Entrance of More Than One Sperm

Question

Entrance of more than one sperm
A)is called polyspermy and is disastrous for animal zygotes.
B)results in epigenesis.
C)is neutralized by fusion with polar bodies.
D)results in formation of a large pronucleus.
E)initiates cleavage.

Accepted Answer

Polyspermy is when more than one sperm fertilizes an egg, resulting in an abnormal number of chromosomes in the zygote. This is disastrous for animal zygotes as it can lead to developmental abnormalities or death.

Answer: C
 In some animals, such as sea urchins, polyspermy can be prevented by the fusion of polar bodies, which are small haploid cells that are formed during oogenesis. The polar bodies essentially act as decoys, tricking the extra sperm into fertilizing them instead of the egg.

Answer: D
 In some organisms, such as many insects, multiple sperm can enter the egg and fuse to form a large pronucleus. This is called polytene nuclear formation and can lead to polyploid offspring with multiple sets of chromosomes.

Answer: E
 While polyspermy is generally disastrous for animal zygotes, some animals can use polyspermy to trigger cleavage and embryonic development. This is called discoidal cleavage and is seen in organisms such as birds and reptiles.