Chapter 11 Pre and Homework

In what way is cytokinesis in plant cells similar to binary fission in a bacterium?

Cell wall material is deposited to separate the daughter cells.

Which one of the statements regarding the S cyclin‐CDK complex is true?

It ensures that DNA is not replicated multiple times.

In meiosis, recombination occurs:

during only prophase I and involves exchange between chromatids of homologous chromosomes.

A cell in prophase I of meiosis has _____ as much DNA as each of the daughter cells following cytokinesis of meiosis II.

four times

A gene associated with promoting normal cell division is called:

a proto‐oncogene.

Which of the processes is most important for passage through the G1 cell cycle checkpoint?

activation of cyclin‐dependent kinases

Asexual reproduction occurs in:

animal cells. plant cells. bacterial cells. unicellular eukaryotes.

Studies of rapidly dividing embryonic animal cells revealed:

increased synthesis of certain proteins in sync with the cell cycle. that increased levels of cyclin proteins is correlated with activation of cyclin‐dependent kinase (CDK) enzymes. (All of these choices are correct.) that inhibition of protein synthesis blocks mitosis. a periodic activation of protein kinases in sync with the cell cycle.

Which of the statements about viruses is true?

(None of the other answer options is correct.) Viruses are a type of prokaryotic cell. Viruses are the root cause of most, if not all, cancers. Human cancers have not been associated with viruses. Viruses contain multiple genes, and each of these genes is an oncogene.

How many chromosome pairs are there in a normal human genome?

23

It is estimated that there are a total of 245 cells (roughly 50 trillion) in the adult the human body. Starting from a fertilized egg, how many cell divisions would be required to produce 245, assuming that every cell divides in every cycle?

45 divisions

The most common form of hemophilia is a defect in blood clotting factor VIII, which is caused by a mutant form of a gene on the X chromosome. Boys who inherit that mutation from their mother suffer from uncontrolled bleeding. Girls carrying one copy of this mutation have near normal blood clotting. Uncommonly, a girl is born with hemophilia even though both parents have normal phenotypes. Which of the statements might explain hemophilia in a girl born to parents with normal blood clotting phenotypes?

Nondisjunction during sperm formation resulted in her receiving no sex chromosome from her father and an X chromosome from her mother; she is XO.

A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. This stage is most likely:

S phase

A student was studying cell growth using cells grown in laboratory cultures. The cultures were synchronized so that all of the cells passed through the same stage of the cell cycle at the same time. The cells were examined during five different periods of time, intervals (A-E). The amount of DNA present per cell was determined for each interval. The graph shows the result of this study. Most of the cells examined during interval A have half as much DNA as those measured in interval C. Therefore, most of the cells at interval B must have been in: LOOK AT GALLERY

S phase.

The second meiotic division resembles mitosis because: (ALL IS CORRECT)

chromosomes decondense during telophase II. the daughter cells have the same number of chromosomes as the parent cell. sister chromatids are separated during anaphase II to become the chromosomes of the daughter cells. spindle microtubules attach from opposite directions to the centromere of each sister chromatid pair.

The division of the cell's cytoplasm in a eukaryotic cell is known as:

cytokinesis.

What process can account for the phenomenon wherein a normal XY male produces a sperm carrying two Y chromosomes?

second‐division nondisjunction

Cell division is regulated by (ALL IS CORRECT)

signals that indicate that DNA has been replicated. growth factor signals. signals about the nutritional status of the cell. signals that indicate that the cell has reached a sufficient size.

During meiosis I:

sister chromatids are not separated.

Phosphorylated p53 is a protein that accumulates in the nuclei of cells that have damaged DNA where it functions to block the cell cycle and activate DNA repair. The p53 gene that encodes this protein is an example of a(n):

tumor suppressor gene.