Question

1. in horses, the coat color black is dominant (b) over chestnut (b). the trotting gait is dominant (t) over the pacing gait (t). if a homozygous black pacer is mated to a homozygous chestnut, heterozygous trotter, what will be the probabilities for genotype and phenotype of the $f_1$ generation?parent 1: bbttparent 2: bbttf1 offspring: genotype percents and ratios =phenotypes percents and ratios =

Explanation:

Step1: Define parent genotypes

Parent 1 (homozygous black pacer): $BBtt$
Parent 2 (homozygous chestnut, heterozygous trotter): $bbTt$

Step2: Identify gamete options

Parent 1 gametes: All $Bt$
Parent 2 gametes: $bT$, $bt$ (each 50% chance)

Step3: Cross gametes for genotypes

• $Bt \times bT = BbTt$
• $Bt \times bt = Bbtt$

Each genotype has a $\frac{1}{2}$ (50%) probability, ratio 1:1.

Step4: Determine phenotypes from genotypes

• $BbTt$: $B$ (black) + $T$ (trotting) → Black, trotting
• $Bbtt$: $B$ (black) + $tt$ (pacing) → Black, pacing

Each phenotype has a $\frac{1}{2}$ (50%) probability, ratio 1:1.

Answer:

Genotype Probabilities/Ratios:

• $BbTt$: 50% (1:2 ratio with $Bbtt$)
• $Bbtt$: 50% (1:2 ratio with $BbTt$)

Phenotype Probabilities/Ratios:

• Black, trotting: 50% (1:2 ratio with black, pacing)
• Black, pacing: 50% (1:2 ratio with black, trotting)