Question

name: _____________________________ date: _______ period: __
punnett square quick check
on an alien planet z lips are a popular type of pet bird. use the information provided
and your knowledge of heredity to complete the practice problems below.

1. write the correct genotype(s) for each pet bird. g represents green, and g represents

blue.
green _____________ blue _____________

1. what would happen if a heterozygous green zip and a blue zip mated? complete

the punnett square to determine the chances of each bird color.

a. what is the probability the popple offspring would
be green? _________
b. what is the probability the popple offspring would
be blue? _________

Explanation:

Step1: Determine genotypes for green and blue

In genetics, for a trait with dominant (G - green) and recessive (g - blue) alleles, a dominant - trait organism (green) can have genotypes \(GG\) (homozygous dominant) or \(Gg\) (heterozygous). A recessive - trait organism (blue) has genotype \(gg\) (homozygous recessive).

Step2: Set up Punnett square for cross \(Gg\times gg\)

The heterozygous green \(Gg\) can produce gametes \(G\) and \(g\). The blue \(gg\) can produce gametes \(g\) and \(g\). The Punnett square is:

	\(G\)	\(g\)
\(g\)	\(Gg\)	\(gg\)

Step3: Calculate probabilities

Out of 4 possible offspring genotypes (\(Gg, gg, Gg, gg\)) from the Punnett square:

• For green (\(Gg\)): There are 2 out of 4. The probability \(P(Gg)=\frac{2}{4}=\frac{1}{2}\)
• For blue (\(gg\)): There are 2 out of 4. The probability \(P(gg)=\frac{2}{4}=\frac{1}{2}\)

Answer:

1. Green: \(GG\) or \(Gg\); Blue: \(gg\)
2. A. \(\frac{1}{2}\); B. \(\frac{1}{2}\)