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GCSE · Biology

B5 Homeostasis and Response

AQA 8461/8462/8463 · Calculator allowed · about 110 minutes

Total Marks

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

Homeostasis is essential for maintaining a stable internal environment in the body.

(a)Define the term 'homeostasis'.(1)

(b)State three internal conditions of the body that are controlled by homeostasis.(3)

(Total for Question 1 is 4 marks)

Rhys accidentally touches a hot pan and pulls his hand away quickly, before he feels any pain.

(a)Identify the type of response described.(1)

(b)Put the following in the correct order to show how information passes through the nervous system during this reflex action: effector, receptor, relay neurone, sensory neurone, motor neurone.(2)

(c)Explain why reflex actions are important for survival.(2)

(Total for Question 2 is 5 marks)

Neurones communicate with each other across small gaps.

(a)Name the gap between two neurones.(1)

(b)Describe how a nerve impulse crosses a synapse to reach the next neurone.(3)

(Total for Question 3 is 4 marks)

Required practical: Aisha and her partner carried out an investigation into human reaction time using the ruler-drop method. Aisha held her thumb and forefinger apart, with her partner suspending a ruler vertically so that the 0 cm mark was level with the top of her thumb. Her partner released the ruler without warning, and Aisha caught it as quickly as she could.

(a)Describe how the distance the ruler falls before being caught is used to find a person's reaction time.(2)

(b)Explain why Aisha and her partner should repeat the test several times and calculate a mean falling distance.(2)

(c)On one attempt, the ruler fell a distance of 0.20 m before Aisha caught it. Using the equation d = 0.5 x g x t² (where g = 9.8 m/s²), calculate Aisha's reaction time, t, in seconds. Give your answer to 2 significant figures.(3)

(Total for Question 4 is 7 marks)

The eye is a sense organ containing receptors sensitive to light intensity and colour.

(a)Name the part of the eye that: (i) refracts light entering the eye (ii) contains the light receptor cells (iii) controls the amount of light entering the eye.(3)

(b)Describe what happens to the pupil in dim light, and explain why this response is useful.(2)

(Total for Question 5 is 5 marks)

The eye can focus on objects at different distances by changing the shape of the lens, a process called accommodation.

(a)Define the term 'accommodation'.(1)

(b)Describe how the shape of the lens changes when the eye focuses on a distant object.(2)

(c)Ffion is short-sighted (myopic), so distant objects appear blurred. State the type of lens used in glasses to correct short-sightedness, and explain how it corrects her vision.(2)

(Total for Question 6 is 5 marks)

Different regions of the brain control different functions, and doctors use various techniques to study the brain.

(a)State which part of the brain is mainly responsible for each of the following: (i) consciousness, intelligence, memory and language (ii) muscular coordination and balance (iii) controlling unconscious activities such as breathing rate and heart rate.(3)

(b)Give one reason why it can be difficult for doctors to investigate and treat damage or disease in the brain.(1)

(c)Name one non-invasive scanning technique that can be used to study the structure or activity of the brain.(1)

(Total for Question 7 is 5 marks)

During a cross country run on a cold day, Callum's core body temperature is monitored. Explain how Callum's body responds to keep his core temperature close to 37 degC, both while he is exercising and generating heat, and if he were to become too cold.

(Total for Question 8 is 6 marks)

Hormones are chemical messengers released directly into the blood by glands, and carried to target organs.

(a)Name the gland, often called the 'master gland', that releases hormones which act on other glands to control the release of their hormones.(1)

(b)State the main hormone released by each of the following glands: (i) the ovaries (ii) the testes (iii) the adrenal glands.(3)

(Total for Question 9 is 4 marks)

Blood glucose concentration is monitored and controlled by the pancreas.

