Hormones in human reproduction — AQA GCSE Combined Science
Test yourself on Hormones in human reproduction with AQA GCSE practice questions.
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Hormones in human reproduction explained
Reproduction is controlled by hormones carried in the blood.
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In females, FSH from the pituitary gland causes an egg to mature in an ovary and stimulates oestrogen release. Oestrogen from the ovaries builds the uterus lining and, at high levels, triggers LH release. A surge of LH from the pituitary gland causes ovulation, the release of a mature egg. After ovulation, the remains of the follicle secrete progesterone, which maintains the uterus lining. If no fertilised egg implants, progesterone falls, the lining breaks down as menstruation, and the cycle restarts. In males, testosterone from the testes stimulates sperm production. These hormones also form the basis of fertility treatments and contraception.
During puberty reproductive hormones cause secondary sex characteristics to develop.
Puberty is the stage when the reproductive system becomes functional. The pituitary gland releases hormones that stimulate the testes to produce testosterone and the ovaries to produce oestrogen. These reproductive hormones travel in the blood and trigger secondary sex characteristics. In males, testosterone causes deepening of the voice, growth of facial and body hair, and increased muscle mass. In females, oestrogen causes breast development, widening of the hips, and growth of pubic hair. These changes prepare the body for reproduction. Understanding this helps explain how the body coordinates growth and development during adolescence.
Oestrogen is the main female reproductive hormone produced in the ovary. At puberty eggs begin to mature and one is released approximately every 28 days. This is called ovulation.
Oestrogen is the main female reproductive hormone, produced by the ovaries. During puberty, it stimulates the development of secondary sex characteristics and helps regulate the menstrual cycle. The cycle is about 28 days long. Each cycle, an egg matures in a follicle in the ovary. Around the middle of the cycle, the follicle bursts and releases the egg. This release is called ovulation. The egg then travels along the oviduct (fallopian tube) towards the uterus. If sperm are present, fertilisation may occur. If not, the egg passes out of the body. Oestrogen also causes the lining of the uterus to thicken, preparing for a possible pregnancy. Understanding ovulation is essential for explaining fertility and the menstrual cycle.
Testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production.
Testosterone is the principal male reproductive hormone. It is produced by the testes and plays a vital role in male fertility by stimulating sperm production. During puberty, testosterone also controls the development of male secondary sexual characteristics, such as a deepening voice and the growth of facial and pubic hair. The hormone is secreted into the bloodstream by the testes and travels to target organs throughout the body. Students should be able to identify the testes as the gland responsible for producing testosterone and clearly state its primary function in stimulating sperm production.
Several hormones are involved in the menstrual cycle of a woman.
The menstrual cycle is a repeating sequence of about 28 days controlled by interacting hormones. FSH from the pituitary gland causes an egg to mature in an ovary and stimulates oestrogen release. Oestrogen from the ovaries repairs and thickens the uterus lining and triggers a surge of LH from the pituitary. The LH surge causes ovulation, the release of the mature egg. After ovulation, the remains of the follicle form the corpus luteum, which secretes progesterone. Progesterone maintains the uterus lining and inhibits FSH and LH, so no new egg matures while the lining is prepared. If fertilisation does not occur, the corpus luteum breaks down, progesterone falls, the lining is shed as menstruation, and FSH rises again to restart the cycle.
Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary.
Follicle stimulating hormone (FSH) is a key reproductive hormone in females. It is secreted by the pituitary gland, often referred to as a 'master gland', and travels in the blood to its target organ, the ovary. In the ovary, FSH causes an egg to mature within a follicle. This maturation is a crucial step in the menstrual cycle, preparing the egg for potential release and fertilisation. Students should clearly link the pituitary gland as the source of FSH, the blood as the transport medium, and the ovary as the target organ where egg maturation occurs. Understanding this pathway helps explain how hormones coordinate reproductive processes.
Luteinising hormone (LH) stimulates the release of the egg.
