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In humans, a cleft chin is dominant and no-cleft is recessive. Assuming Mendel's method of crossing two true-breeding parents with opposite traits is followed, what will the generations look like? Check all that apply.

A. The P generation, F1 generation, and F2 generation will have all cleft chins.
B. The P generation, F1 generation, and F2 generation will have all no-cleft chins.
C. The P generation and F1 generation will have all cleft chins.
D. The F1 generation will have all cleft chins.
E. The P generation and F2 generation will have all no-cleft chins.
F. The P generation and F2 generation will have cleft chins and no-cleft chins.
G. The P generation, F1 generation, and F2 generation will have cleft chins and no-cleft chins.



Answer :

GinnyAnswer
Sure! Let's solve this problem step-by-step.

1. Dominance of Traits:
- Cleft Chin (C) is dominant.
- No-Cleft Chin (c) is recessive.

2. P Generation (Parental Generation):
- True breeding means one parent is homozygous for the dominant trait (CC) and the other is homozygous for the recessive trait (cc).
- Crossing CC (cleft chin) x cc (no-cleft chin).

3. F1 Generation (First Filial Generation):
- Offspring from the P generation will all be heterozygous (Cc) due to the parents' genotypes.
- Since C is dominant, all F1 generation individuals will have cleft chins.

4. F2 Generation (Second Filial Generation):
- When F1 individuals (Cc) are crossed with each other: Cc x Cc.
- Use a Punnett square to determine the possible genotypes of the F2 generation:

```
C c
+----+----+
C | CC | Cc |
+----+----+
c | Cc | cc |
+----+----+
```

- Genotypic ratio: 1 CC : 2 Cc : 1 cc.
- Phenotypic ratio: 3 cleft chin : 1 no-cleft chin.

Based on these steps and results, we get:

- P Generation:
- All offspring have cleft chins (Cc).

- F1 Generation:
- All offspring still have cleft chins (Cc).

- F2 Generation:
- There are both cleft chins (3/4 of the offspring, CC or Cc) and no-cleft chins (1/4 of the offspring, cc).

Thus, the correct selections are:

- The [tex]$P$[/tex] generation and [tex]$F_1$[/tex] generation will have all cleft chins.
- The [tex]$F_2$[/tex] generation will have both cleft chins and no-cleft chins.

Finally, the correct options are:
- The [tex]$P$[/tex] generation and [tex]$F_1$[/tex] generation will have all cleft chins.
- The [tex]$F_2$[/tex] generation will have both cleft chins and no-cleft chins.