Year 11 Paper 3: Energy and Homeostasis
Covers photosynthesis, respiration and exercise, the nervous system and reflexes, hormones and homeostasis, and pathogens and communicable disease.
Year 11 here means a typical teaching order, not a syllabus rule. No exam board defines what belongs to Year 11, and schools sequence the course differently. Check it against your own scheme of work before using it to decide what a class has covered.
Questions
Question 1 [2 marks]
The Nervous System and Reflexes
A reflex arc includes a receptor, an effector, a relay neurone, a sensory neurone and a motor neurone.
State the correct order these are involved in for a simple reflex action.
Question 2 [2 marks]
Pathogens and Communicable Disease
State what is meant by a pathogen, and give one example of a type of pathogen.
Question 3 [2 marks]
Photosynthesis
State the word equation for photosynthesis, and state whether the reaction is exothermic or endothermic.
Question 4 [2 marks]
The Nervous System and Reflexes
State the function of a relay neurone, and state where in the body relay neurones are found.
Question 5 [2 marks]
Hormones and Homeostasis
State what is meant by homeostasis, and give one example of a condition inside the body that is controlled.
Question 6 [2 marks]
Pathogens and Communicable Disease
State two differences between a virus and a bacterium.
Question 7 [2 marks]
Photosynthesis
State where in a plant cell photosynthesis takes place, and state the raw materials needed for photosynthesis.
Question 8 [3 marks]
Hormones and Homeostasis
Describe the role of glucagon in controlling blood glucose concentration when it falls too low, and state which organ releases glucagon.
Question 9 [3 marks]
Respiration and Exercise
State three ways an organism uses the energy released by respiration.
Question 10 [3 marks]
Hormones and Homeostasis
Describe the role of insulin in controlling blood glucose concentration after a meal.
Question 11 [4 marks]
Respiration and Exercise
At rest, a person takes 16 breaths per minute, and each breath takes in 250 cm^3 of air, of which 4% is absorbed as oxygen into the blood.
Calculate the volume of oxygen absorbed into the blood per minute, in cm^3.
Question 12 [4 marks]
The Nervous System and Reflexes
A student measured reaction time using a ruler drop test.
The ruler fell 18 cm before being caught.
Using the relationship distance (m) = 0.5 x 9.8 x time^2, calculate the student's reaction time in seconds, to 2 significant figures.
Question 13 [4 marks]
Pathogens and Communicable Disease
A school recorded the number of pupils absent with a flu-like illness.
On Monday, 18 out of 600 pupils were absent with symptoms. By Friday, 54 out of 600 pupils were absent with symptoms.
Calculate the percentage of pupils absent on each day, then calculate the percentage change in absence over the week.
Question 14 [5 marks]
Respiration and Exercise
A student's breathing rate was recorded before and after exercise. At rest, the student took 15 breaths per minute, each with a volume of 0.5 litres. Immediately after exercise, they took 30 breaths per minute, each with a volume of 2 litres.
Calculate the student's total volume of air breathed per minute (minute ventilation) at rest and immediately after exercise, using minute ventilation = breathing rate x breath volume, and calculate how many times greater the minute ventilation is after exercise compared with at rest.
Question 15 [5 marks]
Photosynthesis
A grower measures that one tomato plant produces 40 g of new dry biomass per week under standard greenhouse conditions. Under improved lighting, this rises to 58 g per week.
Calculate the percentage increase in biomass production per plant, and calculate the total extra biomass produced per week across a greenhouse of 250 plants, assuming every plant shows the same increase.
Question 16 [5 marks]
Pathogens and Communicable Disease
HIV is a virus that can be transmitted through unprotected sexual contact and by sharing needles.
Describe how HIV affects the body if left untreated, and describe two ways its transmission can be prevented.
Question 17 [5 marks]
Photosynthesis
A student wants to test whether light is needed for a plant to produce starch. They cover part of one leaf with aluminium foil to exclude light, and leave the rest of the leaf exposed to light for a day, then test the whole leaf with iodine solution.
Describe the result you would expect, and describe one step the student should take before this test to make sure any starch found is produced only during the experiment.