Luteinising hormone (LH) is a vital reproductive hormone involved in the menstrual cycle. It is produced and secreted by the pituitary gland and travels through the bloodstream to reach its target organ, the ovary. The primary role of LH is to stimulate the release of a mature egg from the ovary, a process known as ovulation. This typically occurs around the middle of the menstrual cycle (approximately day 14). Students must be able to distinguish the specific role of LH from other hormones, remembering that while FSH matures the egg, it is LH that triggers its release into the fallopian tube.
Oestrogen and progesterone are involved in maintaining the uterus lining.
The uterus lining (endometrium) must be thick and blood-rich so that a fertilised egg can implant and develop. Oestrogen, made by the ovaries, stimulates the lining to rebuild and thicken after menstruation. Progesterone, made by the corpus luteum after ovulation, keeps the lining thick and stable, and inhibits FSH and LH so no further eggs mature. If fertilisation does not occur, the corpus luteum breaks down, progesterone falls, and the lining is shed as a period. If fertilisation occurs, the embryo secretes hormones that keep the corpus luteum secreting progesterone, maintaining the lining through pregnancy. For example, a graph of progesterone through the cycle shows a rise after ovulation and a sharp fall just before menstruation.
(HT only) Students should be able to explain the interactions of FSH, oestrogen, LH and progesterone, in the control of the menstrual cycle.
The menstrual cycle is controlled by four interacting hormones in a negative feedback system. FSH, secreted by the pituitary gland, matures a follicle in the ovary and stimulates oestrogen release. Oestrogen, from the developing follicle, thickens the uterus lining and, at high concentrations, triggers a surge of LH from the pituitary. The LH surge causes ovulation around day 14 and forms the corpus luteum, which secretes progesterone. Progesterone maintains the uterus lining and inhibits FSH and LH, preventing new follicles from maturing. If fertilisation does not occur, the corpus luteum breaks down, progesterone falls, inhibition is removed, and FSH rises to begin a new cycle.
(HT only) Students should be able to extract and interpret data from graphs showing hormone levels during the menstrual cycle.
Extracting and interpreting data from interacting hormone graphs is strictly a Higher Tier (HT only) requirement. On a typical cycle graph, the x-axis shows days (0 to 28) and the y-axis shows relative hormone concentration. Four hormones interact: FSH, LH, oestrogen, and progesterone. FSH rises early, maturing a follicle and triggering oestrogen. Oestrogen peaks just before ovulation, stimulating an LH surge. LH peaks around day 14, causing ovulation. Progesterone, released by the corpus luteum, rises after ovulation to maintain the uterus lining. To extract data, read values directly off the axes; to interpret, link each peak to its specific reproductive role, such as identifying imminent ovulation from an LH surge.
Your focus
- Name the hormones involved in the menstrual cycle and state their sources.
- Describe the sequence of hormonal changes and their effects on the ovary and uterus.
- Describe the role of testosterone in sperm production and relate reproductive hormones to fertility treatments or contraception.
Show all 31 objectives
- State that puberty is caused by reproductive hormones.
- Identify testosterone and oestrogen as the main male and female reproductive hormones, and name their organs of production.
- Describe at least two secondary sex characteristics for each sex and link them to the correct hormone.
- State that oestrogen is the main female reproductive hormone produced in the ovary.
- Describe the process of ovulation, including the approximate 28-day cycle.
- Explain the role of oestrogen in the menstrual cycle and the development of secondary sex characteristics.
- Identify the testes as the source of testosterone.
- Describe testosterone as the main male reproductive hormone.
- Explain that testosterone stimulates sperm production.
- Name the hormones involved in the menstrual cycle and identify where each is produced.
- Describe the sequence of hormonal events that leads to ovulation and maintenance of the uterus lining.
- Explain how changes in progesterone and FSH lead to menstruation when fertilisation does not occur.
- Identify the pituitary gland as the source of FSH.
- State that the ovary is the target organ for FSH.
- Describe the role of FSH in causing the maturation of an egg in the ovary.
- Identify the pituitary gland as the source of LH.
- State that the ovary is the target organ for LH.
- Describe the role of LH in stimulating the release of the egg (ovulation).
- State the source and role of oestrogen in rebuilding the uterus lining.
- Describe how progesterone maintains the uterus lining and inhibits FSH and LH.
