With respect to a male erection which of the following statements is incorrect.

Correct Answer: B

Rationale: The correct answer is B because it is incorrect to say that a male erection is triggered by motor inputs to the higher brain regions. Erections are primarily controlled by the autonomic nervous system, specifically the parasympathetic division. Parasympathetic activity leads to vasodilation of penile blood vessels, resulting in increased blood flow and erection. Choices A, C, and D are incorrect because during an erection, there is indeed an increase in parasympathetic activity, a decrease in sympathetic activity, and dilation of arterioles in the penis.

Correct Answer: C

Rationale: The correct answer is C: Implantation. After fertilization, the embryo travels through the fallopian tube and reaches the uterus. During implantation, the embryo attaches itself to the endometrium lining of the uterus for further development. Menopause (A) is the cessation of menstrual cycles, ovulation (B) is the release of an egg from the ovary, and menstruation (D) is the shedding of the uterine lining if fertilization does not occur.

Correct Answer: B

Rationale: The correct answer is B: inside the scrotum. The testicles are located outside the abdominal cavity in a structure called the scrotum. This location is essential for temperature regulation as sperm production requires a slightly lower temperature than the body's core. Choices A, C, and D are incorrect as the testicles are not inside a muscular pouch, at the inguinal canal, or inside the abdominal cavity.

Correct Answer: B

Rationale: The correct answer is B because the seminal vesicle is indeed a pair organ, meaning there are two of them in the male reproductive system. They are located posterior to the urinary bladder and are responsible for producing and secreting a significant portion of the seminal fluid. Choice A is incorrect because the seminal vesicles are located behind the bladder, not above the prostate. Choice C is incorrect as the seminal vesicles are located laterally, not medially from the deferent ducts. Choice D is incorrect because the seminal vesicle is not an endocrine organ; it has an exocrine function in producing seminal fluid.

Correct Answer: D

Rationale: The correct answer is D because primary spermatocytes are diploid cells, containing a complete set of chromosomes (46 in humans). They are formed by spermatogonia through a process called meiosis. During meiosis, the primary spermatocytes undergo two divisions to generate haploid secondary spermatocytes with half the number of chromosomes. Choices A and C are incorrect because primary spermatocytes are formed by spermatogonia undergoing meiosis, not mitosis, and they generate secondary spermatocytes, not the other way around. Choice B is incorrect because primary spermatocytes are diploid, not haploid.