Which is incorrect -
ABO blood groups are controlled by the gene I
Gene I has four alleles
(iii) `A^(I)and I^(B)` produce same type of suger
(iv) I or `I^(@)` produce different type of sugar
(v) `I^(A) and I^(B)` are incomplete dominant

Options

A. I,ii
B. ii
C. ii, iii, iv
D. ii, iii, iv, v

Answer

To determine which statement about ABO blood groups is incorrect, we will analyze each statement one by one.

1. **ABO blood groups are controlled by the gene I.**
- This statement is **correct**. The ABO blood group system is indeed controlled by the gene I, which has different alleles that determine the blood type.

2. **Gene I has four alleles.**
- This statement is **incorrect**. The gene I has **three alleles**: I^A, I^B, and I^O (or I). Therefore, stating that it has four alleles is false.

3. **I^A and I^B produce the same type of sugar.**
- This statement is **incorrect**. I^A and I^B produce different types of sugars (antigens) on the surface of red blood cells. I^A produces A antigen, while I^B produces B antigen.

4. **I or I^O produce different types of sugar.**
- This statement is **correct**. The I^O allele does not produce any antigen, while I^A and I^B produce their respective sugars (antigens). Thus, I^O is different from both I^A and I^B.

5. **I^A and I^B are incompletely dominant.**
- This statement is **incorrect**. I^A and I^B are **codominant**, not incompletely dominant. When both alleles are present (I^A and I^B), they express both A and B antigens, resulting in blood type AB.

### Summary of Statements:
- **Correct Statements**: 1, 4
- **Incorrect Statements**: 2, 3, 5

### Conclusion:
The **incorrect statements** are:
- Gene I has four alleles (Statement 2).
- I^A and I^B produce the same type of sugar (Statement 3).
- I^A and I^B are incompletely dominant (Statement 5).

Thus, the answer to the question is that the statement "Gene I has four alleles" is incorrect.