- Explain how falling progesterone leads to menstruation when fertilisation does not occur.
- Describe the source, target organ, and function of FSH, oestrogen, LH, and progesterone.
- Explain how the four hormones interact in a specific sequence to control the menstrual cycle.
- Apply the concept of negative feedback to explain how progesterone regulates FSH and LH levels.
- Recognise that interpreting interacting hormone graphs is a Higher Tier only requirement.
- Read hormone concentrations and days accurately from a menstrual cycle graph.
- Describe the sequence of FSH, oestrogen, LH and progesterone changes across the 28-day cycle.
- Explain how each hormone peak or trough relates to events such as follicle maturation and ovulation.
Hormones in human reproduction exam tips
Marking Points
- FSH is secreted by the pituitary gland and causes an egg to mature in the ovary.
- Oestrogen is secreted by the ovaries and causes the uterus lining to thicken and repair.
- LH is secreted by the pituitary gland and triggers ovulation.
- Progesterone is secreted by the ovary after ovulation and maintains the uterus lining.
- Testosterone is secreted by the testes and stimulates sperm production.
- A full description sequences the hormones across the cycle and links each to its effect on the ovary or uterus.
- Puberty is triggered by hormones from the pituitary gland, which stimulate the gonads (testes and ovaries).
- Testosterone is the main male reproductive hormone produced by the testes; it causes secondary sex characteristics such as voice deepening and facial hair growth.
- Oestrogen is the main female reproductive hormone produced by the ovaries; it causes secondary sex characteristics such as breast development and hip widening.
- Secondary sex characteristics are physical features that develop during puberty but are not directly involved in reproduction, unlike primary sex characteristics.
- The hormones travel in the bloodstream to target organs, where they bring about specific developmental changes.
- Oestrogen is produced by the ovaries and is the main female reproductive hormone.
- At puberty, eggs begin to mature within follicles in the ovaries.
- Ovulation is the release of a mature egg from an ovary, approximately every 28 days.
- The egg travels along the oviduct (fallopian tube) to the uterus.
- Oestrogen also stimulates the thickening of the uterus lining during the menstrual cycle.
- Testosterone is the main male reproductive hormone.
- It is produced and secreted by the testes.
- Testosterone travels in the blood plasma to reach target organs.
- Its primary function is to stimulate sperm production.
- It also controls the development of male secondary sexual characteristics during puberty.
- FSH is secreted by the pituitary gland and causes an egg to mature in the ovary.
- Oestrogen is secreted by the ovaries, thickens the uterus lining and stimulates the release of LH.
- LH from the pituitary gland triggers ovulation, the release of the mature egg from the ovary.
- Progesterone is secreted by the corpus luteum after ovulation and maintains the uterus lining.
- Progesterone inhibits FSH and LH, so further eggs do not mature during the same cycle.
- If fertilisation does not occur, progesterone falls, the uterus lining breaks down and menstruation occurs.
- FSH is produced and secreted by the pituitary gland.
- It is transported in the blood plasma to its target organ, the ovary.
- FSH causes the maturation of an egg in the ovary.
- The egg matures inside a structure called a follicle.
- LH is produced and secreted by the pituitary gland.
- It is transported in the blood plasma to the ovaries.
- LH stimulates the release of a mature egg from the ovary.
- The release of an egg stimulated by LH is called ovulation.
- Oestrogen is secreted by the ovaries and stimulates the repair and thickening of the uterus lining after menstruation.
- Progesterone is secreted by the corpus luteum and maintains the thickened uterus lining so it does not break down.
- Progesterone inhibits FSH and LH, preventing further follicles maturing while the lining is maintained.
- A fall in progesterone when the corpus luteum breaks down causes the uterus lining to be shed as menstruation.
- If fertilisation occurs, continued progesterone secretion maintains the lining during early pregnancy.
- The two hormones act at different stages: oestrogen early in the cycle, progesterone after ovulation.
- FSH is secreted by the pituitary gland, causing a follicle to mature and stimulating the ovaries to produce oestrogen.
- Oestrogen causes the uterus lining to thicken and, at high levels, stimulates the pituitary gland to release a surge of LH.
