Meiosis

Question 1

Meiosis creates ______ _______ cells from one diploid cell

Answer 1

4 haploid

Question 2

Where does meiosis occur?

Answer 2

germ line cells

Question 3

Where are germ line cells found?

Answer 3

gonads (testes and ovaries)

Question 4

At the end of meiosis what is produced?

Answer 4

gametes (sperm and ova) called gametogensis

Question 5

how many sets of chromosomes do gametes have

Answer 5

one (haploid)

Question 6

during fertilization the nuclei of egg and sperm cell fuse and produce what?

Answer 6

a zygote

Question 7

What does asexual reproduction generate

Answer 7

genetically identical offspring

Question 8

meiosis and fertillization mix genetic information into…

Answer 8

new combinations

Question 9

sexual reproduction generates variability that is the basis of most inherited differences among individual sexually repoducing organisms (T/F)

Answer 9

true

Question 10

how many parts is meiosis

Answer 10

two parts; meiosis I and meiosis II

Question 11

DNa replicates and chromosome proteins are duplicated in the _______ ______ (meiosis)

Answer 11

premeiotic interphase

Question 12

During Meiosis I homologous chromosomes and non sister chromatids undergo…

Answer 12

crossing-over

Question 13

After meiosis I each diploid has…

Answer 13

the diploid number of chromosomes-each chromosome has 2 sister chromatids

Question 14

In meiosis II, sister chromatids… (anaphase)

Answer 14

seperate

Question 15

what happens in synapsis

Answer 15

sister chromatids connect together in synaptonemal complex

Question 16

what is homologous recombination

Answer 16

genetic exchange (crossing over) occurs between homologous cchromosomes

Question 17

what is reduction division

Answer 17

meiosis involves two successive divisions, with no replication of genetic material between them

Question 18

meiosis II do does not have an ____ phase before it

Answer 18

S phase

Question 19

when does recombination (crossing over) occur?

Answer 19

prophase I of Meiosis I

Question 20

What does recombination do?

Answer 20

generates diversity

Question 21

what are alleles?

Answer 21

versions of each gene present in the members of a homologous pair

Question 22

are alleles the same or different?

Answer 22

they can be either

Question 23

for a gene that encodes proteins, what do alleles do

Answer 23

they can encode different versions of the protein, or no protein at all

Question 25

chiasmata is the...

Answer 25

point of contact in crossing over

Question 26

recombination results in identical sister chromatids (T/F)

Answer 26

false

Question 27

the first meiotic division is termed the...

Answer 27

"reduction division"

Question 28

second meiotic division does not further reduce the number of chromosomes (T/F)

Answer 28

true

Question 29

what happens in prophase I of meiosis I

Answer 29

replicated chromosomes (sister chromatids) fold and condense in the nucleus two chromosomes of each homologous pair undergo synapsis (from tetrads) chromatids of homologous chromosomes cross over and form chiasmata

Question 30

what happens in prometaphase I

Answer 30

the nuclear envelope breaks down, spindel enters and chromosomes attach to kinetochor microtubulues

Question 31

what is different between prometaphase of mitosis and prometaphase I of meiosis

Answer 31

sister chromatids remain together in prometaphase I

Question 32

where do spindle microtubules attach to kinetochore proteins

Answer 32

on the outside of each centromere

Question 33

what happens in metaphase I

Answer 33

terminal chiasmata hold homologous pairs together and line up on metaphase plate

Question 34

orientation of homologues is random (T/F)

Answer 34

true

Question 35

what is the formula for independent assortment

Answer 35

2^n (n is chromosome pairs)

Question 36

what are the major sources of genetic variability

Answer 36

crossing over independent assortment sets of male and female gametes that unite in fertilization

Question 37

what happens in anaphase I

Answer 37

spindle fibers shorten and pull centromeres to poles, seperation of homologous chromosomes random orientation results in independent assortment

Question 38

what happens in telophase I

Answer 38

chromosomes are segregated into 2 clusters, one at each pole nuclear membrane reforms

Question 39

what follows meiosis I

Answer 39

G1, G2, meiosis II (no s phase)

Question 40

what happens in prophase II

Answer 40

chromosomes condense and spindle forms, nuc envelope starts to breakdown

Question 41

what happens in prometaphase II

Answer 41

nuclear envelope completely breaks down spindle microtubulues attach to the two kinetochores of each chromosome

Question 42

what happens in metaphase II

Answer 42

spindle microtubules align chromosomes on the metaphase plate

Question 43

what happens in anaphase II

Answer 43

spindles seperate the two chromatid and pull them towards opposite spindle poles

Question 44

what happens in telophase II

Answer 44

chromatids decondence to extend interphase state spindles disassemble and nuc envelopes form around chromatin

Question 45

what happens in nondisjunction

Answer 45

the spindle fails to seperate the homologous chromosomes or sister chromatids

Question 46

zygotes that receive extra copy of chromosome in nondisjuction have...

Answer 46

3 chromosomes instead of 2

Question 47

what chromosome is affected in down syndrome

Answer 47

chromosome 21-trisomy 21

Question 48

what are sex chromosomes

Answer 48

pairs of chromosomes that are different in male and female individuals of the same species i.e. XX vs XY

Question 49

in females the two X chromosomes are fully or partly homolgous

Answer 49

fully

Question 50

in males the X and Y chromosomes are fully or partly homolgous

Answer 50

partly

Question 51

can crossing over occur more than once in the same chromosome pair

Answer 51

yes

Question 52

in animals which phase dominates the life cycle? which phase is reduced?

Answer 52

diploid phase, haploid phase is reduced

Question 53

in animals meiosis is followed directly by what

Answer 53

gamete formation/fertilization

Question 54

plants can have either diploid of haploid dominate the life cycle (T/F)

Answer 54

true

Question 55

in some fungi and algae the diploid phase is limited to what single cell?

Answer 55

the zygote produced by fetrtilization