Question

Assertion :In morula stage the cell divides without increase in size. Reason: Zona pellucida remains till cleavage is finished.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

• The cells of morula do not increase in size but divide rapidly because the zona pellucida is intact and thus the cells cannot grow in size. Therefore the assertion is correct.
• Zona pellucida is the outer covering of the zygote and remains till the cleavage is finished and the embryo is implanted on the uterine wall. The zona pellucida starts degrading during the blastula stage because this is where the implantation takes place and thus the reason is also correct.
• Here both the reason and assertion are correct individually but the reason is not the correct explanation of the assertion. Because there is no relation between the assertion and reason.
• So, the correct option is 'Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion'