resources 3. Produced over thousands of years from moss in wet acidic boggy areas. It is very rich in nutrients and has been dug up and sold for compost 4. loss of a diverse habitat, when the moss is aerated it begins to decay which releases carbon dioxide into the atmosphere and contributes to global warming 5. No tree roots to hold the soil in place. No trees to take up the water. 6. Some undiscovered species will become extinct before their properties have been researched for medicinal properties, to treat diseases. 7. Recycle wood / paper products. Plant new trees for every tree cut down. 8. Slash and burn – removing the trees which take in carbon dioxide when they photosynthesize. Burning the trees which release carbon dioxide when they burn. The release of carbon dioxide from the microbes that decompose the decaying material Global warming (Q) 1. Which two gases are the main greenhouses gases? 2. What are the major sources of these gases? 3. Why has there been an increase in the two major greenhouse gases? 4. Why is global warming affecting the polar bear distribution? 5. How can carbon dioxide be removed from the atmosphere Global warming (A) 1. Methane and carbon dioxide 2. Methane from cattle farming and rice paddy fields. Carbon dioxide from increased combustion (burning) of fossil fuels to supply us with energy. 3. Increased combustion demand for energy. Increased demand for meat – more farming 4. Global warming is increasing sea temperatures which melts the ice caps. Polar bears have less ice to live on 5. Trees and plants take up carbon dioxide by photosynthesis

Biofuels (Q) 1. What is the energy source for making biofuels? 2. Name the three types of biofuels 3. State the advantages and disadvantages of biofuels 4. Why is biogas from landfill sites particularly dangerous? 5. Why is gasohol used in Brazil? 6. Why do we describe biogas as carbon neutral? Biofuels (A) 1. The sunlight used in photosynthesis 2. Wood, Biogas, Bioethanol, 3. Advantages: Reduces fossil fuel usage by providing an alternative fuel, no overall increase in the level of carbon dioxide, doesn’t produce particulates. Disadvantages: habitat loss, extinction of species. 4. It could explode 5. Lots of sugar cane – can be made into bioethanol 6. The carbon dioxide taken in during the growing of the biofuels in photosynthesis is released again when the fuel is burnt Microbes and food production (Q) 1. Name a fungi that can be eaten directly 2. Name two food products produced by yeasts 3. What is mycoprotein? 4. What conditions must be kept constant in the production of mycoprotein? 5. How nutritional is mycoprotein? Microbes and food production (Q) 1. Mushrooms 2. Alcohol and bread 3. A high protein low fat meat substitute that can be flavoured made from a fungus 4. The pH and the temperature 5. High protein, high fibre, low fat. Food chains and food production (Q) 1. How is energy lost from a food chain? 2. Why is it more efficient for humans to eat herbivores and producers rather than carnivores 3. How do farmers maximize energy transfers? 4. How would controlling the temperature of animals reduce energy loss? 5. How would reducing movement reduce energy loss? 6. List the advantages of energy efficiency farming 7. List the disadvantages of energy efficient farming Food chains and food production (A) 1. movement, keeping warm, excretion, reproduction 2. Shorter food chain means less energy is lost. Carnivores will not contain as much energy 3. Reduce animal movement / control the temperature of their animals 4. Warm: Reduce heat loss, less energy wasted in keeping warm. 5. Reduced respiration 6. Less energy transferred out of the food chain, more available for human consumption, less labour intensive, less risk of attack from predators like foxes, cheaper to produce 7. Greater risk of disease spreading between animals, inhumane / cruel, poor quality product

Fishing (Q) 1. What technological advances led to overfishing? 2. Which fish species are caught in UK waters? 3. Which fish species is most likely to disappear from the North Atlantic? 4. What actions have governments taken to prevent overfishing? 5. How effective have these strategies been? 6. What is the disadvantage of these strategies? Fishing (A) 1. Sonar to locate the fish, sophisticated nets designed to prevent fish escaping, well designed boats that can travel long distances and can store fish in big freezers 2. Herring, haddock, cod and mackerel 3. Cod 4. Net size – larger holes to allow younger fish to escape and breed – replenish the population and fishing quotas – prevent endangered species from being overfished 5. Fishing in the North sea is now sustainable. Fishing has been reduced to a level where the fish populations are able to recover. 6. Fishermen are suffering unemployment

QWC 6 MARK QUESTIONS

Q1. White blood cells are part of the immune system. White blood cells help the body to defend itself against pathogens. Describe how pathogens cause infections and describe how the immune system defends the body against these pathogens.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

bacteria and viruses are pathogens

they reproduce rapidly inside the body

bacteria may produce poisons / toxins that make us feel ill

viruses live and reproduce inside cells causing damage

white blood cells help to defend against pathogens by:

o ingesting pathogens to destroy pathogens

o producing antibodies to destroy specific pathogens

o producing antitoxins to counteract toxins released by pathogens

Memory cells lead to immunity from that pathogen.

