Chapter 13 - Meiosis and Sexual Life Cycles

Question 1

heredity

Answer 1

The transmission of traits from one generation to the next.

Question 2

variation

Answer 2

Differences between members of the same species.

Question 3

genetics

Answer 3

The scientific study of heredity and hereditary variation.

Question 4

gene

Answer 4

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).

Question 5

gamete

Answer 5

A haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.

Question 6

somatic cell

Answer 6

Any cell in a multicellular organism except a sperm or egg or their precursors.

Question 7

locus

Answer 7

A specific place along the length of a chromosome where a given gene is located.

Question 8

asexual reproduction

Answer 8

The generation of offspring from a single parent that occurs without the fusion of gametes (by budding, division of a single cell, or division of the entire organism into two or more parts). In most cases, the offspring are genetically identical to the parent.

Question 9

clone

Answer 9

(1) A lineage of genetically identical individuals or cells. (2) In popular usage, an individual that is genetically identical to another individual. (3) As a verb, to make one or more genetic replicas of an individual or cell. <em>See also</em> gene cloning.

Question 10

sexual reproduction

Answer 10

A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from both parents via the gametes.

Question 11

life cycle

Answer 11

The generation-to-generation sequence of stages in the reproductive history of an organism.

Question 12

karyotype

Answer 12

A display of the chromosome pairs of a cell arranged by size and shape.

Question 13

homologous chromosome

Answer 13

A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism’s father, the other from the mother. Also called homologs, or a homologous pair.

Question 14

sex chromosome

Answer 14

A chromosome responsible for determining the sex of an individual.

Question 15

autosome

Answer 15

A chromosome that is not directly involved in determining sex; not a sex chromosome.

Question 16

diploid cell

Answer 16

A cell containing two sets of chromosomes (2<em>n</em>), one set inherited from each parent.

Question 17

haploid cell

Answer 17

A cell containing only one set of chromosomes (<em>n</em>).

Question 18

fertilization

Answer 18

(1) The union of haploid gametes to produce a diploid zygote. (2) The addition of mineral nutrients to the soil.

Question 19

zygote

Answer 19

The diploid cell produced by the union of haploid gametes during fertilization; a fertilized egg.

Question 20

meiosis

Answer 20

A modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DAN replication. It results in cells with half the number of chromosome sets as the original cell.

Question 21

alternation of generations

Answer 21

A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae.

Question 22

meiosis I

Answer 22

The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell.

Question 23

meiosis II

Answer 23

The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell.

Question 24

synapsis

Answer 24

The pairing and physical connection of duplicated homologous chromosomes during prophase I of meiosis.

Question 25

crossing over

Answer 25

The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.

Question 26

chiasma

Answer 26

The X-shaped, microscopically visible region where crossing over has occurred earlier in prophase I between homologous nonsister chromatids. Chiasmata become visible after synapsis ends, with the two homologs remaining associated due to sister chromatid cohesion.

Question 27

recombinant chromosomes

Answer 27

A chromosome created when crossing over combines DNA from two parents into a single chromosome.