Question 1

Which of the following best describes Mendel’s Law of Segregation?

Accepted Answer

Two alleles for a gene separate during gamete formation, so each gamete receives only one allele.

Question 2

A pea plant with genotype $$Pp (P = $$purple, p = white) is crossed with a plant with genotype $$pp. $$What is the expected phenotypic ratio of the offspring?

Accepted Answer

1 purple : 1 white

Question 3

Which scenario is an example of incomplete dominance?

Accepted Answer

A cross between red and white flowers produces pink flowers.

Question 4

In a dihybrid cross between two $$YyRr$$ pea plants (Y = yellow, y = green, R = round, r = wrinkled), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 5

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene causing both sickle-shaped red blood cells and resistance to malaria.

Question 6

A man with achondroplasia (a dominant disorder, genotype $$Dd) $$and a woman without achondroplasia ($$dd) $$have a child. What is the probability that the child will have achondroplasia?

Accepted Answer

$$0.5$$

Question 7

Which of the following best explains why cystic fibrosis affects multiple organ systems?

Accepted Answer

The gene involved is pleiotropic, so one mutation causes effects in lungs, pancreas, and digestive tract.

Question 8

A couple are both carriers for Tay-Sachs disease (autosomal recessive). What is the probability that their child will be a carrier?

Accepted Answer

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

Question 9

Which of the following is an example of codominance?

Accepted Answer

A person with genotype $$I^A I^B$$ has both A and B antigens on their red blood cells.

Question 10

Which of the following best describes polygenic inheritance?

Accepted Answer

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

Question 11

In Labrador retrievers, coat color is determined by two genes: one for pigment color (B = black, b = brown) and one for pigment deposition (E = pigment, e = no pigment). What is the phenotype of a dog with genotype $$bbEe$$?

Accepted Answer

Brown

Question 12

Which of the following is a real-world example of environmental influence on phenotype?

Accepted Answer

Siamese cats have darker fur on cooler parts of their bodies due to temperature-sensitive enzymes.

Question 13

A testcross is performed between a plant with dominant phenotype and a homozygous recessive plant. If all offspring show the dominant phenotype, what is the genotype of the tested plant?

Accepted Answer

Homozygous dominant

Question 14

Which of the following best explains why sickle cell anemia is more common in individuals of African descent?

Accepted Answer

Heterozygotes for the sickle cell allele have increased resistance to malaria.

Question 15

If a woman with genotype $$I^A i$$ and a man with genotype $$I^B i$$ have children, what blood types are possible among their offspring?

Accepted Answer

A, B, AB, and O

Question 16

Which of the following is NOT a feature of Mendel’s particulate hypothesis?

Accepted Answer

Traits are blended together in offspring.

Question 17

A genetic counselor is advising a couple, both carriers for cystic fibrosis (autosomal recessive). What is the probability that their child will have cystic fibrosis?

Accepted Answer

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

Question 18

Which of the following best describes the Law of Independent Assortment?

Accepted Answer

Alleles of different genes assort independently during gamete formation if they are on different chromosomes.

Question 19

Which of the following is an example of epistasis?

Accepted Answer

A gene for pigment deposition masks the effect of a gene for pigment color in Labrador retrievers.

Question 20

Which of the following is a quantitative character likely to show a bell-shaped distribution in a population?

Accepted Answer

Human height

Mendel and the Gene Idea: Patterns and Extensions of Inheritance

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