Question 1

In Mendel's classic pea plant experiment, true-breeding purple-flowered plants (PP) were crossed with true-breeding white-flowered plants (pp). All F1 offspring had purple flowers. When these F1 plants self-pollinated, what was the expected phenotypic ratio of purple to white flowers in the F2 generation?

Accepted Answer

3:1

Question 2

Which of the following best describes the Law of Segregation as demonstrated by Mendel's experiments?

Accepted Answer

Two alleles for a heritable character separate during gamete formation and end up in different gametes.

Question 3

A plant with genotype Pp is crossed with another plant with genotype pp. What fraction of the offspring are expected to have purple flowers, assuming purple (P) is dominant to white (p)?

Accepted Answer

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

Question 4

In a dihybrid cross between two pea plants with genotypes YyRr x YyRr (Y = yellow, y = green, R = round, r = wrinkled), what is the probability of obtaining an offspring with genotype yyrr?

Accepted Answer

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

Question 5

Which of the following scenarios best illustrates the concept of incomplete dominance?

Accepted Answer

A cross between red-flowered and white-flowered snapdragons produces all pink-flowered offspring.

Question 6

A man with blood type AB marries a woman with blood type O. What are the possible blood types of their children?

Accepted Answer

A and B only

Question 7

In Labrador retrievers, coat color is determined by two genes: one for pigment color (B = black, b = brown) and one for pigment deposition (E = color, e = no color). What is the expected phenotypic ratio in the offspring of two BbEe dogs?

Accepted Answer

9 black : 3 brown : 4 yellow

Question 8

A couple, both carriers for a recessive genetic disorder (Aa), have a child. What is the probability that their child will be affected by the disorder?

Accepted Answer

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

Question 9

Which of the following best describes pleiotropy?

Accepted Answer

One gene affects multiple phenotypic traits.

Question 10

Hydrangea flowers of the same genetic variety are blue in acidic soil and pink in basic soil. This is an example of:

Accepted Answer

Environmental influence on phenotype

Question 11

If a genetic counselor determines that both parents are carriers for a rare recessive disease, and each has a 2/3 chance of being a carrier, what is the probability that their child will have the disease?

Accepted Answer

$$\frac{1}{9}$$

Question 12

Which of the following is true about dominant alleles?

Accepted Answer

Dominant alleles mask the expression of recessive alleles in heterozygotes.

Question 13

A testcross is performed between a plant with an unknown genotype showing the dominant phenotype and a homozygous recessive plant. If any offspring display the recessive phenotype, what can be concluded about the unknown parent?

Accepted Answer

It is heterozygous.

Question 14

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute additively to a single trait.

Question 15

In a population of cows, black coat color (B) is dominant to red (b). If two heterozygous cows (Bb) are crossed, what is the probability that an offspring will be red?

Accepted Answer

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

Question 16

Which of the following is an example of codominance?

Accepted Answer

A person with blood type AB expressing both A and B antigens.

Question 17

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 18

Which of the following best explains why consanguineous matings increase the risk of recessive genetic disorders?

Accepted Answer

They increase the likelihood that both parents carry the same rare recessive allele.

Question 19

A woman with genotype IAi and a man with genotype IBi have children. What is the probability that their child will have blood type O?

Accepted Answer

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

Question 20

Which of the following is a multifactorial disorder?

Accepted Answer

Heart disease

Mendelian Genetics: Laws, Patterns, and Applications

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