Exam questions · Biology
Hormones and Reproduction
- 42 exam questions
- 129 marks
- 63 quick checks
The Endocrine System
Just this lesson-
1 State [1 mark]
State what is meant by a hormone.
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Model answer
A chemical messenger that is made in a gland and carried in the blood to a target organ.
Mark scheme
- Chemical messenger made in a gland, carried in the blood — 1 mark
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2 Name [3 marks]
Name the gland that releases each of these hormones: insulin, thyroxine and testosterone.
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Model answer
Insulin is released by the pancreas. Thyroxine is released by the thyroid gland. Testosterone is released by the testes.
Mark scheme
- Pancreas — 1 mark
- Thyroid gland — 1 mark
- Testes — 1 mark
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3 Explain [3 marks]
Explain why a hormone that is released into the blood only affects its target organs.
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Model answer
The hormone is carried to every part of the body. Only cells in the target organs have the receptors that the hormone can bind to, so only those cells respond to it.
Mark scheme
- Carried everywhere in the blood — 1 mark
- Only target cells have receptors — 1 mark
- Only those cells respond — 1 mark
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4 Describe [3 marks]
Describe three differences between the endocrine system and the nervous system.
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Model answer
The endocrine system uses chemicals carried in the blood, but the nervous system uses electrical impulses along neurones. Hormones act more slowly than nerve impulses. The effects of hormones last longer than the effects of nerve impulses.
Mark scheme
- Chemicals and electrical impulses — 1 mark
- Slower and faster — 1 mark
- Longer lasting and short-lived — 1 mark
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5 Explain [4 marks]
A person's blood glucose level is too high after a meal. Describe how the endocrine system could respond to this, naming the gland and the hormone.
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Model answer
The pancreas detects the high glucose, and releases the hormone insulin into the blood. The insulin is carried to the liver and muscles, which are the target organs, and makes them take up glucose, so the blood glucose falls.
Mark scheme
- Pancreas releases insulin — 1 mark
- Carried in the blood — 1 mark
- Target organs are the liver and muscles — 1 mark
- Glucose falls — 1 mark
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6 Evaluate [6 marks]
Explain why the pituitary gland is sometimes called the master gland, and discuss why it is useful to have both a nervous system and an endocrine system.
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Model answer
The pituitary gland releases hormones that control other endocrine glands. For example, it releases TSH, which makes the thyroid gland release thyroxine, and FSH and LH, which act on the ovaries. So it controls the activity of many other glands. Having both systems is useful because the nervous system gives fast responses, such as pulling a hand away from a hot object, which protects the body quickly, and the response is short-lived. The endocrine system gives slower responses, which last for longer, such as growth, the control of blood glucose and reproduction, which need to be controlled over minutes, hours or years. The two systems work together, and the body needs both kinds of response.
Mark scheme
- Pituitary releases hormones that control other glands — 1 mark
- Example such as TSH or FSH — 1 mark
- Nervous system is fast and short-lived — 1 mark
- Example of a nervous response — 1 mark
- Endocrine system is slower and longer lasting — 1 mark
- Example of a hormonal response, and a conclusion — 1 mark
Quick check
-
1
Which gland is called the master gland?
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C: Pituitary
The pituitary gland controls other glands.
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2
How do hormones travel around the body?
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B: In the blood
In the blood.
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3
Which gland releases insulin?
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A: Pancreas
The pancreas.
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4
Which hormone is released by the ovaries?
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D: Oestrogen
Oestrogen.
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5
What is a target organ?
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B: An organ that responds to a hormone
An organ that has receptors for the hormone and responds to it.
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6
Which gland is on top of each kidney?
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C: Adrenal glands
The adrenal glands.
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7
Which statement about the endocrine system is correct?
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A: Its effects are slower and longer lasting than those of nerves
The effects are slower and longer lasting than those of nerves.
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8
Which hormone controls the metabolic rate?
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D: Thyroxine
Thyroxine, from the thyroid gland.
