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Statement-1: Upto morula stage, the cell...

Statement-1: Upto morula stage, the cells divide without any increase in size.
Statement-2: Zona pellucida remains intact till cleavage is complete.

A

Both statement 1 and 2 are correct.

B

Statement 1 is correct but statement 2 is incorrect

C

statement 1 and incorrect but statement 2 is correct.

D

Both statement 1 and 2 are incorrect.

Text Solution

AI Generated Solution

The correct Answer is:
To analyze the statements provided in the question, we will break down the information step by step. ### Step 1: Understanding Statement 1 - **Statement 1** claims that "up to the morula stage, the cells divide without any increase in size." - After fertilization, the zygote undergoes a series of divisions known as cleavage. During this process, the cells divide but do not grow in size. This is because the divisions are rapid and do not allow for growth between them. - The morula stage refers to the stage where the zygote has divided into a solid ball of cells (approximately 16 cells). These divisions are characterized by the increase in the number of cells while the overall size of the embryo remains the same. ### Step 2: Understanding Statement 2 - **Statement 2** states that "the zona pellucida remains intact till cleavage is complete." - The zona pellucida is a protective layer surrounding the ovum and is crucial during fertilization. However, after fertilization, it does not remain intact throughout the cleavage process. - The zona pellucida is primarily needed for the maturation of the oocyte and will eventually degenerate as the embryo develops. It is not necessary once the embryo has formed and is progressing through cleavage. ### Step 3: Conclusion - From the analysis: - Statement 1 is **correct**: Cells divide without increasing in size up to the morula stage. - Statement 2 is **incorrect**: The zona pellucida does not remain intact until cleavage is complete; it degenerates after fertilization. ### Final Answer - Therefore, the correct answer is **Option B**: Statement 1 is correct, and Statement 2 is incorrect. ---
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