Question

The eggs of birds are called
A. Polylecithal
B. Megalecithal
C. Macrolecithal
D. All of the above

Answer 1

Hint: Eggs of some organisms have yolk outside the embryo. It ensures that the yolk does not undergo cleavage. Cleavage constitute the first few mitotic divisions in the zygote to form a multicellular structure with no increase in the size

Complete step by step answer: Birds belong to the class Aves of the superclass Tetrapoda. They are warm-blooded organisms characterized by the presence of feathers to assist in flying. They are oviparous organisms and lay eggs for reproduction.
The developing embryo requires nutrition that is provided in two ways. In viviparous organisms, nutrients are delivered from the mother to the embryo. Yolk represents the reserved food material presence of the oviparous and ovoviviparous organisms.
Based on the amount of the yolk presence of the egg, they are classified into different categories. Alecithal egg has almost no yolk and is a characteristic feature of marsupials. Macrolecithal eggs are also called the oligolecithal eggs. These eggs have a small amount of yolk and are present in tunicates and sea urchins. Mesolecithal eggs have a moderate amount of yolk. Eggs of frogs and Petromyzon are mesolecithal.
Polylecithal eggs have a large amount of yolk. These eggs are also called macrolecithal eggs or the megalecithal eggs. Polylecithal eggs are the characteristic feature of birds, reptiles, insects, and prototherian mammals.
So, the correct answer is option D. All of the above.

Note: Birds and reptiles have telolecithal eggs. They have a large amount of yolk in their eggs. Most of the yolk in these organisms are concentrated at the one end of the egg cell called the vegetal pole.