Question 1

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

Accepted Answer

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

Question 2

A monohybrid cross between two heterozygous pea plants (Yy x Yy) results in which phenotypic ratio in the F2 generation?

Accepted Answer

$$3:1$$

Question 3

In a dihybrid cross (AaBb x AaBb), what is the expected phenotypic ratio in the F2 generation if the genes assort independently?

Accepted Answer

$$9:3:3:1$$

Question 4

A test cross is performed between a plant with an unknown genotype for a dominant trait and a homozygous recessive plant. If all offspring display the dominant phenotype, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant

Question 5

Which of the following is an example of polygenic inheritance?

Accepted Answer

Human height

Question 6

A woman who is a carrier for cystic fibrosis (a recessive disorder) and a man who is homozygous normal have a child. What is the probability that their child will have cystic fibrosis?

Accepted Answer

$$0$$

Question 7

Which of the following statements about dominant and recessive alleles is correct?

Accepted Answer

A dominant allele will mask the expression of a recessive allele in a heterozygote.

Question 8

A pedigree shows a trait that appears in every generation and all affected individuals have at least one affected parent. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 9

Which of the following best explains why some genetic disorders, such as Huntington disease, persist in the population despite being caused by dominant lethal alleles?

Accepted Answer

The disorder only affects individuals after reproductive age, allowing the allele to be passed on.

Question 10

Which of the following is a key difference between Mendelian and non-Mendelian inheritance patterns?

Accepted Answer

Non-Mendelian inheritance can involve multiple genes contributing to a single trait.

Question 11

A child is born with phenylketonuria (PKU), a recessive disorder. Both parents are phenotypically normal. What are the genotypes of the parents?

Accepted Answer

Both are heterozygous carriers

Question 12

Which of the following is an example of a human trait that is dominant but not physically visible?

Accepted Answer

Immunity to poison ivy

Question 13

If a trait is recessive, which of the following is true regarding its appearance in a pedigree?

Accepted Answer

It can skip generations and affected individuals may have parents who do not display the trait.

Question 14

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygote displays a phenotype intermediate between the two homozygotes.

Question 15

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

Accepted Answer

Type A or Type B

Question 16

Which of the following is an example of a sex-linked inherited disorder?

Accepted Answer

Haemophilia

Question 17

A couple has a child with sickle-cell disease, a recessive disorder. If the father is homozygous normal, what is the genotype of the mother?

Accepted Answer

Homozygous recessive

Question 18

Which of the following best explains the concept of penetrance?

Accepted Answer

The proportion of individuals with a particular genotype that actually display the expected phenotype.

Question 19

If a child does not get enough nutrients growing up and is shorter than their peers, despite having the genetic potential for tall stature, this is an example of:

Accepted Answer

Environmental influence on polygenic traits

Question 20

Which of the following is true about carriers of recessively inherited disorders?

Accepted Answer

They have one dominant and one recessive allele and do not show the disorder.

Mendelian Genetics: Principles, Patterns, and Exceptions (Chapter 14: 14.1–14.4)

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