Copy of 25-26 Test - Unit 6 Genetics (5/2/2026)

MEDIUM

Change to incomplete dominance

STAAR 2021 #41 modified

Some flower colors are determined by codominance. Possible genotypes and phenotypes of flowers are shown below.

Which table shows the expected phenotypes of offspring resulting from a cross between a white flower and a striped flower?

LOW

In plants, tall is dominant to short. A heterozygous tall plant is crossed with homozygous tall plant.

Which choice below correctly identifies the parents in this cross?

Medium

In the cross below, what are the genotypes of the parents?

MEDIUM

Tomato plants usually have hairy stems. Hairless stems are present in tomato plants that are homozygous recessive for that trait.

If the stem characteristics are determined by a single gene, what is the expected outcome of crossing two tomato plants that are heterozygous for hairy stems?

MEDIUM

Albinism is an autosomal recessive condition.

Which circle graph shows the genotype probability when an albino female mates with a male that is heterozygous for the albinism trait?

HIGH

In dogs, straight tails (S) are dominant to curly tails (s). Steven's dog has a curly recessive tail (ss).

The appearance of a recessive trait (curly tail) in an animal’s offspring most likely means that…

MEDIUM

In pigeons, no crest is dominant to crest.

What are the expected genotypes of the offspring if a homozygous no crest pigeon mates with a crest pigeon?

MEDIUM

The inheritance pattern for an autosomal dominant trait is shown in the pedigree. Shaded symbols represent individuals that express the dominant trait.

Based on this pedigree, what are the most likely genotypes of individuals I-1 and I-2?

MEDIUM

What are the blood types of the possible children that a woman with type O could produce with a man who is type AB?

MEDIUM

STAAR 2018 #8

In humans blood type is determined by the A, B, and O alleles. The A and B alleles are codominant to each other and dominant over the O allele. An individual with the AO genotype and an individual with the BO genotype can produce offspring with which of the following phenotypes?

HIGH

A model of the genetic control of coat color in rabbits is shown.

Which Punnett square represent a cross that would produce albino offspring?

HIGH

In a group of cats, some individuals have tightly curled fur, some have wavy fur, and some have straight fur. In this group, one of the genes for follicle shape has two alleles. The allele for curved follicles resulting in tightly curled fur (K^R) is incompletely dominant over the allele for straight follicles resulting in straight fur (K^S). So heterozygotes have wavy fur.

Which cross below has the highest probability of producing wavy fur offspring?

MEDIUM

STAAR 2022 #30

In domesticated dogs, hair type is controlled by two different alleles. The allele for wire hair is (H) and the allele for smooth hair is (h).

When two heterozygous dogs are crossed, what percentage of the offspring is expected to be homozygous for smooth hair?

Medium

STAAR 2021 #25

A genetic cross involving two unlinked genes is represented.

AaGG x aaGg

Which genotype is NOT possible in the offspring produced by the cross?

MEDIUM

STAAR 2017 #29

In Holstein cattle the allele for black hair color (B) is dominant over the allele for red hair color (b), and the allele for polled (P), or lacking horns, is dominant over the allele for having horns (p).

What is the expected phenotypic ratio of the offspring of a BbPp × BbPp cross if these alleles sort independently?

medium

Achondroplasia is an inherited condition that affects the formation of bone in humans. The allele for achondroplasia (A) is dominant to the unaffected allele (a).

If a person who is homozygous dominant has children with a person who is homozygous recessive, what percentage of their children will likely have achondroplasia?

Enter your answer in the box. Your answer must be a whole number.

LOW

STAAR 2024 #5

Curly hair and the ability to taste the chemical PTC are inherited traits. Curly hair (H) is always dominant to straight hair (h). The ability to taste PTC (P) is always dominant to not being able to taste PTC (p). The alleles for straight hair and a non-taster for PTC are recessive.

If both parents are heterozygous for both traits, what would the genotype of an offspring with straight hair and the ability to taste PTC?

MEDIUM

2021 STAAR #41 -

Some angelfish colors are determined by codominance. Possible phenotypes and genotypes of angelfish colors are shown below.

Which table shows the expected phenotypes of offspring resulting from a cross between a black angelfish and a black-lace angelfish?

HIGH

Muscular dystrophy is an x-linked recessive trait that causes the progressive weakening of the skeletal muscles. Unfortunately, mothers are responsible for passing this trait on to their sons. A mother who has muscular dystrophy marries a man who is normal.

The couple have a son. What are the chances he has the disorder?

HIGH - Keep as is.

Which type of mutation is most likely responsible for the development of vitiligo?

Which statement BEST describes why vitiligo is seen in multiple generations of a family?