Chapter 12

Question 1

Asexual Reproduction

Answer 1

reproduction without sex

Question 2

Gametes

Answer 2

sex cells

Question 3

Female gamete

Answer 3

egg

Question 4

male gamete

Answer 4

sperm

Question 5

two gametes unite to form a single cell called a ______

Answer 5

zygote

Question 6

The zygote is the first cell of _ ___ __________

Answer 6

a new individual

Question 7

When a cell undergoes meiosis, ____ cells are produced from ___ successive divisions, which generally take place without pausing.

Answer 7

FOUR, TWO

When a cell undergoes meiosis, FOUR cells are produced from TWO successive divisions, which generally take place without pausing.

Question 8

Prophase 1 in Meiosis

3 parts

Answer 8

1. the chromosomes coil, becoming shorter and thicker; the chromosomes also become aligned in homologous pairs.
2. the nuclear envelope and the nucleolus disassociate
3. Parts of each closely associated pair of chromosomes are exchanged with each other.

Question 9

Two homologous chromosomes paired at meiosis are called a ________

Answer 9

bivalent

Question 10

centromere

Answer 10

a dense, constricted area of a chromosome to which spindle fibers become attached

Question 11

spindle fibers

Answer 11

consist of microtubules that look like thin threads

Question 12

Crossing over

Answer 12

results in an exchange of DNA contributed by the two parents, which is the basis for some of the variability seen in the offspring.

Question 13

Chiasma (plural: chiasmata)

Answer 13

an “X” shaped figure that results from each cross over

Question 14

Metaphase 1 of meiosis

2 parts

Answer 14

1. The pairs of chromosomes become aligned at the equator of the cell
2. The now complete spindle becomes more apparent

Question 15

Anaphase 1 of meiosis

1 part

Answer 15

Each chromosome, consisting of two chromatids, migrates to a pole. the two chromosomes migrate to opposite poles

Question 16

Telophase 1 of meiosis

Answer 16

This phase has been completed when the original cell has become 2 cells or 2 nuclei

Question 17

Prophase II

Answer 17

Chromosomes become shorter and thicker, their two stranded nature once becomes more apparent

Question 18

Metaphase II

Answer 18

1. The centromeres of the chromosomes become aligned along the equator
2. New spindles become conspicuous and complete

Question 19

In metaphase II, the two spindles may be formed

Answer 19

either perpendicular to the ones that formed in Metaphase I or along the same plane

Question 20

Anaphase II

Answer 20

The centromeres and chromatids of each chromosome separate and migrate to opposite poles

Question 21

Telophase II (2 parts)

Answer 21

1. the coils of the chromatids relax, so that the chromosomes become longer and thinner. At this point each chromosome consists of one DNA molecule in contrast to the two at the beginning of Meiosis II
2. New nuclear envelopes and nucleoli appear for each group of chromosomes

Question 22

Haploid

Answer 22

any cell having one set of chromosomes

Question 23

Diploid

Answer 23

any cell with two sets of chromosomes

Question 24

by the time meiosis is complete, ____ haploid cells have been produced by ___ diploid cell

Answer 24

FOUR, ONE

Question 25

Triploid

Answer 25

cells that have three sets of chromosomes

Question 26

Alternation of generations

Answer 26

occurs when a diploid SPOROPHYTE phase and a haploid GAMETOPHYTE phase