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Lesson Worksheet: Dihybrid Inheritance Biology

In this worksheet, we will practice constructing and interpreting genetic diagrams of dihybrid crosses.

Q1:

Assume that in flies, body color and wing size are determined by two different genes, as outlined in the table provided.

Body Color AllelesG (gray)g (black)
Wing Size AllelesN (normal)n (small/vestigial)

In a fly that has the genotype GgNn, what combination of alleles can be produced in the gametes?

  • AGg, Nn
  • BGN, Gn, gN, gn
  • CgN, Gn
  • DGN, gn

Q2:

Assume that in plants, seed shape and color are determined by two different genes, outlined in the table provided.

Seed Shape AllelesR (round)r (wrinkled)
Seed Color AllelesG (green)g (yellow)

In a plant that has the genotype RRgg, what combination of alleles can be produced in the gametes?

  • ARG only
  • BRG, Rg, rG, rg
  • CRg only
  • DRg, rG

Q3:

Assume that in plants, seed shape and color are determined by two different genes, outlined in the table provided.

Seed Shape AllelesR (round)r (wrinkled)
Seed Color AllelesG (green)g (yellow)

In a plant that has the genotype RrGg, what combination of alleles can be produced in the gametes?

  • ARg, Gr
  • BRg, gR, rg, GR
  • CRG, Rg, rG, rg
  • DRG, rg

Q4:

Which of the following best explains what is meant by dihybrid inheritance?

  • AThe possibility that three or more alleles may exist for each locus on a chromosome.
  • BThe inheritance of two different genes, located on different chromosomes, together.
  • CThe formation of gametes using alleles inherited from both parents.
  • DThe inheritance of a single characteristic that is controlled by one gene alone.

Q5:

Assume that, in guinea pigs, the allele for black fur (B) is dominant to the allele for white fur (b), and the allele for smooth fur (F) is dominant to the allele for rough fur (f). A guinea pig with genotype BbFf is crossed with a guinea pig with genotype BbFf. What is the probability 16 that the offspring will have black, smooth fur?

  • A1616
  • B116
  • C316
  • D916

Q6:

Assume that, in plants, the allele for tall stems (D) is dominant to the allele for short stems (d), and the allele for purple flowers (P) is dominant to the allele for white flowers (p). A plant with genotype DdPp is crossed with a plant with genotype DdPp. What is the probability 16 that the offspring will have a tall stem and purple flowers?

  • A316
  • B916
  • C116
  • D1616

Q7:

Assume that in fruit flies, the allele for a grey body (G) is dominant to the allele for a black body (g), and the allele for normal wings (N) is dominant to the allele for small wings (n).

A fly with a genotype GgNn is crossed with a fly with a genotype ggnn.

What is the probability (%) that the offspring will have a black body and normal wings?

Q8:

Assume that in plants, seed shape and color are determined by two different genes, as outlined in the table provided.

Seed Shape AllelesR (round)r (wrinkled)
Seed Color AllelesG (green)g (yellow)

In a plant that has the genotype rrGg, what combination of alleles can be produced in the gametes?

  • Arg only
  • BRg only
  • CrG, rg
  • DRG, rg

Q9:

Assume that in guinea pigs, the allele for black fur (B) is dominant to the allele for white fur (b), and the allele for smooth fur (F) is dominant to the allele for rough fur (f). A guinea pig with genotype Bbff is crossed with a guinea pig with genotype bbFF. What is the probability, in percent, that the offspring will have black, smooth fur?

Q10:

What is the expected phenotypic ratio of a dihybrid cross between two heterozygous individuals?

  • A9 : 3 : 3 : 1
  • B9 : 6 : 1
  • C12 : 3 : 1
  • D16 : 0 : 0 : 0

This lesson includes 19 additional questions and 4 additional question variations for subscribers.

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