Question

question 7
mendel crossed a heterozygous purple flower pea plant with a heterozygous purple flower plant. what is the expected genotypic ratio in the f2 plants?
25% homozygous dominant / 50% heterozygous / 25% homozygous recessive
50% homozygous dominant / 0% heterozygous / 50% homozygous recessive
75% homozygous dominant / 25% heterozygous / 0% homozygous recessive
33% homozygous dominant / 34% heterozygous / 33% homozygous recessive
question 8
mendel crossed a heterozygous purple flower pea plant with a heterozygous purple flower plant. what is the expected phenotypic ratio in the f2 plants?
100% purple / 0% white
50% purple / 50% white
25% purple / 75% white
75% purple / 25% white

Explanation:

Step1: Determine the genotypes of the parents

Let \(P\) represent the dominant allele (purple) and \(p\) represent the recessive allele (white). The parents are both heterozygous, so their genotypes are \(Pp\).

Step2: Create a Punnett square

Gametes of Parent 1	Gametes of Parent 2
\(P\)	\(PP\)	\(Pp\)
\(p\)	\(Pp\)	\(pp\)

Step3: Calculate the genotypic ratio

From the Punnett square:

• \(PP\) (homozygous dominant): \(1/4 = 25\%\)
• \(Pp\) (heterozygous): \(2/4=50\%\)
• \(pp\) (homozygous recessive): \(1/4 = 25\%\)

Step4: Calculate the phenotypic ratio

Since \(P\) is dominant over \(p\), \(PP\) and \(Pp\) show the purple phenotype. \(pp\) shows the white phenotype.

• Purple (\(PP + Pp\)): \(\frac{1 + 2}{4}=\frac{3}{4}=75\%\)
• White (\(pp\)): \(\frac{1}{4}=25\%\)

Answer:

Question 7: 25% homozygous dominant / 50% heterozygous / 25% homozygous recessive
Question 8: 75% purple / 25% white