Question 1

Which of the following best describes the Law of Segregation as demonstrated by Mendel's monohybrid cross with pea plants?

Accepted Answer

Alleles for a trait separate during gamete formation, so each gamete carries only one allele for each gene.

Question 2

A woman with blood type AB (universal recipient) and a man with blood type O (universal donor) have a child. Which blood types are possible for their child?

Accepted Answer

A or B

Question 3

In a dihybrid cross between two heterozygous tomato plants (PpCc x PpCc), where P = purple stem (dominant), p = green stem (recessive), C = cut leaf (dominant), and c = potato leaf (recessive), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

9 purple, cut : 3 purple, potato : 3 green, cut : 1 green, potato

Question 4

A male is homozygous dominant for green feathers (G) and large beak (B) in parakeets (genotype GGBB). He is crossed with a female who is homozygous recessive for both traits (ggbb). What will be the genotype and phenotype of all F1 offspring?

Accepted Answer

Genotype: GgBb; Phenotype: All green feathers, large beak

Question 5

Which of the following best explains why males are more likely than females to express sex-linked recessive diseases?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will cause the disease.

Question 6

A cross between a true-breeding tall pea plant (TT) and a true-breeding dwarf pea plant (tt) produces all tall offspring in the F1 generation. If two F1 plants are crossed, what is the expected genotypic ratio in the F2 generation?

Accepted Answer

$$1\ TT : 2\ Tt : 1\ tt$$

Question 7

In chickens, the frizzle trait shows incomplete dominance. If a bird with genotype Ff (mild frizzle) is crossed with another Ff bird, what is the expected phenotypic ratio in the offspring?

Accepted Answer

1 fully barbed : 2 mild frizzle : 1 highly frizzled

Question 8

Which of the following is an example of codominance?

Accepted Answer

A flower with red and white patches from parents with red and white flowers

Question 9

A woman who is a carrier for a sex-linked recessive disease (X	extsuperscript{N}X	extsuperscript{n}) and a normal man (X	extsuperscript{N}Y) have a son. What is the probability that their son will have the disease?

Accepted Answer

$$50\%$$

Question 10

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute to a single trait, resulting in a range of phenotypes.

Question 11

If nondisjunction occurs during meiosis, which of the following is a possible result in the offspring?

Accepted Answer

Aneuploidy, such as Down syndrome (trisomy 21)

Question 12

Which of the following statements about autosomes and sex chromosomes in humans is correct?

Accepted Answer

Humans have 22 pairs of autosomes and 1 pair of sex chromosomes.

Question 13

A test cross is performed between an individual with an unknown genotype for a dominant trait and a homozygous recessive individual. If the unknown individual is heterozygous, what is the expected phenotypic ratio of the offspring?

Accepted Answer

$$1\ dominant : 1\ recessive$$

Question 14

Which of the following best explains why a female can be a carrier of a sex-linked disease but not express it?

Accepted Answer

She has two X chromosomes, so a normal allele can mask the effect of the recessive allele.

Question 15

Which cross would produce a 3:1 phenotypic ratio in the offspring for a single gene with complete dominance?

Accepted Answer

Heterozygous x Heterozygous

Question 16

Which of the following is true about the universal donor and universal recipient blood types?

Accepted Answer

Type O is the universal donor and type AB is the universal recipient.

Question 17

If a plant with genotype Tt is crossed with a plant with genotype tt, what is the probability that the offspring will be tall (T is dominant to t)?

Accepted Answer

$$50\%$$

Question 18

Which of the following best describes a locus?

Accepted Answer

The specific physical location of a gene on a chromosome

Question 19

Which of the following is an example of incomplete dominance?

Accepted Answer

A pink flower from red and white parents

Question 20

If a female expresses a sex-linked recessive disease, which of the following must be true?

Accepted Answer

She inherited two copies of the recessive allele, one from each parent.

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