B2–Cell division

Question 1

Name and explain the first stage of the cell cycle.

Answer 1

Interphase/preparation) Cell grows, DNA is replicated, organelle are duplicated

Question 2

Name and explain the second stage of the cell cycle.

Answer 2

Mitosis) Chromosomes split to each pole of nucleus, nucleus splits into two.

Question 3

Name and explain the third stage of the cell cycle.

Answer 3

Cytokenesis) Cell wall and membrane split to form two identical daughter cells.

Question 4

What is a stem cell?

Answer 4

An undifferentiated (unspecialised) cell that can have different genes turned on/off to specialise into a specific type of cell with a specific function

Question 5

What is a stem cell that can differentiate into all the types of cell in the body called?

Answer 5

Totipotent

Question 6

What is a stem cell that can differentiate into a few types of cell in the body called?

Answer 6

Multipotent

Question 7

How many chromosomes does a human have? Where are they located?

Answer 7

46 (23 pairs) in the nucleus of each cell

Question 8

What are new cells needed for?

Answer 8

Growth, repair (damaged tissue), replacing (worn out cells)

Question 9

What is a gene?

Answer 9

Small sections of DNA that code for a protein.

Question 10

What is a chromosome?

Answer 10

Large sections of DNA that contain many genes

Question 11

What is a zygote?

Answer 11

A sperm cell fused with an egg cell

Question 12

What is meiosis?

Answer 12

Reduction divison in a cell in which the chromosomes halve from diploid to haploid to form 4 non-identical gametes (sex cells)

Question 13

Where are stem cells found in plants?

Answer 13

Meristems

Question 14

What are the sources of embryonic stem cells?

Answer 14

Aborted embryos, spare embryos donated from IVF

Question 15

What are the problems with using adult stem cells for transferring stem cells?

Answer 15

They could be infected, causing the recipient to also get infected.
They could be rejected by the immune system, which creates a need for immunosuppressant dugs, which can increase succeptibility of infection.

Question 16

What is therapeutic cloning?

Answer 16

Removal of cells from a patient, and using them to derive a cloned early embryo of the patient. Stem cells are removed from this and used to grow and differentiate into different tissues and organs, which could then be transplanted to the patient. They would be seen as ‘self’ by the immune system and face no risk of immunal rejection.

Question 17

How can plants be cloned?

Answer 17

By cutting up a leaf and placing it into a growth medium

Question 18

What are the cons of therapeutic cloning?

Answer 18

Expensive, slow, difficult to control
Embryo dies
Cancer possibility
Consent of donor needed
Collection of egg cells is painful

Question 19

What are the pros of therapeutic cloning?

Answer 19

Patient specific stem cells-lessens rusk of immunal rejection
Organ donors are not needed
Any type of tissue can be produced

Question 20

Why is therapeutic clonig used?

Answer 20

To producenan embryo with the same genes as patient to retrieve stem cells and differentiate
Avoid rejection

Question 21

Discuss the ethical issues surrounding the use of embryonic stem cells in medicine and research.

Answer 21

Some people feel that embryonic stem cells from human embryos shouldn’t be used for experiments since each one is a human life or has the potential to be a human life.
* Some people may argue that there are other sources of stem cells that scientists could use, so using embryos to create stem cells is unjustified.
* Some people think that using embryonic stem cells to cure patients who already exist and who are suffering is more important than the rights of embryos.
* Some people argue that many embryonic stem cells are sourced from unwanted embryos from fertility clinics, which would probably be destroyed anyway.