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GCSE · Biology

B5b Hormonal Coordination and Homeostasis

AQA 8464 · Calculator allowed · about 100 minutes

Total Marks

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

Hormones, homeostasis and the endocrine system

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The body's endocrine system is a network of glands that release hormones, chemical messengers carried in the blood, directly into the bloodstream to bring about an effect in a target organ elsewhere in the body. Compared with the nervous system, hormonal responses are usually slower to start but tend to last longer. Many hormones work as part of negative feedback systems, control loops that detect when a level in the body has moved away from its normal range and trigger a response that brings it back again. Blood glucose concentration is regulated in this way by insulin and glucagon from the pancreas, and the water content of the blood is regulated by ADH acting on the kidneys. Hormones also drive the menstrual cycle and can be used medically, in contraception and in fertility treatment. Plants, too, use hormones such as auxin, gibberellin and ethene to control and coordinate their growth and development.

The endocrine system is made up of glands that release chemical messages, called hormones, straight into the bloodstream.

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

(b)Name the gland that produces insulin.(1)

(c)Name the pair of glands, found just above the kidneys, that produce adrenaline.(1)

(d)State one way in which the speed of a hormonal response is different from the speed of a nervous response.(1)

(Total for Question 1 is 4 marks)

After eating a meal containing carbohydrate, a person's blood glucose concentration rises above its normal level.

(a)Name the hormone that is released to lower blood glucose concentration back to normal, and name the gland that releases it.(2)

(b)State what happens to the rate of insulin secretion as blood glucose concentration falls back towards its normal level.(1)

(c)Explain how insulin causes blood glucose concentration to decrease, referring to both the body's cells and the liver.(2)

(Total for Question 2 is 5 marks)

If blood glucose concentration falls below its normal level, for example between meals, a different pancreatic hormone is released to raise it again.

(a)Name this hormone.(1)

(b)Explain the effect that this hormone has on the liver.(2)

(c)State the general term used to describe a control system, such as blood glucose regulation, that keeps a level in the body close to a normal range.(1)

(Total for Question 3 is 4 marks)

Diabetes is a condition in which a person's blood glucose concentration is not properly controlled.

(a)State the cause of type 1 diabetes.(1)

(b)State how type 1 diabetes is usually treated.(1)

(c)State the cause of type 2 diabetes.(1)

(d)Give two risk factors linked to the development of type 2 diabetes.(2)

(e)Suggest one way that type 2 diabetes can often be managed without using insulin injections.(1)

(Total for Question 4 is 6 marks)

Aaliyah has type 1 diabetes. She calculates her mealtime insulin doses using an insulin-to-carbohydrate ratio and a correction factor.

Her insulin-to-carbohydrate ratio is 1 unit of insulin for every 10 g of carbohydrate she eats.
Her correction factor is that 1 unit of insulin lowers her blood glucose concentration by 3 mmol/L.
Her target blood glucose concentration before a meal is 6 mmol/L.

(a)Aaliyah is about to eat a meal containing 70 g of carbohydrate. Calculate the units of insulin she needs for the carbohydrate in this meal.(2)

(b)Before this meal, Aaliyah's blood glucose concentration is 15 mmol/L. Calculate the extra correction dose of insulin she needs to bring her blood glucose down to her target of 6 mmol/L.(2)

(c)Calculate the total dose of insulin Aaliyah should inject before this meal.(1)

(Total for Question 5 is 5 marks)

A student without diabetes measured his blood glucose concentration before and after eating a meal containing carbohydrate.

Time after meal (hours) -- Blood glucose concentration (mmol/L)
0 -- 5.0
1 -- 7.8
2 -- 6.2
3 -- 5.1
4 -- 4.8

(a)Calculate the rate of change of blood glucose concentration between 0 and 1 hour after the meal, in mmol/L per hour.(2)

(b)Explain, in terms of insulin, why blood glucose concentration decreases between 1 hour and 3 hours after the meal.(2)

(c)At 4 hours, the blood glucose concentration (4.8 mmol/L) is slightly lower than it was before the meal (5.0 mmol/L). Suggest one reason for this.(1)

(Total for Question 6 is 5 marks)

A group of students carried out the required practical investigation into the effect of light on the growth of newly germinated seedlings, using cress seedlings.

