Q.42 - Biology

Question

Why do mammalian eggs have a small concentration of yolk, while bird and reptile eggs have a large concentration of yolk? 

Step-by-Step Solution

Answer

• Mammalian eggs have a small concentration of yolk because the developing fetus obtains nutrients from the mother. 
• Bird and reptile eggs have a large concentration of yolk because the fetus develops outside of the mother's body, which require a lot of yolk in the egg to nourish the embryo during development.

Step 1. Introduction

Yolk is the medium for nutrition of the developing embryo. 

The yolk is the nutrient bearing portion of the egg whose primary function is to supply food for the development of the embryo. 

Step 2. Explanation

• Mammalian eggs do not need a lot of yolk because the developing fetus obtains nutrients from the mother. 
• Other species, in which the fetus develops outside of the mother's body, such as occurs with birds, require a lot of yolk in the egg to nourish the embryo during development.