(a)Name the organ that monitors and controls blood glucose concentration.(1)

(b)Describe what happens, in terms of hormone release and its effect on the liver, when blood glucose concentration rises after a meal.(3)

(c)Explain the difference between type 1 and type 2 diabetes.(2)

(Total for Question 10 is 6 marks)

Jamal weighs 88 kg and is 1.60 m tall. Body Mass Index (BMI) can be calculated using the equation: BMI = mass (kg) / [height (m)]^2. A BMI above 30 is classified as 'obese'.

(a)Calculate Jamal's BMI. Give your answer to 1 decimal place.(2)

(b)Using your answer to part (a), suggest why Jamal may have an increased risk of developing type 2 diabetes.(2)

(Total for Question 11 is 4 marks)

The menstrual cycle is controlled by the interaction of several hormones, including FSH, LH, oestrogen and progesterone, over a 28-day cycle.

(a)Name the hormone, released by the pituitary gland, that stimulates the maturation of an egg in the ovary.(1)

(b)Name the hormone responsible for triggering ovulation, and state on which day of a 28-day cycle this typically occurs.(2)

(c)If the egg is not fertilised, the concentration of progesterone falls sharply towards the end of the cycle. Explain the effect this has on the lining of the uterus.(2)

(Total for Question 12 is 5 marks)

Couples can use different methods of contraception to reduce the chance of pregnancy.

(a)Give one example of a hormonal method of contraception.(1)

(b)Explain how the combined contraceptive pill prevents pregnancy.(2)

(c)Give one non-hormonal method of contraception, and explain how it prevents pregnancy.(2)

(Total for Question 13 is 5 marks)

In vitro fertilisation (IVF) can be used to help couples who are struggling to conceive naturally.

(a)Give one reason why a couple might choose to have IVF treatment.(1)

(b)Describe the main stages of the IVF process.(3)

(c)Suggest one social or ethical issue associated with IVF treatment.(1)

(Total for Question 14 is 5 marks)

Thyroxine, released by the thyroid gland, helps regulate metabolic rate and is itself controlled by negative feedback.

(a)Name the gland that releases thyroxine.(1)

(b)Explain, using the principle of negative feedback, what happens if the concentration of thyroxine in the blood becomes too high.(3)

(Total for Question 15 is 4 marks)

Required practical: Sofia set up an investigation into the effect of light direction on the growth of germinating cress seedlings. She placed one pot of seedlings in a box with a hole cut in one side, so light could only enter from that direction, and left an identical pot of seedlings uncovered in normal light as a comparison.

(a)Identify the independent variable in Sofia's investigation.(1)

(b)State two variables Sofia should control to make her investigation a fair test.(2)

(c)Predict and explain what Sofia would observe in the pot exposed to light from one direction only, in terms of the distribution of the plant hormone auxin in the shoot tip.(3)

(Total for Question 16 is 6 marks)

Sofia measured the height of a seedling shoot growing towards a lamp over a 4-day period. At the start (day 0), the shoot was 20 mm tall; by day 4, it had grown to 32 mm tall.

(a)Calculate the mean rate of growth of the shoot, in mm per day, over the 4-day period.(2)

(b)Sofia's teacher suggests she should repeat the investigation using several seedlings, rather than just one. Explain why this would improve her investigation.(2)

(Total for Question 17 is 4 marks)

Gibberellins and ethene are two other plant hormones with important commercial uses.

(a)Name the plant hormone group associated with ending seed dormancy and initiating germination, and give one commercial use of this hormone group.(2)

(b)Ethene is a plant hormone that controls cell division and the ripening of fruit. Suggest why this makes ethene useful commercially in the food industry.(1)

(Total for Question 18 is 3 marks)

Scientists use different methods to study the brain and map its functions, including studying patients with brain damage, electrically stimulating regions of the brain during surgery, and using MRI scanning. Evaluate the strengths and limitations of these different methods.

(Total for Question 19 is 6 marks)

A nerve impulse travels along a motor neurone axon that is 0.85 m long. It takes 0.0085 seconds for the impulse to travel the full length of the axon.

