Cell Cycle

Question 1

Process of mitosis

Answer 1

• interphase
• prophase
• metaphase
• anaphase
• telophase

Question 2

Definition of mitosis

Answer 2

• cell division that produce 2 daughter cells that have same number chromosomes and same genetic material as parents cell

Question 3

Purpose of interphase

Answer 3

• DNA duplication
• prepare for mitosis

Question 4

Process of prophase

Answer 4

• preparing
• chromosomes condense from chromatin, so become visible to long and thin structure
• centrioles move to two poles
• spindle fibres develops in centrioles
• nucleus disappear
• chromosomes drawn to middle of the cell and attach to centromere

Question 5

Process of metaphase

Answer 5

• middle
• chromosomes line up at the centre of the cell

Question 6

Process of anaphase

Answer 6

• apart
• chromatids pull apart to opposite poles by spindle fibres
• requires a lot of energy so needed a mitochondria to provide ATP

Question 7

Process of telophase and cytokinesis

Answer 7

• Two
• chromosomes reach respective poles
• spindle fibres disintegrate
• nuclear envelope and nucleolus re form
• cytoplasm divide - cytokinesis

Question 8

Formula of mitotic index

Answer 8

• no. of cells with visible chromosomes / total no.of cells observed
• answer in a decimal

Question 9

Purpose of mitosis

Answer 9

• growth- 2 haploid cell fuse to form diploid cell to form new organism
• repair- replace damaged and dead cells
• reproduction of single called organism- asexual reproduction

Question 10

What should be done when counting cells to ensure mitotic index is accurate?

Answer 10

• only count whole cells
• examine large numbers of sample
• ensure representative sample
• repeat count
• standardised counting

Question 11

How chemical affects mitosis?

Answer 11

• stops anaphase,prevent telophase and cytokinesis
• by stopping spindle fibres to form
• prevent separation of sister chromatids
• so no new daughter cells added

Question 12

3 stages of cell cycle

Answer 12

Interphase
Nuclear division
Cytokinesis

Question 13

How is cancer caused ?

Answer 13

• by disorder of cells
• results of damage to the genes that regulate mitosis and cell cycle= uncontrolled growth and division of cells

Question 14

Characteristics of benign and malignant tumours

Answer 14

B / M :
- grow slow/ fast
- more / less compact
- less / more likely to be life threatening

Question 15

Treatment of cancer

Answer 15

• killing dividing cells by blocking a part of cell cycle
  = cell cycle disrupted and cell division = no growth

Question 16

How does Chemotherapy treat cancer ?

Answer 16

• preventing DNA from replicating
• inhibiting metaphase by interfering the spindle formation

Question 17

Describe and explain the appearance of chromosomes in metaphase (2)

Answer 17

• each chromosomes consist of 2 chromatids
• chromatids attached to centromere

Question 18

Describe viral replication (3)

Answer 18

1) attachment proteins attach to receptors
2) viral nucleic Acid enters cell, transcribe RNA into viral DNA
3) cell produce viral proteins and viral proteins assembled and release new virus

Question 19

How the chemical stops growth of roots in cell cycle (3)

Answer 19

1) stops anaphase completing
2) stop spindle fibres forming
3) so sister chromatids won’t be separated

Question 20

Describe behaviours of chromosomes during P, M, Anaphase (4)

Answer 20

1) P- chromosomes condense, centromeres attached with spindle fibres
2) M- chromosomes line at centre of cell
3) A- centromeres divide, chromatids pulled to opposite poles of cell due to spindle fibres shorten