Choose the correct sequence of events in the post-fertilization cleavage process.

Correct Answer: A

Rationale: The correct sequence is A: Zygote - morula - 2 cells - 4 cells - 8 cells - blastula. After fertilization, the zygote undergoes cleavage to form the morula, which then divides into 2 cells, then 4 cells, and further into 8 cells. These cells then rearrange to form the blastula. This sequence aligns with the natural progression of post-fertilization cleavage in embryonic development. Choices B, C, and D are incorrect because they do not follow the correct chronological order of events in post-fertilization cleavage. In these sequences, the order of cell divisions is mixed up, leading to an inaccurate representation of the cleavage process. It is crucial to understand the logical progression of events in embryonic development to identify the correct sequence of post-fertilization cleavage.

Correct Answer: C

Rationale: The correct answer is C: Bleeding from the vagina. This finding is concerning in a postmenopausal woman as it could indicate underlying serious conditions such as endometrial cancer. Immediate action is needed to investigate the cause and provide appropriate care. A: Vaginal dryness is common in postmenopausal women and can be managed with lubricants or hormone therapy. B: Not having a Pap test for 3 years is important for cervical cancer screening but does not require immediate action. D: Leakage of urine, while a concern, does not require immediate action as it is not directly related to a potentially life-threatening condition.

Correct Answer: B

Rationale: The correct answer is B: seminiferous tubules. Testicular cancer arises from the cells within the seminiferous tubules where sperm production occurs. These tubules are the most common site for testicular cancer to develop. The other choices are incorrect because testicular cancer typically does not originate from the scrotal sac (A), epididymis (C), or interstitial cells (D). The scrotal sac contains the testicles but does not produce cancer, the epididymis is a different structure involved in sperm maturation, and interstitial cells produce hormones rather than sperm.

Correct Answer: D

Rationale: The correct answer is D: blood leaves erectile tissue. During penile erection, blood flows into the erectile tissue, causing the penis to become erect. Parasympathetic stimulation and arterial dilation are essential for promoting blood flow into the penis, while venous compression helps to trap blood within the erectile tissue, sustaining the erection. However, if blood were to leave the erectile tissue, it would result in a loss of erection. Therefore, choice D is not compatible with penile erection.

Correct Answer: A

Rationale: The corona radiata cells appear at birth because they are a crucial part of the ovum and are present as soon as the ovum is released from the ovary. The other choices are incorrect because corona radiata cells are not formed at 12, 28, or 1 day after birth. They are specifically associated with the ovum and its release during ovulation, making option A the most accurate.