The wrong statement about fertilization /post fertilization change in humans is

Options

A. Fertilisation can occur only if sperm and ovum simultaneously reach the ampulla of the fallopian tube .
B. During fertilisation , the sperm comes in contact with cell membrane of the ovum first .
C. The division of the morula leads to the formation of blastocyst.
D. The embryo is formed by the differentiation of inner cell mass

Answer

To solve the question regarding the wrong statement about fertilization or post-fertilization changes in humans, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Understanding Fertilization**:
- Fertilization in humans typically occurs in the ampulla of the fallopian tube, where the sperm and ovum must meet.

**Hint**: Remember that fertilization requires both sperm and ovum to be present in the same location at the same time.

2. **Evaluating the First Statement**:
- The first statement claims that fertilization can only occur if sperm and ovum simultaneously reach the ampulla of the fallopian tube.
- This statement is **correct** because the ampulla is indeed the most common site for fertilization.

**Hint**: Think about where fertilization takes place in the female reproductive system.

3. **Evaluating the Second Statement**:
- The second statement mentions that during fertilization, the sperm comes in contact with the cell membrane of the ovum first.
- This statement is **incorrect** because the sperm first encounters the corona radiata, which is the outer layer surrounding the ovum, before it reaches the cell membrane.

**Hint**: Consider the layers that surround the ovum and the order in which the sperm interacts with them.

4. **Evaluating the Third Statement**:
- The third statement states that the division of morula leads to the formation of a blastocyst.
- This statement is **correct** as the morula stage indeed develops into the blastocyst stage during embryonic development.

**Hint**: Recall the stages of early embryonic development and how they progress.

5. **Evaluating the Fourth Statement**:
- The fourth statement asserts that the embryo is formed by the differentiation of the inner cell mass.
- This statement is also **correct** because the inner cell mass of the blastocyst differentiates to form the embryo.

**Hint**: Think about the role of the inner cell mass in embryonic development.

6. **Conclusion**:
- After evaluating all statements, the second statement is identified as the wrong statement about fertilization/post-fertilization changes in humans.

### Final Answer:
The wrong statement about fertilization/post-fertilization change in humans is: "During fertilization, the sperm comes in contact with the cell membrane of the ovum first."