(a)Calculate the speed of the nerve impulse, in m/s.(2)

(b)Reflex responses are consistently faster than responses that involve conscious thought in the brain, even where the distance travelled by the impulse is similar. Suggest one reason for this, other than distance travelled.(2)

(Total for Question 20 is 4 marks)

Mark scheme · B5 Homeostasis and Response

Question 1

(a) B1 the regulation/maintenance of a constant internal environment in response to internal and external changes, oe
(a) Answer: Homeostasis is the regulation of a constant internal environment in the body, in response to internal and external changes.
(b) B1 body temperature
(b) B1 blood glucose concentration
(b) B1 water content/levels (or ion content); allow blood pressure
(b) Answer: Body temperature; blood glucose concentration; water (or ion) content.

Question 2

(a) B1 a reflex (action), oe
(a) Answer: A reflex action.
(b) B1 receptor first and effector last identified, oe
(b) B1 fully correct order: receptor, sensory neurone, relay neurone, motor neurone, effector
(b) Answer: Receptor, sensory neurone, relay neurone, motor neurone, effector.
(c) B1 reflex actions are automatic and do not need conscious thought/involvement of the brain, oe
(c) B1 this makes the response much faster, reducing the time taken to react to a potentially damaging/dangerous stimulus, oe
(c) Answer: Reflex actions do not involve conscious thought in the brain, so they happen very quickly, reducing the risk of harm from a dangerous stimulus.

Question 3

(a) B1 synapse
(a) Answer: Synapse.
(b) B1 the electrical impulse arriving at the synapse triggers the release of a chemical (neurotransmitter), oe
(b) B1 the neurotransmitter diffuses across the synapse (gap), oe
(b) B1 the neurotransmitter binds to receptor molecules on the membrane of the next neurone, triggering a new electrical impulse in that neurone, oe
(b) Answer: The impulse triggers release of a neurotransmitter, which diffuses across the synapse and binds to receptors on the next neurone, triggering a new electrical impulse.

Question 4

(a) B1 the distance the ruler falls (the reading level with the top of the thumb/finger when caught) is recorded, oe
(a) B1 this distance is used (e.g. with a conversion table or calculation) to work out the time taken to react, since a longer falling distance means a longer/slower reaction time, oe
(a) Answer: The distance the ruler falls before it is caught is measured; a greater distance means the ruler fell for longer, so the person's reaction time was longer.
(b) B1 a single reading could be an anomaly, or could be affected by chance factors (e.g. Aisha anticipating the drop, or being distracted), oe
(b) B1 repeating and taking a mean reduces the effect of random variation/anomalous results, giving a more reliable value for reaction time, oe
(b) Answer: A single reading could be affected by chance or anticipation; repeating the test and calculating a mean reduces the effect of random variation, giving a more reliable result.
(c) M1 equation rearranged: t = √2d / g, oe
(c) M1 values substituted: t = √(2 x 0.20) / 9.8, oe
(c) A1 0.20 s, awrt, cao
(c) Answer: 0.20 s

Question 5

(a) B1 (i) cornea
(a) B1 (ii) retina
(a) B1 (iii) iris
(a) Answer: (i) cornea (ii) retina (iii) iris.
(b) B1 the pupil widens/dilates in dim light, oe
(b) B1 this allows more light to enter the eye, so the retina can still detect enough light to form a clear image, oe
(b) Answer: The pupil widens (dilates) in dim light, allowing more light to enter the eye so the retina can still detect enough light to form an image.

