Question 1

Which of the following best explains why Mendel's particulate theory of inheritance was revolutionary compared to the blending theory?

Accepted Answer

It demonstrated that discrete units (genes) are inherited unchanged from each parent, allowing traits to reappear in later generations.

Question 2

A pea plant with genotype $$PpYy is $$allowed to self-pollinate. According to Mendel's law of independent assortment, what is the expected phenotypic ratio in the F2 generation for flower color and seed color?

Accepted Answer

9:3:3:1

Question 3

In Mendel's experiments, what was the significance of starting with true-breeding pea plants?

Accepted Answer

It guaranteed that the parental plants had homozygous genotypes, making inheritance patterns easier to interpret.

Question 4

Which of the following best describes the law of segregation?

Accepted Answer

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

Question 5

A testcross is performed between a pea plant with a dominant phenotype and a plant with a recessive phenotype. If half the offspring display the recessive phenotype, what is the genotype of the dominant parent?

Accepted Answer

Heterozygous

Question 6

Which equation represents the probability of obtaining a homozygous recessive offspring from a monohybrid cross ($$Pp 	imes Pp$$)?

Accepted Answer

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

Question 7

In snapdragons, red flowers ($$C^R) $$and white flowers ($$C^W) $$produce pink flowers ($$C^R C^W) in $$the F1 generation. What type of inheritance is demonstrated?

Accepted Answer

Incomplete dominance

Question 8

A couple, both with blood type A, have a child with blood type O. What are the genotypes of the parents?

Accepted Answer

$$I^A i$$ and $$I^A i$$

Question 9

Which of the following is an example of pleiotropy?

Accepted Answer

Sickle-cell disease causing multiple symptoms in affected individuals

Question 10

If a plant is heterozygous at two independent loci ($$PpYy$$), what types of gametes can it produce?

Accepted Answer

Four gamete types: $$PY$$, $$Py$$, $$pY$$, $$py$$

Question 11

Which of the following best describes codominance?

Accepted Answer

Both alleles are expressed separately and equally in the phenotype.

Question 12

A pedigree shows a trait that skips generations and appears only in individuals with two affected parents. What mode of inheritance is most likely?

Accepted Answer

Autosomal recessive

Question 13

Which of the following statements about sickle-cell disease is correct?

Accepted Answer

Heterozygotes are less susceptible to malaria and may have mild symptoms.

Question 14

A man with Huntington’s disease (a dominant disorder) has a daughter who is 25 years old and a grandson who is 2 years old. What is the probability that the daughter will develop the disease?

Accepted Answer

50%

Question 15

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes independently affect a single trait.

Question 16

In a dihybrid cross between $$AaBb 	imes AaBb$$, what is the probability of obtaining an offspring with genotype $$aabb$$?

Accepted Answer

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

Question 17

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

Accepted Answer

Height, influenced by both genes and environment

Question 18

A genetic counselor is working with a couple who have just had a child with Tay-Sachs disease. Neither parent has Tay-Sachs, nor does anyone in their families. What should the counselor say?

Accepted Answer

Any child you have has a 25% chance of having the disease.

Question 19

Which of the following best explains the physical basis for Mendel’s law of segregation?

Accepted Answer

The movement of chromosomes during meiosis, separating homologous chromosomes into different gametes.

Mendelian Genetics and Extensions: Principles of Heredity

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