Question

The correct sequence of embryonic development is :

• A. Blastula - Morula - Zygote - Gastrula - Embryo
• B. Zygote - Blastula - Morula - Gastrula - Embryo
• C. Zygote - Morula - Blastula - Gastrula - Embryo
• D. Gastrula - Morula - Zygote - Blastula - Embryo

Answer 1

The correct option is (B):

Explanation of the correct option:

1. ​​Following fertilization, the mitotic division starts as the zygote moves towards the isthmus of the oviduct towards the uterus and this process is called cleavage.
   
2. The cleavage converts the egg into a compact mass of blastomeres called a morula, which ultimately transforms into a blastula by continuous divisions.
   
3. The blastula precedes the formation of the gastrula, in which the germ layers of the embryo form.
4. Gastrulation is followed by organogenesis when individual organs develop within the newly formed germ layers.
   
5. Each layer gives rise to specific tissues and organs in the developing embryo thus, the correct sequence is: Zygote --> Morula --> Blastula --> Gastrula --> Embryo
   

Final Answer: The correct sequence of embryonic development is: Zygote - Morula - Blastula - Gastrula - Embryo.