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9
A hormone reaches all parts of the body, but only the liver responds. What explains this?
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B: Only liver cells have receptors for it
Only liver cells have the receptors for the hormone.
Adrenaline: Fight or Flight (Higher tier)
Just this lesson-
1 State [1 mark]
State where adrenaline is produced.
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Model answer
In the adrenal glands.
Mark scheme
- Adrenal glands — 1 mark
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2 State [2 marks]
State two effects of adrenaline on the body.
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Model answer
Any two from: increased heart rate; increased blood pressure; increased blood flow to the muscles; the liver changes glycogen into glucose, so the blood sugar level rises.
Mark scheme
- First — 1 mark
- Second — 1 mark
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3 Explain [3 marks]
Explain how an increased heart rate helps a person who is running away from danger.
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Model answer
A faster heart rate pumps more blood each minute. This delivers oxygen and glucose to the muscles more quickly, so that they can release more energy by aerobic respiration, and removes carbon dioxide faster.
Mark scheme
- More blood pumped each minute — 1 mark
- More oxygen and glucose delivered to the muscles — 1 mark
- More aerobic respiration, so more energy released — 1 mark
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4 Explain [3 marks]
Explain how adrenaline raises the level of glucose in the blood.
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Model answer
Adrenaline is carried in the blood to the liver, which is a target organ. It stimulates the liver to change the stored glycogen into glucose. The glucose is released into the blood, so the blood sugar level rises.
Mark scheme
- Carried to the liver — 1 mark
- Liver changes glycogen into glucose — 1 mark
- Glucose released into the blood — 1 mark
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5 Calculate [3 marks]
A person's heart rate is 64 beats per minute at rest, and 96 beats per minute after a shock. Calculate the percentage increase in the heart rate.
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Model answer
96 − 64 = 32. 32 ÷ 64 = 0.5. 0.5 × 100 = 50%.
Mark scheme
- Increase of 32 — 1 mark
- Divided by 64 — 1 mark
- 50% — 1 mark
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6 Evaluate [6 marks]
A student says that adrenaline is only useful when a person is in danger. Evaluate this statement.
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Model answer
Adrenaline is produced when there is a threat, and it prepares the body for fight or flight by increasing the heart rate, the blood pressure and the blood flow to the muscles, and by making the liver release glucose. This helps a person to escape from danger or to fight, so in this sense the statement is right. However, adrenaline is also released in other situations that are not dangerous, such as before a sports event or an exam, where the extra energy and the alertness may be useful, although the response may be unhelpful if the person feels anxious. Adrenaline is also used as a medicine, to treat anaphylaxis, where it raises the blood pressure and opens the airways. So the statement is true of its natural role, but adrenaline has other uses.
Mark scheme
- Prepares for fight or flight — 1 mark
- Effects: heart rate, blood pressure, blood flow — 1 mark
- Liver releases glucose — 1 mark
- Released in other situations, such as before sport — 1 mark
- Medical use such as anaphylaxis — 1 mark
- A reasoned conclusion — 1 mark
Quick check
-
1
Which gland produces adrenaline?
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B: Adrenal
The adrenal glands.
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2
What does adrenaline do to the heart rate?
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A: Increases it
It increases it.
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3
What does adrenaline stimulate the liver to do?
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C: Change glycogen to glucose
It changes glycogen into glucose.
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4
Why does adrenaline increase the blood flow to the muscles?
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D: To deliver more oxygen and glucose
To deliver more oxygen and glucose for aerobic respiration.
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5
What is meant by fight or flight?
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B: A response that prepares the body to fight or run away
The body is prepared to fight a threat or to run away from it.
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6
How is adrenaline carried to its target organs?
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A: In the blood
In the blood.
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7
What happens to the blood sugar level when adrenaline is released?
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C: It rises
It rises.
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8
A heart rate rose from 60 to 90 beats per minute. What is the percentage increase?
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D: 50%
\(30 \div 60 \times 100 = 50\%\).
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9
Which is a medical use of adrenaline?
