As a result of monohybrid cross among Pea plants, the genotypic ratio obtained by Mendel is

Options

A. `1:1`
B. `1:3:1`
C. `1:2:1`
D. `3:1`

Answer

To solve the question regarding the genotypic ratio obtained from a monohybrid cross among pea plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Monohybrid Cross**: A monohybrid cross involves two individuals that differ in a single trait. In Mendel's experiments with pea plants, he often used tall (T) and dwarf (t) plants as his subjects.

2. **Identify the Parental Genotypes**: In this case, we have:
- Tall parent: Homozygous dominant (TT)
- Dwarf parent: Homozygous recessive (tt)

3. **Gamete Formation**: Each parent produces gametes:
- The tall parent (TT) can only produce gametes with the allele T.
- The dwarf parent (tt) can only produce gametes with the allele t.

4. **F1 Generation**: When these gametes fuse during fertilization, all offspring (F1 generation) will have the genotype:
- Tt (heterozygous, tall phenotype)

5. **Selfing the F1 Generation**: To find the genotypic ratio, we need to self-fertilize the F1 plants (Tt x Tt). The possible gametes from each Tt plant are T and t.

6. **Punnett Square**: Set up a Punnett square to visualize the combinations:
```
T t
----------------
T | TT | Tt |
----------------
t | Tt | tt |
----------------
```

7. **Determine the Genotypes**: From the Punnett square, we can see the offspring genotypes:
- 1 TT (homozygous dominant)
- 2 Tt (heterozygous)
- 1 tt (homozygous recessive)

8. **Calculate the Genotypic Ratio**: The genotypic ratio from the cross is:
- 1 TT : 2 Tt : 1 tt

### Final Answer:
The genotypic ratio obtained by Mendel from a monohybrid cross among pea plants is **1 : 2 : 1**.

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