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 morule leads to the formation of blastocyst.
D. The embryo is formed by the 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 options.

### Step-by-Step Solution:

1. **Understanding Fertilization**:
- Fertilization in humans occurs when a sperm cell successfully penetrates an ovum (egg) to form a zygote. This process typically happens in the ampulla of the fallopian tube.

**Hint**: Remember that fertilization requires both sperm and ovum to meet at the right location.

2. **Evaluating the First Statement**:
- The first statement claims that fertilization can occur only 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**: Identify the key location where fertilization occurs.

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

**Hint**: Consider the layers surrounding the ovum and the order of contact.

4. **Evaluating the Third Statement**:
- The third statement mentions that the division of morula leads to the formation of a blastocyst.
- This statement is **correct**. After fertilization, the zygote divides to form a morula, which then develops into a blastocyst.

**Hint**: Recall the stages of development post-fertilization.

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

**Hint**: Focus on the role of the inner cell mass in embryonic development.

### Conclusion:
After evaluating all the statements, the **wrong statement** is the second one, which incorrectly states that the sperm contacts the cell membrane of the ovum first.

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