In Lathyrus odoratus, hybrid blue flowered and long pollen plant is test crosses with homozygous recessive red flowered and round pollen plant then how many parental types are obtained when genes are present in cis stage in parents ?

Options

A. `50%`
B. `43.7%`
C. `87.4%`
D. `12.6%`

Answer

To solve the problem, we need to analyze the genetic cross involving Lathyrus odoratus (sweet pea) and determine how many parental types are obtained when the genes are in a cis configuration.

### Step-by-Step Solution:

1. **Identify the Traits and Alleles**:
- The traits being studied are flower color and pollen shape.
- Flower color: Blue (dominant, B) and Red (recessive, b).
- Pollen shape: Long (dominant, L) and Round (recessive, l).

2. **Determine the Genotypes of the Parents**:
- The hybrid plant has blue flowers and long pollen, indicating it is heterozygous for both traits: Genotype = BbLl.
- The homozygous recessive plant has red flowers and round pollen: Genotype = bbll.

3. **Define the Cis Configuration**:
- In the cis configuration, the dominant alleles are on the same chromosome. Thus, the genotype of the hybrid parent can be represented as:
- B L / b l (where B and L are on one chromosome and b and l on the homologous chromosome).

4. **Gamete Formation**:
- The hybrid parent (BbLl) can produce the following gametes due to the cis configuration:
- BL (dominant alleles together)
- bl (recessive alleles together)
- The homozygous recessive parent (bbll) can only produce one type of gamete:
- bl (both alleles are recessive).

5. **Perform the Test Cross**:
- The test cross involves crossing the gametes from the hybrid parent with those from the homozygous recessive parent.
- The possible combinations from the gametes are:
- BL (from hybrid) with bl (from recessive) → BbLl (Blue flowers, Long pollen)
- bl (from hybrid) with bl (from recessive) → bbll (Red flowers, Round pollen)

6. **Count the Progeny Types**:
- The resulting offspring from this cross will be:
1. BbLl (Blue flowers, Long pollen) - parental type
2. bbll (Red flowers, Round pollen) - parental type
- Since the gametes from the homozygous recessive parent only produce one type, we will only see these two phenotypes.

7. **Conclusion**:
- The total number of parental types obtained from this cross is **2** (BbLl and bbll).

### Final Answer:
**2 parental types are obtained when the genes are present in cis stage in the parents.**