How many offspring genotypes are expected in a trihybrid cross between...
The number of genotypes in trihybrid cross is given by 3n where n = number of genes
Number of genes here = 3
∴ 3n = 33 = 27
Hence 27 genotypes.
View all questions of this test
How many offspring genotypes are expected in a trihybrid cross between...
Understanding Trihybrid Crosses
In a trihybrid cross, we consider three traits that follow Mendelian inheritance, specifically with each trait having a dominant and a recessive allele. When both parents are heterozygous for all three traits (AaBbCc x AaBbCc), we can determine the expected offspring genotypes and phenotypes.
Calculating Genotypes
- Each trait has two alleles (dominant and recessive), leading to the following combinations:
- Trait A: AA, Aa, aa
- Trait B: BB, Bb, bb
- Trait C: CC, Cc, cc
- Thus, for three traits, the combinations can be calculated as:
- Total genotypes = 3 (for A) x 3 (for B) x 3 (for C) = 27 genotypes
Calculating Phenotypes
- Each trait can express one of two phenotypes (dominant or recessive):
- Trait A: Dominant (A_) or Recessive (aa)
- Trait B: Dominant (B_) or Recessive (bb)
- Trait C: Dominant (C_) or Recessive (cc)
- Therefore, the total number of distinct phenotypes is calculated as:
- Total phenotypes = 2 (for A) x 2 (for B) x 2 (for C) = 8 phenotypes
Conclusion
From the calculations, we find:
- Total Genotypes: 27
- Total Phenotypes: 8
Thus, the correct answer is option 'D': 27 genotypes and 8 phenotypes. This aligns with Mendelian genetics principles, showcasing the diversity in offspring from a trihybrid cross.