Physical Basis of Heredity - Handout

Question 1

Actively dividing eukaryote cells pass through a series of stages known collectively as the

Answer 1

cell cycle

Question 2

cell double checks the duplicated chromosomes for error, making any needed repairs

Answer 2

G2

Question 3

each of the 46 chromosomes is duplicated by the cell

Answer 3

s phase

Question 4

cellular contents, excluding the chromosomes, are duplicate

Answer 4

G1

Question 5

Metabolic changes prepare the cell for division. At a certain point - the restriction
point - the cell is committed to division and moves into the S phase

Answer 5

G1 phase

Question 6

DNA synthesis replicates the genetic material. Each chromosome now consists of
two sister chromatids

Answer 6

s phase

Question 7

. Metabolic changes assemble the cytoplasmic materials necessary for mitosis and
cytokinesis.

Answer 7

g2 phase

Question 8

e. A nuclear division (mitosis) followed by a cell division (cytokinesis)

Answer 8

m phase

Question 9

s is a form of eukaryotic cell division that produces two daughter cells with the same
genetic component as the parent cell

Answer 9

mitosis

Question 10

Chromosomes replicated during the S phase are divided
in such a way as to ensure that each daughter cell receives a copy of every chromosome. In
actively dividing animal cells, the whole process takes about

Answer 10

one hour

Question 11

The replicated chromosomes are attached to a

Answer 11

mitotic apparatus

Question 12

’ that aligns them and then
separates the sister chromatids to produce an even partitioning of the genetic material

Answer 12

mitotic apparatus

Question 13

separation of the genetic material in a mitotic nuclear division

Answer 13

karyokinesis

Question 14

separation of the cell cytoplasm in a cellular division

Answer 14

cytokinesis

Question 15

In some single-celled organisms mitosis forms the basis of a

Answer 15

asexual reproduction

Question 16

In diploid
multicellular organisms sexual reproduction involves the fusion of two __ gametes to produce a diploid zygote

Answer 16

haploid

Question 17

five stages of mitosis

Answer 17

prophase
prometaphase
metaphase
anaphase
telophase

Question 18

occupies over half of mitosis. The nuclear membrane breaks down to form a
number of small vesicles and the nucleolus disintegrates

Answer 18

prophase

Question 19

structure known as the
___ duplicates itself to form two daughter centrosomes that migrate to opposite ends
of the cell. T

Answer 19

centrosome

Question 20

. The centrosomes organise the production of microtubules that form the spindle
fibres that constitute the

Answer 20

mitotic spindle

Question 21

s. Each replicated chromosome can now be seen to consist of two identical

Answer 21

chromatids

Question 22

Each replicated chromosome can now be seen to consist of two identical
chromatids (or sister chromatids) held together by a structure known as the

Answer 22

centromere

Question 23

The chromosomes, led by their centromeres, migrate to the ___ plane in the midline of
cell - at right-angles to the axis formed by the centrosomes

Answer 23

equatorial plate

Question 24

The chromosomes, led by their centromeres, migrate to the equatorial plane in the midline of
cell - at right-angles to the axis formed by the centrosomes. This region of the mitotic spindle
is known as the

Answer 24

metaphase plate

Question 25

The spindle fibres bind to a structure associated with the centromere of each chromosome called a

Answer 25

kinetochore

Question 26

The chromosomes align themselves along the metaphase plate of the spindle apparatus.

Answer 26

metaphase

Question 27

The shortest stage of mitosis.

Answer 27

anaphase

Question 28

s. The centromeres divide, and the sister chromatids of each chromosome are pulled apart - or 'disjoin' - and move to the opposite ends of the cell, pulled by spindle fibres attached to the kinetochore regions. The separated sister chromatids are now referred to as

Answer 28

daughter chromosomes

Question 29

The final stage of mitosis, and a reversal of many of the processes observed during prophase.

Answer 29

telophase

Question 30

The final cellular division to form two new cells

Answer 30

cytokinesis

Question 31

in plants, this forms during cytokinesis

Answer 31

cell plate

Question 32

in animals, this form along the line of metaphase plate in cytokinessi

Answer 32

constriction of cytoplasm

Question 33

s is the form of eukaryotic cell division that produces haploid sex cells or gametes

Answer 33

meiosis

Question 34

a special cell division reduces the cell from diploid to haploid.

Answer 34

meiosis I

Question 35

The homologous chromosomes pair and exchange DNA to form recombinant chromosomes. what stage in meiosis

Answer 35

prophase I

Question 36

Prophase I is divided into five phases:

Answer 36

leptotene zygotene pachytene diplotene diakinesis

Question 37

chromosomes start to condense what stage of prophase I

Answer 37

leptotene

Question 38

homologous chromosomes become closely associated (synapsis) to form pairs of chromosomes (bivalents) consisting of four chromatids (tetrads). what stage in prophase I

Answer 38

zygotene

Question 39

pairs of chromosomes in zygotene

Answer 39

bivalents

Question 40

crossing over between pairs of homologous chromosomes to form chiasmata (sing. chiasma). what phase in prophase I

Answer 40

pachytene

Question 41

homologous chromosomes start to separate but remain attached by chiasmata

Answer 41

diplotene

Question 42

s: homologous chromosomes continue to separate, and chiasmata move to the ends of the chromosomes.

Answer 42

diakinesis

Question 43

Spindle apparatus formed, and chromosomes attached to spindle fibres by kinetochores. stage of meiosis I

Answer 43

prometaphase I

Question 44

Homologous pairs of chromosomes (bivalents) arranged as a double row along the metaphase plate. The arrangement of the paired chromosomes with respect to the poles of the spindle apparatus is random along the metaphase plate.

Answer 44

metaphase I

Question 45

This is a source of genetic variation through random assortment, as the paternal and maternal chromosomes in a homologous pair are similar but not identical

Answer 45

metaphase I

Question 46

The number of possible arrangements is 2n, where n is the number of chromosomes in a haploid set. Human beings have 23 different chromosomes, so the number of possible combinations is

Answer 46

223

Question 47

The homologous chromosomes in each bivalent are separated and move to the opposite poles of the cell.

Answer 47

anaphse I

Question 48

The chromosomes become diffuse and the nuclear membrane reforms. what phase in meiosis I

Answer 48

telophase

Question 49

The final cellular division to form two new cells, followed by Meiosis II. M

Answer 49

cytokinesis

Question 50

Meiosis generates genetic diversity through (3)

Answer 50

the exchange of genetic material between homologous chromosomes during Meiosis I (pachytene) the random alignment of maternal and paternal chromosomes in Meiosis I (metaphase I) the random alignment of the sister chromatids at Meiosis II

Question 51

what stage of Meiosis I does the first polar body form

Answer 51

teloophase I

Question 52

which stage of Meiosis II does the egg cell turn into polar body and mature egg cell

Answer 52

cytokinesis