Question 6

(a) B1 the ability of the eye to change focus (by changing the shape of the lens) to focus on objects at different distances, oe
(a) Answer: Accommodation is the ability of the eye to change focus, by changing the shape of the lens, to view objects at different distances.
(b) B1 the ciliary muscles relax, oe
(b) B1 the suspensory ligaments are pulled tight, so the lens is pulled into a thinner/less curved shape, oe
(b) Answer: The ciliary muscles relax, pulling the suspensory ligaments tight, which pulls the lens into a thin, less curved shape.
(c) B1 a concave (diverging) lens
(c) B1 the lens causes light rays to diverge slightly before entering the eye, so they focus further back, on the retina, rather than in front of it, oe
(c) Answer: A concave (diverging) lens is used; it makes light rays diverge slightly before they enter the eye, moving the point of focus back onto the retina instead of in front of it.

Question 7

(a) B1 (i) cerebral cortex (cerebrum)
(a) B1 (ii) cerebellum
(a) B1 (iii) medulla oblongata (medulla)
(a) Answer: (i) cerebral cortex (ii) cerebellum (iii) medulla oblongata.
(b) B1 the brain is complex/delicate and difficult to access safely (protected by the skull), so investigating or operating on it carries a high risk of causing further damage, oe
(b) Answer: The brain is complex and delicate, and protected by the skull, so it is difficult to access without risking further damage to it.
(c) B1 MRI scanning (accept CT scanning or PET scanning)
(c) Answer: MRI scanning (accept CT scanning or PET scanning).

Question 8

Level 1 (1-2): Simple, isolated statements are made, e.g. sweating or shivering is named, with little or no reasoning or reference to negative feedback.
Level 2 (3-4): Describes some responses to being too hot and/or too cold (e.g. sweating, vasodilation, shivering, vasoconstriction), with some reasoning about how they change heat loss or heat production.
Level 3 (5-6): Gives a clear, well-linked explanation covering responses to both overheating and overcooling, correctly using vasodilation, vasoconstriction, sweating and shivering, and explains that the thermoregulatory centre (in the hypothalamus) monitors and corrects temperature by negative feedback.
Indicative content:
- The thermoregulatory centre, in the hypothalamus of the brain, monitors the temperature of the blood and receives information from thermoreceptors in the skin
- While exercising, heat produced by respiring muscles raises core temperature above 37 degC
- Blood vessels supplying the skin capillaries dilate (vasodilation), increasing blood flow near the skin surface so more heat is lost by radiation
- Sweat glands release more sweat, which evaporates from the skin and transfers heat energy away from the body, cooling it
- If Callum becomes too cold, blood vessels supplying the skin capillaries constrict (vasoconstriction), reducing blood flow near the surface and reducing heat loss
- Shivering occurs: muscles contract involuntarily and rapidly, and the extra respiration needed for this releases heat
- These are examples of negative feedback: once the core temperature returns to around 37 degC, the responses are reduced/switched off

Question 9

(a) B1 pituitary gland
(a) Answer: Pituitary gland.
(b) B1 (i) oestrogen
(b) B1 (ii) testosterone
(b) B1 (iii) adrenaline
(b) Answer: (i) oestrogen (ii) testosterone (iii) adrenaline.

Question 10

(a) B1 pancreas
(a) Answer: Pancreas.
(b) B1 the pancreas releases (more) insulin into the blood, oe
(b) B1 insulin causes the liver (and muscle cells) to take up glucose from the blood, oe
(b) B1 glucose is converted into glycogen for storage, so blood glucose concentration falls back towards normal, oe
(b) Answer: The pancreas releases insulin, which causes the liver (and muscles) to take up glucose from the blood and convert it into glycogen for storage, lowering blood glucose concentration.
(c) B1 in type 1 diabetes, the pancreas produces little or no insulin, so insulin injections are needed to control blood glucose concentration, oe
(c) B1 in type 2 diabetes, the body's cells no longer respond properly to insulin (insulin resistance), often controlled through diet, exercise, medication, oe
(c) Answer: Type 1 diabetes: the pancreas produces little or no insulin, treated with insulin injections. Type 2 diabetes: body cells stop responding properly to insulin, often managed by diet, exercise or medication.

