Question

name: anthony elison per: 3rd date: 11/10/2025 dihybrid cross practice problems 1. set up a punnett square using the following information: - dominate allele for tall plants = d - recessive allele for dwarf plants = d - dominate allele for purple flowers = w - recessive allele for white flowers = w cross a homozygous dominant parent with a homozygous recessive parent. ddww × ddww using the punnett square above: a. what is the probability of producing tall plants with purple flowers? possible genotype(s)? b. what is the probability of producing dwarf plants with white flowers? possible genotype(s)? c. what is the probability of producing tall plants with white flowers? possible genotype(s)? d. what is the probability of producing dwarf plants with purple flowers? possible genotype(s)?

Explanation:

Step1: Analyze the cross

The cross is \(DDWW\times ddww\). The homozygous dominant parent \(DDWW\) can only produce \(DW\) gametes. The homozygous recessive parent \(ddww\) can only produce \(dw\) gametes. But looking at the Punnett - square (assuming it's a mis - representation and we consider the general dihybrid cross rules), for a dihybrid cross \(DdWw\times DdWw\) (if we assume self - cross, but based on the given cross \(DDWW\times ddww\) the offspring is \(DdWw\), and if we assume further self - cross of \(DdWw\) which is a common dihybrid cross problem setup). The probability of \(D-\) (tall) is \(\frac{3}{4}\) (since \(DD:Dd:dd = 1:2:1\)), and the probability of \(W-\) (purple) is \(\frac{3}{4}\). The probability of \(dd\) (dwarf) is \(\frac{1}{4}\), and the probability of \(ww\) (white) is \(\frac{1}{4}\).

Step2: Calculate probabilities

• a. Tall plants with purple flowers

The probability of \(D - W-\) (tall and purple) is \(P(D -)\times P(W -)=\frac{3}{4}\times\frac{3}{4}=\frac{9}{16}\). The genotype \(D - W-\) includes \(DDWW\), \(DDWw\), \(DdWW\), \(DdWw\).

• b. Dwarf plants with white flowers

The probability of \(ddww\) (dwarf and white) is \(P(dd)\times P(ww)=\frac{1}{4}\times\frac{1}{4}=\frac{1}{16}\). The genotype is \(ddww\).

• c. Tall plants with white flowers

The probability of \(D - ww\) (tall and white) is \(P(D -)\times P(ww)=\frac{3}{4}\times\frac{1}{4}=\frac{3}{16}\). The genotypes are \(DDww\), \(Ddww\).

• d. Dwarf plants with purple flowers

The probability of \(ddW-\) (dwarf and purple) is \(P(dd)\times P(W -)=\frac{1}{4}\times\frac{3}{4}=\frac{3}{16}\). The genotypes are \(ddWW\), \(ddWw\).

Answer:

a. Probability: \(\frac{9}{16}\), Genotypes: \(DDWW\), \(DDWw\), \(DdWW\), \(DdWw\)
b. Probability: \(\frac{1}{16}\), Genotype: \(ddww\)
c. Probability: \(\frac{3}{16}\), Genotypes: \(DDww\), \(Ddww\)
d. Probability: \(\frac{3}{16}\), Genotypes: \(ddWW\), \(ddWw\)