Which statement is wrong

Options

A. Law of independent assortment is because of crossing over
B. Apart from Pisum sativum, Mendel had also worked on Hieraceum
C. A plant with genotype TTRR will produce 3 kinds of gametes
D. The test cross ratio of a dihybrid is 1:1:1:1

Answer

To determine which statement is wrong, we need to analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The first statement claims that the law of independent assortment is because of crossing over.
- **Analysis:** The law of independent assortment states that alleles of different genes assort independently of one another during gamete formation. This is primarily due to the random orientation of homologous chromosomes during metaphase I of meiosis, not directly because of crossing over.
- **Conclusion:** This statement is incorrect.

2. **Evaluate the Second Statement:**
- The second statement mentions that apart from *Pisum sativum*, Mendel also worked on *Hiracium*.
- **Analysis:** Mendel is known for his experiments with *Pisum sativum* (pea plants) and he also worked with *Hiracium* (a type of flowering plant).
- **Conclusion:** This statement is correct.

3. **Evaluate the Third Statement:**
- The third statement states that a plant with genotype TTRR will produce three kinds of gametes.
- **Analysis:** The genotype TTRR can only produce one type of gamete, which is TR, because both alleles for each gene are homozygous (TT and RR).
- **Conclusion:** This statement is incorrect.

4. **Evaluate the Fourth Statement:**
- The fourth statement claims that the test cross from a dihybrid is in the ratio of 1:1:1:1.
- **Analysis:** In a dihybrid cross, when a heterozygous individual is crossed with a homozygous recessive individual, the expected phenotypic ratio is indeed 1:1:1:1.
- **Conclusion:** This statement is correct.

### Final Conclusion:
The wrong statements are the first and third statements. However, since the question asks for which statement is wrong, the most clear and direct answer is the third statement about the gametes.