Question 11

(a) M1 88 / (1.60)² substituted, oe
(a) A1 34.4, awrt, cao
(a) Answer: 34.4
(b) B1 Jamal's BMI (34.4) is above 30, so he is classed as obese, oe
(b) B1 obesity is linked to the body's cells becoming less responsive to insulin (insulin resistance), which increases the risk of developing type 2 diabetes, oe
(b) Answer: Jamal's BMI of 34.4 classes him as obese; obesity is linked with reduced cell response to insulin (insulin resistance), which increases the risk of type 2 diabetes.

Question 12

(a) B1 FSH (follicle stimulating hormone)
(a) Answer: FSH (follicle stimulating hormone).
(b) B1 LH (luteinising hormone)
(b) B1 day 14
(b) Answer: LH (luteinising hormone); day 14.
(c) B1 progesterone is needed to maintain the thickened lining of the uterus, oe
(c) B1 as its concentration falls, the lining is no longer maintained, so it breaks down and is shed (menstruation begins), oe
(c) Answer: Progesterone maintains the uterus lining; as its concentration falls, the lining is no longer supported and breaks down, leading to menstruation.

Question 13

(a) B1 the contraceptive pill (accept contraceptive injection, implant or patch)
(a) Answer: The contraceptive pill (accept injection, implant or patch).
(b) B1 it contains oestrogen (and/or progesterone), oe
(b) B1 which inhibits the release of FSH from the pituitary gland, so no eggs mature/are released (ovulation is inhibited), oe
(b) Answer: The pill contains oestrogen (and progesterone), which inhibits the release of FSH, so no eggs mature and ovulation does not occur.
(c) B1 a named non-hormonal method, e.g. condom, diaphragm, copper intrauterine device (IUD), spermicide, or abstinence during the fertile period
(c) B1 a correct explanation of how it works, e.g. a condom acts as a barrier, preventing sperm reaching an egg, oe
(c) Answer: For example, a condom acts as a physical barrier, preventing sperm from reaching and fertilising an egg.

Question 14

(a) B1 to help a couple have a baby when one or both partners are infertile/struggling to conceive naturally, oe
(a) Answer: To help a couple conceive when one or both partners are infertile.
(b) B1 FSH and LH are given to stimulate the maturation of several eggs in the ovaries, oe
(b) B1 the eggs are collected from the ovary/ovaries and fertilised with sperm in a laboratory dish, oe
(b) B1 the fertilised eggs develop into embryos, and one or two embryos are inserted into the mother's uterus (womb), oe
(b) Answer: Hormones (FSH and LH) stimulate several eggs to mature; eggs are collected and fertilised with sperm in a laboratory dish; the resulting embryos develop, and one or two are inserted into the uterus.
(c) B1 any valid social/ethical issue, e.g. multiple births carry increased health risks to mother and babies; unused embryos are destroyed, which some people object to; treatment is expensive, emotionally stressful, and not always successful, oe
(c) Answer: For example, multiple embryos may lead to multiple births, which carries increased health risks for the mother and babies.

Question 15

(a) B1 thyroid gland
(a) Answer: Thyroid gland.
(b) M1 the high thyroxine concentration is detected (by the pituitary gland), oe
(b) M1 this reduces the release of TSH (thyroid stimulating hormone) from the pituitary gland, oe
(b) A1 less TSH means the thyroid gland is stimulated less, so it releases less thyroxine, bringing the concentration back towards normal, oe
(b) Answer: High thyroxine is detected by the pituitary gland, which releases less TSH; this reduces stimulation of the thyroid gland, so less thyroxine is released, returning the concentration to normal.

