Question

In tomatoes, red fruit (R) is dominant over yellow fruit (r). A plant that is heterozygous for red fruit is crossed with a plant that has yellow fruit. What will be the genotype ratio of the offspring be?

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Answer 1

To determine the genotype ratio of the offspring from a cross between a heterozygous red fruit tomato plant (Rr) and a yellow fruit tomato plant (rr), we can set up a Punnett square.

1. **Parental Genotypes:**
- Heterozygous red fruit plant: Rr
- Yellow fruit plant: rr

2. **Possible Gametes:**
- The Rr parent can produce gametes: R and r
- The rr parent can only produce gametes: r

3. **Punnett Square:**
```
r r
--------------
R | Rr | Rr |
--------------
r | rr | rr |
--------------
```

4. **Offspring Genotypes:**
- From the Punnett square, the genotypes of the offspring will be:
- Rr (red fruit) - 2 occurrences
- rr (yellow fruit) - 2 occurrences

5. **Genotype Ratio:**
- The ratio of genotypes among the offspring is:
- 2 Rr : 2 rr or simplified to 1 Rr : 1 rr

Thus, the genotype ratio of the offspring will be **1 Rr : 1 rr**.