Question

Compare the size of a fertilised egg of frog with the size of its blastula and gastrula stages. Now choose the correct observation regarding size of them.

• A. Zygote and blastula will be of same size, while gastrula will be larger
• B. Progressive increase in size from zygote to blastula than gastrula is observed
• C. All the three remain of same size
• D. Blastula and gastrula will be larger/same size, while zygote will be smaller

Answer 1

The correct option is A Zygote and blastula will be of same size, while gastrula will be larger

After the egg gets fertilised, a zygote is formed which undergoes cleavage to form a 2-celled stage and then a 4-celled stage which is called blastula. Blastula is of the same size as that of zygote because as the cells divide their size decrease but the overall size of the mass of cells formed is same as that of the zygote. After germinal layers are formed around the embryo, it is called gastrula which is larger in size than gastrula.

Hence, zygote and blastula will be of the same size while gastrula will be larger.

So, the correct answer is 'Zygote and blastula will be of the same size, while gastrula will be larger'.