Human Reproduction Test - 20

Yolk is concentrated towards vegetal pole. The nucleus and major part of cytoplasm is displaced to animal pole as in mesolecithal and macrolecithal eggs of vertebrates.

Blastopore is the opening by which the cavity of the gastrula (gastrocoel), communicates with the exterior. It is formed as a result of invagination of endoderm during embryonic development.

During maturation of some animals it evolves into the anus or the mouth; in others it is covered over and contributes to the canal joining the primitive gut with the cavity of the neural tube.

Testis in males and ovary in females developed from the Mesothelium layer of the peritoneum.

During the process of ovulation, the release of the egg occurs at the secondary oocyte stage in which meiosis-I has been completed.

So, the correct answer is 'Secondary oocyte stage'

The region outside the seminiferous tubules in testes is called interstitial spaces. It contains small blood vessels and interstitial cell. These interstitial cells are called Leydig cells. These cells constitute the endocrine tissue of testes.

It synthesises and secretes testicular hormones called androgens. Androgens are group of male sex hormones, mainly testosterone.

Egg (ovum) secretes a chemical named Fertilizin (composed of glycoprotein = Monosaccharides + amino acids). Sperm has on its surface a protein substance called antifertilizin (composed of acidic amino acids).

The Fertilizin of an egg interacts with the antifertilizin of a sperm of the same species. This interaction makes the sperms stick to the egg surface. The adhesion of sperm to the egg of the same species through chemical recognition is known as agglutination.

The cells of morula do not increase in size but divide rapidly because the zona pellucida is intact and thus the cells cannot grow in size. Therefore the assertion is correct.

Zona pellucida is the outer covering of the zygote and remains till the cleavage are finished and the embryo is implanted on the uterine wall. The zona pellucida starts degrading during the blastula stage because this is where the implantation takes place and thus the reason is also correct.

In human male, the urethra is about 8 inches long and opens at the end of the penis. The urethra provides an exit from the urine (excretory system) as well as for the semen (reproductive system) during ejaculation.

The pattern of cleavage is determined by the amount of yolk and its distribution. In holoblastic cleavage, the segmentation lines pass through the entire egg. Hence, it divides egg completely.

Egg in this type of cleavage contains moderate to sparse amount of yolk. For example, frog, human egg. In meroblastic cleavage, the segmentation lines do not completely pass through the egg and remain confined to a part of the egg. Hence, it does not divide egg completely.

Egg in this type of cleavage contains a large amount of yolk. For example, insects, birds