genetics lecture 5: mitosis and meiosis

Which stage of the cell cycle includes DNA replication?
A. G1 phase
B. G2 phase
C. S phase
D. M phase

S phase

What is the result of DNA replication during S phase?
A. Four haploid cells
B. Chromosomes with single chromatids
C. A cell with half the DNA content
D. A cell with duplicated genetic material

A cell with duplicated genetic material

In which mitotic phase do chromosomes first become visible under a light microscope?
A. Metaphase
B. Prophase
C. Anaphase
D. Telophase

Prophase

What structure connects sister chromatids?
A. Kinetochore
B. Centrosome
C. Centromere
D. Telomere

Centromere

Which structure generates spindle fibers during mitosis?
A. Centromere
B. Ribosome
C. Centrosome
D. Nucleolus

Centrosome

What happens during metaphase of mitosis?
A. Chromosomes decondense
B. Chromatids are pulled apart
C. Chromosomes line up at the metaphase plate
D. DNA replication occurs

Chromosomes line up at the metaphase plate

When do sister chromatids become individual chromosomes?
A. Metaphase
B. Anaphase
C. Telophase
D. Cytokinesis

Anaphase

What marks the end of the M phase?
A. Breakdown of spindle
B. Nuclear envelope formation
C. Chromosome alignment
D. Cytokinesis

Cytokinesis

Which checkpoint ensures the DNA is replicated properly before mitosis begins?
A. G1/S
B. S/M
C. G2/M
D. M/A

G2/M

What is the main role of mitosis in multicellular organisms?
A. Gamete formation
B. Genetic variation
C. Growth and tissue repair
D. Production of haploid cells

Growth and tissue repair

Which term describes chromosomes that carry the same genes but may have different alleles?
A. Nonhomologous chromosomes
B. Sister chromatids
C. Homologous chromosomes
D. Tetrads

Homologous chromosomes

How are acrocentric chromosomes characterized?
A. No centromere
B. Centromere in the center
C. Centromere near one end
D. Circular DNA structure

Centromere near one end

Which of the following is true of diploid cells?
A. They contain two identical alleles
B. They contain homologous chromosome pairs
C. They undergo meiosis only
D. They are only found in gametes

They contain homologous chromosome pairs

How do sister chromatids form?
A. Through fertilization
B. Through chromosome pairing
C. Through DNA replication during S phase
D. Through crossing over

Through DNA replication during S phase

What is a kinetochore?
A. Site of crossing-over
B. Attachment point for spindle fibers
C. DNA replication enzyme
D. Region that forms the metaphase plate

Attachment point for spindle fibers

What is the purpose of meiosis?
A. Increase chromosome number
B. Create genetically identical cells
C. Create haploid gametes
D. Duplicate somatic cells

Create haploid gametes

What happens in Anaphase I of meiosis?
A. Homologous chromosomes separate
B. Sister chromatids separate
C. DNA is replicated
D. Nuclear envelope reforms

Homologous chromosomes separate

Which meiotic stage involves crossing-over?
A. Leptotene
B. Zygotene
C. Pachytene
D. Diakinesis

Pachytene

Which substage of prophase I involves synapsis?
A. Zygotene
B. Leptotene
C. Pachytene
D. Metaphase I

Zygotene

What is true of metaphase II compared to metaphase I?
A. It involves homologs
B. It includes crossing over
C. It aligns sister chromatids
D. It includes synapsis

It aligns sister chromatids

At the end of meiosis II, how many cells are produced?
A. Two diploid cells
B. Four diploid cells
C. Two haploid cells
D. Four haploid cells

Four haploid cells

What does it mean that males are hemizygous for X-linked genes?
A. They have no sex chromosomes
B. They carry two X chromosomes
C. They have only one copy of X-linked genes
D. They lack Y chromosome genes

They have only one copy of X-linked genes

Which process results in genetically identical daughter cells?
A. Meiosis I
B. Meiosis II
C. Mitosis
D. Crossing over

Mitosis

What observation in Morgan's experiments suggested sex-linked inheritance?
A. Only females had white eyes
B. White-eyed trait was dominant
C. Only males had white eyes in F2
D. Equal eye color distribution

Only males had white eyes in F2

Which of the following best defines nondisjunction?
A. Synapsis of nonhomologs
B. Double chromosome replication
C. Failure of chromosome separation
D. Replication of centromeres

Failure of chromosome separation