(a)Name the plant hormone responsible for phototropism, the growth response of a shoot towards light.(1)

(b)Describe how the students could set up this investigation to find out the effect of the direction of light on shoot growth, including how they would set up a suitable control.(4)

(c)Identify one variable, other than the direction of light, that should be kept the same for both groups, and explain why this is important.(2)

(d)Describe the difference you would expect to see, after several days, between the shoots grown with light from one side and the shoots in the control set-up.(2)

(f)Suggest two improvements that could be made to this investigation to increase the validity of the conclusion.(3)

(g)The class recorded the mean angle of bend of the shoots, measured from the vertical, after 5 days: seedlings lit from one side = 42 degrees; control seedlings (lit evenly from all sides) = 3 degrees. Calculate the difference between these two mean angles.(2)

(Total for Question 7 is 14 marks)

Higher tier only. In the investigation in Question 7, the seedlings exposed to light from one side grow towards the light.

(a)Explain, in terms of the distribution of auxin, why this happens.(3)

(Total for Question 8 is 3 marks)

Auxin is a plant hormone with a number of commercial and agricultural uses, in addition to controlling phototropism.

(a)Name the type of chemical, sprayed onto lawns and crop fields, that uses very high concentrations of auxin to kill unwanted plants.(1)

(b)Explain why a weedkiller based on auxin kills broad-leaved weeds growing in a lawn, but does not kill the narrow-leaved grass around them.(1)

(c)Give one other commercial use of auxin, other than as a weedkiller.(1)

(Total for Question 9 is 3 marks)

A horticulturalist tested the effect of gibberellin concentration on the percentage of seeds that germinated within two weeks.

Gibberellin concentration (mg/l) -- Seeds germinated (%)
0 -- 12
10 -- 46
20 -- 78
30 -- 80

(a)Describe the trend shown by the data.(2)

(b)Calculate the increase in the percentage of seeds germinated between a gibberellin concentration of 0 mg/l and 20 mg/l.(1)

(c)Give one commercial use of gibberellins in agriculture or horticulture, other than promoting seed germination.(1)

(d)Name the plant hormone that is used commercially to ripen fruit, such as bananas, during transport and storage, and explain why this is useful to food retailers.(2)

(Total for Question 10 is 6 marks)

Higher tier only. The kidneys and the hormone ADH (antidiuretic hormone) control the water content of the blood.

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

(b)State what happens to the concentration of ADH released into the blood when a person becomes dehydrated.(1)

(c)Explain the effect of this increase in ADH concentration on the kidneys, and on the volume and concentration of the urine produced.(4)

(Total for Question 11 is 6 marks)

The table shows the average daily volumes of water gained and lost by an adult, in cm^3.

Water gained -- Volume (cm³)
From food -- 750
From drinks -- 1500
From respiration (metabolic water) -- 250

Water lost -- Volume (cm³)
In urine -- 1400
Through the skin (sweating) -- 450
In faeces -- 150
Via exhaled air -- not recorded

(a)Calculate the total volume of water gained per day.(1)

(b)The volumes of water gained and lost by the body are normally balanced. Calculate the volume of water lost via exhaled air each day.(2)

(c)Suggest what would happen to the volume of urine produced on a hot day, if a person sweats more but drinks the same volume of water as usual.(2)

(Total for Question 12 is 5 marks)

Higher tier only. If a person's kidneys fail, urea and excess ions build up in their blood. One treatment is dialysis, using a dialysis machine.

(a)Explain why a person with kidney failure may need treatment such as dialysis.(1)

(b)During dialysis, a person's blood passes on one side of a partially permeable membrane, next to dialysis fluid that contains no urea and normal, safe concentrations of glucose and ions. Explain, in terms of diffusion, how urea moves out of the blood and into the dialysis fluid.(3)

(Total for Question 13 is 4 marks)

The menstrual cycle is controlled by a number of hormones, released mainly by the pituitary gland and the ovaries.

