B2- Cell division

Question 1

Order of size from smallest to largest
Nucleus, dna, chromosomes, gene, cell

Answer 1

Gene-DNA-chromosome-nucleus-cell

Question 2

How many chromosomes do…
Body cells have?
Sex cells have?

Answer 2

Body- 46
Sex- 23

Question 3

3 reasons mitosis is important

Answer 3

For an organism to grow
To replace cells
To repair damaged tissue

Question 4

Asexual reproduction

Answer 4

Offspring produced from single organism, inherit genes of 1 parent

Question 5

Stage 1 of mitosis

Answer 5

Cell grows, DNA replicates forms 2 copies of each chromosome, increases no. of sub-cellular structures. Longest stage

Question 6

Stage 2 of mitosis

Answer 6

Chromosomes align in the centre of the cell, one set is pulled to each end of the cell, nucleus divides

Question 7

Stage 3 of mitosis

Answer 7

Cytoplasm and cell membrane divide to form two genetically identical daughter cells

Question 8

How long does the cell cycle take?
What stage of life is it fastes?

Answer 8

Could be less than 24 hours or several years
Faster during childhood

Question 9

Calculation for length of time in phase?

Answer 9

observed cells at that stage / total cells observed
x total length of cycle

Question 10

How do most specialised animal cells divide?

Answer 10

Mitosis

Question 11

What do adult stem cells do?

Answer 11

Replace specialised cells that can’t divide

Question 12

Where are undifferentiated plant cells formed?

Answer 12

Meristems

Question 13

Cloning definition

Answer 13

Producing identical offspring

Question 14

How to clone plants

Answer 14

-tiny piece of leaf tissue
-right conditions, the cell specialises into any form
-new plant is identical to original

Question 15

Why are stem cells and research important? 2 reasons

Answer 15

Could replace damaged cells
Benefit millions of people

Question 16

Stem cells in plants
3 uses

Answer 16

-Can produce a large no. of plants reliably
-Helps with research, producing rare plants
-Used to produce plants for sale and crop plants

Question 17

Embryonic stem cell

Answer 17

Undifferentiated cell found in embryo, can become any cell in body

Question 18

Adult stem cell

Answer 18

Undifferentiated cell found in bone marrow of adult, can become some cells in body

Question 19

Plant stem cell

Answer 19

Undifferentiated cell found in meristems, can be used to make clones

Question 20

3 problems with embryonic stem cells

Answer 20

-Some against it due to human rights
-Possibility of being rejected by patient
-Very expensive and time consuming

Question 21

Pros and Cons of embryonic and adult stem cells

Answer 21

Embryonic: can become any cell in the body, unethical
Adult: no ethical issues, becomes a few types

Question 22

What 3 illnesses could stem cells potentially treat?

Answer 22

-Spinal cord injuries
-Diabetes
-Eyesight problems

Question 23

What is therapeutic cloning

Answer 23

Transfer the nucleus from a patient’s cell to donor’s egg cell with removed nucleus, won’t be rejected by the body