Biology Chapter 12

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A) 64 B) 4 C) 8 D) 32 E) 16

32

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 A) G2. B) G1. C) metaphase. D) prophase. E) anaphase.

G1

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? A) cytokinesis B) G2 C) S D) G1 E) M

G1

Which of the following correctly matches a phase of the cell cycle with its description? A) G2: cell division B) G1: follows cell division C) M: duplication of DNA D) S: immediately precedes cell division E) All of the above are correctly matched.

G1: follows cell division

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable? A) It does not alter metabolically active cells. B) It interferes with rapidly dividing cells. C) It interferes with cells entering G0. D) It only attacks cells that are density dependent. E) It is safe enough to limit all apoptosis.

It interferes with rapidly dividing cells.

All cell cycle checkpoints are similar in which way? A) They activate or inactivate other proteins. B) They respond to the same cyclins. C) They utilize the same Cdks. D) They each have only one cyclin/Cdk complex. E) They give the go-ahead signal to progress to the next checkpoint.

They give the go-ahead signal to progress to the next checkpoint.

Why is it difficult to observe individual chromosomes with a light microscope during interphase? A) The DNA has not been replicated yet. B) The spindle must move them to the metaphase plate before they become visible. C) They leave the nucleus and are dispersed to other parts of the cell. D) Sister chromatids do not pair up until division starts. E) They have uncoiled to form long, thin strands.

They have uncoiled to form long, thin strands.

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis? A) They need only meiosis if they produce egg cells. B) They need only mitosis to make large numbers of cells such as sperm. C) A single-celled organism only needs mitosis. D) They need both if they are producing animal gametes. E) They need meiosis if the cells are producing organs such as ovaries.

They need both if they are producing animal gametes.

What is a cleavage furrow? A) the separation of divided prokaryotes B) a groove in the plasma membrane between daughter nuclei C) the space that is created between two chromatids during anaphase D) a ring of vesicles forming a cell plate E) the metaphase plate where chromosomes attach to the spindle

a groove in the plasma membrane between daughter nuclei

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) a bacterial cell dividing. B) a plant cell in the process of cytokinesis. C) an animal cell in the S phase of the cell cycle. D) a plant cell in metaphase. E) an animal cell in the process of cytokinesis.

a plant cell in the process of cytokinesis.

During which phase of mitosis do the chromatids become chromosomes? A) prophase B) metaphase C) anaphase D) telophase E) cytokinesis

anaphase

One difference between cancer cells and normal cells is that cancer cells A) are unable to synthesize DNA. B) cannot function properly because they are affected by density-dependent inhibition. C) continue to divide even when they are tightly packed together. D) are arrested at the S phase of the cell cycle. E) are always in the M phase of the cell cycle.

continue to divide even when they are tightly packed together.

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this? A) a decrease in chromosome number B) inability to duplicate DNA C) large cells containing many nuclei D) a rapid rate of gamete production E) division of the organism into many cells, most lacking nuclei

large cells containing many nuclei

At which phase are centrioles beginning to move apart in animal cells? A) prophase B) prometaphase C) anaphase D) metaphase E) telophase

prophase

Which of the following does not occur during mitosis? A) spindle formation B) replication of the DNA C) condensation of the chromosomes D) separation of the spindle poles E) separation of sister chromatids

replication of the DNA

Which of the following is true of benign tumors, but not malignant tumors? A) They have an unusual number of chromosomes. B) They migrate from the initial site of transformation to other organs or tissues. C) They remain confined to their original site D) They can divide indefinitely if an adequate supply of nutrients is available. E) They are the result of the transformation of normal cells.

They remain confined to their original site

Where do the microtubules of the spindle originate during mitosis in animal cells? A) centromere B) chromatid C) kinetochore D) centrosome E) centriole

centrosome