Which is incorrect regarding fertilisation

Options

A. Fertilisation occurs in fallopian tube
B. Fertilisation is physico-chemical event
C. Cleavage leads to increased mass of protoplasm
D. Cleavage produces morula.

Answer

To determine which statement is incorrect regarding fertilization, let's analyze the process step by step:

### Step 1: Understand the Process of Fertilization
Fertilization is the process where a sperm cell and an ovum (egg) unite to form a zygote. This typically occurs in the fallopian tubes of the female reproductive system.

**Hint:** Remember that fertilization is the union of sperm and egg, leading to the formation of a zygote.

### Step 2: Identify the Site of Fertilization
Fertilization occurs specifically at the junction of the ampulla and isthmus of the fallopian tube. This is a well-established fact in human reproduction.

**Hint:** The fallopian tube is crucial for the fertilization process; focus on its specific parts.

### Step 3: Understand the Nature of Fertilization
Fertilization is described as a physicochemical event, meaning it involves both physical and chemical changes. This includes the fusion of the sperm and egg membranes and the subsequent changes that lead to the formation of the zygote.

**Hint:** Consider how physical interactions and chemical reactions play a role in fertilization.

### Step 4: Analyze the Cleavage Process
After fertilization, the zygote undergoes cleavage, which is a series of rapid cell divisions. Importantly, during cleavage, the overall mass of protoplasm decreases as the cells divide into smaller sizes. This means that while the number of cells increases, the size of each individual cell decreases.

**Hint:** Think about how cell division affects size and mass during early development.

### Step 5: Evaluate the Given Statements
Now, let’s evaluate the statements provided in the question:
1. Fertilization occurs in the fallopian tube. (True)
2. Fertilization is a physicochemical event. (True)
3. Cleavage leads to increased mass of protoplasm. (False)
4. Cleavage produces Morula. (True)

The third statement is incorrect because cleavage does not lead to an increased mass of protoplasm; rather, it leads to a decrease in the size of individual cells.

**Hint:** Look for the statement that contradicts the established facts about cleavage.

### Conclusion
The incorrect statement regarding fertilization is: **"Cleavage leads to increased mass of protoplasm."**

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