Which one of the following statements about morula in humans is correct ?

Options

A. It has more cytoplasm and more DNA than an uncleaved zygote
B. It has almost equal quantity of cytoplasm as an uncleaved zygote but much more DNA
C. It has far less cytoplasm as well as less DNA than in an uncleaved zygote
D. It has more or less equal quantity of cytoplasm and DNA as in uncleaved zygote

Answer

To determine the correct statement about the morula in humans, let's analyze the options step by step:

### Step 1: Understand the Morula Stage
The morula is an early stage of embryonic development that occurs after several rounds of cell division (cleavage) of the fertilized egg (zygote). It consists of a solid ball of cells.

### Step 2: Compare Morula with Unclived Zygote
- **Cytoplasm**: The morula has almost equal quantity of cytoplasm compared to the unclived zygote. This means that the amount of cytoplasm does not significantly increase or decrease during the initial cleavage stages.
- **DNA**: The amount of DNA in the morula increases as the zygote divides, but the total quantity of cytoplasm remains relatively constant.

### Step 3: Evaluate the Options
1. **Option 1**: "It has more cytoplasm and more DNA than an unclived zygote."
- This is incorrect because the cytoplasm remains almost equal, while the DNA content increases.

2. **Option 2**: "It has almost equal quantity of cytoplasm as an unclived zygote but more DNA."
- This statement is correct as it accurately describes the relationship between the morula and the unclived zygote.

3. **Option 3**: "It has far less cytoplasm as well as less DNA than an unclived zygote."
- This is incorrect because the morula does not have less cytoplasm; it has more DNA.

4. **Option 4**: "It has more or less equal quantity of cytoplasm and DNA as an unclived zygote."
- This is incorrect because while the cytoplasm is equal, the DNA content is greater in the morula.

### Conclusion
The correct statement about the morula in humans is **Option 2**: "It has almost equal quantity of cytoplasm as an unclived zygote but more DNA."

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