Question

The human egg is
A. Centrolecithal
B. Alecithal
C. Telolecithal
D. Megalecithal

Answer 1

The egg is a unique cell which is larger than the most somatic cells. It is a non motile and food laden cell. The cell fated to segregate from the organism and develop into an individual.

Complete Answer:
Let us analyse the options and find the correct answer.
Option A: The yolk concentrated in the centre of the egg with cytoplasm surrounding it is called Centrolecithal. Ex, insects and some hydrozoa.Therefore, this is an incorrect answer.

Option B: Egg without yolk is called Alecithal. Ex, human egg. Therefore, this is the correct option.
The human egg is one of the biggest cells in the body and it has a size of 100 microns. The human egg contains a nucleus which is haploid in nature, i.e. it has only half the number of chromosomes.

Option C: The egg in which the yolk is concentrated towards one pole i.e., vegetable pole and nucleus along with major part of cytoplasm is displaced is animal pole is called Telolecithal. Ex, amphibians. Therefore, this is an incorrect answer.

Option D : The egg which contains an enormous amount of yolk is called Megalecithal. Ex, reptiles, birds. Therefore, this is an incorrect answer.

Thus, the correct option is B) Alecithal.

Note: The human egg is 0.1mm in diameter.
- Yolk is the reserve food material in the cytoplasm of eggs. It may be formed of phospholipids, proteins, lipids and carbohydrates.
- The process of formation of yolk and its deposition in egg is called vitellogenesis.