Free Human Reproductive System MCQs with Answers

21. The changes of puberty in boys, such as a deeper voice and facial hair, are driven mainly by

• A. testosterone
• B. oestrogen
• C. progesterone
• D. insulin

Explanation: Testosterone from the Leydig cells stimulates the development of male secondary sexual characteristics and continues to support sperm production. Oestrogen and progesterone are the principal female sex hormones, though small amounts occur in both sexes.

22. The narrow lower end of the uterus that opens into the vagina is called the

• A. oviduct
• B. cervix
• C. ovary
• D. urethra

Explanation: The cervix produces mucus that changes through the cycle, guides sperm and protects the uterus during pregnancy. The urethra is part of the urinary system, a common confusion since both open near each other in the female.

23. At the start of the menstrual cycle, rising levels of FSH stimulate

• A. ovulation
• B. the shedding of the endometrium
• C. the development of follicles in the ovary
• D. the formation of the placenta

Explanation: FSH, follicle stimulating hormone, recruits a batch of follicles at the beginning of the cycle, and the growing follicle then secretes oestrogen. Ovulation comes later, triggered by LH, and the placenta only forms after pregnancy begins.

24. During the first half of the menstrual cycle, the hormone that rebuilds the lining of the uterus is

• A. progesterone
• B. LH
• C. FSH
• D. oestrogen

Explanation: Oestrogen from the developing follicle drives the endometrium to proliferate after menstruation. Progesterone takes over after ovulation to maintain the rebuilt lining, so the two hormones divide the cycle between them.

25. After ovulation, progesterone from the corpus luteum

• A. maintains the thickened endometrium ready for implantation
• B. immediately triggers menstruation
• C. stimulates a second ovulation
• D. dissolves the zona pellucida of the egg

Explanation: Progesterone makes the endometrium glandular and rich in blood supply, the state needed for an embryo to implant. Menstruation follows only when the corpus luteum fails and progesterone levels drop.

26. As a follicle matures, its rising oestrogen output suppresses the secretion of FSH by the

• A. ovary itself
• B. anterior pituitary through negative feedback
• C. posterior pituitary
• D. hypothalamus releasing oxytocin

Explanation: Oestrogen feeds back on the anterior pituitary to reduce FSH, which prevents several follicles from maturing at once. This negative feedback keeps the cycle to a single dominant follicle in humans.

27. The luteal phase of the menstrual cycle is the period

• A. of menstruation itself
• B. before the follicle begins to grow
• C. between ovulation and the start of the next menstruation
• D. during which the egg is fertilised

Explanation: After ovulation the corpus luteum secretes progesterone for about fourteen days, the luteal phase. If no embryo implants, the corpus luteum degenerates, hormone levels fall and menstruation begins.

28. Oral contraceptive pills prevent pregnancy mainly by

• A. killing sperm in the vagina
• B. blocking the oviducts mechanically
• C. thickening the cervical mucus only
• D. suppressing ovulation through their oestrogen and progesterone content

Explanation: The steady hormones of the pill inhibit FSH and LH, so no follicle matures and no egg is released. Thickened cervical mucus adds a secondary barrier, but the suppression of ovulation is the principal mechanism.

29. If fertilisation does not occur, the corpus luteum

• A. degenerates into a scar called the corpus albicans
• B. continues to grow throughout the cycle
• C. develops into the placenta
• D. starts secreting hCG

Explanation: Without hCG from an embryo, the corpus luteum survives only about ten days and then degenerates, its progesterone falling to trigger menstruation. Only in pregnancy does it persist, sustained by embryonic hCG.

30. The hormones FSH and LH that regulate the menstrual cycle are secreted by the

• A. ovary
• B. anterior pituitary gland
• C. uterus
• D. thyroid gland

Explanation: The anterior pituitary releases both gonadotropins under direction from hypothalamic GnRH. The ovary responds to them by producing oestrogen and progesterone, so the control runs from the brain to the ovary, not the reverse.