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B: To treat anaphylaxis
To treat anaphylaxis, as it raises the blood pressure and opens the airways.
Thyroxine and Negative Feedback (Higher tier)
Just this lesson-
1 State [1 mark]
State what is meant by metabolic rate.
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Model answer
The speed of the chemical reactions in the cells of the body.
Mark scheme
- Rate of chemical reactions in the cells — 1 mark
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2 Name [2 marks]
Name the hormone that is released by the hypothalamus, and the hormone that is released by the pituitary gland, in the control of thyroxine.
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Model answer
The hypothalamus releases TRH, and the pituitary gland releases TSH.
Mark scheme
- TRH — 1 mark
- TSH — 1 mark
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3 Describe [3 marks]
Describe what happens in the body when the level of thyroxine in the blood falls below normal.
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Model answer
The hypothalamus makes TRH, which stimulates the pituitary gland to release TSH. The TSH acts on the thyroid gland, which makes more thyroxine, so the level rises.
Mark scheme
- Hypothalamus makes TRH — 1 mark
- Pituitary gland releases TSH — 1 mark
- Thyroid gland makes more thyroxine — 1 mark
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4 Explain [3 marks]
Explain why this is an example of negative feedback.
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Model answer
The change, a low level of thyroxine, causes a response that increases thyroxine. When the level is normal, the thyroxine inhibits TRH and TSH, so that the response stops. The response reverses the change, which is negative feedback.
Mark scheme
- Response reverses the change — 1 mark
- Normal level inhibits TRH and TSH — 1 mark
- So the level stays steady — 1 mark
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5 Explain [4 marks]
A person has a thyroid gland that makes too much thyroxine. Explain the effects on the person, and on the levels of TRH and TSH.
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Model answer
The metabolic rate increases, so the person feels hot and restless and may lose mass. The high level of thyroxine inhibits the release of TRH and TSH, so the levels of TRH and TSH are low.
Mark scheme
- High metabolic rate — 1 mark
- Feels hot, restless, loses mass — 1 mark
- High thyroxine inhibits TRH and TSH — 1 mark
- So their levels are low — 1 mark
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6 Evaluate [6 marks]
Some people in the past developed a goitre because they did not have enough iodine in their diet. Explain how the lack of iodine leads to a goitre, and why adding iodine to salt can prevent it.
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Model answer
The thyroid gland needs iodine to make thyroxine. Without it, the gland cannot make enough thyroxine, so the level in the blood is low. A low level does not inhibit the hypothalamus and the pituitary gland, so there is no negative feedback, and they keep releasing TRH and TSH. TSH stimulates the thyroid gland, and makes it grow larger, which is the goitre. If iodine is added to salt, people get enough to make thyroxine, so the level of thyroxine rises to normal, the negative feedback is restored, TSH falls, and the gland stays a normal size.
Mark scheme
- Iodine is needed to make thyroxine — 1 mark
- Low level of thyroxine — 1 mark
- No negative feedback, so TRH and TSH stay high — 1 mark
- TSH makes the gland grow — 1 mark
- Iodine in salt allows thyroxine to be made — 1 mark
- Feedback restored, so TSH falls — 1 mark
Quick check
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1
Which gland makes thyroxine?
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C: Thyroid
The thyroid gland.
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2
Which hormone does the hypothalamus release in the control of thyroxine?
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A: TRH
TRH.
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3
What does TSH stimulate?
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D: The thyroid gland
TSH stimulates the thyroid gland to make thyroxine.
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4
What effect does a high level of thyroxine have on TRH release?
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B: It inhibits it
It inhibits it, which is negative feedback.
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5
What does thyroxine control?
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C: The metabolic rate
The metabolic rate.
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6
What would a person with too little thyroxine be likely to feel?
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A: Tired and cold
Tired and cold, because the metabolic rate is low.
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7
What is negative feedback?
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D: A response that reverses a change
A response that reverses a change.
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8
What element is needed to make thyroxine?
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B: Iodine
Iodine.