(a)Name the hormone, released by the pituitary gland, that causes an egg to mature in the ovary.(1)

(b)Name the hormone, also released by the pituitary gland, that stimulates ovulation, the release of a mature egg from the ovary.(1)

(c)State where in the body oestrogen is produced.(1)

(d)Name the hormone that maintains the lining of the uterus (womb) during the second half of the menstrual cycle.(1)

(e)Describe what happens to the level of progesterone if the egg released is not fertilised, and explain the effect this has on the lining of the uterus.(2)

(Total for Question 14 is 6 marks)

Hormones can be used to reduce fertility, for example in the combined contraceptive pill.

(a)Name the two hormones contained in the combined contraceptive pill.(2)

(b)Explain how these hormones in the combined pill help to prevent pregnancy.(2)

(Total for Question 15 is 4 marks)

A family planning clinic gives patients the following information to help them choose a method of contraception.

Combined pill: taken daily; over 99% effective with perfect use, about 91% effective with typical use; does not protect against sexually transmitted infections (STIs); some users report side effects such as mood changes or headaches; fertility usually returns quickly after stopping.

Male condom: used during intercourse; about 98% effective with perfect use, about 82% effective with typical use; the only common method that also protects against most STIs; no hormonal side effects; effectiveness depends on being used correctly every time.

Compare the combined contraceptive pill with the male condom as methods of contraception, and evaluate which might be more suitable for a couple who are also concerned about the risk of catching an STI.

(Total for Question 16 is 6 marks)

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

(a)Name the two hormones given to a woman before her eggs are collected during IVF treatment, and state why they are given.(2)

(b)Describe what happens to the resulting embryo(s) before pregnancy can begin.(1)

(c)Give one social, ethical or economic issue associated with IVF treatment.(1)

(Total for Question 17 is 4 marks)

Adrenaline is a hormone released rapidly in response to fear or stress, preparing the body for 'fight or flight'.

(a)Name the glands, found above the kidneys, that release adrenaline.(1)

(b)Give two effects that adrenaline has on the body that help to prepare it for 'fight or flight'.(2)

(Total for Question 18 is 3 marks)

Higher tier only. Thyroxine is a hormone released by the thyroid gland that helps to regulate the body's metabolic rate. Its release is controlled by negative feedback.

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

(b)State one effect of thyroxine on the body.(1)

(c)The pituitary gland releases a hormone called TSH (thyroid-stimulating hormone), which stimulates the thyroid gland to release thyroxine. Explain, using ideas about negative feedback, what happens to the amount of TSH released by the pituitary gland if the concentration of thyroxine in the blood rises too high.(4)

(Total for Question 19 is 6 marks)

Idris has type 1 diabetes. He measured his blood glucose concentration before and after a 30-minute run.

Before the run: 9.6 mmol/L
Immediately after the run: 5.4 mmol/L

(a)Calculate the fall in Idris's blood glucose concentration caused by the run.(1)

(b)Calculate this fall as a percentage of his blood glucose concentration before the run.(2)

(c)Suggest, in terms of respiration in muscle cells, why Idris's blood glucose concentration fell during the run.(2)

(d)Idris's blood glucose concentration of 5.4 mmol/L after the run is close to the lower end of the normal range. Explain one risk to Idris if he does not eat some carbohydrate soon after finishing his run.(3)

(Total for Question 20 is 8 marks)

Mark scheme · B5b Hormonal Coordination and Homeostasis

Question 1

(a) B1 a chemical messenger, produced in a gland and carried in the blood, that alters the activity of one or more target organs, oe
(a) Answer: A hormone is a chemical messenger, produced in a gland, that is carried in the blood to a target organ where it alters activity (oe).
(b) B1 pancreas
(b) Answer: The pancreas.
(c) B1 adrenal glands
(c) Answer: The adrenal glands.
(d) B1 hormonal responses are slower to start (but tend to last longer) than nervous responses, oe
(d) Answer: Hormonal responses are generally slower to start than nervous responses, though they tend to last longer.

