Chapter 11

Question 1

Alternation of generations

Answer 1

life-cycle type in which the diploid and haploid stages alternate

Question 2

Chiasmata

Answer 2

(singular, chiasma) the structure that forms at the crossover points after genetic material is exchanged

Question 3

Cohesin

Answer 3

proteins that form a complex that seals sister chromatids together at their centromeres until anaphase II of meiosis

Question 4

Crossover

Answer 4

exchange of genetic material between nonsister chromatids resulting in chromosomes that incorporate genes from both parents of the organism

Question 5

Fertilization

Answer 5

union of two haploid cells from two individual organisms

Question 6

Gametophyte

Answer 6

a multicellular haploid life-cycle stage that produces gametes

Question 7

Germ cells

Answer 7

specialized cell line that produces gametes, such as eggs or sperm

Question 8

Interkinesis

Answer 8

(also, interphase II) brief period of rest between meiosis I and meiosis II

Question 9

Life cycle

Answer 9

the sequence of events in the development of an organism and the production of cells that produce offspring

Question 10

Meiosis

Answer 10

a nuclear division process that results in four haploid cells

Question 11

Meiosis I

Answer 11

first round of meiotic cell division; referred to as reduction division because the ploidy level is reduced from diploid to haploid

Question 12

Meiosis II

Answer 12

second round of meiotic cell division following meiosis I; sister chromatids are separated into individual chromosomes, and the result is four unique haploid cells

Question 13

Recombination nodules

Answer 13

protein assemblies formed on the synaptonemal complex that mark the points of crossover events and mediate the multistep process of genetic recombination between nonsister chromatids of a homologous pair

Question 14

Reduction division

Answer 14

nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division

Question 15

Somatic cell

Answer 15

all the cells of a multicellular organism except the gametes or reproductive cells

Question 16

Spore

Answer 16

haploid cell that can produce a haploid multicellular organism or can fuse with another spore to form a diploid cell

Question 17

Sporophyte

Answer 17

a multicellular diploid life-cycle stage that produces haploid spores by meiosis

Question 18

Synapsis

Answer 18

formation of a close association between homologous chromosomes during prophase I

Question 19

Synaptonemal complex

Answer 19

protein lattice that forms between homologous chromosomes during prophase I, supporting crossover

Question 20

Tetrad

Answer 20

two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I