Question

1. complete the punnett squares.

1. in pea plants, round seed is a dominant trait while wrinkled seed is a recessive trait. two pea plants with round seeds are crossed. in the next generation pea plants, about 25% have wrinkled seeds, which is a new genetic variation. using r for the dominant round allele and r for the recessive wrinkle allele, draw a punnett square to illustrate how this new genetic variation (wrinkled seeds) is due to a new allele combination, not due to a dna mutation during meiosis.

p1 genotype _______
p2 genotype _______
punnett square

1. list the two causes of genetic variation in a population.

Explanation:

Step1: Complete Punnett Square (Q3)

Combine row/column alleles:
Top-left: $A + a = Aa$
Top-right: $A + a = Aa$
Bottom-left: $a + a = aa$
Bottom-right: $a + a = aa$

Step2: Identify parent genotypes (Q4)

Since 25% offspring are wrinkled ($rr$), parents must be heterozygous (carry recessive allele but show dominant trait).
P1 genotype: $Rr$
P2 genotype: $Rr$

Step3: Build Punnett Square (Q4)

Combine row/column alleles for $Rr \times Rr$:
Top-left: $R + R = RR$
Top-right: $R + r = Rr$
Bottom-left: $r + R = Rr$
Bottom-right: $r + r = rr$

Step4: List genetic variation causes (Q5)

Identify two core sources of population genetic variation.

Answer:

Question 3 Completed Punnett Square:

	$a$	$a$
$a$	$aa$	$aa$

Question 4:

P1 genotype: $Rr$
P2 genotype: $Rr$

Punnett Square:

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

(The 25% wrinkled offspring come from the $rr$ genotype, a new combination of existing parental alleles, not a mutation)

Question 5:

1. Recombination (crossing over during meiosis)
2. Random fertilization of gametes