Answer :
To understand the generational patterns when crossing two true-breeding parents with opposite traits for cleft chin (dominant, represented by [tex]\( C \)[/tex]) and no-cleft chin (recessive, represented by [tex]\(c\)[/tex]), we can follow Mendel's method of genetic inheritance. Let's break it down step-by-step:
1. P Generation (Parental Generation):
- One parent is homozygous dominant ([tex]\( CC \)[/tex]) for cleft chin.
- The other parent is homozygous recessive ([tex]\(cc\)[/tex]) for no-cleft chin.
- When these two parents are crossed, their offspring will be heterozygous ([tex]\(Cc\)[/tex]).
2. F1 Generation (First Filial Generation):
- All offspring (F1) from the P generation are heterozygous ([tex]\(Cc\)[/tex]).
- Since cleft chin ([tex]\(C\)[/tex]) is dominant, all F1 individuals will display the cleft chin phenotype.
3. F2 Generation (Second Filial Generation):
- F1 individuals ([tex]\(Cc\)[/tex]) are crossed with each other.
- By constructing a Punnett square for the [tex]\(Cc \times Cc\)[/tex] cross:
```
C c
+---+---+
C | CC | Cc |
+---+---+
c | Cc | cc |
+---+---+
```
- Genotype ratio: 1 [tex]\(CC\)[/tex]: 2 [tex]\(Cc\)[/tex]: 1 [tex]\(cc\)[/tex]
- Phenotype ratio: 3 with cleft chin (1 [tex]\(CC\)[/tex] + 2 [tex]\(Cc\)[/tex]) : 1 with no-cleft chin (1 [tex]\(cc\)[/tex]).
Based on this analysis, we can answer the given options:
1. The P generation, [tex]$F_1$[/tex] generation, and [tex]$F_2$[/tex] generation will have all cleft chins.
- False. The F2 generation will have a mix of cleft chin and no-cleft chin individuals.
2. The P generation, [tex]$F_1$[/tex] generation, and [tex]$F_2$[/tex] generation will have all no-cleft chins.
- False. The P generation and F1 generation will have cleft chins due to the dominant gene, and the F2 generation will have a mix.
3. The P generation and [tex]$F_1$[/tex] generation will have all cleft chins.
- True. The P generation (with [tex]\(CC\)[/tex] and [tex]\(cc\)[/tex]) and F1 generation (with [tex]\(Cc\)[/tex]) will all exhibit cleft chins.
4. The [tex]$F_1$[/tex] generation will have all cleft chins.
- True. All members of the F1 generation are [tex]\(Cc\)[/tex], therefore all will have cleft chins due to the dominant [tex]\(C\)[/tex] allele.
5. The P generation and [tex]$F_2$[/tex] generation will have all no-cleft chins.
- False. The P generation will have cleft chins, and the F2 generation is mixed.
6. The P generation and [tex]$F_2$[/tex] generation will have cleft chins and no-cleft chins.
- False. Only the F2 generation will have both cleft and no-cleft chins.
7. The P generation, [tex]$F_1$[/tex] generation, and [tex]$F_2$[/tex] generation will have cleft chins and no-cleft chins.
- False. The P generation and F1 generation will only have cleft chins. Only the F2 generation will show both traits.
Therefore, the correct options are:
- The P generation and [tex]\(F_1\)[/tex] generation will have all cleft chins.
- The [tex]\(F_1\)[/tex] generation will have all cleft chins.
So, your selected answer should include:
- "The P generation and [tex]$F_1$[/tex] generation will have all cleft chins."
- "The [tex]$F_1$[/tex] generation will have all cleft chins."
1. P Generation (Parental Generation):
- One parent is homozygous dominant ([tex]\( CC \)[/tex]) for cleft chin.
- The other parent is homozygous recessive ([tex]\(cc\)[/tex]) for no-cleft chin.
- When these two parents are crossed, their offspring will be heterozygous ([tex]\(Cc\)[/tex]).
2. F1 Generation (First Filial Generation):
- All offspring (F1) from the P generation are heterozygous ([tex]\(Cc\)[/tex]).
- Since cleft chin ([tex]\(C\)[/tex]) is dominant, all F1 individuals will display the cleft chin phenotype.
3. F2 Generation (Second Filial Generation):
- F1 individuals ([tex]\(Cc\)[/tex]) are crossed with each other.
- By constructing a Punnett square for the [tex]\(Cc \times Cc\)[/tex] cross:
```
C c
+---+---+
C | CC | Cc |
+---+---+
c | Cc | cc |
+---+---+
```
- Genotype ratio: 1 [tex]\(CC\)[/tex]: 2 [tex]\(Cc\)[/tex]: 1 [tex]\(cc\)[/tex]
- Phenotype ratio: 3 with cleft chin (1 [tex]\(CC\)[/tex] + 2 [tex]\(Cc\)[/tex]) : 1 with no-cleft chin (1 [tex]\(cc\)[/tex]).
Based on this analysis, we can answer the given options:
1. The P generation, [tex]$F_1$[/tex] generation, and [tex]$F_2$[/tex] generation will have all cleft chins.
- False. The F2 generation will have a mix of cleft chin and no-cleft chin individuals.
2. The P generation, [tex]$F_1$[/tex] generation, and [tex]$F_2$[/tex] generation will have all no-cleft chins.
- False. The P generation and F1 generation will have cleft chins due to the dominant gene, and the F2 generation will have a mix.
3. The P generation and [tex]$F_1$[/tex] generation will have all cleft chins.
- True. The P generation (with [tex]\(CC\)[/tex] and [tex]\(cc\)[/tex]) and F1 generation (with [tex]\(Cc\)[/tex]) will all exhibit cleft chins.
4. The [tex]$F_1$[/tex] generation will have all cleft chins.
- True. All members of the F1 generation are [tex]\(Cc\)[/tex], therefore all will have cleft chins due to the dominant [tex]\(C\)[/tex] allele.
5. The P generation and [tex]$F_2$[/tex] generation will have all no-cleft chins.
- False. The P generation will have cleft chins, and the F2 generation is mixed.
6. The P generation and [tex]$F_2$[/tex] generation will have cleft chins and no-cleft chins.
- False. Only the F2 generation will have both cleft and no-cleft chins.
7. The P generation, [tex]$F_1$[/tex] generation, and [tex]$F_2$[/tex] generation will have cleft chins and no-cleft chins.
- False. The P generation and F1 generation will only have cleft chins. Only the F2 generation will show both traits.
Therefore, the correct options are:
- The P generation and [tex]\(F_1\)[/tex] generation will have all cleft chins.
- The [tex]\(F_1\)[/tex] generation will have all cleft chins.
So, your selected answer should include:
- "The P generation and [tex]$F_1$[/tex] generation will have all cleft chins."
- "The [tex]$F_1$[/tex] generation will have all cleft chins."
