Review Questions

A diploid cell has_______ the number of chromosomes as a haploid cell.

1. one-fourth
2. half
3. twice
4. four times

An organism’s traits are determined by the specific combination of inherited _____.

1. cells.
2. genes.
3. proteins.
4. chromatids.

The first level of DNA organization in a eukaryotic cell is maintained by which molecule?

1. cohesin
2. condensin
3. chromatin
4. histone

Identical copies of chromatin held together by cohesin at the centromere are called _____.

1. histones.
2. nucleosomes.
3. chromatin.
4. sister chromatids.

Chromosomes are duplicated during what stage of the cell cycle?

1. G₁ phase
2. S phase
3. prophase
4. prometaphase

Which of the following events does not occur during some stages of interphase?

1. DNA duplication
2. organelle duplication
3. increase in cell size
4. separation of sister chromatids

The mitotic spindles arise from which cell structure?

1. centromere
2. centrosome
3. kinetochore
4. cleavage furrow

Attachment of the mitotic spindle fibers to the kinetochores is a characteristic of which stage of mitosis?

1. prophase
2. prometaphase
3. metaphase
4. anaphase

Unpacking of chromosomes and the formation of a new nuclear envelope is a characteristic of which stage of mitosis?

1. prometaphase
2. metaphase
3. anaphase
4. telophase

Separation of the sister chromatids is a characteristic of which stage of mitosis?

1. prometaphase
2. metaphase
3. anaphase
4. telophase

The chromosomes become visible under a light microscope during which stage of mitosis?

1. prophase
2. prometaphase
3. metaphase
4. anaphase

The fusing of Golgi vesicles at the metaphase plate of dividing plant cells forms what structure?

1. cell plate
2. actin ring
3. cleavage furrow
4. mitotic spindle

At which of the cell cycle checkpoints do external forces have the greatest influence?

1. G₁ checkpoint
2. G₂ checkpoint
3. M checkpoint
4. G₀ checkpoint

What is the main prerequisite for clearance at the G₂ checkpoint?

1. cell has reached a sufficient size
2. an adequate stockpile of nucleotides
3. accurate and complete DNA replication
4. proper attachment of mitotic spindle fibers to kinetochores

If the M checkpoint is not cleared, what stage of mitosis will be blocked?

1. prophase
2. prometaphase
3. metaphase
4. anaphase

Which protein is a positive regulator that phosphorylates other proteins when activated?

1. p53
2. retinoblastoma protein (Rb)
3. cyclin
4. cyclin-dependent kinase (Cdk)

Many of the negative regulator proteins of the cell cycle were discovered in what type of cells?

1. gametes
2. cells in G₀
3. cancer cells
4. stem cells

Which negative regulatory molecule can trigger cell suicide (apoptosis) if vital cell cycle events do not occur?

1. p53
2. p21
3. retinoblastoma protein (Rb)
4. cyclin-dependent kinase (Cdk)

___________ are changes to the order of nucleotides in a segment of DNA that codes for a protein.

1. Proto-oncogenes
2. Tumor suppressor genes
3. Gene mutations
4. Negative regulators

A gene that codes for a positive cell cycle regulator is called a(n) _____.

1. kinase inhibitor.
2. tumor suppressor gene.
3. proto-oncogene.
4. oncogene.

A mutated gene that codes for an altered version of Cdk that is active in the absence of cyclin is a(n) _____.

1. kinase inhibitor.
2. tumor suppressor gene.
3. proto-oncogene.
4. oncogene.

Which molecule is a Cdk inhibitor that is controlled by p53?

1. cyclin
2. anti-kinase
3. Rb
4. p21

Which eukaryotic cell cycle event is missing in binary fission?

1. cell growth
2. DNA duplication
3. karyokinesis
4. cytokinesis

FtsZ proteins direct the formation of a _______ that will eventually form the new cell walls of the daughter cells.

1. contractile ring
2. cell plate
3. cytoskeleton
4. septum