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9
In a person with a low level of thyroxine caused by a thyroid gland that does not work, which is likely to be found?
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C: High TRH and TSH
With no feedback from thyroxine, TRH and TSH levels are high.
The Menstrual Cycle
Just this lesson-
1 State [1 mark]
State the day of the menstrual cycle on which ovulation usually occurs.
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Model answer
Day 14.
Mark scheme
- Day 14 — 1 mark
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2 Name [2 marks]
Name the two hormones from the ovaries that control the menstrual cycle.
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Model answer
Oestrogen and progesterone.
Mark scheme
- Oestrogen — 1 mark
- Progesterone — 1 mark
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3 Describe [3 marks]
Describe what happens to the lining of the uterus during the 28 days of a menstrual cycle.
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Model answer
In the first days of the cycle the lining breaks down and is lost in the period. Then it is repaired and thickens, and after ovulation it is maintained as a thick lining with many blood vessels. If there is no pregnancy, it breaks down again at the end of the cycle.
Mark scheme
- Breaks down at the start — 1 mark
- Repaired and thickens — 1 mark
- Maintained after ovulation — 1 mark
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4 Explain [3 marks]
Explain why the lining of the uterus breaks down at the end of a cycle in which the woman does not become pregnant.
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Model answer
The level of progesterone falls, because there is no embryo. Progesterone maintains the lining, so when the level falls, the lining can no longer be maintained, and it breaks down.
Mark scheme
- Progesterone level falls — 1 mark
- Progesterone maintains the lining — 1 mark
- So the lining breaks down — 1 mark
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5 Calculate [2 marks]
A woman's last period began on 5 June, and she has a regular 28-day cycle. State the date on which she is likely to ovulate.
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Model answer
Ovulation is on day 14, which is 18 June.
Mark scheme
- Day 14 — 1 mark
- 18 June — 1 mark
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6 Evaluate [6 marks]
Explain how oestrogen and progesterone work together to prepare the uterus for a possible pregnancy, and what happens if the woman does become pregnant.
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Model answer
In the first half of the cycle, oestrogen is made by the follicle in the ovary, and it causes the lining of the uterus to repair and thicken after the period. Around day 14 an egg is released, at ovulation. After this the empty follicle makes progesterone, which maintains the thick lining, so that it is ready for an embryo to implant. If the egg is fertilised, it implants in the lining, and the level of progesterone stays high, so the lining is kept, and there is no period. If there is no fertilisation, the level of progesterone falls, the lining cannot be maintained, and it breaks down, and the cycle begins again.
Mark scheme
- Oestrogen repairs and thickens the lining — 1 mark
- Egg released at ovulation — 1 mark
- Progesterone maintains the lining — 1 mark
- Embryo implants if the egg is fertilised — 1 mark
- Progesterone stays high, so no period — 1 mark
- No fertilisation: progesterone falls and the lining breaks down — 1 mark
Quick check
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1
How many days does a typical menstrual cycle last?
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B: 28
About 28 days.
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2
What is ovulation?
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C: The release of an egg from the ovary
The release of a mature egg from an ovary.
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3
Which hormone repairs and thickens the lining of the uterus?
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A: Oestrogen
Oestrogen.
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4
Which hormone maintains the lining of the uterus?
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D: Progesterone
Progesterone.
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5
On which days does menstruation usually take place?
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B: Days 1 to 5
Days 1 to 5.
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6
What happens to the level of progesterone if the woman is not pregnant?
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C: It falls
It falls, so the lining breaks down.
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7
Where are oestrogen and progesterone made?
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A: The ovaries
In the ovaries.
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8
A woman's period starts on 10 September. She has a 28-day cycle. When will she ovulate?
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D: 23 September
Day 14 is 23 September.
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9
Why is the lining of the uterus kept thick after ovulation?
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B: To be ready for an embryo
To be ready for an embryo to implant if the egg is fertilised.
Hormones and the Menstrual Cycle (Higher tier)
Just this lesson-
1 State [1 mark]
State the hormone that causes ovulation.
