Question 1

Which of the following best describes autosomal dominant inheritance in humans?

Accepted Answer

Each individual who has the trait has at least one parent with the trait.

Question 2

In a pedigree, what does a filled square represent?

Accepted Answer

A male who expresses the trait

Question 3

If two heterozygous parents (Rr) for an autosomal dominant trait have children, what is the probability that a child will not express the trait?

Accepted Answer

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

Question 4

Which stage of mitosis is characterized by the maximum condensation of chromosomes and their alignment at the cell's equator?

Accepted Answer

Metaphase

Question 5

What is the main difference between mitosis and meiosis regarding chromosome number in the resulting cells?

Accepted Answer

Mitosis produces two diploid cells; meiosis produces four haploid cells.

Question 6

A pedigree shows a trait appearing in siblings but not in their parents, and both males and females are affected equally. What type of inheritance is most likely?

Accepted Answer

Autosomal recessive

Question 7

During meiosis, what event is the mechanical basis for Mendel’s law of independent assortment?

Accepted Answer

Random alignment of homologous chromosomes in metaphase I

Question 8

In mammals, which gene is responsible for initiating male sex determination?

Accepted Answer

SRY gene on the Y chromosome

Question 9

If a pedigree shows two affected parents (autosomal recessive trait), what is the expected genotype of their children?

Accepted Answer

All children will be homozygous recessive

Question 10

Which formula correctly represents the probability of two heterozygous parents (Aa) having a homozygous recessive child (aa)?

Accepted Answer

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

Question 11

Which of the following is NOT a characteristic of autosomal dominant inheritance?

Accepted Answer

Affected individuals are often born to unaffected parents

Question 12

What is the chromosome constitution of a normal female in mammals?

Accepted Answer

XX

Question 13

Which process during meiosis increases genetic diversity among gametes?

Accepted Answer

Crossing over during prophase I

Question 14

A pedigree shows a trait that skips generations and is seen only among siblings. What is the most likely explanation?

Accepted Answer

The trait is autosomal recessive

Question 15

In birds, which sex chromosome system determines sex?

Accepted Answer

ZW system

Question 16

Which stage of the cell cycle is associated with DNA replication?

Accepted Answer

Interphase

Question 17

If a pedigree shows two unaffected parents having an affected child, what type of inheritance is most likely?

Accepted Answer

Autosomal recessive

Question 18

Which of the following best explains why meiosis produces genetically different gametes?

Accepted Answer

Homologous chromosomes pair and undergo crossing over.

Question 19

What is the expected ratio of phenotypes in the offspring of two heterozygous parents for an autosomal recessive trait?

Accepted Answer

$$ 1:3 $$

Question 20

Which of the following is true about the SRY gene?

Accepted Answer

It is found on the Y chromosome and initiates male development.

Genetics Exam 2 Review: Transmission Genetics, Cell Division, and Sex Determination

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