Chapter 13

Question 1

autosomes

Answer 1

any chromosomes that is not a sex chromosome

Question 2

homologs

Answer 2

contain the same genes in the
same position along the chromosome; contain different versions of genes

Question 3

locus

Answer 3

position of a gene

Question 4

diploid

Answer 4

two sets of chromosomes
- one from each parent

Question 5

what does a ploidy indicate

Answer 5

number of complete chromosomes sets it contains

Question 6

what does meiosis convert cells to

Answer 6

diploid to haploid

Question 7

what is the difference between haploid and diploid

Answer 7

diploid cells have 2 pairs of homologous sets of chromosomes and haploid only have 1 set of chromosomes

Question 8

zygote

Answer 8

has a diploid chromosome number,
one set from each parent
- fertilized egg

Question 9

what is the importance of meiosis

Answer 9

• genetic variation
• prevents chromosome # from doubling

Question 10

what are the phases of meiosis 1

Answer 10

Early prophase I
Late prophase I
Metaphase I
Anaphase I
Telophase I

Question 11

late prophase 1

Answer 11

• homologs begin to separate but remain attached at points called chiasmata
• crossing over occurs between homologous non sister chromatids

Question 12

chiasmata

Answer 12

where genetic material is exchanged

Question 13

synapsis

Answer 13

when chromosomes first cross over

Question 14

metaphase 1

Answer 14

• paired of homologs line up at metaphase plate randomly

Question 15

anaphase 1

Answer 15

homologs separate and move to opposite ends of cell

Question 16

telophase 1

Answer 16

homologs finishing moving to poles of cell

Question 17

what happens at the end of meiosis 1

Answer 17

cytokinesis and results in daughter cells with only one chromosome of each homologous pair

Question 18

what are the phases of meiosis 2

Answer 18

Prophase II
Metaphase II
Anaphase II
Telophase II

Question 19

what does not occur in meiosis 2

Answer 19

no chromosomes replication occurs

Question 20

what does meiosis 2 only work with

Answer 20

sister chromatids

Question 21

what does meiosis 2 result in

Answer 21

four haploid daughter cells with each type of chromosome
- four haploid cells with un replicated chromosomes

Question 22

random fertilization

Answer 22

combination of each
unique sperm with each unique egg increases genetic
variability.

Question 23

when does independent orientation occur

Answer 23

at metaphase 1

Question 24

independent orientation

Answer 24

• Each pair of chromosomes independently aligns at the
  cell equator.
• equal probability of the maternal or
  paternal chromosome facing a given pole

Question 25

what could happen if things go wrong in meiosis

Answer 25

• chromosomes may not get pulled apart correctly
• both homologs or sister chromatids could move to same pole
• products will be abnormal

Question 26

nondisjunction

Answer 26

meiotic error that results in abnormal gametes
- both homologs or sister chromatids could move to same pole

Question 27

how do mistakes occur

Answer 27

nondisjunction results in gametes that
- Contain an extra chromosome (n + 1)
- Lack one chromosome (n − 1)

Question 28

what type of gametes lead to trisomy

Answer 28

n+1
- too many chromosomes

Question 29

what type of gametes lead to monosomy

Answer 29

n-1

Question 30

aneuploid

Answer 30

Cells with too many or too few of a chromosome

Question 31

what causes mistakes to occur

Answer 31

• random errors
• maternal age
• egg devolvement

Question 32

when do primary oocytes enter during embryonic devolvement

Answer 32

meiosis 1

Question 33

where do oocytes rest until sexual maturation

Answer 33

prophase 1

Question 34

what can also cause a error in meiosis

Answer 34

longer time period occurs until ovulation, greater the chances of something going wrong

Question 35

mitosis vs meiosis

Answer 35

• meiosis is followed by two consecutive cell divisions and mitosis is followed by only 1 cell division
• each gametes in meiosis is genetically different from one another