Chapter 13: Meiosis and Sexual Reproduction (Test 3)

Question 1

___ is the transmission of traits from one generation to the next

Answer 1

•Heredity

Question 2

•Variation is demonstrated by ___ that offspring show from parents and siblings

Answer 2

the differences in appearance

Question 3

•Genetics is ___

Answer 3

the scientific study of heredity and variation

Question 4

• In a literal sense, children do not inherit particular physical traits from their parents
• It is ___ that are actually inherited

Answer 4

genes

Question 5

•Genes are the ___, and are made up of ___. Genes are packaged on chromosomes.

Answer 5

units of heredity

segments of DNA

Question 6

•The ___ is the entire set of genetic instructions within an organism.

Answer 6

genome

Question 7

•Each gene has a specific location called a ___ on a certain chromosome

Answer 7

locus

Question 8

•Genes are passed to the next generation through reproductive cells called ___ (sperm and eggs)

Answer 8

gametes

Question 9

•After FERTILIZATION - fusion of a sperm cell and ovum (egg), genes from both parents are present in the nucleus of the fertilized egg, or ___.

Answer 9

ZYGOTE

Question 10

•Every living species has a characteristic number of chromosomes. Humans have ___ in their somatic cells.

Answer 10

23 pairs (or 46) chromosomes

Question 11

•In asexual reproduction, one parent produces genetically identical offspring by___

Answer 11

mitosis

Question 12

•In ___, two parents give rise to offspring that have unique combinations of genes inherited from the two parents

Answer 12

sexual reproduction

Question 13

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

Answer 13

life cycle

Question 14

•A life cycle starts at ___ and continues until the organism ___.

Answer 14

conception of an organism

produces its own offspring

Question 15

•Human ___ cells (any cell other than a gamete) have 23 pairs of chromosomes

Answer 15

somatic

Question 16

•A ___ is an ordered display of the pairs of chromosomes from a cell

Answer 16

karyotype

Question 17

•___, are pairs of chromosomes that are the same length and carry genes controlling the same inherited characters

Answer 17

Homologous chromosomes

Question 18

• Each human somatic cell has ___ of sex chromosomes.
• Human females have a ___
• Human males have ___

Answer 18

ONE pair

homologous pair of X chromosomes (XX)

one X and one Y chromosome (XY)

Question 19

•The other 22 pairs of homologous chromosomes that do not determine sex are called ___

Answer 19

autosomes

Question 20

• Each pair of homologous chromosomes includes one chromosome from each parent
• The 46 chromosomes in a human somatic cell are two sets of 23: one set from the mother and one set from the father

Answer 20

just review

Question 21

• A ___ (2n) has two sets of chromosomes. Somatic cells are DIPLOID.
• For humans, the diploid number is 46 (2n = 46)

Answer 21

diploid cell

Question 22

• In a cell in which DNA synthesis has occurred, each chromosome is ___
• Each replicated chromosome consists of two ___

Answer 22

replicated

identical sister chromatids

Question 23

•Sperm cells or ova (gametes) contains a single set of chromosomes, and is ___(n)

Answer 23

haploid

Question 24

• Each set of 23 consists of ___
• An unfertilized ovum contains ___
• A sperm cell contains ___

Answer 24

22 autosomes and a single sex chromosome

22 autosomes and an X

22 autosomes and an X or Y

Question 25

•Fertilization is ___ (the sperm and egg).Each gamete is haploid (n)

Answer 25

the union of gametes

Question 26

•The fertilized egg is called a ___ and has one set of chromosomes from each parent. The zygote is \_\_\_(2n)

Answer 26

zygote diploid

Question 27

•At sexual maturity, the ovaries and testes produce \_\_\_

Answer 27

haploid (n) gametes

Question 28

* Gametes are the only types of human cells produced by \_\_\_, rather than mitosis * Meiosis results in ___ in each gamete (gametes are haploid)

Answer 28

meiosis one set of chromosomes

Question 29

•Gametes fuse to form a ___ that divides by mitosis to develop into a multicellular organism

Answer 29

diploid zygote

Question 30

•Like mitosis, meiosis is preceded by \_\_\_

Answer 30

the replication of chromosomes

Question 31

* Meiosis takes place in two sets of cell divisions, called \_\_\_ * The two cell divisions result in \_\_\_, rather than the two daughter cells in mitosis

Answer 31

meiosis I and meiosis II four daughter cells

Question 32

The Stages of Meiosis I ## Footnote * In the first cell division (meiosis I), ___ separate * This results in 2 haploid cells (each daughter cell only has one set of replicated chromosomes)

Answer 32

homologous chromosomes

Question 33

Animal cell division 1 of 2

Answer 33

Question 34

Animal cell division 2 of 2

Answer 34

Question 35

The stages of Meiosis II ## Footnote * In the second cell division (meiosis II), ___ separate * The two cell divisions result in \_\_\_, * Each daughter cell has ___ as the parent cell

Answer 35

sister chromatids four daughter cells only half as many chromosomes

Question 36

A comparion of Mitosis and Meiosis * Meiosis reduces the number of chromosomes sets from two (diploid) to one (haploid), producing cells that differ genetically from each other and from the parent cell * Mitosis conserves the number of chromosome sets, producing cells that are genetically identical to the parent cell

Answer 36

you remember?

Question 37

Three events are unique to meiosis I and these events result in VARIATION amongst gametes – Synapsis and crossing (prophase I): Homologous chromosomes physically connect and exchange genetic information – Alignment of homologous chromosomes (homologs) on the metaphase plate instead of individual replicated chromosomes as in mitosis – Separation of homologous chromosomes at anaphase I instead of sister chromatids as in mitosis

Answer 37

remember?

Question 38

Genetic variation produced in sexual life cycles contributes to evolution ## Footnote * Mutations (changes in an organism’s DNA) are the original source of genetic diversity * Mutations create different versions of genes called \_\_\_ * Reshuffling of alleles during sexual reproduction produces genetic variation

Answer 38

alleles

Question 39

Origins of Genetic Variation Among Offspring ## Footnote * The behavior of chromosomes during meiosis and fertilization is responsible for most of the variation that arises in each generation * Three mechanisms contribute to genetic variation: –Independent assortment of chromosomes (metaphase I/anaphase I of meiosis) –Crossing over (prophase I of meiosis) –Random fertilization

Question 40

Independent Assortment of Chromosomes ## Footnote * Homologous pairs of chromosomes orient randomly at metaphase I of meiosis * In independent assortment, each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of the other pairs

Answer 40

remember?

Question 41

* The number of combinations possible when chromosomes assort independently into gametes is 2n, where n is the \_\_\_ * For humans (n = \_\_\_), there are more than 8 million (223) possible combinations of chromosomes

Answer 41

haploid number 23

Question 42

Crossing Over (Prophase I) ## Footnote * Crossing over produces \_\_\_, which combine genes inherited from each parent * In crossing over, homologous portions of two nonsister chromatids trade places at\_\_\_ * A “hybrid” chromosome is produced by combining two non-identical chromatids into a single chromosome (contains shuffled genetic info from maternal and paternal chromosomes)

Answer 42

recombinant chromosomes synapsis

Question 43

Random Fertilization ## Footnote * Random fertilization adds to genetic variation because any sperm can fuse with any ovum (unfertilized egg) * The fusion of two gametes (each with 8 million possible chromosome combinations from independent assortment alone) produces a zygote with any of about 70 trillion diploid combinations!!!!!

Answer 43

remember?

Question 44

Answer 44

hopefully this makes sense to you lol