Question

in humans, a cleft chin is dominant and no - cleft is recessive. what will the generations look like? assume that mendel’s method of crossing two true breeding parents with opposite traits is followed. check all that apply.
□ the p generation, f₁ generation, and f₂ generation will have all cleft chins.
□ the p generation, f₁ generation, and f₂ generation will have all no - cleft chins.
□ the p generation and f₁ generation will have all cleft chins.
□ the f₁ generation will have all cleft chins.
□ the p generation and f₂ generation will have all no - cleft chins.
□ the p generation and f₂ generation will have cleft chins and no - cleft chins.
□ the p generation, f₁ generation, and f₂ generation will have cleft chins and no - cleft chins.
done

Explanation:

1. Understand True - Breeding Parents and Traits:

• True - breeding parents (P generation) with opposite traits: One is homozygous dominant for cleft chin (e.g., CC) and the other is homozygous recessive for no - cleft chin (e.g., cc).
• Cleft chin (C) is dominant, no - cleft (c) is recessive.

1. Analyze F₁ Generation:

• When we cross CC (P generation, cleft chin) and cc (P generation, no - cleft chin), the offspring (F₁ generation) will have the genotype Cc. Since C is dominant, all F₁ individuals will have cleft chins.

1. Analyze F₂ Generation:

• When we cross two F₁ individuals (Cc x Cc), we use a Punnett square. The possible genotypes of the F₂ generation are CC, Cc, and cc. The phenotypic ratio of cleft chin (CC and Cc) to no - cleft chin (cc) is 3:1. So the F₂ generation will have both cleft and no - cleft chins.

1. Analyze P Generation:

• The P generation consists of two true - breeding parents: one with all cleft chins (CC) and one with all no - cleft chins (cc). So the P generation has both cleft and no - cleft chins.
• Now let's check each option:
• Option 1: The P generation has both cleft and no - cleft, F₂ has both, so this is wrong.
• Option 2: The P generation has both, F₁ has cleft, F₂ has both, so this is wrong.
• Option 3: The P generation has one with cleft and one with no - cleft, so it's not all cleft. This is wrong.
• Option 4: F₁ generation has genotype Cc, so all have cleft chins. This is correct.
• Option 5: P generation has one with cleft and one with no - cleft, F₂ has both, so this is wrong.
• Option 6: P generation has one with cleft (CC) and one with no - cleft (cc), F₂ has both cleft (CC, Cc) and no - cleft (cc) chins. This is correct.
• Option 7: F₁ generation has all cleft chins, so this is wrong.

Answer:

D. The \( F_1 \) generation will have all cleft chins.
F. The \( P \) generation and \( F_2 \) generation will have cleft chins and no - cleft chins.