Question

Relative sizes of the egg cell, morula, blastula, and gastrula cells are
a) The egg cell is the smallest and gastrula cell is the largest
b) All are of equal size
c) The egg cell is the largest and morula cell is the smallest
d)The egg cell is the largest and the gastrula cell is the smallest.

Answer 1

Hint: The egg when fertilized it passes various stages in which it regularly increases in size. These stages start from the point when the unicellular egg divides to form multicellular. This repeated division leads to the formation of the morula.

Complete answer:
The egg cell is the largest cell among the four. The egg cell is visible to the naked eye and doesn’t require a microscope to see it. The smallest among the four is the morula which results due to the rapid division of the zygote into a 32-celled stage. The morula is then differentiated into the blastula stage in which the egg has divided into 200-300 cells. The rapid division of the cells which occur in the zygote is called the cleavage. The blastula has a fluid-filled cavity which is called the blastocoel. The blastula can then undergo either the meroblastic cleavage or the holoblastic cleavage depending upon the yolk needed by the embryo. The blastula rearranges itself and forms folds which will lead to the three germ layers of the embryo. This stage is known as the gastrula stage. These germ layers then give rise to the various organs and the body system of the developing embryo.

So, the answer is ‘egg cell is the largest and gastrula cell is the smallest’.

Note:
The development of the fertilized egg takes place in various stages in which rapid division of the cell takes place. This rapid division of the cell helps in the formation of the organs and the body structure of the embryo developing inside the womb of the mother.