B3 Cell Division

Question 1

What does the nucleus contain?

Answer 1

It contains chromosomes.

Question 2

What do chromosomes carry?

Answer 2

A large number of genes.

Question 3

Are chromosomes found singularly or in pairs?

Answer 3

In pairs.

Question 4

What are chromosomes made out of?

Answer 4

They are made of DNA molecules.

Question 5

What is the cell cycle?

Answer 5

When the body cells divide to form two identical daughter cells.

Question 6

Where can mitosis be found?

Answer 6

In asexual reproduction.

Question 7

What is stage 1 of the cell cycle?

Answer 7

•cell grows bigger
•DNA replicates (chromosomes are duplicated)
•increase in number of sub-cellular structures, such as ribosomes and mitochondria

Question 8

What is stage 2 of the cell cycle?

Answer 8

Mitosis
•a complete set of chromosomes is pulled to each end of the cell
•the nucleus divides to form two nuclei

Question 9

What is stage 3 of the cell cycle?

Answer 9

•cytoplasm and cell membrane divide to form two identical daughter cells

Question 10

What is a stem cell?

Answer 10

A cell that is undifferentiated that can develop into one or more types of specialised cell.

Question 11

What are the two types of stem cells found in mammals?

Answer 11

Adult step cells and embryonic stem cells.

Question 12

What does it mean when step cells are ‘cloned’?

Answer 12

They produce a large number of identical cells.

Question 13

Where are adult stem cells found?

Answer 13

Specific parts of the body, for example, bone marrow.

Question 14

What can adult stem cells differentiate into?

Answer 14

Only certain types of cell, for example, stem cells from bone marrow can only differentiate into types of blood cells.

Question 15

What are the advantage of adult stem cells?

Answer 15

•fewer ethical issues (adults can consent to have their stem cells removed and used
•an established technique for treating diseases such as leukaemia
•relatively safe to use as a treatment and donors recover quickly

Question 16

What can embryonic cells differentiate into?

Answer 16

Any type of specialised cell.

Question 17

What are the advantages of embryonic cells?

Answer 17

•can treat a wide range of diseases as can form any specialised cell
•may be possible to grow whole replacement organs
•usually no donor needed as they are obtained from spare embryos from fertility clinics

Question 18

Where are plant meristem found?

Answer 18

In the roots and shoots of plants.

Question 19

What can plant meristem differentiate into?

Answer 19

Can differentiate into all cell types, can create clones of whole plants

Question 20

What are the advantages of plant meristem?

Answer 20

•rare species of plants can be cloned to prevent extinction
•plants with desirable traits, such as disease resistance, can be cloned to produce large numbers of identical plants
•fast and low-cost production of large numbers of plants

Question 21

What are the disadvantages of adult stem cells?

Answer 21

•requires a donor, potentially meaning a long wait time to find someone suitable
•can only differentiate into certain types of specialised cells, so can be used to treat fewer diseases

Question 22

What are the disadvantages of embryonic stem cells?

Answer 22

•ethical issues as the embryo is destroyed and each embryo is a potential human life
•risk of transferring viral infections to the patient
•newer treatment so relatively under researched- not yet clear if they can cure as many diseases as thought

Question 23

What are the disadvantages of plant meristem?

Answer 23

•cloned plants are genetically identical, so a whole crop is at risk of being destroyed by a single disease or genetic defect

Question 24

What is therapeutic cloning?

Answer 24

Cells from a patient’s body are used to create a cloned early embryo of themselves.

Question 25

Benefits of therapeutic cloning?

Answer 25

Stem cells from this embryo can be used for medical treatments and growing new organs.

Question 26

Benefits when transferring to a patient using therapeutic cloning?

Answer 26

These stem cells have the same genes as the patient, so are less likely to be rejected when transplanted.