Question 2

(a) B1 insulin
(a) B1 pancreas
(a) Answer: Insulin, released by the pancreas.
(b) B1 the rate of insulin secretion decreases, oe
(b) Answer: The rate of insulin secretion decreases.
(c) B1 insulin causes body cells to take up more glucose from the blood, for respiration, oe
(c) B1 insulin causes the liver (and muscles) to convert excess glucose into glycogen for storage, oe
(c) Answer: Insulin causes body cells to take up more glucose from the blood for respiration, and causes the liver (and muscles) to convert excess glucose into glycogen for storage, lowering blood glucose concentration.

Question 3

(a) B1 glucagon
(a) Answer: Glucagon.
(b) B1 it stimulates the liver to break down its stores of glycogen, oe
(b) B1 converting it into glucose, which is released into the blood, raising blood glucose concentration, oe
(b) Answer: Glucagon stimulates the liver to break down its stores of glycogen and convert it into glucose, which is released into the blood, raising blood glucose concentration.
(c) B1 negative feedback
(c) Answer: Negative feedback.

Question 4

(a) B1 the pancreas produces little or no insulin, oe
(a) Answer: The pancreas produces little or no insulin.
(b) B1 insulin injections, or use of an insulin pump, oe
(b) Answer: With insulin injections, or the use of an insulin pump.
(c) B1 the body's cells no longer respond properly to insulin (insulin resistance), and/or the pancreas does not produce enough insulin, oe
(c) Answer: The body's cells no longer respond properly to insulin, and/or the pancreas does not produce enough insulin.
(d) B1 any one valid risk factor, e.g. obesity/being overweight, a diet high in sugar and/or fat, or lack of regular exercise
(d) B1 any second valid risk factor, e.g. increasing age, or a family history of type 2 diabetes
(d) Answer: Any two of: obesity/being overweight; a diet high in sugar and/or fat; lack of regular exercise; increasing age; a family history of type 2 diabetes.
(e) B1 a carbohydrate-controlled diet, regular exercise, losing weight, or medication other than insulin, oe
(e) Answer: A carbohydrate-controlled diet, regular exercise, losing weight, or medication other than insulin.

Question 5

(a) M1 70 / 10
(a) A1 7 units cao
(a) Answer: 7 units
(b) M1 (15 - 6) / 3
(b) A1 3 units cao
(b) Answer: 3 units
(c) B1 their (a) + their (b), ft, i.e. 7 + 3 = 10 units cao
(c) Answer: 10 units

Question 6

(a) M1 (7.8 - 5.0) / 1
(a) A1 2.8 mmol/L per hour cao
(a) Answer: 2.8 mmol/L per hour
(b) B1 the rise in blood glucose concentration stimulates the pancreas to release (more) insulin, oe
(b) B1 insulin causes cells to take up glucose and the liver to convert glucose into glycogen, lowering blood glucose concentration, oe
(b) Answer: The rise in blood glucose concentration after the meal stimulates the pancreas to release more insulin, which causes cells to take up glucose and the liver to convert glucose into glycogen, lowering blood glucose concentration.
(c) B1 e.g. glucagon has not yet raised blood glucose back to its normal resting value, or the body's cells are continuing to use glucose in respiration and none has been eaten since the meal, oe
(c) Answer: For example, glucagon may not yet have raised his blood glucose concentration back to its usual resting value, or his cells have continued to use glucose for respiration since the meal, without any further carbohydrate being eaten.

