Ch. 12 & Ch.13 Bio Review + AP BIO Collegeboard Questions

What is the expected percent change in the DNADNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1G1 phase to the end of the G2G2 phase?

100%

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n=8)

16

Based on Figure 1, what percent of the time required to complete a full cycle do the cells typically spend in interphase?

95% Interphase is composed of the *G1, S, and G2 phases*

Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in the initiation of a cancerous tumor?

Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in the initiation of a cancerous tumor?

Glycogen synthetase kinase 3 beta is a protein kinase that has been implicated in many types of cancer. Depending on the cell type, the gene for glycogen synthetase kinase 3 beta (GSK3β)(GSK3β) can act either as an oncogene or as a tumor suppressor. Which of the following best predicts how GSK3βGSK3β mutations can lead to the development of cancer?

Cells with inactive GSK3βGSK3β fail to trigger apoptosis.

Meiosis II: Prophase II

Chromosomes condense again and become visible. Spindle fibers again form. Nuclear membrane disintegrates again.

Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of cell division.

Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells

Meiosis I

Divides homologous chromosomes producing two haploid cells with duplicated chromosomes.

Meiosis II: Metaphase II

Duplicated chromosomes align at the cell equator. Each chromosome still has two sister chromatids at this stage.

Homologous chromosomes are divided in meosis II

False

Is DNA copied between Meosis I and Meosis II?

False

Sister Chromatids are divided in meosis I

False

T or F: During Mitosis, homologous chromosomes pair up along the cell equator. During Meosis, homologous chromsomes never pair up.

False. During *Meiosis*, homologous chromosomes pair up along the cell equator, while in *Mitosis* homologous chromosomes *never* pair up.

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in

G1

Meiosis I: Anaphase I

Homologous pairs separate and move toward opposite poles of the cell *Sister chromatids remain together during this step and throughout meiosis I*

Crossing over

Occurs at the chiasmata, during prophase I or meiosis I

Most cells that have become transformed into cancer cells have which of the following characteristics when compared to normal, healthy cells?

Shorter cell cycle

Meosis II: Anaphase II

Sister chromatids are pulled apart from each other and move to the opposite sides of the cell.

Meosis II: Telophase II and Cytokinesis

Spindle fibers break apart, and the cell undergoes cytokinesis. The end result is four haploid cells with a combination of chromosomes from the mother and father.

Meiosis I: Telophase I and Cytokinesis

Spindle fibers disassemble and Cytokinesis occurs, dividing cell in two The end result is two cells that each have a unique combination of 23 duplicated chromosomes from both parents.

Which of the following conditions will most likely cause a normal body cell to become a cancer cell?

The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins.

Meiosis I: Metaphase I

The homologous chromosome pairs are aligned midway between spindle poles (23 chromosomes)

Meiosis I: Prophase I

The nuclear membrane begins to break down and disintegrate. The replicated chromosomes begin to condense and become visible. Homologous chromosomes synapse (pair up) to form bivalents. Spindle microtubules begin to form.

Researchers studying cell cycle regulation in budding yeast have observed that a mutation in the CDC15 gene causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?

The yeast cells will replicate their chromosomes but will fail to complete cytokinesis.

Before meiosis begins, DNA has already been copied

True

Homologous Chromosomes are divided in meiosis I

True

Meiosis II divides sister chromatids and results in undoubled chromosomes.

True

Meiosis results in diploid cells.

True

Mitosis results in haploid cells.

True

Sister Chromatids are divided in meiosis II

True

T or F. Meiosis has two cell divisions and Mitosis has only one.

True

T or F: Genetic Variation occurs in Meiosis

True

T or F: In anaphase I of meiosis, sister chromatids *remain together*. In anaphase of *mitosis*, sister chromatids *seperate*.

True

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely

a plant cell in the process of cytokinesis

A human cell containing 22 autosomes and a Y chromosome is

a sperm

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

cells with more than one nucleus.

The drug Cytochalsin B can dissociate microtubules and stops cells from dividing.

cleavage furrow formation and cytokinesis

One difference between cancer cells and normal cells is that cancer cells

continue to divide even when tightly packed together

Types of genetic variation

crossing over, independent assortment, random fertilization

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubles, its effectiveness must be related to

disruption of mitotic spindle formation

Homologous chromosomes move toward opposite poles of a dividing cell during

meosis I

Which life cycle stage is found in plants but not animals?

multicellular haploid

Which of the following does not occur during mitosis?

replication of the DNA

Meosis II is similar to mitosis in that

sister chromatids seperate during anaphase.

The decline of MPF activity at the end of mitosis is due to

the degradation of cyclin

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be

x

If we continued to follow the cell lineage, from question 5 then the DNA content of a single cell at metaphase of meosis II would be

x