mitosis & meiosis

How many bivalents are formed in a cell with 20 chromosomes at the beginning of meiosis I?

10

Which of the following events does NOT occur during prophase?

Chromosomes replicate themselves.

Classify the following descriptions of stages of the cell cycle into interphase and mitosis.

Interphase G₁ S G₂ Mitosis Cytokinesis Telophase Anaphase Metaphase Late prophase Prophase

Which of the following choices describes Interphase?

Occupies the majority of the cell cycle Includes G1, S and G2 stages Results in an increase in cell size

During which stage of meiosis does crossing-over occur?

Prophase I of meiosis I

Which of the following events do NOT occur in prophase of mitosis?

Chromosomes are replicated.

In which phase of the cell cycle are cells that are no longer dividing?

G0 phase

During which phase of the cell cycle is cell growth most significant?

G1 phase

The critical checkpoints that control the cell cycle are at the

G1 to S stage and G2 to M stage.

Select from the following list of statements all of the ways in which meiosis II differs from meiosis I.

Interkinesis doesn't involve the replication of chromosomes, whereas interphase does. Interkinesis doesn't involve the replication of chromosomes, whereas interphase does. Crossing-over doesn't occur in prophase II, whereas it does in prophase I. Cells in meiosis II are haploid and cells in meiosis I are diploid. Cells in meiosis II are haploid and cells in meiosis I are diploid. Sister chromatids separate in anaphase II, whereas homologous chromosomes separate in anaphase I.

Place the correct phase of meiosis in the proper sentence. Then list the phases of meiosis in the correct order

Synapsis and crossing over occur during prophase I. During metaphase I the bivalents (pairs of homologous chromosomes) are organized along the metaphase plate. During anaphase I, the homologous chromosomes (paired bivalents) separate from each other. Homologues reach their respective poles during telophase I, the nuclear membrane re-forms to produce two separate nuclei. At the beginning of prophase II, homologues have already separated; nuclear membrane dissociates; chromatids condense; spindle apparatus forms and the nucleolus disappears. During metaphase II, all sister chromatids align themselves along the metaphase plate. As anaphase II proceeds sister chromatids are separated and are pulled toward the pole to which they are attached. During telophase II, sister chromatids reach their respective poles and decondense; nuclear membrane re-forms and nucleoli reappear.

Which of the following phrases best describes the events that occur during anaphase?

The spindle fibers shorten and the sister chromatids begin to separate and move to opposite ends of the cell.

Which of the following statements about microtubules during anaphase is TRUE?

Those attached to chromosomes shorten, whereas those that are unattached elongate.

The purpose of the spindle fibers is to

aid in sorting and aligning the chromosomes for their movement to opposite ends of the cell.

Which of the following events occur during prophase I?

breakdown of the nuclear envelope, condensation of chromosomes, and movement of centrosomes

Which of the following choices lists events in order as they occur during cell division through mitosis. Keep in mind that not all events may occur during the process of mitosis itself.

chromatin replicates and condenses into chromosomes → spindle fibers attach to sister chromatids and align them at the center of the cell → spindle fibers begin to shorten and drag the sister chromatids to opposite ends of the cell → the nucleus re-forms around the chromosomes → the plasma membrane pinches apart into two distinct cells

Centromeres divide during metaphase

false

During prophase II of meiosis, the nuclear membrane stays fully intact

false

At the end of meiosis II, there are

four haploid cells, with each chromosome consisting of a single chromatid.

The function of mitosis is

growth of the organism and tissue repair. to ensure that each new cell receives a complete set of genetic information. asexual reproduction in some species. Only the first two answers are correct

The mitotic spindle fibers attach to chromosomes via special structures termed __________.

kinetochores

The spindle apparatus forms during

prometaphase II.

Which of the following represents the correct order of the phases of mitosis?

prophase -> metaphase -> anaphase -> telophase

The exchange of genetic material between nonsister chromatids is called crossing-over and occurs during which phase of meiosis?

prophase I

Which of the following events occurs during anaphase I?

separation of homologous chromosomes

Separation of ________ occurs in anaphase II of meiosis.

sister chromatids

What cells in the body are most likely to have originated through the process of meiosis?

sperm and egg cells

Sister chromatids can best be described as

the two genetically identical chromatids that result from the replication of the chromosome.

What is the overall purpose of meiosis?

to produce four genetically different haploid cells

At the end of meiosis I, there are two haploid cells, each with two sister chromatids per chromosome.

true

Cytokinesis in animal cells occurs by means of a cleavage furrow.

true

In animal cells, cytokinesis is accomplished by the formation of a cleavage furrow

true

The period between meiosis I and II is termed interkinesis.

true

The overall purpose of mitosis is to produce

two daughter cells that are genetically identical to one another

During which phase of the cell cycle are the chromosomes duplicated?

S phase