Question 7

(a) B1 auxin
(a) Answer: Auxin.
(b) B1 grow at least two groups of similar cress seedlings, under otherwise identical conditions, oe
(b) B1 expose one group to light from one direction only (unilateral light), e.g. using a lamp positioned to one side, or a box with a single slit cut in one side, oe
(b) B1 set up a control group that is either kept in the dark, or lit evenly from all sides (e.g. inside a clear box with no slit, or a box with slits on all sides), oe
(b) B1 observe and record the direction of shoot growth (e.g. using a ruler or protractor to measure the angle, or by photographing the seedlings) after the same number of days for each group, oe
(b) Answer: Grow at least two groups of similar cress seedlings under otherwise identical conditions. Expose one group to light from one direction only, for example using a lamp positioned to one side or a box with a single slit cut in one side. Set up a control group that is either kept in the dark or lit evenly from all sides, for example inside a box with slits on all sides. After the same number of days, observe and record the direction of shoot growth in each group, for example by measuring the angle of the shoots with a protractor.
(c) B1 a valid variable, e.g. temperature, the volume of water given, the species/age of seedling, or the number of seedlings in each group
(c) B1 so that the direction of light is the only factor that differs between the two groups, making it a fair test/valid comparison, oe
(c) Answer: Temperature should be kept the same for both groups, so that light direction is the only factor that differs between them, making it a fair, valid comparison.
(d) B1 the shoots exposed to light from one side bend and grow towards the light source, oe
(d) B1 the shoots in the control group grow straight upwards (if lit evenly from all sides), oe
(d) Answer: The shoots exposed to light from one side bend and grow towards the light source. The shoots in the control group, lit evenly from all sides, grow straight upwards.
(f) B1 use a larger number of seedlings in each group, so a mean can be calculated and any anomalous results identified, oe
(f) B1 measure the angle of bend precisely, e.g. using a protractor, rather than judging it by eye, to make the result more objective/precise, oe
(f) B1 any other valid improvement, e.g. keep both set-ups in the same room/at the same temperature, so that temperature cannot also affect the result, oe
(f) Answer: Use a larger number of seedlings in each group, so a mean can be calculated and any anomalous results identified. Also measure the angle of bend precisely using a protractor, rather than judging it by eye, and keep both set-ups in the same room so that temperature cannot also affect the result.
(g) M1 42 - 3
(g) A1 39 degrees cao
(g) Answer: 39 degrees

Question 8

(a) B1 auxin is produced in the tip of the shoot and is transported down through the shoot, oe
(a) B1 when light comes from one side, auxin is redistributed to (accumulates on) the shaded side of the shoot, away from the light, oe
(a) B1 the higher concentration of auxin on the shaded side causes the cells there to elongate (grow) more than the cells on the illuminated side, so the shoot bends towards the light, oe
(a) Answer: Auxin is produced in the tip of the shoot and transported down through it. When light comes from one side, auxin is redistributed to the shaded side of the shoot. The higher concentration of auxin there causes the cells on the shaded side to elongate more than the cells on the illuminated side, so the shoot bends towards the light.

Question 9

(a) B1 selective weedkiller (herbicide), oe
(a) Answer: A selective weedkiller (herbicide).
(b) B1 broad-leaved weeds absorb much more of the auxin-based weedkiller than narrow-leaved grasses do (through their larger leaf surface area), and are much more sensitive to it, so it disrupts their growth and kills them, while the grass is barely affected, oe
(b) Answer: Broad-leaved weeds absorb much more of the auxin-based weedkiller, through their larger leaf surface area, and are much more sensitive to it, so their growth is disrupted and they die, while the narrow-leaved grass absorbs far less and is barely affected.
(c) B1 e.g. used in rooting powder, to encourage cuttings to grow roots, oe
(c) Answer: It is used in rooting powder, to encourage cuttings taken from plants to grow roots.

Question 10

(a) B1 as gibberellin concentration increases, the percentage of seeds that germinate increases, oe
(a) B1 reference to data, e.g. from 12% at 0 mg/l up to 80% at 30 mg/l, and the increase becomes smaller between 20 and 30 mg/l (levelling off), oe
(a) Answer: As gibberellin concentration increases, the percentage of seeds that germinate increases, from 12% at 0 mg/l up to 80% at 30 mg/l, although the increase becomes smaller between 20 mg/l and 30 mg/l, suggesting the effect is levelling off.
(b) B1 66 percentage points (78 - 12), cao
(b) Answer: 66 percentage points
(c) B1 e.g. to promote flowering, to produce seedless fruit, or to make fruit grow larger, oe
(c) Answer: For example, to promote flowering, to produce seedless fruit, or to make fruit grow larger.
(d) B1 ethene
(d) B1 fruit can be picked and transported while still unripe and firmer/less easily damaged, then ripened using ethene closer to when it will be sold, reducing spoilage/wastage, oe
(d) Answer: Ethene. Fruit can be picked and transported while still unripe and firmer, less easily damaged, then ripened using ethene closer to when it will be sold, reducing spoilage and wastage.