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Model answer
LH (luteinising hormone).
Mark scheme
- LH — 1 mark
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2 Name [2 marks]
State the roles of FSH and of progesterone in the menstrual cycle.
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Model answer
FSH causes a follicle to mature, and stimulates the ovary to make oestrogen. Progesterone maintains the lining of the uterus.
Mark scheme
- FSH matures a follicle — 1 mark
- Progesterone maintains the lining — 1 mark
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3 Explain [3 marks]
Explain how oestrogen causes ovulation.
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Model answer
Oestrogen is made by the follicle as it matures. When the level of oestrogen is high enough, it stimulates the pituitary gland to release a surge of LH. The LH causes the follicle to release the egg, which is ovulation.
Mark scheme
- High oestrogen — 1 mark
- Stimulates a surge of LH from the pituitary gland — 1 mark
- LH causes ovulation — 1 mark
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4 Explain [3 marks]
Explain why a high level of progesterone after ovulation stops another egg from maturing.
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Model answer
Progesterone inhibits the release of FSH and LH from the pituitary gland. FSH is needed for a follicle to mature, so with the level of FSH low, no more follicles mature, and no more eggs are released.
Mark scheme
- Progesterone inhibits FSH and LH — 1 mark
- FSH needed for follicle to mature — 1 mark
- So no more eggs mature — 1 mark
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5 Describe [3 marks]
The graph of hormone levels shows that FSH is high at the start of the cycle and falls as the level of oestrogen rises. Describe and explain this pattern.
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Model answer
The level of FSH falls as the level of oestrogen rises. This is because oestrogen inhibits the release of FSH, which is negative feedback, and it means that only one follicle usually matures.
Mark scheme
- FSH falls as oestrogen rises — 1 mark
- Oestrogen inhibits FSH — 1 mark
- Negative feedback, so one follicle matures — 1 mark
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6 Evaluate [6 marks]
Explain how the control of the menstrual cycle by hormones ensures that the uterus is ready to receive an embryo at the time that an egg is released.
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Model answer
At the start of the cycle FSH causes a follicle to mature, and the ovary to make oestrogen. Oestrogen causes the lining of the uterus to repair and thicken, so that it is thick when the egg is released. When the level of oestrogen is high enough, it stimulates a surge of LH, which causes ovulation at about day 14. The empty follicle then makes progesterone, which maintains the thick lining with a good blood supply. Progesterone also inhibits FSH and LH, so no more eggs are released. The timing of these hormones means that the lining is thick and ready just as the egg arrives, and it is maintained while an embryo could implant. If there is no pregnancy, progesterone falls, and the lining breaks down.
Mark scheme
- FSH matures a follicle which makes oestrogen — 1 mark
- Oestrogen repairs and thickens the lining — 1 mark
- High oestrogen stimulates an LH surge — 1 mark
- LH causes ovulation — 1 mark
- Progesterone maintains the lining — 1 mark
- Timing ensures that the lining is ready — 1 mark
Quick check
-
1
Which hormone is released by the pituitary gland and makes a follicle mature?
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C: FSH
FSH.
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2
Which hormone causes ovulation?
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A: LH
LH.
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3
Which hormone is made by the empty follicle after ovulation?
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D: Progesterone
Progesterone.
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4
What does a high level of oestrogen stimulate?
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B: A surge of LH
A surge of LH from the pituitary gland.
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5
What causes menstruation?
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C: A fall in progesterone
A fall in the level of progesterone.
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6
What does progesterone inhibit?
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A: FSH and LH
FSH and LH.
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7
On which day is the LH level at its highest?
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D: Day 14
About day 14.
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8
Why does only one follicle usually mature in each cycle?
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B: Because oestrogen inhibits FSH
Oestrogen inhibits FSH as its level rises.
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9
A woman takes a drug that blocks the release of LH. What is the most likely effect?
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A: No ovulation
With no LH surge, there is no ovulation.
