Question

bikini bottom genetics review
name

1. use your notes to complete each definition.

purebred - also called and consists of gene pairs with genes that are the .
hybrid - also called and consists of gene pairs with genes that are .
genotype is the actual makeup represented by .
phenotype is the appearance of a trait, such as a body color.

1. classify each of the following gene pairs as heterozygous (he) or homozygous (ho).

tt bb dd ff rr

1. give the possible genotypes for each trait based on the

information provided in the chart.

characteristic	dominant gene	recessive gene
body color	yellow (y)	blue (y)
eye shape	round (r)	oval (r)

purebred squarepants - blue body -
hybrid round eyes - purebred roundpants -
heterozygous squarepants - homozygous yellow body -

1. give the phenotypes for each genotype based on the information provided in the chart.

ss - yy - rr -
rr - ss - yy -

1. spongebobs cousin, spongejimbob, is a heterozygous yellow sponge. he recently married a blue sponge gal.

create a punnett square to help you answer the questions.
what are the possible genotypes and phenotypes for the offspring?
what percentage would be yellow? %
what percentage would be blue? %

1. spongejimbob has oval eyes, while his bride is believed to be homozygous for her round eye shape. create a

punnett square to help you answer the questions.
what are the possible genotypes and phenotypes for the offspring?
what percentage would have round eyes? %
what percentage would have oval eyes? %

Explanation:

Step1: Complete genetics definitions

Purebred - Also called Homozygous and consists of gene pairs with genes that are the same.
Hybrid - Also called Heterozygous and consists of gene pairs with genes that are different.
Genotype is the actual genetic makeup represented by letters (alleles).
Phenotype is the physical/observable appearance of a trait, such as a yellow/blue body color.

Step2: Classify gene pairs

Homozygous = identical alleles; Heterozygous = different alleles.

• TT: Ho
• Bb: He
• dd: Ho
• Ff: He
• Rr: He

Step3: Find genotypes from trait chart

Use dominant (uppercase) and recessive (lowercase) gene labels:

• Purebred squarepants: $SS$
• Blue body: $yy$
• Hybrid round eyes: $Rr$
• Purebred roundpants: $ss$
• Heterozygous squarepants: $Ss$
• Homozygous yellow body: $YY$

Step4: Find phenotypes from genotypes

Dominant traits show with 1+ dominant allele; recessive needs 2 recessive alleles:

• $SS$: Squarepants
• $Yy$: Yellow body
• $rr$: Oval eyes
• $Rr$: Round eyes
• $ss$: Roundpants
• $YY$: Yellow body

Step5: Body color Punnett square

SpongeJimBob: $Yy$; Blue spouse: $yy$
Punnett square:

	$Y$	$y$
$y$	$Yy$	$yy$

• Possible genotypes: $Yy$, $yy$; Phenotypes: Yellow body, Blue body
• Yellow percentage: $\frac{2}{4} \times 100 = 50$%
• Blue percentage: $\frac{2}{4} \times 100 = 50$%

Step6: Eye shape Punnett square

SpongeJimBob: $rr$; Bride: $RR$
Punnett square:

	$r$	$r$
$R$	$Rr$	$Rr$

• Possible genotypes: $Rr$; Phenotype: Round eyes
• Round eyes percentage: $\frac{4}{4} \times 100 = 100$%
• Oval eyes percentage: $0$%

Answer:

1.

• Purebred: Homozygous; same
• Hybrid: Heterozygous; different
• Genotype: genetic; letters (alleles)
• Phenotype: physical/observable; yellow/blue

2.

• TT: Ho
• Bb: He
• dd: Ho
• Ff: He
• Rr: He

3.

• Purebred squarepants: $SS$
• Blue body: $yy$
• Hybrid round eyes: $Rr$
• Purebred roundpants: $ss$
• Heterozygous squarepants: $Ss$
• Homozygous yellow body: $YY$

4.

• $SS$: Squarepants
• $Yy$: Yellow body
• $rr$: Oval eyes
• $Rr$: Round eyes
• $ss$: Roundpants
• $YY$: Yellow body

5.

• Possible genotypes: $Yy$, $yy$; Phenotypes: Yellow body, Blue body
• Yellow percentage: 50%
• Blue percentage: 50%

6.

• Possible genotypes: $Rr$; Phenotype: Round eyes
• Round eyes percentage: 100%
• Oval eyes percentage: 0%