Infertility could develop when the sperm cells display _____.

Correct Answer: D

Rationale: The correct answer is D because a low sperm count (less than 20 million per ml semen) can lead to infertility as it decreases the chances of successful fertilization. A high sperm count (choice A) is actually beneficial for fertility. Increased acrosomal activity (choice B) can enhance fertilization potential. Normal morphology (choice C) refers to the shape and size of sperm, which is important for fertility but not the primary factor in infertility due to low sperm count. Overall, a low sperm count is the most significant factor in infertility.

Correct Answer: A

Rationale: The correct answer is A: labia major. The scrotum in males corresponds to the labia major in females as they both serve as protective structures for the reproductive organs. The labia major in females is analogous to the scrotum in males in terms of function and location. The other choices are incorrect because the labia minor (B) is a smaller structure located inside the labia major, the pudendal cleft (C) refers to the space between the labia major and labia minor, and the mons pubis (D) is a rounded, fatty area located over the pubic bone.

Correct Answer: A

Rationale: The correct sequence is A: FSH, as it initiates the menstrual cycle by stimulating the growth of follicles in the ovaries. LH then triggers ovulation. Estrogen is produced by the developing follicles and peaks before ovulation, while progesterone rises after ovulation. The other choices are incorrect as they do not follow the physiological sequence of hormonal actions in the menstrual cycle.

Correct Answer: B

Rationale: The correct answer is B (44 autosomes) because a human primary spermatocyte is a diploid cell containing a total of 44 autosomes. This is because humans have 22 pairs of autosomes in their somatic cells. During meiosis I, the primary spermatocyte undergoes replication and recombination, resulting in 22 pairs of autosomes (44 autosomes) that will be divided into two haploid secondary spermatocytes. Choices A, C, and D are incorrect because they do not reflect the correct number of autosomes present in a human primary spermatocyte.

Correct Answer: B

Rationale: The correct answer is B (50-100) because each lobule in the testis contains multiple seminiferous tubules where sperm production occurs. The average number of seminiferous tubules per lobule ranges from 50 to 100. This is supported by anatomical studies and research on testicular structure. Explanation: A: 1-3 - This is too low as each lobule contains more seminiferous tubules for efficient sperm production. C: 200-300 - This is too high as it overestimates the number of seminiferous tubules per lobule. D: 500 or more - This is excessive and not accurate based on scientific findings. In summary, choice B is correct because it accurately reflects the typical range of seminiferous tubules per lobule, while the other choices either underestimate or overestimate this number.