- LH triggers ovulation (release of the egg) and causes the empty follicle to develop into the corpus luteum, which secretes progesterone.
- Progesterone maintains the thick uterus lining and inhibits the release of both FSH and LH by the pituitary gland.
- When progesterone levels fall due to the breakdown of the corpus luteum, the inhibition of FSH is lifted, allowing a new cycle to begin.
- Identify the axes: days of the cycle on the x-axis and relative hormone concentration on the y-axis, naming the specific hormones shown.
- Read specific values from the graph, such as the exact day of the LH peak or the relative concentration of oestrogen at its maximum.
- Describe the shape of each curve: FSH rises early, oestrogen peaks before ovulation, LH surges around day 14, and progesterone rises after ovulation.
- Link each hormone pattern to its function, for example stating that the LH surge causes ovulation and progesterone maintains the uterus lining.
- Compare curves to identify cause and effect, such as rising oestrogen preceding and triggering the LH surge.
- Use data to support a conclusion, quoting figures such as 'LH peaks at day 14' rather than describing the graph generally.
Examiner Tips
- 💡Learn the order FSH, oestrogen, LH, progesterone and link each to one clear effect.
- 💡Use the terms 'mature the egg', 'build the lining', 'ovulation' and 'maintain the lining' precisely.
- 💡If asked to compare, set out male and female hormones side by side rather than mixing them in one paragraph.
- 💡Learn at least two secondary sex characteristics for each sex and link each to the correct hormone.
- 💡Use the terms 'testosterone' and 'oestrogen' accurately, and state the organ that produces each.
- 💡When describing the role of the pituitary gland, mention that it stimulates the gonads to release reproductive hormones.
- 💡State clearly that oestrogen is produced in the ovary and name its role in ovulation and the menstrual cycle.
- 💡Use the term 'ovulation' correctly and link it to the release of an egg approximately every 28 days.
- 💡When describing the journey of the egg, mention the oviduct (fallopian tube) and the uterus.
- 💡Clearly state that the testes produce testosterone; do not just refer to 'male reproductive organs'.
- 💡Link testosterone directly to the stimulation of sperm production when asked about its role in human reproduction.
- 💡Name the gland or organ that secretes each hormone, because marks often depend on correct sources.
- 💡Sequence the events in order: FSH → egg maturation and oestrogen → LH surge → ovulation → progesterone → maintenance or menstruation.
- 💡Use the terms inhibit and stimulate precisely when describing how the hormones affect each other.
- 💡Name the pituitary gland as the source of FSH and the ovary as the target organ in written answers.
- 💡Use the exact phrase 'maturation of an egg' rather than vague wording such as 'makes an egg' or 'grows an egg'.
- 💡Use the term 'ovulation' when describing the release of the egg, and clearly link this process to LH.
- 💡Contrast LH with FSH carefully: remember 'FSH for maturation, LH for release' to avoid mixing up their functions.
- 💡Link each hormone to its source, its target tissue and its effect in one sentence to show clear cause and effect.
- 💡Use the words rebuild, maintain and shed to describe the lining at the correct stages of the cycle.
- 💡When describing a graph, quote the stage of the cycle and whether the hormone is rising or falling before explaining the effect on the lining.
- 💡Explaining the complex interactions and negative feedback between these four hormones is assessed at Higher Tier only; ensure you can sequence them correctly.
- 💡For extended response questions, systematically link each hormone to its source gland, its target organ, and its specific effect on the next hormone in the sequence.
- 💡Use the term 'negative feedback' explicitly when describing how progesterone prevents further follicles from maturing by inhibiting FSH and LH.
- 💡Foundation students should note that extracting and interpreting these complex interacting hormone graphs is a Higher Tier only skill.
- 💡Quote specific days and values from the graph to support each point, for example 'LH is highest at day 14'.
- 💡Check the command word: 'extract' requires specific values read from the graph, while 'interpret' requires linking those values to hormone function.
Common Mistakes
- Confusing the roles of FSH and LH; correction: FSH matures the egg, while LH triggers ovulation.