Contraception
Just this lesson-
1 State [1 mark]
State what is meant by contraception.
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Model answer
A method of preventing pregnancy.
Mark scheme
- Prevents pregnancy — 1 mark
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2 State [2 marks]
State two hormones that are in the combined contraceptive pill.
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Model answer
Oestrogen and progesterone.
Mark scheme
- Oestrogen — 1 mark
- Progesterone — 1 mark
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3 Explain [3 marks]
Explain how the combined contraceptive pill prevents pregnancy.
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Model answer
The hormones in the pill keep the levels of FSH and LH low, so that no egg matures, and no egg is released. If there is no egg, there is nothing to be fertilised. The hormones also make the mucus thicker, so that sperm cannot get through, and keep the lining of the uterus thin.
Mark scheme
- FSH and LH kept low — 1 mark
- No egg released, so no fertilisation — 1 mark
- Thick mucus or thin lining — 1 mark
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4 Describe [3 marks]
Describe how a condom prevents pregnancy, and why it is also useful in preventing the spread of STIs.
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Model answer
A condom is a barrier that stops sperm from reaching the egg, as it prevents them from entering the vagina. It also stops body fluids from passing from one person to another, so it prevents the spread of STIs.
Mark scheme
- Barrier stops sperm reaching the egg — 1 mark
- Stops body fluids passing between people — 1 mark
- So it prevents the spread of STIs — 1 mark
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5 Calculate [3 marks]
In one year, 4 out of 100 women using the injection, and 13 out of 100 women using the male condom, became pregnant. Calculate how many times more likely a woman was to become pregnant using the condom.
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Model answer
13 ÷ 4 = 3.25, so about 3.3 times as likely.
Mark scheme
- Division of 13 by 4 — 1 mark
- 3.25 — 1 mark
- About 3 times as likely — 1 mark
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6 Evaluate [6 marks]
A couple have been together for six months. They want to avoid pregnancy, and they have each had only one other partner. Evaluate the use of the combined pill and of condoms for this couple.
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Model answer
The combined pill is more effective than the condom, as 7 out of 100 women using it became pregnant in a year, compared with 13 out of 100 for the condom. It works by stopping ovulation. However, the pill has to be taken every day, and may have side effects, such as headaches and a small increase in the risk of blood clots, and it gives no protection against sexually transmitted infections. A condom has no hormonal side effects and protects against STIs, which matters because they have both had other partners, but it is less effective and must be used correctly each time. For this couple it would be best to use both, so they would have the greater protection against pregnancy from the pill, and against infection from the condom.
Mark scheme
- Pill more effective, with data — 1 mark
- Pill stops ovulation — 1 mark
- Pill side effects, and daily use — 1 mark
- Condom protects against STIs — 1 mark
- Condom less effective — 1 mark
- Reasoned conclusion, such as both — 1 mark
Quick check
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1
What do the hormones in the pill stop?
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B: Ovulation
Ovulation.
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2
Which method of contraception also protects against STIs?
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A: A condom
Condoms.
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3
Which hormones are in the combined pill?
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C: Oestrogen and progesterone
Oestrogen and progesterone.
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4
What does progesterone do to the mucus at the entrance to the uterus?
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D: It makes it thicker
It makes it thicker, so that sperm cannot get through.
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5
Which method does not use hormones?
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B: A copper IUD
A copper IUD.
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6
Which is a possible side effect of hormonal contraception?
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A: Headaches
Headaches or mood changes.
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7
Which method is the most effective in the data?
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C: The implant
The implant, with fewer than 1 pregnancy per 100 women.
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8
13 out of 100 women using a method became pregnant. What percentage is this?
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D: 13%
13%.
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9
Why can the effectiveness of the combined pill be lower than that of the implant?
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B: It must be remembered every day
The pill has to be remembered every day, but the implant does not.
Assisted Reproductive Technology (Higher tier)
Just this lesson-
1 State [1 mark]
State what is meant by IVF.
