lect. 15 quiz

Match each of the following terms with its definition. Definitions may be used once, more than once, or not at all. A. the physical breakage and reunion of non-sister chromatids during prophase I B. the region of a chromosome where sister chromatids remain attached C. chromatids in a bivalent that do not share a centromere D. a four-stranded structure of homologous chromosomes in alignment E. the microtubule organizing center F. paired chromosomes that share the same set of genes G. crosslike structures found in bivalents H. alignment of homologous chromosomes during prophase I a. non-sister chromatids b. homologous chromosomes c. synapsis d. chiasmata e. centrosome f. centromere g. bivalent h. crossing over

1.h 2.f 3.a 4.g 5.e 6.b 7.d 8.c

During meiosis I: a. All of these choices are correct. b. non-sister chromatids exchange maternal and paternal DNA. c. chromosomes undergo reductional division. d. sister chromatids are not separated. e. bivalents are formed during prophase I and are taken apart during anaphase I.

a. All of these choices are correct.

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

a. All of these choices are correct.

The centrosome is: a. a region of the chromosome where microtubules attach to chromosomes during mitosis. b. the microtubule organizing center for the mitotic spindle. c. All of these choices are correct. d. a region of the chromosome where sister chromatids are attached to each other. e. a region of the chromosome where kinetochores attach.

b. the microtubule organizing center for the mitotic spindle.

Reproduction by mitotic cell division: a. continues in mature adult humans to replace damaged and worn-out cells. b. results in two daughter cells that are genetically identical. c. is asexual reproduction. d. All of these choices are correct. e. persists in mature plant cells for continued growth.

d. All of these choices are correct.

The second meiotic division resembles mitosis because: a. chromosomes decondense during telophase II. b. spindle microtubules attach from opposite directions to the centromere of each sister chromatid pair. c. sister chromatids are separated during anaphase II to become the chromosomes of the daughter cells. d. All of these choices are correct. e. the daughter cells have the same number of chromosomes as the parent cell..

d. All of these choices are correct.

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

d. They are genetically identical to other gametes formed during meiosis.

Which of the following statements is NOT true about sister chromatids? a. They are formed in the S phase of the cell cycle when the chromosome undergoes replication. b. They are identical or nearly identical DNA sequences. c. All of these statements about sister chromatids are true. d. They are the same as homologous chromosomes. e. They are attached to each other at the centromere.

d. They are the same as homologous chromosomes.

Interphase involves all of the following steps except a. All of these steps occur during interphase. b. preparation for DNA replication. c. DNA replication. d. the synthesis of cellular components necessary for mitosis. e. an increased condensation of chromatin.

e. an increased condensation of chromatin.

When homologous chromosomes are aligned with each other and arranged as pairs in order of decreasing size, the resulting portrait is referred to as a(n)

karyotype