Chapter 13

Question 1

Living organisms are distinguished by their ability to …

Answer 1

reproducing offspring that resemble their parents but may look slightly different (demonstrating variation)

Question 2

Variation

Answer 2

shows that offspring differ somewhat in appearance from parents and siblings

Question 3

Genetics

Answer 3

the study of heredity and hereditary variation (uniqueness)

Question 4

Offspring acquire genes from parents by…

Answer 4

inheriting gene on chromosomes

Question 5

Genes

Answer 5

the units of heredity and are composed of segments of DNA

Question 6

Each gene in an organism’s DNA has a …

Answer 6

specific locus (location) on a certain chromosome

Question 7

In sexual reproduction,

in terms of genes

Answer 7

we inherit one set of chromosomes from our mother and one set from our father

Question 8

In asexual reproduction,

Answer 8

one parent produces genetically identical or exact copy (clone) offspring by mitosis
- more simple process

i.e. the multicellular hydra reproduces by budding

Question 9

In sexual reproduction,

Answer 9

2 parents (produce gametes) give rise to offspring that have unique combinations of genes inherited from the two parents

Question 10

Fertilization and meiosis alternate in…

Answer 10

sexual life cycles

Question 11

Life Cycle

Answer 11

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

Question 12

in humans, each somatic cell has…

Answer 12

46 chromosomes

made up of 2 sets, one from each parent

Question 13

Karyotype

Answer 13

an ordered, arranged, visual representation of the chromosomes in a cell that can be used to determine their homology or similarity

Question 14

Homologous chromosomes (autosomes)

Answer 14

a pair of chromosomes that have the same characteristics

humans have 22 autosome pairs

Question 15

Heredity

Answer 15

the transmission of genes on chromosomes and their traits from one generation to the next

Question 16

Sex Chromosomes

Answer 16

distinct from each other and are represented as X and Y

determine the “sex” of an individual
XX = female
XY = male

Question 17

Diploid Cell

Answer 17

has 2 sets of each of its chromosomes and a human has 46 chromosomes (2n=46)

where n = the number of single set chromosomes

Question 18

n =

Answer 18

the number of single set chromosomes

Question 19

Haploid

Answer 19

sperm and ova (gametes)

have only one set of chromosomes

Question 20

In a cell in which DNA synthesis has occurred…

Answer 20

the chromosomes are duplicated and consist of 2 identical sister chromatids

Question 21

Gametes

Answer 21

unlike somatic cells, gametes only contain 1 set of chromosomes

Question 22

Meiosis

Answer 22

variety and the production of new cells that are genetically distinct

cells produce non-identical daughter cells that are used in reproduction
cells contain genes

at sexual maturity, the ovaries and testes produce haploid gametes by this process

Question 23

Forming a Diploid Zygote

Answer 23

during fertilization, the gametes, sperm, and ovum fuse forming a diploid zygote that develops into an adult organism

Question 24

3 main types of sexual cycles differ in the …

Answer 24

timing of meiosis and fertilization

Question 25

In animals,

Answer 25

meiosis occurs during gamete formation and the gametes are the only haploid cells

Question 26

plants and some algae exhibit...

Answer 26

an alternation of generations where the life cycle includes both diploid (sporophyte) and haploid (gametophyte) multicellular stages

Question 27

in most fungi and some protists, meiosis produces

Answer 27

haploid cells that gives rise to a haploid multicellular adult organism that carries out mitosis, producing cells that will become gametes

Question 28

haploid multicellular organism

Answer 28

predominant phase in plants

Question 29

diploid multicellular organism

Answer 29

predominant phase in animals/humans

Question 30

Meiosis

Answer 30

resembles mitosis but reduces the number of chromosome sets from diploid to haploid takes place in 2 sets of divisions

Question 31

2 sets of meiosis division

Answer 31

1) Meiosis I | 2) Meiosis II

Question 32

Meiosis I

Answer 32

separates the chromosomes and makes the chromosomes haploid Prophase I Metaphase I: the tetrads line up on equator (Cross-over occurs here) Anaphase I: homologous chromosomes pull apart sister chromatids Telophase I and Cytokinesis

Question 33

Meiosis II

Answer 33

separates the sister chromatids and makes 4 daughter cells containing 1/2 the chromosomes as the parent cell (different than parental) Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis

Question 34

Meiosis can be distinguished from mitosis by 3 events in Meiosis I

Answer 34

1) Synapsis and direct crossing over of homologous chromosomes through physical contact and exchange genetic information 2) Tetrads on the metaphase plate, during metaphase I of meiosis, paired homologous chromosomes (tetrads) are positioned on the metaphase plates 3) Separation of Homologous at anaphase I of meiosis, homologous pairs move toward opposite poles of the cell => in anaphase II of meiosis, the sister chromatids separate

Question 35

Tetrads

Answer 35

paired homologous chromosomes

Question 36

Genetic Variation

Answer 36

produced in sexual life cycles (meiosis) contributes to species diversity and the reshuffling of genetic material in each generation provides the "raw material" for biological changes that are beneficial to the organism and its offspring

Question 37

3 mechanisms contribute to genetic variation

Answer 37

1) Independent assortment 2) Crossing over 3) Random Fertilization

Question 38

Independent assortment | of chromosomes

Answer 38

each pair of chromosomes sorts its maternal and paternal homologues into daughter cells independently of the other pairs

Question 39

Crossing Over

Answer 39

produces recombinant chromosomes that carry genes derived from 2 different parents during metaphase I

Question 40

Random Fertilization

Answer 40

the fusion of gametes will produce a zygote with any of about 64 trillion diploid combinations

Question 41

Mutations

Answer 41

a source of genetic variation

Question 42

Sexual reproduction

Answer 42

produces new combinations of variant genes, adding more genetic diversity and variability

Question 43

Chiasma

Answer 43

physical site where the two chromosome can exchange genetic material