Chapter 36, Problem 18A

Summary Introduction

Introduction:

The Sequence of development is the process through which a baby is developed and finally takes birth. Early development is the first week of the human development period. Many developmental changes occur at this period as the zygote travels through the oviduct.

Answer to Problem 18A

Correct answer:

The correct answer is option (C) Developing humans get their nourishment from the placenta.

Explanation of Solution

Explanation/justification for the correct answer:

Option (C) Developing humans get their nourishment from the placenta.  Placenta offers the embryo nutrients inside the mother's body. The foetus develops into the womb of the mother and feeds from the tissue called the placenta from mother's blood. The placenta is a transient organ that forms during pregnancy in the uterus. So, this is the correct option.

Explanation for incorrect answer: 

Option (A) The yolk in humans is converted into muscle. The human yolk sac is smaller than the chick yolk sac because developing humans get their nourishment from the placenta. The yolk in humans is not converted into muscle. So, this is an incorrect option.

Option (B) The yolk sac in chicks keeps the embryo warm. The human yolk sac is smaller than the chick yolk sac because developing humans get their nourishment from the placenta. So, this is an incorrect answer.

Option (D) The yolk sac serves no purpose for a developing human. The human yolk helps in developing human. So, this is an incorrect option.