Q2. Table 1 shows how the concentration of glucose varied in blood samples from five diabetic people. Measurements were made both before and after getting a medical response dog.

Table 1

Mean percentage of blood samples with different concentrations of glucose from the five diabetic people

Number of blood samples measured

Low glucose

Within normal range of glucose

High glucose

Before getting a dog

1704 32.6 54.8 12.6

After getting a dog 1724 18.6 61.6 19.8

A survey was made of the effect of a medical response dog on the lives of 16 diabetic people. Table 2 shows how well these diabetic people agreed with each statement in the survey.

Table 2

Statement in survey Totally agree

Somewhat agree

Neither agree nor disagree

Somewhat disagree

Totally disagree

I am more independent since getting my dog.

12 2 2 0 0

There are disadvantages to having a medical response dog.

0 0 4 4 8

I trust my dog to alert me when my sugar levels are low.

11 3 1 0 1

I trust my dog to alert me when my sugar levels are high.

6 7 0 1 2

Evaluate how useful medical response dogs are for warning diabetic people that the concentration of glucose in their blood is outside the normal range.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

Pro:

% below normal decreases

% in normal increases

reliable / repeatable / valid data as large number of samples (DO NOT allow accurate / precise)

patients express satisfaction.

Con:

may not be reliable as blood glucose measurements for only 5 patients / survey of only 16 (dog owners)

% above normal increases / dogs are less good at detecting high glucose.

Q2. Table 3 shows the concentrations of some substances in the urine of a non-diabetic person and in the urine of a diabetic person.

Table 3

Concentration of substance in urine in g per dm3

Substance Non-diabetic person Diabetic person

Protein 0 0

Glucose 0 2.0

Urea 20.0 19.5

Sodium ions 6.0 5.8

Compare the results for the non-diabetic person and the diabetic person. Give reasons for any differences. Use your knowledge of how the kidney works.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

glucose in urine of diabetic and not in the non-diabetic

urea and Na+ ions are similar in each / slightly lower in diabetic

no protein in either urine sample because protein too large / does not pass through filter

glucose passes through filter in kidney

non-diabetic: the / all glucose is reabsorbed / taken back into blood

diabetic: (too much glucose so) cannot all be reabsorbed

because diabetic has high concentration of glucose in blood

urea and Na+ lower in diabetic because less water is reabsorbed (due to extra glucose in filtrate).

Q3. Homeostasis keeps conditions in the body relatively constant. The amount of water in the body is controlled by homeostasis. Kidney function is controlled by a gland in the brain. Describe how the water content of the blood is controlled.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

if water content too low, ADH released

from pituitary gland

into the blood

causing kidney reabsorbs more water

more concentrated / small volume urine produced

if water content too high, ADH lowered / not produced

less water reabsorbed by kidney

more dilute / larger volume urine produced

Q4. The human body is kept at a constant internal temperature of about 37 °C. Body temperature is monitored and controlled by the thermoregulatory centre in the brain. Describe what happens in the body to keep the body temperature constant.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

temperature receptors in TC

the TC detects (core) body / blood temperature

temperature receptors in the skin send impulses to the TC, giving information about skin temperature

if the core body temperature is too high = vasodilation (blood vessels going to the skin capillaries dilate)

vasodilation causes more blood flow through the skin and more heat is lost

sweat glands release more sweat to cool the body by evaporation

if the core body temperature is too low = vasoconstriction (blood vessels going to skin capillaries

constrict)

vasoconstriction reduces the flow of blood through the skin and less heat is lost.

muscles may shiver to release (heat) energy from respiration, some of which is lost as heat

Q5. Deforestation affects the environment. Deforestation is causing a change in the amounts of different gases in the atmosphere. This change causes global warming and climate change. Give the reasons why deforestation is taking place. Describe how deforestation is causing the change in the amounts of different gases in the atmosphere. KEY POINTS TO INCLUDE IN YOUR ANSWER:

Reasons for deforestation

timber for construction / furniture / boat building / paper production

growing plants for biofuels for motor fuel / aviation / lawnmowers

use of wood as a fuel

land for building or agriculture to provide food, such as rice fields and cattle ranching

Effects of deforestation

increase in carbon dioxide in atmosphere

due to burning

due to activities of microbes

less carbon dioxide taken in / locked up (by trees)

less photosynthesis

increase in methane in atmosphere

due to rice production / cattle

Q7. Human cells cannot make some of the amino acids which we need. We must obtain these amino acids from our diet. The table shows the amounts of four of these amino acids present in mycoprotein, in beef and in wheat.

