Question 1

During interphase, which event is most directly responsible for the doubling of DNA content in a eukaryotic cell?

Accepted Answer

The replication of chromosomes during the S phase

Question 2

Why does the nuclear envelope degrade during prophase of mitosis?

Accepted Answer

To allow spindle fibers to attach to chromosomes

Question 3

Which of the following best describes the difference between plant and animal cell cytokinesis?

Accepted Answer

Plant cells form a cell plate, while animal cells form a cleavage furrow

Question 4

At which phase of mitosis do sister chromatids separate?

Accepted Answer

Anaphase

Question 5

Cyclin-dependent kinases (CDKs) are regulated by:

Accepted Answer

The presence of cyclins

Question 6

Asexual reproduction in eukaryotes most commonly involves which type of cell division?

Accepted Answer

Mitosis

Question 7

If an organism has a diploid number of 8 chromosomes, how many chromosomes will be found in its gametes?

Accepted Answer

$$4$$

Question 8

The source of abnormal chromosome numbers in humans is most often:

Accepted Answer

Nondisjunction during meiosis

Question 9

Homologous chromosomes are best described as:

Accepted Answer

Chromosomes that carry the same genes but may have different alleles

Question 10

In a monohybrid cross between two heterozygous individuals ($$Aa 	imes Aa$$), what is the expected proportion of offspring with the dominant phenotype?

Accepted Answer

$$\frac{3}{4}$$

Question 11

Which of the following best defines pleiotropy?

Accepted Answer

A single gene affects multiple traits

Question 12

In Thomas Hunt Morgan’s experiments with fruit flies, what was the key finding regarding sex-linked characteristics?

Accepted Answer

Traits linked to the X chromosome are inherited differently in males and females

Question 13

If a male with genotype $$X^N Y$$ mates with a female with genotype $$X^N X^n$$, what proportion of their sons will have the recessive phenotype?

Accepted Answer

$$0$$

Question 14

Which scenario best illustrates incomplete dominance?

Accepted Answer

A red flower and a white flower produce pink offspring

Question 15

Epistasis occurs when:

Accepted Answer

One gene masks the expression of another gene

Question 16

In the pedigree chart provided, what is the most likely mode of inheritance for the trait shown (filled symbols)?

Accepted Answer

Autosomal recessive

Question 17

If nondisjunction occurs during meiosis I, what is the expected outcome for the gametes?

Accepted Answer

Half will have an extra chromosome, half will have one less

Question 18

Which of the following best describes the law of independent assortment?

Accepted Answer

Alleles of different genes are distributed independently during gamete formation

Question 19

Given the cross $$AaBB 	imes aaBb$$, what proportion of offspring will have the recessive phenotype for character 'a' and the dominant phenotype for character 'b'?

Accepted Answer

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

Question 20

In a pedigree chart, if both parents are unaffected but have an affected child, what is the most likely genotype of the parents for an autosomal recessive trait?

Accepted Answer

Heterozygous carriers

Cell Division, Mendelian Genetics, and Chromosomal Inheritance: BIOL 105 Exam 3 Study Guide

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