Question
Globozoospermia is a genetic condition that leads to male infertility due to the production of abnormal sperm. The diagram compares a normal sperm cell with one produced by a man with globozoospermia.
Why are sperm from males with this condition unable to fertilize eggs?
A. They lack enzymes to digest the follicle cells.
B. They have less genetic material.
C. They have no energy to swim through the oviducts.
D. They fail to reach the plasma membrane of the egg.
▶️Answer/Explanation
Answer: D. They fail to reach the plasma membrane of the egg.
Explanation:
Globozoospermia is a condition where sperm have round heads and lack an acrosome a structure that contains enzymes needed to digest the egg’s outer layers (like the follicle cells and zona pellucida). Without these enzymes, the sperm cannot penetrate the egg to fertilize it.
Let’s analyze the options:
A. Correct – They lack the acrosome, so they don’t have the enzymes to digest the follicle cells and reach the egg.
B. Incorrect – DNA content is normal; genetic material is not the issue.
C. Incorrect – Energy for movement may be normal; the main issue is penetration, not motility.
D. Incorrect – They fail to reach the egg membrane because they can’t digest the outer layers — this is a result, not the root cause.
Question
The image of the pregnancy test shows a positive result. The band indicating pregnancy forms when molecules on the test strip become immobilized after binding to the female hormone HCG.
What are the molecules that bind to HCG?
A. HCG antigens obtained from human plasma
B. HCG antibodies synthesised by human lymphocytes
C. HCG antibodies made by modified plasma cells of small mammals
D. HCG antigens extracted from myeloma cells of mice
▶️Answer/Explanation
Answer: C. HCG antibodies made by modified plasma cells of small mammals
Explanation:
Pregnancy tests detect HCG using antibodies that specifically bind to the hormone. These antibodies are made in small mammals (like mice) by exposing them to HCG, then collecting the antibodies from their plasma cells.
Let’s analyze the options:
A. Incorrect – HCG is the hormone being detected, not used to detect.
B. Incorrect – Human lymphocytes don’t produce the antibodies used in test kits.
C. Correct – The antibodies are made by modified plasma cells from small mammals (e.g., mice).
D. Incorrect – Antigens aren’t used to detect HCG; also, myeloma cells help produce antibodies, not antigens.
Question
The diagram shows changes in the uterus lining of a woman throughout her menstrual cycle.
Between which days is she likely to be fertile?
A. 1–6
B. 7–10
C. 11–16
D. 17–21
▶️Answer/Explanation
Answer: C. 11–16
Explanation:
Fertile window in the menstrual cycle
A woman is most likely to be fertile during ovulation, which typically occurs around the middle of the menstrual cycle. For a standard 28-day cycle:
- Ovulation usually occurs around day 14.
- The fertile window includes the days just before and after ovulation (usually days 11–16) because sperm can survive in the female reproductive tract for up to 5 days, and the egg is viable for about 24 hours after release.
During this time, estrogen levels peak, the uterus lining thickens, and cervical mucus becomes thinner all of which support fertilization.
Let’s analyze the options:
A. Incorrect – Days 1–6 are during menstruation; the uterus is shedding its lining, and hormone levels are low. Fertility is unlikely.
B. Incorrect – Days 7–10 are just after menstruation. The uterine lining is rebuilding, but ovulation hasn’t happened yet. Fertility is increasing but not at its peak.
C. Correct – Days 11–16 include ovulation and the few days before and after it. This is the fertile window, when chances of fertilization are highest.
D. Incorrect – Days 17–21 are after ovulation. The egg has either been fertilized or has degenerated. Fertility rapidly declines.
The concentration of which hormone peaks sharply triggering ovulation?
A. FSH
B. LH
C. Estrogen
D. Progesterone
▶️Answer/Explanation
Answer: B. LH (Luteinizing Hormone)
Explanation:
Ovulation the release of an egg from the ovary is triggered by a sudden spike in luteinizing hormone (LH). This surge usually happens around the middle of the menstrual cycle (around day 14 in a 28-day cycle). The LH surge causes the mature follicle to rupture and release the egg. Other hormones like FSH, estrogen, and progesterone play supporting roles, but LH is the direct trigger for ovulation.
Let’s analyze the options:
A. FSH (Follicle Stimulating Hormone) – Incorrect: FSH stimulates the growth of ovarian follicles in the early part of the cycle, but it does not cause ovulation.
B. LH (Luteinizing Hormone) – Correct: A sharp surge in LH triggers the release of a mature egg from the ovary this is ovulation.
C. Estrogen – Incorrect: Estrogen levels rise before ovulation and help thicken the uterine lining. High estrogen levels stimulate the LH surge, but estrogen itself does not trigger ovulation.
D. Progesterone – Incorrect: Progesterone rises after ovulation and helps maintain the uterine lining for possible pregnancy.
The diagram shows a section through the male reproductive system. Which structure represents the prostate gland?
Answer/Explanation
Answer: B
Explanation:
A. Sperm Duct (Vas Deferens)
- This is the tube that carries sperm from the testes to the urethra.
- It travels up from the testis, loops over the bladder, and joins with the duct from the seminal vesicle.
- It is long and thin, as seen in label A.
B. Prostate Gland (Correct)
- The prostate gland is located just below the bladder and surrounds the first part of the urethra.
- It secretes a fluid that nourishes and protects sperm.
- This fluid is alkaline and helps sperm survive in the acidic environment of the vagina.
- In the diagram, B is exactly in the position below the bladder and encircling the urethra which is classic prostate gland position.
C. Urethra
- The urethra is a tube that runs through the penis and carries urine and semen out of the body.
- It passes through the prostate gland, which you can see in the diagram.
- So, C represents this continuous tube leading outward.
D. Testis
- Located in the scrotum, it’s where sperm and testosterone are produced.
- D is clearly in the lower part of the diagram, inside the scrotal sac, so it’s the testis.
Question
Which flower structures are indicated by the letters Y and Z?
▶️Answer/Explanation
Answer: D
Explanation:
Let’s Observe:
Y is pointing to the rounded base of the carpel (female part).
- This base is the ovary, not the ovule.
- Ovules are inside the ovary, not visible unless cut open.
- So, Y = Ovary
Z is pointing to the long stalk that supports the anther (male part).
- That stalk is the filament.
- So, Z = Filament
So the correct match is:
- Y = Ovary
- Z = Filament