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Model answer
In vitro fertilisation, in which an egg is fertilised by sperm in a laboratory dish.
Mark scheme
- Fertilisation of an egg in a dish — 1 mark
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2 State [2 marks]
State the two hormones that are used to make several eggs mature in IVF.
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Model answer
FSH and LH.
Mark scheme
- FSH — 1 mark
- LH — 1 mark
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3 Explain [3 marks]
Explain how clomifene helps a woman who does not ovulate to become pregnant.
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Model answer
Clomifene blocks the receptors for oestrogen in the brain, so the hypothalamus and the pituitary gland do not detect the oestrogen, and negative feedback is reduced. The pituitary gland releases more FSH and LH, so a follicle matures, and ovulation occurs.
Mark scheme
- Blocks oestrogen receptors — 1 mark
- More FSH and LH are released — 1 mark
- So follicle matures and ovulation occurs — 1 mark
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4 Describe [4 marks]
Describe the main stages of IVF.
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Model answer
The woman is given FSH and LH to mature several eggs. The eggs are collected from the ovaries, and mixed with sperm in a dish, where they are fertilised. The embryos are kept for a few days, and one or two are placed in the uterus.
Mark scheme
- FSH and LH to mature eggs — 1 mark
- Eggs collected — 1 mark
- Fertilised in a dish — 1 mark
- One or two embryos put in the uterus — 1 mark
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5 Calculate [3 marks]
A clinic treated 250 women with IVF, and 70 gave birth. Each cycle cost £3000. Calculate the success rate, and the cost of each baby, if each woman had one cycle.
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Model answer
70 ÷ 250 × 100 = 28%. Total cost = 250 × 3000 = £750 000. £750 000 ÷ 70 = £10 714, which is about £10 700.
Mark scheme
- 28% — 1 mark
- Total cost £750 000 — 1 mark
- About £10 700 per baby — 1 mark
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6 Evaluate [6 marks]
Evaluate the use of IVF to treat infertility.
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Model answer
IVF gives people who cannot conceive naturally, for example because the oviducts are blocked, a chance of having a baby, and embryos can be tested for genetic disorders before they are transferred. However, only about 3 in 10 cycles in women under 35 are successful, and the chance falls with age, so many people have to try several times. The treatment is costly, and it can be stressful, and the hormones can cause side effects. If more than one embryo is transferred, there is a greater chance of twins or triplets, which are a risk to the mother and the babies. Some people also object to the production and destruction of spare embryos. Overall, IVF has great benefits for those who cannot have a baby in other ways, but the costs and risks must be weighed up.
Mark scheme
- Chance of a baby for people who cannot conceive — 1 mark
- Genetic testing of embryos — 1 mark
- Low success rate — 1 mark
- Cost, stress and side effects — 1 mark
- Risk of multiple births, or ethical issues about spare embryos — 1 mark
- A reasoned conclusion — 1 mark
Quick check
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1
Which hormones are used to make several eggs mature in IVF?
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C: FSH and LH
FSH and LH.
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2
Where does fertilisation take place in IVF?
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A: In a laboratory dish
In a dish in the laboratory.
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3
What is clomifene used for?
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D: To help ovulation
To help women who do not ovulate to release eggs.
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4
How does clomifene cause an increase in FSH and LH?
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B: It blocks oestrogen receptors
It blocks the oestrogen receptors, so there is less negative feedback.
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5
How many embryos are usually put into the uterus in IVF?
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A: One or two
One or two.
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6
Why are only one or two embryos transferred?
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C: To reduce the risk of multiple births
To reduce the risk of multiple births.
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7
In a trial, 45 of 150 women gave birth after IVF. What is the success rate?
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D: 30%
\(45 \div 150 \times 100 = 30\%\).
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8
Which is a disadvantage of IVF?
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B: It has a low success rate
It has a low success rate, and may cause multiple births.
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9
A woman has blocked oviducts. Which treatment is most suitable?
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A: IVF
IVF, because the egg is fertilised outside the body, so the blocked oviducts are bypassed.