Question 18 [5 marks]
Pathogens and Communicable Disease
Tuberculosis (TB) is a bacterial disease that mainly affects the lungs.
Describe how TB is spread between people, describe one symptom of TB, and describe one way its spread can be reduced.
Model solutions
| Question 1[2 marks] | |
|---|---|
| Answer or working | Marks |
| identifying the receptor as first and the effector as last | M1 |
| receptor -> sensory neurone -> relay neurone -> motor neurone -> effector | A1 |
| Question 2[2 marks] | |
|---|---|
| Answer or working | Marks |
| a pathogen is a microorganism that causes disease | B1 |
| a valid example, such as bacteria, viruses, fungi or protists | B1 |
| Final answer: A pathogen is a microorganism that causes disease, e.g. bacteria, viruses, fungi or protists | |
| Question 3[2 marks] | |
|---|---|
| Answer or working | Marks |
| carbon dioxide + water -> glucose + oxygen | B1 |
| endothermic | B1 |
| Final answer: Carbon dioxide + water -> glucose + oxygen; endothermic | |
| Question 4[2 marks] | |
|---|---|
| Answer or working | Marks |
| a relay neurone connects a sensory neurone to a motor neurone (passing on the electrical impulse) within the central nervous system | B1 |
| found in the spinal cord (or brain) | B1 |
| Final answer: A relay neurone connects a sensory neurone to a motor neurone; it is found in the spinal cord (or brain) | |
| Question 5[2 marks] | |
|---|---|
| Answer or working | Marks |
| homeostasis is the regulation of the internal conditions of the body to maintain a stable internal environment, in response to internal and external changes | B1 |
| a valid example, such as blood glucose concentration, body temperature or water levels | B1 |
| Final answer: Homeostasis maintains a stable internal environment, e.g. by controlling blood glucose concentration, body temperature or water levels | |
| Question 6[2 marks] | |
|---|---|
| Answer or working | Marks |
| viruses are much smaller than bacteria | B1 |
| viruses can only reproduce inside a host cell, whereas bacteria can reproduce independently (by simple cell division) | B1 |
| Final answer: Viruses are much smaller than bacteria, and can only reproduce inside a host cell, while bacteria can reproduce independently | |
| Question 7[2 marks] | |
|---|---|
| Answer or working | Marks |
| the chloroplasts | B1 |
| carbon dioxide and water | B1 |
| Final answer: Photosynthesis takes place in the chloroplasts, using carbon dioxide and water as raw materials | |
| Question 8[3 marks] | |
|---|---|
| Answer or working | Marks |
| the pancreas detects low blood glucose concentration and releases glucagon | B1 |
| glucagon causes the liver to break down stored glycogen into glucose, which is released into the blood | B1 |
| this raises the blood glucose concentration back towards normal | B1 |
| Final answer: The pancreas releases glucagon when blood glucose is low; glucagon causes the liver to break down glycogen into glucose, raising blood glucose concentration | |
| Question 9[3 marks] | |
|---|---|
| Answer or working | Marks |
| movement/muscle contraction | B1 |
| keeping warm (maintaining a constant body temperature in mammals and birds) | B1 |
| building larger molecules from smaller ones, such as building proteins from amino acids (or for growth/active transport) | B1 |
| Final answer: Energy from respiration is used for movement, keeping warm, and building larger molecules (e.g. proteins) from smaller ones | |
| Question 10[3 marks] | |
|---|---|
| Answer or working | Marks |
| after a meal, blood glucose concentration rises | B1 |
| the pancreas detects this and releases insulin into the blood | B1 |
| insulin causes glucose to move from the blood into cells, especially liver and muscle cells, where excess is stored as glycogen, lowering blood glucose concentration | B1 |
| Final answer: The pancreas releases insulin when blood glucose rises; insulin causes cells to take up glucose and store the excess as glycogen, lowering blood glucose concentration | |
| Question 11[4 marks] | |
