B2 Cell Division

Question 1

What is a stem cell?

Answer 1

undifferentiated cell that can differentiate into one or more specialised cell types

Question 2

What are adult stem cells?

Answer 2

stem cells from adults that can only differentiate into certain specialised cells

Question 3

Where can adult stem cells be found?

Answer 3

bone marrow

Question 4

What are embryonic stem cells?

Answer 4

stem cells from embryos that can differentiate into any specialised cell

Question 5

Where are embryonic stem cells found?

Answer 5

early human embryos (usually from spare embryos from fertility clinics)

Question 6

What is therapeutic cloning?

Answer 6

patient’s cells are used to create an early embryo clone of themselves - stem cells from the embryo can then be used to treat the patient’s medical conditions

Question 7

Give one advantage of using therapeutic cloning.

Answer 7

stem cells from the embryo are not rejected when transplanted because they have the same genes as the patient

Question 8

Give one advantage of using adult stem cells.

Answer 8

fewer ethical issues as obtained from adults who can consent to their use

Question 9

Give two disadvantages of using adult stem cells.

Answer 9

• can take a long time for a suitable donor to be found
• can only differentiate into some specialised cell types, so treat fewer diseases

Question 10

Give two advantages of using embryonic stem cells.

Answer 10

• can differentiate into any specialised cell, so can be used to treat many diseases
• easier to obtain as they are found in spare embryos from fertility clinics

Question 11

Give two disadvantages of using embryonic stem cells.

Answer 11

• ethical issues surrounding their use, as every embryo is a potential life
• potential risks involved with treatments, such as transfer of viral infections

Question 12

What are plant meristems?

Answer 12

area where rapid cell division occurs in the tips of roots and shoots

Question 13

Give two advantages of using plant meristems to clone plants.

Answer 13

• rare species can be cloned to protect them from extinction
• plants with special features (e.g., disease resistance) can be cloned to produce many copies

Question 14

Give one disadvantage of using plant meristems to clone plants.

Answer 14

no genetic variation, so, for example, an entire cloned crop could be destroved by a disease

Question 15

What is cell division by mitosis?

Answer 15

body cells divide to form two identical daughter cells

Question 16

What is the purpose of mitosis?

Answer 16

growth and repair of cells, asexual reproduction

Question 17

What happens during the first stage of the cell cycle?

Answer 17

cell grows bigger, chromosomes duplicate, number of subcellular structures (e.g. ribosomes and mitochondria) increases

Question 18

What happens during mitosis?

Answer 18

one set of chromosomes is pulled to each end of the cell and the nucleus divides

Question 19

What happens during the third stage of the cell cycle?

Answer 19

the cytoplasm and cell membrane divide, forming two identical daughter cells

Question 20

What is the term for cell division in bacteria?

Answer 20

Binary fission