Question

1. one of spongebobs cousins, spongebillybob, recently met a cute squarepants gal, spongegerdy, at a local dance and fell in love. use your knowledge of genetics to answer the questions below.

(a) if spongegerdys father is a heterozygous squarepants and her mother is a roundpants, what is her genotype? complete the first punnett square to show the possible genotypes.
based on your results, what would gerdys genotype have to be? ______
(b) complete the second punnett square to show the possibilities that would result if billy bob & gerdy had children.
note: spongebillybob is heterozygous for his squarepantsshape.
(c) what is the probability of kids with squarepants? ______ %
(d) what is the probability of kids with roundpants? ______ %

Explanation:

Step1: Define allele notation

Let $S$ = dominant squarepants allele, $s$ = recessive roundpants allele.

Step2: (a) Set up parental genotypes

SpongeGerdy's father: $Ss$ (heterozygous squarepants), mother: $ss$ (roundpants).
Punnett square for her possible genotypes:

	$S$	$s$
$s$	$Ss$	$ss$

Gerdy has squarepants, so her genotype must be $Ss$ (only dominant phenotype genotype possible from this cross).

Step3: (b) Set up cross for offspring

SpongeBillyBob: $Ss$ (heterozygous squarepants), Gerdy: $Ss$.
Punnett square for their offspring:

	$S$	$s$
$s$	$Ss$	$ss$

Step4: (c) Calculate squarepants probability

Squarepants genotypes: $SS, Ss$. Count of favorable genotypes: 3 out of 4.
Probability: $\frac{3}{4} \times 100 = 75\%$

Step5: (d) Calculate roundpants probability

Roundpants genotype: $ss$. Count of favorable genotype: 1 out of 4.
Probability: $\frac{1}{4} \times 100 = 25\%$

Answer:

(a) Gerdy's genotype: $Ss$
Punnett square for Gerdy's possible genotypes:

	$S$	$s$
$s$	$Ss$	$ss$

(b) Punnett square for BillyBob & Gerdy's offspring:

	$S$	$s$
$s$	$Ss$	$ss$

(c) $75$
(d) $25$