Answer:
25% of the progeny with genotype S3S4 is expected to express 5 units of color
Step-by-step explanation:
Available data:
- Skin color in a certain species of fish is inherited via a gene with four different alleles
- allele S1 confers one unit of color, S2 has two units, S3 has three units, and S4 confers four units.
Cross:
Parentals) S1 S3 x S2S4
Gametes) S1 S3 S2 S4
Punnett square) S1 S3
S2 S1S2 S2S3
S4 S1S4 S3S4
F1) 1/4 = 25% of the progeny is expected to be S1S2, expressing 3 units of color ⇒ allele S1 provides one unit, allele S2 provides two units of color
1/4 = 25% of the progeny is expected to be S2S3, expressing 5 units of color ⇒ allele S2 provides two units, allele S3 provides three units of color
1/4 = 25% of the progeny is expected to be S1S4, expressing 5 units of color ⇒ allele S1 provides one unit, allele S4 provides four units of color
1/4 = 25% of the progeny is expected to be S3S4, expressing 7 units of color ⇒ allele S3 provides three units, allele S4 provides four units of color
25% of the progeny with genotype S3S4 is expected to express 5 units of color