Cell Division

Question 1

what does each cell have?

Answer 1

pair of chromosomes one inherited from each parent

Question 2

name of two chromosomes that carry the same genes?

Answer 2

Homologous chromosomes

Question 3

significance of mitosis?

Answer 3

replacement of cells and tissue repair

Question 4

what is every cell derived from?

Answer 4

the zygote previously formed by two gametes fused, divides until a multi cellular organism is formed

Question 5

what is Asexual reproduction?

Answer 5

production of new species by a parent organism e.g. bacteria

Question 6

what else can happen in multi cellular organisms?

Answer 6

new individual can bud off from parent, vegetative propagation

Question 7

what must happen before mitosis?

Answer 7

DNA must replicate this is in Interphase, chromosomes aren’t visible , period of high metabolic activity. DNA content is doubling

Question 8

stages of mitosis?

Answer 8

Prophase
Metaphase
Anaphase
Telophase

Question 9

what happens in Prophase ? mitosis

Answer 9

chromosomes shorten and thicken, become visible, comprise of 2 chromatids joined at centromere. centrioles in cytoplasm move to poles, spindle fibres are made of microtubules, nucleus disappears and the nuclear membrane disintegrates

Question 10

what happens in metaphase? mitosis

Answer 10

chromosomes arrange at equator attach to spindle fibres at centromere fibres contract and pull chromatids slightly apart.

Question 11

what happens in Anaphase? mitosis

Answer 11

spindle fibres shorten cause 2 chromatids to separate migrate to opposite poles, energy for contraction provided by ATP

Question 12

what happens in Telophase? mitosis

Answer 12

chromatids arrive at poles nuclear envelope forms around chromatids, uncoil become invisisble - spindle fibres disintegrate nucleolus reforms in each new nucleus

Question 13

what happens in mitosis in animals?

Answer 13

constriction of cell as cell divides

Question 14

what happens at the end of mitosis?

Answer 14

cell division or cytokinesis occurs

Question 15

what is a haploid cell?

Answer 15

cell with 1 set of chromosomes

Question 16

stages of meiosis?

Answer 16

interphase
E prophase 1
M prophase 1
L prophase 1
metaphase 1
anaphase 1
telophase 1
prophase 2
metaphase 2
anaphase 2
telophase 2
cytokenisis

Question 17

what happens in interphase?

Answer 17

DNA replicates, centrioles replicate

Question 18

what happens in E prophase 1?

Answer 18

chromosomes shorten and become visible, made of 2 identical sister chromatids joined by centromere, nuclear envelope breaks down, centrioles move towards poles

Question 19

what happens in m prophase 1?

Answer 19

each homologous chromosome pair come together form bivalent, called synapsis

Question 20

what happens in L prophase 1?

Answer 20

chromatids from homologous chromosomes cross over at chiasmata, sections of chromatids are swapped

Question 21

what happens in metaphase 1?

Answer 21

bivalents arrange on equator of spindle, independent assortment, they attach to spindle fibres by centromeres

Question 22

what happens in anaphase 1?

Answer 22

homologous pairs of chromosomes separate and 1 of each pair, pulled by spindle fibres towards poles

Question 23

what happens in telophase 1?

Answer 23

cells divide, the nuclear and nucleolus reform, this doesn’t occur in plants they go straight to metaphase 2

Question 24

what happens in prophase 2?

Answer 24

nuclear envelope breaks down and disappears, centrioles replicate and move to poles. chromosomes shorten and thicken

Question 25

what happens in Metaphase 2?

Answer 25

chromosomes arrange across the equator

Question 26

what happens in anaphase 2?

Answer 26

centromeres divide chromatids pulled apart by spindle fibres

Question 27

what happens in telophase 2?

Answer 27

nuclear envelope and nucleolus reform

Question 28

what happens in cytokenisis?

Answer 28

cell division occurs, tetrad of 4 haploid cells with half the chromosome number of the parent

Question 29

what is the aim of mitosis?

Answer 29

produce 4 unique gametes genetically different to parent cell

Question 30

what is mitosis?

Answer 30

sexual reproduction

Question 31

what are haploid cells?

Answer 31

one set of chromosomes, maintain chromosome number when gametes fuse

Question 32

how many deaths does cancer cause?

Answer 32

1 in 4

Question 33

what is most common cancer in men?

Answer 33

Lung cancer

Question 34

what is most common cancer in women?

Answer 34

breast cancer

Question 35

how does cancer arise?

Answer 35

uncontrolled cell division, gene mutation (oncogenes), uncontrolled mitosis tumour forms

Question 36

what are carcinogens?

Answer 36

things that cause cancer e.g ionising radiation, tar, virus infection, hereditary predisposition