cell and nuclear division

Question 1

Outline the steps of cytokinesis in animal cells

Answer 1

• actin and myosin proteins form a contractile ring that pinches the membrane together forming a cleavage furrow.
• Furrow deepens and splits cytoplasm into two daughter cells

Question 2

Outline the steps of cytokinesis in plant cells

Answer 2

• vesicles containg cell wall materials fuse together forming a cell plate
• cell plate splitds parent cell into two daughter cells

Question 3

What are two examples of unequal division of cytoplasm?

Answer 3

• oogenesis
• yeast budding

Question 4

explain why oogenesis is an unequal division of cytoplasm

Answer 4

produces one large egg cell + three smaller polar bodies

Question 5

explain why yeast budding is an unequal division of cytoplasm

Answer 5

small bud grows from parent cell

Question 6

Outline the role of mitosis

Answer 6

forms two identical daughter cells from parent cell

Question 7

Outline the role of meiosis

Answer 7

forms 4 haploid cells with unique genetic material which develop into gametes.

Question 8

Describe the shared features of mitosis and meiosis.

Answer 8

• DNA replication happens before both
• similar stages PMAT
• spindle formation

Question 9

Explain why meiosis is a reduction division.

Answer 9

goes from 46 chromosomes to only 23

Question 10

How many chromosomes + chromatids does meiosis start with?

Answer 10

46 chromosomes
92 chromatids

Question 11

How many chromosomes + chromatids does meiosis end with?

Answer 11

23 chromosomes
23 chromatids

Question 12

Describe the causes of non-disjunction.

Answer 12

an error in meiosis where homologous chromosomes or sister chromatids fail to separate properly

Question 13

At what stages in meiosis does genetic variation occur?

Answer 13

• M1:P1
• M1:M1
• M2: A2

Question 14

what are the 2 consequences of non-disjunction?

Answer 14

• down syndrome
• turner syndrome

Question 15

Outline the need for cell proliferation.

Answer 15

• growth
• repair
• reproduction

Question 16

Outline the phases of the cell cycle.

Answer 16

1. interphase
2. mitosis
3. cytokinesis

Question 17

Describe the changes that occur in a cell during interphase.

Answer 17

G1 phase: Cell growth, protein + organelle synthesis
S phase: DNA replication
G2 phase: Further growth and preparation for mitosis

Question 18

Describe how cyclins control the cell cycle.

Answer 18

• Bind to CDKs to activate events like DNA replication.
• regulate checkpoints to make sure everything is correct before moving onto the next stage

Question 19

Explain the possible consequences of mutations in genes that control the cell cycle.

Answer 19

uncontrolled cell division - malignant tumour and benign tumor

Question 20

describe malignant tumours

Answer 20

• cancerous
• can spread

Question 21

describe benign tumours

Answer 21

• localised
• non-cancerous

Question 22

definition of mutagens

Answer 22

agents that cause gene mutations

Question 23

State examples of mutagens

Answer 23

• carcinogens (present in tobacco)
• X-rays
• UV light
• some viruses

Question 24

definition of oncogene

Answer 24

A gene that has mutated and helps in the growth of a tumor.