Question 1

Which of the following best explains why Mendel chose the garden pea (Pisum sativum) for his genetic experiments?

Accepted Answer

Pea plants have a short generation time, produce many offspring, and have easily observable traits with distinct variations.

Question 2

In Mendel's experiments, what is the difference between a 'character' and a 'trait'?

Accepted Answer

A character is a heritable feature, such as flower color, while a trait is a specific variant of a character, such as purple or white flowers.

Question 3

Which of the following statements best describes the law of segregation?

Accepted Answer

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

Question 4

A plant with genotype $$Yy ($$yellow seeds) is crossed with a plant with genotype $$yy ($$green seeds). What is the expected phenotypic ratio in the offspring?

Accepted Answer

1 yellow : 1 green

Question 5

Which of the following best describes a testcross and its purpose?

Accepted Answer

A testcross involves crossing an individual with a dominant phenotype (but unknown genotype) with a homozygous recessive individual to determine the unknown genotype.

Question 6

In a dihybrid cross between two heterozygous pea plants ($$YyRr 	imes YyRr$$), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

9:3:3:1

Question 7

Which phase of meiosis is responsible for the law of segregation?

Accepted Answer

Anaphase I

Question 8

A couple has a child with cystic fibrosis, a recessive genetic disorder. Neither parent has the disorder. What are the possible genotypes of the parents?

Accepted Answer

Both parents are heterozygous carriers.

Question 9

Which of the following is an example of a human disorder caused by a dominant allele?

Accepted Answer

Huntington's disease

Question 10

What is the probability of obtaining a pea plant with genotype $$aa$$ from a cross between two heterozygous ($$Aa) $$plants? Use the multiplication rule.

Accepted Answer

$$0.25$$

Question 11

Which of the following best describes the chromosomal theory of inheritance?

Accepted Answer

Genes are located on chromosomes, and the behavior of chromosomes during meiosis accounts for inheritance patterns.

Question 12

A pedigree shows a trait that skips generations and appears equally in males and females. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 13

Which of the following terms describes an individual who is heterozygous for a recessive genetic disorder but does not show symptoms?

Accepted Answer

Carrier

Question 14

Which step in meiosis explains Mendel's law of independent assortment?

Accepted Answer

Random alignment of homologous chromosomes during Metaphase I

Question 15

If a genetic counselor is using amniocentesis, what is the purpose of this procedure?

Accepted Answer

To obtain fetal cells for genetic testing by sampling amniotic fluid

Question 16

Which of the following best explains why humans are not ideal subjects for Mendelian genetic studies?

Accepted Answer

Humans have long generation times, produce few offspring, and controlled crosses are unethical.

Question 17

A genetic counselor is analyzing a pedigree for a family with a history of a dominant genetic disorder. What pattern would you expect to see?

Accepted Answer

The disorder appears in every generation and affected individuals have at least one affected parent.

Question 18

Which of the following Punnett squares correctly predicts the offspring of a cross between $$Aa$$ and $$aa$$ individuals?

Accepted Answer

50% $$Aa$$, 50% $$aa$$

Question 19

Which probability rule would you use to determine the chance of two independent events both occurring, such as inheriting two unlinked traits?

Accepted Answer

Multiplication rule

Question 20

A woman is a carrier for a recessive allele causing a genetic disorder, and her partner is also a carrier. What is the probability that their child will be unaffected (either carrier or non-carrier)?

Accepted Answer

$$0.75$$

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