- Saying oestrogen maintains the uterus lining throughout the cycle; correction: oestrogen builds the lining, but progesterone maintains it after ovulation.
- Naming the ovaries as the source of FSH and LH; correction: FSH and LH come from the pituitary gland, while oestrogen and progesterone come from the ovaries.
- Confusing primary and secondary sex characteristics. Correction: primary sex characteristics are the reproductive organs present at birth; secondary sex characteristics develop during puberty.
- Thinking that only females have oestrogen or only males have testosterone. Correction: both hormones are present in both sexes, but in different concentrations.
- Believing that puberty is controlled by the reproductive organs alone. Correction: the pituitary gland in the brain releases hormones that stimulate the testes and ovaries to produce their hormones.
- Confusing ovulation with menstruation. Correction: ovulation is the release of an egg; menstruation is the breakdown and loss of the uterus lining.
- Thinking that ovulation occurs every 28 days exactly for all women. Correction: the average cycle is about 28 days, but it can vary between individuals and cycles.
- Believing that oestrogen is only involved in secondary sex characteristics. Correction: oestrogen also regulates the menstrual cycle and prepares the uterus lining for pregnancy.
- Saying testosterone is produced by the sperm themselves; correction: sperm are the male gametes, while testosterone is a hormone secreted by the testes.
- Confusing testosterone with oestrogen; correction: testosterone is the main male reproductive hormone, whereas oestrogen is the main female reproductive hormone.
- Claiming testosterone only affects the testes; correction: it is carried in the blood to various target organs to trigger secondary sexual characteristics.
- Saying oestrogen triggers ovulation; correction: oestrogen stimulates LH release, and it is the LH surge that causes ovulation.
- Saying progesterone is produced by the pituitary gland; correction: progesterone is produced by the corpus luteum in the ovary after ovulation.
- Saying FSH maintains the uterus lining; correction: FSH causes egg maturation, while progesterone maintains the lining.
- Stating that FSH is produced by the ovary; correction: FSH is produced by the pituitary gland and acts on the ovary.
- Saying that FSH releases the egg; correction: FSH causes maturation of the egg, whereas LH stimulates the release of the egg.
- Confusing the roles of different hormones; correction: ensure you specifically link FSH to egg maturation, not to thickening the uterus lining.
- Stating that LH matures the egg; correction: FSH causes maturation of the egg, while LH stimulates its release.
- Saying that LH is produced by the ovary; correction: LH is produced by the pituitary gland and acts on the ovary.
- Confusing ovulation with menstruation; correction: ovulation is the release of an egg from the ovary triggered by LH, whereas menstruation is the shedding of the uterus lining.
- Saying oestrogen maintains the lining throughout the cycle: correct this by stating oestrogen rebuilds and thickens the lining, while progesterone maintains it after ovulation.
- Confusing the ovary and corpus luteum as sources: correct this by naming the ovaries for oestrogen and the corpus luteum for progesterone.
- Claiming progesterone causes ovulation: correct this by stating that a surge of LH triggers ovulation, and progesterone instead maintains the lining and inhibits FSH and LH.
- Reversing the roles of FSH and LH: correct this by remembering that FSH (Follicle Stimulating Hormone) matures the follicle early in the cycle, whereas LH (Luteinising Hormone) triggers ovulation at day 14.
- Stating that oestrogen only inhibits FSH: correct this by explaining that while low levels inhibit FSH, a high concentration of oestrogen stimulates the LH surge required for ovulation.
- Forgetting the source glands for each hormone: correct this by explicitly stating that FSH and LH are released by the pituitary gland, while oestrogen and progesterone are released by the ovaries.
- Confusing which hormone peaks at ovulation: LH peaks around day 14, not FSH; correct by linking the LH surge directly to the release of the egg.
- Reading the y-axis as absolute units when it is often relative concentration; correct by quoting the scale exactly as shown and avoiding invented units.
- Describing the graph without interpreting it; correct by adding what each peak or trough means for the cycle, such as follicle maturation or lining maintenance.
- Assuming progesterone peaks before ovulation; correct by noting it rises after ovulation because it is secreted by the corpus luteum.