Question

During fertilization of a frog embryo, what appears at the opposite end of sperm entry?

A) The fertilization envelope forms, preventing polyspermy and protecting the developing embryo.
B) A contractile vacuole develops, expelling excess water from the fertilized egg.
C) The first mitotic spindle aligns, initiating the division of the zygote into two cells.
D) Cytoplasmic rearrangements occur, leading to the establishment of embryonic polarity.

Answer 1

The correct option is A). At the opposite end of sperm entry during frog embryo fertilization, a fertilization envelope forms to prevent polyspermy and ensure embryonic viability.

Step-by-step explanation:

During fertilization of a frog embryo, at the opposite end of sperm entry, the cortical reaction leads to the formation of the fertilization envelope. This fertilization envelope serves as a barrier to prevent further sperm entry, a phenomenon known as polyspermy. It thus ensures that only one sperm fertilizes the oocyte, which is critical for the development of a viable embryo with the correct number of chromosomes.