Paper 1 - Mitosis / Tumours

Question 1

What is a tumour ?

Answer 1

A lump of cells caused by rapid cell division

Question 2

What are cancer cells ?

Answer 2

Cells undergoing uncontrollable cell division

Question 3

When is mitosis / cell division required ?

Answer 3

-when an organisms grows
-when an organism becomes damaged and needs new cells for repair
-organisms like bacteria reproduce asexually
It is important that any cells produced contain genetic information that is identical to the parent cell.

Question 4

What are the 3 stages of the cell cycle?

Answer 4

Interphase
Mitosis
Cytokinesis

Question 5

What occurs during interphase ?

Answer 5

• cell makes extra subcellular parts
• DNA replication occurs
• the copies of the chromosomes stay attached to each other forming an ‘X’ shape. -> diploid have two sets of chromosomes

Question 6

What happens during mitosis?

Answer 6

Cell splits, two identical daughter cells produced.

Question 7

What happens during prophase?

Answer 7

Nucleus starts to break down and spindel fibres appear.

Question 8

What happens during metaphase?

Answer 8

By the end of metaphase, chromosomes lined up on the spindel fibres along the middle of the cell - (equator)

Question 9

What happens during anaphase ?

Answer 9

Chromosome copies are separated and moved to opposite ends of the cell on spindel fibres

Question 10

What happens during telephase?

Answer 10

A membrane forms around each set of chromosomes to form Nuclei.

Question 11

What happens during cytokinesis ?

Answer 11

A cell surface membrane forms to separate the two cells. (Cellulose cell walls formed in plants)

Question 12

What happens during asexual reproduction, what does it rely on ?

Answer 12

• Relies on mitosis
• Offspring are genetically identical to parents
• Faster than sexual reproduction
• Does NOT produce variation

Question 13

Examples of asexual reproduction

Answer 13

Strawberry plants, using runners - stems that run along the ground, potatoes use tubers.
Aphids (animal) can asexually reproduce.

Question 14

What are the two types of tumors ?

Answer 14

Tumour a group of cancerous cells -> damage or even death

Benign and malignant.

Question 15

What is a benign tumour / features ?

Answer 15

• grows slowly
• usually grow within a membrane so can be easily removed
• do not invade other parts of the body.

Question 16

What Is a malignant tumour / features ?

Answer 16

• grows quickly
• invade neighbouring tissues and can spread to other parts of the body through the bloodstream.
• as the tumour grows, cancer cells can detach and form secondary tumours in other parts of the body. Divide and invade surrounding tissue -> METASTASIS

Question 17

What is a carcinogen ?

Answer 17

Chemicals and other agents that result in cancer.
-cause cancer by damaging DNA, cause mutations to occur -> several mutations required to cause cancer -> more likely as we age.

Question 18

Risk factors for cancer

Answer 18

• Industrial and environmental factors at work (chemical carcinogens eg. Cigarette + ionising radiation eg. Ultraviolet causing skin cancer from the sun)
• lifestyle factors - large fat or salt intake
• genetic factors
• viruses linked to cancer being spread through sexual intercourse.