Question 16

(a) B1 the direction light reaches the seedlings from (light from one direction only, versus light from all directions), oe
(a) Answer: The direction from which light reaches the seedlings.
(b) B1 any suitable control variable, e.g. same species/number of seedlings
(b) B1 a second suitable control variable, e.g. same volume of water, same temperature, same type of compost, same starting height, same duration of experiment
(b) Answer: For example, the same species and number of seedlings, and the same volume of water given to each pot.
(c) B1 the shoot tip bends and grows towards the light (positive phototropism), oe
(c) B1 auxin, produced in the shoot tip, accumulates on the shaded (darker) side of the shoot, oe
(c) B1 auxin causes the cells on that shaded side to elongate more than the cells on the lit side, causing the shoot to bend towards the light, oe
(c) Answer: The shoot bends towards the light; auxin accumulates on the shaded side of the tip, causing cells there to elongate more than cells on the lit side, bending the shoot towards the light.

Question 17

(a) M1 (32 - 20) / 4 calculated, oe
(a) A1 3 mm/day, cao (units required)
(a) Answer: 3 mm per day
(b) B1 using only one seedling means an anomalous or unrepresentative result could not be identified/would not be detected, oe
(b) B1 using several seedlings and calculating a mean growth rate reduces the effect of natural variation between individual seedlings, making the result more reliable, oe
(b) Answer: Using several seedlings and calculating a mean reduces the effect of natural variation between individual seedlings, making the result more reliable and reducing the impact of any anomalies.

Question 18

(a) B1 gibberellins
(a) B1 a valid commercial use, e.g. ending seed dormancy so seeds germinate reliably/uniformly for crop production, inducing flowering, or producing seedless fruit, oe
(a) Answer: Gibberellins; used commercially to end seed dormancy so seeds germinate uniformly, or to induce flowering, or to produce seedless fruit.
(b) B1 fruit can be transported while still unripe/firmer, and then ripened using ethene once it has arrived, reducing spoilage/damage during transport, oe
(b) Answer: Fruit can be picked and transported while still unripe (and firmer, less easily damaged), then ripened using ethene when needed, reducing spoilage and waste.

Question 19

Level 1 (1-2): A simple strength or limitation of one method is identified, with little or no reasoning or comparison between methods.
Level 2 (3-4): Strengths and/or limitations of two of the three methods are described, with some reasoning linking them to how reliable or useful the conclusions from that method are.
Level 3 (5-6): A well-linked evaluation of all three methods is given, with clear reasoning about the reliability, safety and practicality of each, and a reasoned overall conclusion (e.g. that combining methods gives more reliable conclusions than any one method alone).
Indicative content:
- Studying patients with brain damage can show which functions are lost or affected, linking a damaged region to a function
- This method relies on naturally occurring damage, so the location and extent of damage cannot be controlled, and damage often affects more than one region, making it hard to isolate a single function
- Electrically stimulating regions of the brain during surgery allows doctors to observe a patient's immediate response (e.g. movement or sensation) linked to the stimulated region
- This method is invasive and carries a risk of damaging brain tissue, so it is normally only used when a patient is already undergoing brain surgery for another medical reason
- MRI scanning is non-invasive and safe, and can produce detailed images of brain structure, or show which regions are active in real time (functional MRI)
- MRI scanning is expensive, requires the patient to remain still, and may not give as direct a causal link between a region and a function as damage or stimulation studies do
- Using a combination of these methods gives more reliable conclusions than relying on any single method alone, since the limitations of one method can be offset by the strengths of another

Question 20

(a) M1 speed = distance / time = 0.85 / 0.0085, oe
(a) A1 100 m/s, cao (units required)
(a) Answer: 100 m/s
(b) B1 a reflex pathway involves fewer synapses than a pathway that includes conscious processing in the brain, oe
(b) B1 transmission across a synapse takes longer than transmission along an axon, and a reflex does not require impulses to reach and be processed by the brain, so there is less delay overall, oe
(b) Answer: A reflex pathway involves fewer synapses and does not require impulses to travel to and be processed by the brain, so there is less delay from (relatively slow) synaptic transmission and brain processing.

Homeostasis and Response - Worksheets, Questions and Revision