Choose the incorrect statement from the following

Options

A. In birds and mammals internal fertilisation takes place
B. Colostrum contains antibodies and nutrients
C. Polyspermy is prevented by the physical changes in the egg surface
D. In the human female implantation occurs almost seven days after fertilisation

Answer

To solve the question of identifying the incorrect statement from the given options, we will analyze each statement one by one.

### Step 1: Analyze Statement 1
**Statement:** In birds and mammals, internal fertilization takes place.
**Analysis:** This statement is correct. Birds and mammals both exhibit internal fertilization, where the male and female gametes fuse inside the female's body.

**Hint:** Remember that internal fertilization is a characteristic of certain animal groups, including birds and mammals.

### Step 2: Analyze Statement 2
**Statement:** Cholostrum contains antibodies and nutrients.
**Analysis:** This statement is also correct. Colostrum is the first milk produced after childbirth, rich in antibodies (especially immunoglobulin A) and nutrients, providing passive immunity to the newborn.

**Hint:** Colostrum is essential for newborns as it provides both immunity and nutrition.

### Step 3: Analyze Statement 3
**Statement:** Polyspermy is prevented by the physical changes in the egg surface.
**Analysis:** This statement is incorrect. While physical changes do occur, polyspermy is primarily prevented by chemical changes, specifically the release of cortical enzymes that harden the zona pellucida, preventing additional sperm from entering the egg.

**Hint:** Consider both physical and chemical mechanisms when discussing biological processes like fertilization.

### Step 4: Analyze Statement 4
**Statement:** In the human female, implantation occurs almost seven days after fertilization.
**Analysis:** This statement is correct. Implantation typically occurs about 6 to 7 days after fertilization, when the embryo embeds itself into the uterine lining.

**Hint:** Timing of implantation is crucial in understanding early pregnancy stages.

### Conclusion
After analyzing all the statements, we find that the incorrect statement is **Statement 3**, which claims that polyspermy is prevented solely by physical changes in the egg surface.

**Final Answer:** The incorrect statement is Statement 3.