Year 11 Paper 1: Homeostasis and Disease
Covers the nervous system and reflexes, hormones and homeostasis, digestion and the circulatory system, pathogens and communicable disease, and the body's defence systems and how disease is treated.
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]
Human Defence Systems and Treating Disease
State what an antibiotic is, and state what type of pathogen antibiotics are effective against.
Question 2 [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 3 [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 4 [3 marks]
The Nervous System and Reflexes
State the function of a sensory neurone and the function of a motor neurone, and state one way a neurone is adapted for its function.
Question 5 [3 marks]
Pathogens and Communicable Disease
Rose black spot is a fungal disease that affects rose plants.
Describe how rose black spot spreads between plants, and describe one way its spread can be reduced.
Question 6 [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 7 [3 marks]
Digestion and the Circulatory System
State three differences in structure between an artery and a vein.
Question 8 [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 9 [4 marks]
Hormones and Homeostasis
A doctor prescribes insulin at a dose of 0.4 units per kg of body mass.
Calculate the dose, in units, needed for a patient with a body mass of 65 kg, and calculate the dose needed for a patient with a body mass of 80 kg.
Question 10 [5 marks]
Human Defence Systems and Treating Disease
Herd immunity against a disease is achieved once 80% of a population is immune, making it very unlikely an unvaccinated person will come into contact with the pathogen.
In a town of 50,000 people, 32,000 are currently immune to the disease (through vaccination or previous infection). Calculate the percentage of the town's population that is currently immune, and calculate how many more people would need to become immune to reach the 80% herd immunity threshold.
Question 11 [4 marks]
Digestion and the Circulatory System
A student investigated the effect of temperature on the rate of starch digestion by amylase.
The time taken for starch to disappear was 240 seconds at 20 deg C and 60 seconds at 35 deg C.
Calculate the rate of reaction at each temperature in arbitrary units of 1/time (s^-1), then state which temperature gave the faster rate.
Question 12 [5 marks]
Human Defence Systems and Treating Disease
Explain, in terms of antigens and antibodies, why a person's white blood cells can produce an antibody that is specific to just one type of pathogen.
Model solutions
| Question 1[2 marks] | |
|---|---|
| Answer or working | Marks |
| an antibiotic is a medicine/drug that kills bacteria (or prevents their growth) inside the body | B1 |
| antibiotics are effective against bacterial pathogens (not viruses) | B1 |
| Final answer: An antibiotic kills bacteria (or stops them growing) inside the body; antibiotics are effective against bacteria, not viruses | |
| Question 2[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 3[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 4[3 marks] | |
|---|---|
| Answer or working | Marks |
| a sensory neurone carries electrical impulses from a receptor to the central nervous system (spinal cord/brain) | B1 |
| a motor neurone carries electrical impulses from the central nervous system to an effector (muscle or gland) | B1 |
| a neurone having a long axon to carry impulses over a distance, or having a myelin sheath to speed up the impulse | B1 |
| Final answer: Sensory neurones carry impulses from receptors to the CNS; motor neurones carry impulses from the CNS to effectors; neurones have long, often myelinated axons adapted for carrying impulses quickly over distance | |
| Question 5[3 marks] | |
|---|---|
| Answer or working | Marks |
| rose black spot spreads in water (e.g. rain splash) or by wind, carrying fungal spores between plants | B1 |
| a valid symptom, such as purple or black spots developing on leaves, which often turn yellow and drop early, reducing photosynthesis | B1 |
| a valid prevention/treatment, e.g. removing and destroying affected leaves, or using a fungicide | B1 |
| Final answer: Rose black spot spreads by water or wind carrying fungal spores between plants, causing black/purple spots and leaf loss; removing affected leaves or using a fungicide reduces its spread | |
| Question 6[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 7[3 marks] | |
|---|---|
| Answer or working | Marks |
| arteries have thicker, more muscular walls than veins | B1 |
| arteries have a narrower lumen than veins | B1 |
| veins have valves to prevent the backflow of blood, but arteries do not | B1 |
| Final answer: Arteries have thicker, more muscular walls, a narrower lumen, and (unlike veins) no valves | |
| Question 8[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 9[4 marks] | |
|---|---|
| Answer or working | Marks |
| using dose = rate per kg x body mass | M1 |
| the 65 kg patient, 0.4 x 65 | M1 |
| 26 units | A1 |
| the 80 kg patient, 0.4 x 80 = 32 units | A1independent |
| Final answer: 26 units for the 65 kg patient and 32 units for the 80 kg patient | |
| Question 10[5 marks] | |
|---|---|
| Answer or working | Marks |
| using percentage immune = (32000/50000) x 100 | M1 |
| 64% | A1 |
| finding the number needed for herd immunity = 80% of 50000 | M1 |
| finding the further number needed = 40000 - 32000 | M1 |
| 8000 more people | A1 |
| Final answer: 64% of the town's population is currently immune; a further 8000 people would need to become immune to reach the 80% herd immunity threshold | |
| Question 11[4 marks] | |
|---|---|
| Answer or working | Marks |
| using rate = 1 / time | M1 |
| rate at 20 deg C = 1/240 = 0.00417 s^-1 (accept 4.17 x 10^-3) | M1 |
| rate at 35 deg C = 1/60 = 0.0167 s^-1 (accept 1.67 x 10^-2) | M1 |
| 35 deg C gave the faster rate, because its rate value is larger | A1 |
| Final answer: Rate at 20 deg C = 0.00417 s^-1, rate at 35 deg C = 0.0167 s^-1; 35 deg C is faster | |
| Question 12[5 marks] | |
|---|---|
| Answer or working | Marks |
| pathogens have proteins on their surface called antigens | B1 |
| different pathogens have antigens with different shapes | B1 |
| antibodies have a shape that is complementary to a specific antigen, like a lock and key | B1 |
| an antibody produced against one pathogen's antigen will not fit (bind to) a different pathogen's antigen | B1 |
| this means each type of antibody is specific and can only be used to target one type of pathogen | B1 |
| Final answer: Pathogens have surface antigens of a specific shape, and antibodies have a complementary shape that binds only to that antigen (like a lock and key), so each antibody type is specific to one pathogen | |