|---|---|
| Answer or working | Marks |
| volume of air per minute = 16 x 250 | M1 |
| 4000 cm^3 | A1 |
| oxygen absorbed = 4% of 4000 | M1 |
| 160 cm^3 | A1 |
| Final answer: 160 cm^3 of oxygen is absorbed into the blood per minute | |
| Question 12[4 marks] | |
|---|---|
| Answer or working | Marks |
| converting 18 cm to 0.18 m | M1 |
| rearranging to time = sqrt(distance / (0.5 x 9.8)) | M1 |
| substituting 0.18 into the rearranged equation | M1 |
| 0.19 seconds | A1 |
| Question 13[4 marks] | |
|---|---|
| Answer or working | Marks |
| Monday percentage = (18/600) x 100 = 3% | M1 |
| Friday percentage = (54/600) x 100 = 9% | M1 |
| percentage change = ((9 - 3)/3) x 100 | M1 |
| a 200% increase | A1 |
| Final answer: Monday 3%, Friday 9%, a 200% increase over the week | |
| Question 14[5 marks] | |
|---|---|
| Answer or working | Marks |
| resting minute ventilation = 15 x 0.5 | M1 |
| 7.5 litres per minute | A1 |
| post-exercise minute ventilation = 30 x 2 = 60 litres per minute | M1 |
| using ratio = post-exercise value / resting value | M1 |
| 60 / 7.5 = 8 times greater | A1 |
| Final answer: Resting minute ventilation = 7.5 litres per minute; after exercise = 60 litres per minute, which is 8 times greater | |
| Question 15[5 marks] | |
|---|---|
| Answer or working | Marks |
| the increase = 58 - 40 = 18 g | M1 |
| percentage increase = (18 / 40) x 100 | M1 |
| 45% | A1 |
| total extra biomass = 18 x 250 | M1 |
| 4500 g | A1 |
| Final answer: A 45% increase per plant; across 250 plants this is an extra 4500 g of biomass per week | |
| Question 16[5 marks] | |
|---|---|
| Answer or working | Marks |
| HIV attacks and destroys white blood cells of the immune system (lymphocytes) | B1 |
| without treatment this severely weakens the immune system over time, leading to late-stage HIV/AIDS | B1 |
| a person with late-stage infection cannot fight off other infections that would not normally be life-threatening | B1 |
| a prevention method: using a condom during sexual contact | B1 |
| a prevention method: not sharing needles | B1 |
| Final answer: Untreated, HIV destroys white blood cells and weakens the immune system, eventually leading to AIDS where other infections become life-threatening; transmission is reduced by using condoms and not sharing needles | |
| Question 17[5 marks] | |
|---|---|
| Answer or working | Marks |
| the exposed (uncovered) part of the leaf turns blue-black with iodine, showing starch is present | B1 |
| the covered part of the leaf, which was kept in the dark, stays orange/brown with iodine, showing no starch is present | B1 |
| this showing light is needed for a plant to produce starch (via photosynthesis) | B1 |
| before the test, the plant should be left in the dark (destarched) for at least 24 hours, to remove any starch already stored in the leaves | B1 |
| this ensuring any starch found afterwards must have been made during the test itself, rather than being present beforehand | B1 |
| Final answer: The uncovered part turns blue-black (starch present) but the foil-covered part stays orange/brown (no starch), showing light is needed for starch production; the plant should first be destarched by leaving it in the dark for 24 hours, so any starch found is from the test itself | |
| Question 18[5 marks] | |
|---|---|
| Answer or working | Marks |
| TB is spread through the air, in droplets from the coughs or sneezes of an infected person | B1 |
| spread is more likely in crowded or poorly ventilated conditions | B1 |
| a valid symptom, e.g. a persistent cough, coughing up blood, weight loss or fever | B1 |
| a valid prevention: vaccination (BCG vaccine) | B1 |
| a further valid prevention: people with TB avoiding close contact with others until treated, or improved ventilation | B1 |
| Final answer: TB spreads through airborne droplets from coughs and sneezes, especially in crowded conditions, causing symptoms such as a persistent cough and weight loss; vaccination and avoiding close contact while infectious reduce its spread | |