Question 11

(a) B1 pituitary gland
(a) Answer: The pituitary gland.
(b) B1 it increases, oe
(b) Answer: It increases.
(c) B1 ADH makes the kidney tubules (nephrons) more permeable to water, oe
(c) B1 so more water is reabsorbed back into the blood from the kidney tubules, oe
(c) B1 this means a smaller volume of urine is produced, oe
(c) B1 and the urine produced is more concentrated, oe
(c) Answer: The increase in ADH concentration makes the kidney tubules more permeable to water, so more water is reabsorbed back into the blood. This means a smaller volume of more concentrated urine is produced.

Question 12

(a) B1 2500 cm³ (750 + 1500 + 250), cao
(a) Answer: 2500 cm³
(b) M1 2500 - (1400 + 450 + 150)
(b) A1 500 cm³ cao
(b) Answer: 500 cm³
(c) B1 more water is lost from the body via sweating, so there is less water available in the blood, oe
(c) B1 a smaller volume of more concentrated urine will be produced, as the kidneys conserve water, oe
(c) Answer: More water is lost from the body via sweating, leaving less water available in the blood, so a smaller volume of more concentrated urine will be produced as the kidneys conserve water.

Question 13

(a) B1 their kidneys can no longer remove urea (and excess water and ions) from the blood, which would otherwise build up to dangerous/toxic levels, oe
(a) Answer: Their kidneys can no longer remove urea, and excess water and ions, from the blood, which would otherwise build up to dangerous, toxic levels.
(b) B1 there is a much higher concentration of urea in the blood than in the dialysis fluid (a concentration gradient exists), oe
(b) B1 urea molecules are small enough to diffuse through the partially permeable membrane, oe
(b) B1 urea diffuses (moves) from the blood, where it is in high concentration, into the dialysis fluid, where it is in low concentration, down the concentration gradient, oe
(b) Answer: There is a much higher concentration of urea in the blood than in the dialysis fluid. Urea molecules are small enough to diffuse through the partially permeable membrane, so urea diffuses from the blood, where it is in high concentration, into the dialysis fluid, where it is in low concentration, down the concentration gradient.

Question 14

(a) B1 FSH (follicle-stimulating hormone)
(a) Answer: FSH (follicle-stimulating hormone).
(b) B1 LH (luteinising hormone)
(b) Answer: LH (luteinising hormone).
(c) B1 the ovaries
(c) Answer: The ovaries.
(d) B1 progesterone
(d) Answer: Progesterone.
(e) B1 the level of progesterone falls, as the corpus luteum breaks down, oe
(e) B1 this causes the lining of the uterus to break down, and it is lost/shed from the body (menstruation, a period), oe
(e) Answer: If the egg is not fertilised, the level of progesterone falls as the corpus luteum breaks down. This causes the lining of the uterus to break down and be shed from the body, as a period.

Question 15

(a) B1 oestrogen
(a) B1 progesterone
(a) Answer: Oestrogen and progesterone.
(b) B1 they inhibit (stop/reduce) the release of FSH from the pituitary gland, oe
(b) B1 so no eggs mature and are released from the ovaries, meaning fertilisation cannot occur, oe
(b) Answer: The hormones inhibit the release of FSH from the pituitary gland, so no eggs mature and are released from the ovaries, meaning fertilisation cannot occur.

Question 16

Level 1 (1-2): Basic, isolated statement(s) about one method or one piece of data, with little or no comparison or evaluation. The answer may be a simple list.
Level 2 (3-4): Some accurate comparison of the two methods' effectiveness and/or protection against STIs, but the evaluation is incomplete, one-sided, or not always clearly linked to the couple's situation.
Level 3 (5-6): A clear, logically structured comparison of both methods, covering effectiveness and STI protection, leading to a well-reasoned evaluation that directly addresses the couple's concern about STIs, using the data given.
Indicative content:
- The combined pill is more effective at preventing pregnancy than the male condom, both with perfect use (over 99% vs about 98%) and, more noticeably, with typical/everyday use (about 91% vs about 82%)
- However, the combined pill provides no protection at all against sexually transmitted infections
- The male condom is the only one of the two methods that also protects against most STIs
- The combined pill can cause hormonal side effects, such as mood changes or headaches, that the condom does not
- The condom's effectiveness depends heavily on being used correctly every time, which is why its typical-use effectiveness is noticeably lower than its perfect-use effectiveness
- Because this couple are specifically concerned about STI risk, the male condom would be more suitable for them, despite being somewhat less effective at preventing pregnancy, since the pill offers no STI protection at all
- A balanced answer might suggest using both methods together (dual protection), gaining the pill's higher contraceptive effectiveness alongside the condom's STI protection

