Chapter 36, Problem 4STP

Summary Introduction

Introduction :

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 4STP

Correct answer : 

The correct answer is option (B) egg➝ zygote➝ morula ➝blastocyst

Explanation of Solution

Explanation/justification for the correct answer :

Option (B) egg→zygote→morula→blastocyst. This is the correct sequence of human development in the first week. With the fertilization of the egg by sperm creating the first cell that is the zygote, the first week of human life starts. The division of cells contributes to a ball of cells, the morula. The blastocyst is formed by the more cell break and cavity forming in the cell core.So, this is the correct option.

Explanation for incorrect answer : 

Option (A) egg→morula→blastocyst→ zygote. The first week in human development undergoes the sequence of fertilization of egg and then creating zygote and cell division occurs leading to morula and then forming blastocyst. So this is an incorrect option.

Option (C) morula→blastocyst→egg-→zygote this is not the correct sequence as during the first week egg fertilizes first. So, this is an incorrect answer.

Option (D) morula→egg→zygote→blastocyst. Morula occurs after formation of eggs and zygote. So, this is an incorrect option.