Question 1
The following take part in the fecundation process:
- A. a single ovule;
- B. a single fecundated spermatozoon;
- C. one ovule with two nuclei, which means the pregnancy is monovitelline twin;
- D. two ovules, which means the pregnancy is bivitelline twin;
Show answer and rationale
Correct answer: C — one ovule with two nuclei, which means the pregnancy is monovitelline twin;
The correct answer is C, one ovule with two nuclei, which means the pregnancy is monovitelline twin. This is correct because during fertilization, a single sperm fertilizes an ovum, resulting in the formation of a zygote with two nuclei. Monovitelline twins originate from the splitting of a single fertilized egg, leading to two embryos with shared genetic material. The other choices, A and B, are incorrect as they do not accurately represent the process of fecundation. Choice A refers to a single ovule before fertilization, and choice B refers to a single spermatozoon, which is involved in fertilization but does not lead to the formation of twins. Choice D is also incorrect as it describes bivitelline twins, which result from the fertilization of two separate eggs by two different sperm, leading to genetically distinct individuals.