Meiosis Test

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

12

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

All of these choices are correct.

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

All of these choices are correct.

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

All of these choices are correct.

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

All of these choices are correct.

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

All of these choices are correct.

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

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 transition from G1 to S phase -the transition from G2 to M phase -the beginning of M phase

All of these events include a checkpoint in the cell cycle

Which of the following is NOT a characteristic of meiotic cell division? -Daughter cells are genetically identical. -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.

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

False

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

G2 checkpoint

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

Nothing would happen because sister chromatids are genetically 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? -All of these cells have entered mitosis. -Within these cells, the cell cycle has been halted at the G2/M transition. -These cells are normal. -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 fuse to form a new organism during fertilization. -They have half as many chromosomes as a somatic cell of the same individual. -They are formed by meiotic cell division. -They are called eggs and sperm in animals. -They are genetically identical to other gametes formed during meiosis.

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 recycled. -All of these choices are correct. -They are made through protein synthesis.

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: -activation of microtubules. -activation of DNA polymerase. -changes in membrane polarization. -activation of kinase enzymes. -inhibition of cyclin proteins.

activation of kinase enzymes.

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

anaphase II

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

homologous chromosomes.

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

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

pairing of homologous chromosomes in prophase I.

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: -phosphorylation of specific proteins. -ATP synthesis. -polymerization of tubulin. -signal transduction.

phosphorylation of specific proteins.

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

sister chromatids are separated.

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

twice