2.2

Question 1

interphase

Answer 1

s phase - dna replicates semi conservatively
= 2 chromatids joined at centromere
g1,g2 no of organelles and volume of cytoplasm increases and protein synthesis

Question 2

mitosis

Answer 2

nucleus divides
2 nuclei - identical copies of dna produced by parent cell

Question 3

cytokinisis

Answer 3

cytoplasm and cell membrane divide
2 genetically identical daughter cells

Question 4

prophase

Answer 4

chromosomes condense
short and thick
appear as two sister chromatids joined by centromere
nuclear envelope breaks down
centrioles move to opposite poles of cell forming spindle network

Question 5

metaphase

Answer 5

SF attach to chromosomes by their centromeres
chromosomes line up along equator

Question 6

anaphase

Answer 6

SF contract
centromere divides
pulling chromatids from each pair to opposite poles of cell

Question 7

telophase

Answer 7

chrom uncoil
long and thin
nuclear envoplope reform = 2 nuclei
SF centrioles break down

Question 8

why do not all elk undergo cell cycle

Answer 8

dont all retain ability to divide

Question 9

importance of mitosis

Answer 9

Growth of multicellular organisms by increasing cell number
Replacing cells to repair damaged tissues
Asexual reproduction

Question 10

how tumours and cancers form

Answer 10

mutation in genes or dna controlling mitosis leads to uncontrolled cell division
tumour forms if this results in mass of abnormal cells

Question 11

cancer treatment controlling rate of cell division

Answer 11

some distrupt spindle formation
chrome cant attach to spindle by their centromere
chromatids cant be separated to opposite poles of cell slowing mitosis
some prevent dna replication during interphase
so cant make two copies of each chromosome slowing mitosis

Question 12

prok cell division

Answer 12

replication of circular dna
replication of plasmids
division of cytoplasm = 2 daughter cells
single copy of circular dna
variable no of plasmids

Question 13

how do viruses replicate

Answer 13

AP attach to comp receptors on host cell
inject nucleic acid into host cell
infected host cells replicate virus particles
nucleic acid replicated
capsid enzymes produced. by cell
virus assembled then released

Question 14

Give two pieces of evidence from Figure 1 that this cell was undergoing
mitosis. Explain your answers.

Answer 14

individual chromsomes are visible as they are condensed
(Each) chromosome is made up of two chromatids because DNA has
replicated;

Question 15

how does the chemical stop the growth of roots at anaphase

Answer 15

stops mitosis
by stopping SF forming
stops separation of sister chromatids

Question 16

The student concluded that the cell in the image above was in the
anaphase stage of mitosis.
Was she correct? Give two reasons for your answer.

Answer 16

chromosomes in two groups at poles of spindle
v shape shows sister chromatids have been pulled apart

Question 17

Explain how the behaviour of chromosomes causes these changes in the
amount of DNA per cell between F and G.

Answer 17

chromosomes and dna replicates
homologous chromosomes separate
sister chromatids separate