Tallness (T)in snapdragon plants is dominant to dwarfness (t),and red (C^R)flower color is not dominant to white (C^W).The heterozygous condition results in pink (C^RC^W)flower color.If snapdragons are heterozygous for height as well as for flower color,a mating between them will result in what ratio?

Question

Quizplus · Accepted Answer

The genotype of the first parent is TtRrWw (heterozygous for tallness, red flower color, and white flower color).
The genotype of the second parent is also TtRrWw.
Therefore, the possible gametes for the first parent are TRW, TRw, TrW, Trw, tRW, tRw, trW, trw.
Similarly, the possible gametes for the second parent are TRW, TRw, TrW, Trw, tRW, tRw, trW, trw.
Now, we can use a Punnett square to determine the different possible offspring:
```
|    TRW     |    TRw     |    TrW     |    Trw     |    tRW     |    tRw     |    trW     |    trw     |
|------------|------------|------------|------------|------------|------------|------------|------------|
| TRW | TTRRWW    | TTRrWW    | TtRRWW    | TtRrWW    | tTRRWW    | tTRrWW    | ttRRWW    | ttRrWW    |
| TRw | TTRRWw    | TTRrWw    | TtRRWw    | TtRrWw    | tTRRWw    | tTRrWw    | ttRRWw    | ttRrWw    |
| TrW | TtRRWW    | TtRrWW    | TTrrWW    | TtrrWW    | ttRRWW    | ttRrWW    | ttrrWW    | ttrrWW    |
| Trw | TtRRWw    | TtRrWw    | TTrrWw    | TtrrWw    | ttRRWw    | ttRrWw    | ttrrWw    | ttrrWw    |
| tRW | tTRRWW    | tTRrWW    | ttRRWW    | ttRrWW    | TTRRWW    | TTRrWW    | TtRRWW    | TtRrWW    |
| tRw | tTRRWw    | tTRrWw    | ttRRWw    | ttRrWw    | TTRRWw    | TTRrWw    | TtRRWw    | TtRrWw    |
| trW | ttRRWW    | ttRrWW    | ttrrWW    | ttrrWW    | ttRRWW    | ttRrWW    | TTrrWW    | TtrrWW    |
| trw | ttRRWw    | ttRrWw    | ttrrWw    | ttrrWw    | ttRRWw    | ttRrWw    | TTrrWw    | TtrrWw    |
```
Therefore, the offspring will have the following genotypic distribution:
- 6 TTRRWW (tall, red and white flowers)
- 3 TTRrWW (tall, pink and white flowers)
- 3 TtRRWW (tall, red and white flowers)
- 2 TTRRWw (tall, red and white flowers)
- 2 TTRrWw (tall, pink and white flowers)
- 2 TtRRWw (tall, red and white flowers)
- 1 TTrrWW (tall, white flowers)
- 1 TtrrWW (dwarf, red and white flowers)
- 1 ttRRWW (dwarf, red and white flowers)
- 1 TTrrWw (tall, white flowers)
- 1 TtrrWw (dwarf, pink and white flowers)
- 1 ttRRWw (dwarf, red and white flowers)
- 1 ttrrWW (dwarf, white flowers)
- 1 ttrrWw (dwarf, pink and white flowers)

Therefore, the ratio of the different genotypes is:
6:3:3:2:2:2:1:1:1:1:1:1:1:1 
which can be simplified to 
6:6:4:2:2:2:1:1:1:1:1:1:1:1 or 
6:2:2:1:1:1:1:1:1. 
This corresponds to answer choice B.

Tallness (T)in Snapdragon Plants Is Dominant to Dwarfness (T),and Red