Chapter 13

Question 1

Heredity

Answer 1

The transmission of traits from one generation to the next

Question 2

Variation

Answer 2

Demonstrated by the differences in appearance that offspring show from parents and siblings

Question 3

Genetics

Answer 3

the scientific study of heredity

Question 4

Genes

Answer 4

the units of heredity and are made up of segments of DNA

Question 5

Gametes

Answer 5

sperm and egg; the reproductive cells that pass genes to the next generation

Question 6

Somatic cells

Answer 6

All the cells of the body except gametes and their precursors; these have 46 chromosomes in humans

Question 7

Locus

Answer 7

A gene’s specific position along a chromosome

Question 8

Asexual reproduction

Answer 8

a single individual passes all of its genes to its offspring without the fusion of gametes

Question 9

Clone

Answer 9

a group of genetically identical individuals from the same parent

Question 10

Sexual reproduction

Answer 10

two parents give rise to offspring that have unique combinations of gene inherited from the two parents

Question 11

Life Cycle

Answer 11

the generation-to-generation sequence of states in the reproductive history of an organism; Develop -> survive -> reproduce

Question 12

homologous chromosomes

Answer 12

or homologs; the two chromosomes in each pair

Question 13

Sex chromosomes

Answer 13

These determine the sex of the individual and are called X and Y; females have a homologous pair of X (XX) and males have an X and a Y (XY)

Question 14

Autosomes

Answer 14

the remaining 22 pairs of chromosomes that are not sex chromosomes

Question 15

Diploid cell

Answer 15

(2n) has two sets of chromosomes

Question 16

Karyotype

Answer 16

a visual representation of an organism’s complete set of chromosomes, including their number, size, and shape

Question 17

Haploid cell

Answer 17

A gamete (sperm or egg) that contains a single set of chromosomes (n)

Question 17

Maternal

Answer 17

from the mother

Question 18

Paternal

Answer 18

from the father

Question 19

The human life cycle

Answer 19

Meiosis -> gametes ->fertilization -> mitosis

Question 20

Three types of sexual life cycles

Answer 20

1) Animals
2) Plants and some algae
3) Most fungi and some protists

Question 21

Animal sexual life cycle

Answer 21

Gametes are the only haploid cells; gametes are produced by meiosis and undergo no further cell division before fertilization; gametes fuse to form a diploid zygote

Question 22

Plants and some algae sexual life cycle

Answer 22

Each spore grows by mitosis into a haploid organism called a gametophyte; a gametophyte makes haploid gametes by mitosis; fertilization of gametes results in a diploid sporophyte

Question 23

Most fungi and some protists sexual life cycle

Answer 23

The only diploid stage is the single-celled zygote - there is non multicellular diploid stage; the zygote produces haploid cells by meiosis; each haploid cell grows by mitosis into a haploid multicellular organism; the haploid adulate produces gametes by mitosis

Question 24

Only a ________ cell can undergo meiosis

Answer 24

diploid

Question 25

Meiosis I

Answer 25

The first stage of meiosis; When homologous chromosomes separate (One cell that splits into two with sister chromatids still together)

Question 26

Meiosis II

Answer 26

second stage of meiosis; When the sister chromatids of the two cells split, forming four cells

Question 27

Prophase I

Answer 27

In early prophase I, each chromosome pairs with its homolog and crossing over occurs; X-shaped regions called chiasmata are crossover sites

Question 28

Metaphase I

Answer 28

pairs of homologs line up at the metaphase plate, with one chromosome facing each pole; microtubules connect to the kinetochore of each chromosome

Question 29

Anaphase I

Answer 29

Pairs of homologous chromosomes separate; one chromosome of each pair moves toward opposite poles, guided by the spindle apparatus

Question 30

Telophase I and Cytokinesis

Answer 30

Each half of the cell has a haploid set of chromosomes; each chromosome consists of two sister chromatids; cytokinesis usually occurs simultaneously, forming two haploid daughter cells

Question 31

Prophase II

Answer 31

A spindle apparatus forms; Chromosomes move toward the metaphase plate

Question 32

Metaphase II

Answer 32

Sister chromatids are arranged at the metaphase plate (because of crossing over, each chromosome are no longer genetically identical); kinetochores of sister chromatid attach to microtubules extending from opposite poles

Question 33

Anaphase II

Answer 33

Sister chromatids separate; Sister chromatids now move as two newly individual chromosomes towards opposite poles

Question 34

Telophase II and Cytokinesis

Answer 34

The chromosomes arrive at opposite poles; Nuclei form and the chromosomes begin decondensing; cytokinesis the cytoplasm

Question 35

synaptonemal complex

Answer 35

A zipper-like structure that holds one homolog tightly to the other during crossing over

Question 36

synapsis

Answer 36

the fusion of chromosome parts during crossing over

Question 37

random fertilization

Answer 37

adds to genetic variation because any sperm can fuse with any egg