Question 1

Which of the following best explains why the white-flowered trait disappeared in the F1 generation but reappeared in the F2 generation in Mendel's pea plant experiments?

Accepted Answer

The white allele was masked by the dominant purple allele in heterozygotes, but segregation during gamete formation allowed it to reappear in the F2 generation.

Question 2

According to Mendel's law of segregation, what is the expected ratio of phenotypes in the F2 generation when two heterozygous pea plants (Pp) are crossed?

Accepted Answer

$$3:1$$

Question 3

A plant with genotype $$Rr$$ produces gametes. What is the probability that a gamete will carry the $$r$$ allele?

Accepted Answer

$$\frac{1}{2}$$

Question 4

In a dihybrid cross between two individuals with genotype $$AaBb$$, what is the probability of producing an offspring with genotype $$aabb$$?

Accepted Answer

$$\frac{1}{16}$$

Question 5

Which inheritance pattern is demonstrated by the ABO blood group system in humans?

Accepted Answer

Codominance and multiple alleles

Question 6

A genetic counselor is working with a couple who are both carriers for cystic fibrosis (genotype $$Nn). $$What is the probability that their fourth child will have cystic fibrosis, given that their first three children do not?

Accepted Answer

$$\frac{1}{4}$$

Question 7

Which of the following is an example of pleiotropy?

Accepted Answer

Sickle-cell disease affecting multiple phenotypic traits

Question 8

If a trait is determined by the additive effects of two or more genes, which inheritance pattern does this describe?

Accepted Answer

Polygenic inheritance

Question 9

A pedigree shows a trait that appears in every generation. Which of the following is the most likely mode of inheritance?

Accepted Answer

Dominant

Question 10

Which of the following best describes the effect of the sickle-cell allele in populations where malaria is common?

Accepted Answer

Heterozygotes have a selective advantage because they are less susceptible to malaria.

Question 11

Which of the following scenarios is an example of epistasis?

Accepted Answer

A gene for pigment deposition masks the expression of a gene for pigment color in mice.

Question 12

If two genes are involved in a cross and the offspring show a phenotypic ratio of $$9:3:3:1$$, what can you infer about the parents?

Accepted Answer

Both parents are heterozygous for both genes.

Question 13

Which rule would you use to calculate the probability of an offspring inheriting two independent traits simultaneously?

Accepted Answer

Multiplication rule

Question 14

A woman with genotype $$I^A I^B$$ and a man with genotype $$I^B i$$ have a child. What is the probability that the child will have blood type B?

Accepted Answer

$$\frac{1}{2}$$

Question 15

Which of the following is NOT a feature of Mendel's law of independent assortment?

Accepted Answer

It applies to genes that are closely linked on the same chromosome.

Question 16

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygous phenotype is intermediate between the two homozygous phenotypes.

Question 17

A couple has a child with a recessive genetic disorder, but neither parent shows symptoms. What are the most likely genotypes of the parents?

Accepted Answer

Both are heterozygous carriers.

Question 18

Which of the following is an example of a multifactorial disorder?

Accepted Answer

Heart disease influenced by both genetic and environmental factors

Question 19

If an individual with genotype $$AaBbCc$$ produces gametes, how many different types of gametes can be formed?

Accepted Answer

$$8$$

Question 20

Which of the following statements about dominant lethal alleles is true?

Accepted Answer

They are usually eliminated from the population if they cause death before reproductive age.

Mendelian Genetics and Extensions: Patterns of Inheritance

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