Question

1. in garden peas, tallness (t) is dominant to shortness (t), and axillary flowers (a) are dominant to terminal flowers (a). what are the expected genotypes and phenotypes of the offspring if a heterozygous tall, heterozygous axillary plant is crossed with a heterozygous tall, terminal plant? show your work in the form of a punnett square and write your answers as a phenotypic ratio.

Explanation:

Step1: Identify parent genotypes

Parent 1: Heterozygous tall, heterozygous axillary = $TtAa$
Parent 2: Heterozygous tall, terminal = $Ttaa$

Step2: Find gamete combinations

Gametes for $TtAa$: $TA, Ta, tA, ta$
Gametes for $Ttaa$: $Ta, ta$

Step3: Build Punnett Square

	$TA$	$Ta$	$tA$	$ta$
$ta$	$TtAa$	$Ttaa$	$ttAa$	$ttaa$

Step4: Classify phenotypes

• Tall, axillary: $TTAa, TtAa, TtAa$ (3)
• Tall, terminal: $TTaa, Ttaa, Ttaa$ (3)
• Short, axillary: $ttAa$ (1)
• Short, terminal: $ttaa$ (1)

Step5: Calculate phenotypic ratio

Simplify counts to whole number ratio.

Answer:

Phenotypic ratio: 3 Tall, axillary : 3 Tall, terminal : 1 Short, axillary : 1 Short, terminal (or $3:3:1:1$)
Genotypes of offspring: $TTAa, TTaa, TtAa, Ttaa, ttAa, ttaa$