Question 1

In diploid species, diploid cells may undergo either mitosis or meiosis. Haploid cells may undergo mitosis (for certain species) but not meiosis because:

Accepted Answer

homologous chromosomes cannot pair.

Question 2

Which of the following best describes a 'trait' as used in Mendelian genetics?

Accepted Answer

A variant for a character, such as purple or white color for flowers.

Question 3

Mendel’s law of segregation states that:

Accepted Answer

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

Question 4

A testcross is used to determine the genotype of an individual with a dominant phenotype. Which cross would you perform?

Accepted Answer

Cross the individual with a homozygous recessive individual.

Question 5

If a plant with genotype Pp is self-crossed, what is the probability that an offspring will be homozygous recessive?

Accepted Answer

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

Question 6

Which of the following is an example of incomplete dominance?

Accepted Answer

A red-flowered plant crossed with a white-flowered plant produces pink-flowered offspring.

Question 7

Which of the following best explains why the ABO blood group in humans is an example of multiple alleles?

Accepted Answer

The gene exists in more than two allelic forms in the population.

Question 8

A couple are both carriers for cystic fibrosis, a recessive genetic disorder. What is the probability that their child will have cystic fibrosis?

Accepted Answer

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

Question 9

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene affects multiple phenotypic traits, such as sickle-cell disease.

Question 10

In a dihybrid cross between two heterozygotes (YyRr x YyRr), what is the probability of obtaining an offspring with the genotype yyrr?

Accepted Answer

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

Question 11

Which of the following statements about dominant alleles is correct?

Accepted Answer

Dominant alleles are not necessarily more common than recessive alleles.

Question 12

Which of the following best describes codominance?

Accepted Answer

Both alleles are expressed in the heterozygote in distinguishable ways.

Question 13

A genetic counselor is working with a couple who both have a sibling with a recessive genetic disorder, but neither parent is affected. What is the probability that both members of the couple are carriers?

Accepted Answer

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

Question 14

Which of the following is true about the law of independent assortment?

Accepted Answer

It applies only to genes on different, nonhomologous chromosomes or those far apart on the same chromosome.

Question 15

A plant with genotype TtAa is crossed with a plant with genotype ttaa. What proportion of the offspring will have tall stems and axial flowers, assuming T (tall) and A (axial) are dominant?

Accepted Answer

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

Question 16

Which of the following best explains why normal gametes produced from one meiotic event are not genetically identical to each other?

Accepted Answer

Crossing over and independent assortment create genetic variation.

Question 17

Which of the following is an example of epistasis?

Accepted Answer

One gene affects the expression of another gene, such as coat color in Labrador retrievers.

Question 18

If a heterozygous plant (Pp) is crossed with a homozygous recessive plant (pp), what is the expected phenotypic ratio of the offspring?

Accepted Answer

1:1

Question 19

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes independently affect a single trait, such as human skin color.

Mendelian Genetics and Extensions: Study Notes for General Biology

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