Meiosis

The epithelial cells in the skin of an animal have 24 chromosomes. How many chromosomes are present in the gametes of this animal? 48 24 6 12

12

Cell cycle checkpoints: can involve the protein p53. act as a brake on cell division if something is not right. All of these choices are correct. provide opportunities to check if the cell has carried out steps necessary for cell division.

All of these choices are correct

Cell division is regulated by: signals about the nutritional status of the cell. signals that indicate that DNA has been replicated. All of these choices are correct. growth factor signals. signals that indicate that the cell has reached a sufficient size.

All of these choices are correct

How would the loss of p53 activity affect a cell? CDK activity would not be appropriately regulated. The G1/S checkpoint would not be functional. All of these choices are correct. DNA damage could accumulate.

All of these choices are correct

Which of the following statements regarding the cell cycle is TRUE? Different levels of cyclins are observed at different cell cycle stages. It is regulated by cyclins and CDKs. All of these choices are correct. It has many major cell cycle checkpoints. It can be "paused" by the action of p53.

All of these choices are correct

Sexual reproduction results in an increase in genetic diversity because: during metaphase I, the bivalents line up in a random orientation so that gametes inherit a random set of maternally and paternally derived chromosomes. All of these choices are correct. during prophase I, genes that are paternally and maternally derived recombine so that the gametes have chromosomes that are different from the parents' chromosomes. during fertilization, the gametes that fuse are random so that a large number of chromosomal combinations are possible in the new organism.

All of these choices are correct.

Sexual reproduction results: in a new generation with the same number of chromosomes as each parent. in offspring that are not genetically identical. in a new generation that is not genetically identical to its parents. All of these choices are correct. from combining genetic material from two gametes.

All of these choices are correct.

Which of these events does NOT include a checkpoint in the cell cycle? All of these events include a checkpoint in the cell cycle. the beginning of M phase the transition from G2 to M phase the transition from G1 to S phase

All of these events include a checkpoint in the cell cycle

Which of the following is NOT a characteristic of meiotic cell division? Cell division results in the formation of four daughter cells. Cell division requires two rounds of nuclear division. Cell division results in the production of gametes. Daughter cells are genetically identical.

Daughter cells are genetically identical.

During meiosis, two rounds of DNA synthesis are required to form four gametes from one parent cell. True False

False

Which major checkpoint delays the cell cycle when DNA replication is incomplete? M checkpoint G2 checkpoint G1 checkpoint G1, G2, and the M checkpoints None of the checkpoints delays the cell cycle when DNA replication is incomplete.

G2 checkpoint

What would happen if crossing over occurred between sister chromatids? Genetic diversity would decrease due to the loss of gene combinations. Gene rearrangement would lead to changes in gene expression. Nothing would happen because sister chromatids are genetically identical or nearly identical. Genetic diversity would increase due to the addition of gene combinations.

Nothing would happen because sister chromatids are gentically identical or nearly identical

A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells? These cells are normal. Within these cells, the cell cycle has been halted at the G2/M transition. All of these cells have entered mitosis. All of these cells have entered meiosis. These cells likely contain damaged DNA.

These cells likely contain damaged DNA

Which of the following is NOT true about gametes? They are formed by meiotic cell division. They have half as many chromosomes as a somatic cell of the same individual. They are called eggs and sperm in animals. They are genetically identical to other gametes formed during meiosis. They fuse to form a new organism during fertilization.

They are genetically identical to other gametes formed during meiosis.

How do new cyclin proteins appear in the cytoplasm? They are imported from outside the cell. They are made through protein synthesis. They are recycled. All of these choices are correct.

They are made through protein synthesis

Most of the significant changes in activities and functions that accompany passage through a cell cycle checkpoint are regulated by the: inhibition of cyclin proteins. activation of DNA polymerase. activation of microtubules. changes in membrane polarization. activation of kinase enzymes.

activation of kinase enzymes

When do sister chromatids separate in meiosis? metaphase II anaphase I telophase I anaphase II

anaphase 2

Another name for non-sister chromatids is: bivalents. diploids. homologous chromosomes. chiasmata.

homologous chromosomes

In meiosis, recombination occurs: only during prophase I and involves exchange between chromatids of homologous chromosomes. during prophase I and II and involves exchange of chromosome fragments between sister chromatids. during prophase I and II and involves exchange of chromosome fragments between all four chromatids. only during prophase I and involves exchange of chromosome fragments between sister chromatids.

only during prophase 1 and involves exchange between chromatids of homologous chromosomes

Synapsis is best described as the: exchange of genetic information between non-sister chromatids. pairing of homologous chromosomes in prophase I. alignment of non-sister chromatids at the metaphase plate. exchange of genetic information between sister chromatids.

pairing of homologous chromosomes in prophase 1.

Many of the specific functions that are triggered when a cell passes one of the cell cycle checkpoints result from activation of enzymes and other proteins. A common mechanism for this activation is: signal transduction. phosphorylation of specific proteins. polymerization of tubulin. ATP synthesis.

phosphorylation of specific proteins

During meiosis II: chromosomes undergo reductional division. non-sister chromatids exchange maternal and paternal DNA. bivalents are formed during prophase II and are taken apart during anaphase II. All of these choices are correct. sister chromatids are separated.

sister chromatids are seperated

A cell in prophase I of meiosis has _____ as many chromosomes as each of the daughter cells following cytokinesis of meiosis II. twice half four times one quarter

twice