Question 17

(a) B1 FSH and LH (accept either or both named)
(a) B1 to stimulate the ovaries to produce/mature several eggs at the same time, oe
(a) Answer: FSH and LH, given to stimulate the ovaries to produce and mature several eggs at the same time.
(b) B1 one or more embryos are inserted/transferred into the mother's uterus (womb), oe
(b) Answer: One or more of the embryos are transferred into the mother's uterus (womb).
(c) B1 any valid issue, e.g. it is expensive/not always funded by public healthcare, it has a relatively low success rate and can cause emotional stress, implanting multiple embryos can lead to multiple births which carry higher risks, or ethical concerns about unused embryos, oe
(c) Answer: For example, IVF is expensive and not always funded by public healthcare, and it has a relatively low success rate, which can cause considerable emotional stress for patients.

Question 18

(a) B1 adrenal glands
(a) Answer: The adrenal glands.
(b) B1 any one valid effect, e.g. increased heart rate, increased breathing rate, or pupils dilating
(b) B1 any second valid effect, e.g. blood diverted to the muscles (and away from the digestive system), or blood glucose concentration increasing
(b) Answer: Any two of: increased heart rate; increased breathing rate; blood diverted to the muscles and away from the digestive system; pupils dilating; increased blood glucose concentration.

Question 19

(a) B1 thyroid gland
(a) Answer: The thyroid gland.
(b) B1 it increases the basal (resting) metabolic rate, oe
(b) Answer: It increases the body's basal (resting) metabolic rate.
(c) B1 the pituitary gland detects that thyroxine concentration is too high, oe
(c) B1 the pituitary gland responds by releasing less TSH, oe
(c) B1 less TSH means the thyroid gland is stimulated less, so it releases less thyroxine, oe
(c) B1 this brings the concentration of thyroxine in the blood back down towards its normal level, oe
(c) Answer: The pituitary gland detects that thyroxine concentration is too high and responds by releasing less TSH. Less TSH means the thyroid gland is stimulated less, so it releases less thyroxine, bringing the blood thyroxine concentration back down towards its normal level.

Question 20

(a) B1 4.2 mmol/L (9.6 - 5.4), cao
(a) Answer: 4.2 mmol/L
(b) M1 4.2 / 9.6 x 100, ft from (a)
(b) A1 43.75%, or awrt 44%, cao
(b) Answer: 43.75% (awrt 44%)
(c) B1 his exercising leg muscles needed more energy, so respired at a faster rate, oe
(c) B1 muscle cells took up more glucose from the blood to use in (aerobic) respiration, lowering his blood glucose concentration, oe
(c) Answer: His exercising leg muscles needed more energy, so respired at a faster rate, taking up more glucose from the blood to use in aerobic respiration and lowering his blood glucose concentration.
(d) B1 his blood glucose concentration could continue to fall, especially if he still has insulin active in his body from an earlier injection, oe
(d) B1 this risks hypoglycaemia (dangerously low blood glucose), which can cause symptoms such as shaking, sweating, confusion or dizziness, oe
(d) B1 he should eat/drink a source of fast-acting carbohydrate soon, to raise his blood glucose concentration back to a safe level, oe
(d) Answer: His blood glucose concentration could continue to fall, especially if he still has insulin active in his body from an earlier injection, risking hypoglycaemia (dangerously low blood glucose), which can cause symptoms such as shaking, sweating, confusion or dizziness. He should eat or drink a source of fast-acting carbohydrate soon to raise his blood glucose concentration back to a safe level.

Hormonal Coordination and Homeostasis - Worksheets, Questions and Revision