Name of amino acid

Amount of amino acid per 100 g in mg

Daily amount needed by a 70 kg human in mg

Mycoprotein Beef Wheat

Lysine 910 1600 300 840

Methionine 230 500 220 910

Phenylalanine

540 760 680 980

Threonine 610 840 370 490

A diet book states that mycoprotein is the best source of amino acids for the human diet. Evaluate this statement. Remember to include a conclusion in your evaluation.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

beef is best or beef is better than mycoprotein

mycoprotein mainly better than wheat

more phenylalanine in wheat than in mycoprotein

but no information given on other amino acids / costs / foods

Overall conclusion:

statement is incorrect because

o it would be the best source for vegetarians

o for given amino acids, beef is the best source

o three foods provide insufficient data to draw a valid conclusion

Q8. A dairy farmer washes out his cow shed each day. The waste water contains urine and faeces. The waste water overflows into a stream by mistake. The waste water will have an effect on the plants and invertebrates living in the stream. Explain why. KEY POINTS TO INCLUDE IN YOUR ANSWER:

this contains mineral ions and organic matter

this increases growth of algae / water plants

the plants / algae (underneath) die

due to lack of light / photosynthesis / space

decomposers / microorganisms feed on decaying matter or multiply rapidly

the respiration of decomposers uses up all the oxygen

so invertebrates die due to lack of oxygen

this is called eutrophication

Q9. Give methods used in the factory farming of animals. Explain the advantages and disadvantages of these methods.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

Factory farming methods e.g.:

Kept in cramped conditions / battery hens / calf crates / pig barns / fish tanks

Controlled temperature / heating

Controlled feeding / modified food given / growth hormones

Controlled lighting

Treated with prophylactic antibiotics

Advantages e.g.:

Increased efficiency / profit / greater food production / cheaper food / faster growth

Farmer can have more livestock

Less energy is lost through movement

Less energy is used keeping warm

Food is high in calories / protein so animals will grow faster / lay more eggs

Easier to vaccinate all the animals

Easier to protect animals from predators

Antibiotic treatment stops infections in animals

Disadvantages e.g.:

Stress / cruelty / inhumane / unethical

Restricted movement / overcrowding

Faster spread of diseases

Antibiotics in the food chain / residual chemicals in the food chain

Wasting fossil fuels / increasing global warming

Increased pollution from animal waste and from additional transport

Q11. A person with the kidney disease could be treated either by using a dialysis machine or by a kidney transplant operation. Compare the advantages and disadvantages of these two methods of treatment. Use your knowledge and understanding of the two methods in your answer.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

Advantages of transplant over dialysis

no build-up of toxins / keeps blood concentration constant

prevent high blood pressure

don’t need restricted diet / restricted fluid intake or

time wasted on dialysis

blood clots may result from dialysis

infection may result from dialysis

with dialysis, blood may not clot properly due to

anti-clotting drugs

cost issues (ie transplant cheaper)

Disadvantages of transplant over dialysis

rejection / problem finding tissue match

use of immuno-suppressant drugs leading to other infections

dangers during operation

Q12. Coal is used in many power stations. Describe, in as much detail as you can, how using coal in power stations can damage the environment.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

burning → named gas → correct

coal / fossil fuel is burned

water vapour and carbon dioxide and sulphur dioxide formed

gases dissolve / react in rain

make acid rain

damages trees, plants, animals and buildings

makes rivers /lakes acidic

Q13. It is suggested that the increased level of carbon dioxide in the air is causing the atmosphere to warm up (the “Greenhouse Effect”). Describe, as fully as you can, two major effects of global warming and how these may affect the human population.

KEY POINTS TO INCLUDE IN YOUR ANSWER:

climate change

o warmer/colder/drier/wetter

o food production affected/starvation

o mayor ecosystems destroyed/damaged

sea level rise and low land flooded due to polar ice caps melting and sea water expanding

o less food grown/starvation

o homes/factories flooded