Which of the following statements is incorrect?

Options

A. Placenta allows exchange of materials between mother and fetus.
B. The fetal part of placenta consists of the cells of chorion which produce projections called chorionic villi.
C. Antibodies cannot cross the placenta from mother to fetus.
D. Placenta secretes pregnancy hormones required for supporting fetal growth and metabolic changes in mother during pregnancy.

Answer

To determine which statement is incorrect regarding the placenta and its functions, we need to analyze the provided statements one by one.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "Placenta allows exchange of material between mother and fetus."
- This statement is correct. The placenta facilitates the exchange of nutrients, gases, and waste products between the mother and the developing fetus.

- **Statement 2**: "Placenta is a cord-like structure."
- This statement is incorrect. The placenta is not a cord-like structure; it is a flat, disc-shaped organ that attaches to the uterine wall. The cord-like structure referred to is the umbilical cord, which connects the fetus to the placenta.

- **Statement 3**: "Fetal part of placenta consists of the cells of chorion which produce projections called chorionic villi."
- This statement is correct. The chorion is indeed the outer fetal membrane that forms the placenta, and chorionic villi are projections that increase the surface area for exchange.

- **Statement 4**: "Antibodies cannot cross the placenta from mother to fetus."
- This statement is incorrect. While most antibodies do not cross the placenta, IgG antibodies can cross the placenta and provide immunity to the fetus.

- **Statement 5**: "Placenta secretes pregnancy hormones required for supporting fetal growth and metabolic changes in mother during pregnancy."
- This statement is correct. The placenta produces hormones such as human chorionic gonadotropin (hCG), human placental lactogen (hPL), and others that support pregnancy.

2. **Conclusion**:
- The incorrect statements are Statement 2 ("Placenta is a cord-like structure") and Statement 4 ("Antibodies cannot cross the placenta from mother to fetus"). However, since the question asks for one incorrect statement, we can conclude that Statement 2 is the primary incorrect statement regarding the structure of the placenta.

### Final Answer:
The incorrect statement is: "Placenta is a cord-like structure."