B2: Cell division/Specialisation

Question 1

What is mitosis?

Answer 1

Part of the cell cycle where one set of new chromosomes is pulled to each end of the cell forming 2 identical nuclei, during cell division.

Question 2

What is the cell cycle?

Answer 2

the series of stages where body cells divide.

Question 3

Why is mitotic cell division important in the cell cycle? (3)

Answer 3

• growth
• repair/replacement of worn cells
• development
  of multicellular organisms

Question 4

What is the difference in differentiation process between animal and plant cells? (2)

Answer 4

Animal cells differentiate at early stage

Plant cells retain the ability to differentiate throughout life

Question 5

What happens when cells differentiate? (2)

Answer 5

• it gets different sub-cellular structures that enable it to carry out a particular function.
• cell specialise

Question 6

what is the importance of differentiation in the development of a baby?(2)

Answer 6

• cells need to specialise to become part of body
• babies need different types of cells
• without differentiation cells won’t specialise so organs can’t develop

Question 7

Explain the stages of the cell cycle and mitosis.

Answer 7

3) before dividing again, cells need to grow and increase ribosome/mitochondria numbers

4) DNA replicates to form 2 copies of each chromosome
5) one set of chromosomes is pulled to each end of the cell and cell divides
6) The cytoplasm/cell membranes also divide to form 2 identical daughter cells - cytokinesis

Question 8

Where in the plant is mitosis constantly happening?

Answer 8

The meristems

Question 9

What is a stem cell?

Answer 9

An undifferentiated cell that can form other types of cells/tissues.

Question 10

What conditions could stem cells help to treat?

Answer 10

Paralysis 
Diabetes 
Transplant surgeries
Infertility 
Dementia

Question 11

What is meant by therapeutic cloning?

Answer 11

Where an embryo is produced with the same genes as the patient so the stem cells produced are not rejected/ may be used for treatment

Question 12

Risks of using stem cells to treat conditions.

Answer 12

• can cause cancer
• stem cells could be infected with viruses and transfer infection
• low no. stem cell donors

Question 13

Objections of using embryonic stem cells for treatment.

Answer 13

• embryo can’t give permission
• violation of human rights
• interrupts process of human reproduction
• destroys potential life

Question 14

How does an embryonic stem cell differ from an adult stem cell? (3)

Answer 14

• Adult stem cells form many but not ALL types of cell
• Embryonic stem cells are found in embryos/early development
• Adult stem cells are present throughout an animal/human regardless of age

Question 15

What is differentiation?

Answer 15

The process where cells become specialised for a particular function.

Question 16

Suggest one disadvantage of cloning plants from meristems. (1)

Answer 16

• lack of genetic variation which makes cloned populations more susceptible to environmental changes (e.g. disease)

Question 17

How can embryonic stem cells be used to treat paralysis? (3)

Answer 17

• paralysis is caused by damage to neurones in spinal chord
• embryonic stem cells are undifferentiated and can be manipulated to differentiate into neurones
• replacing the damaged cells

Question 18

what are the different sources of adult stem cells? (4)

Answer 18

• bone marrow
• umbilical chord
• skin
• organs e.g. liver, brain

Question 19

How can diabetes be treated using stem cells?

Answer 19

• caused by inability of pancreas to produce insulin to control blood sugar levels
• stem cells can be differentiated into insulin-producing pancreatic cells which are transplanted into patients body

Question 20

Benefits of using embryonic stem cells/therapeutic cloning for medical treatment.

Answer 20

• can treat wide variety of diseases
• they have been used successfully in a no. of cases
• painless

Therapeutic cloning

• won’t be rejected bc has same genes as patient
• reduces waiting time for organ transplants

Question 21

How can stem cells be used to protect plant populations?

Answer 21

• can be cloned quickly/economically
• producing large no. rare plants reliable/safely
• saves them from extinction

Question 22

Advantage of cloning plants from meristems.

Answer 22

• plant cloning gives us a way of producing large populations of identical plants from research - scientists can see effects of different variables /quicker and economical
• used in horticulture - producing large no. Identical plants for sale - quick and economical than natural reproduction
• in agriculture - produce large o. plants with special features

Question 23

How do plant stem cells differ from animal stem cells ?

Answer 23

Plant stem cells continue to differentiate throughout life

-Can differentiate again if needed

Question 24

ad/ disadvantages of using adult stem cells?

Answer 24

AD : - less ethical issues
- won’t be rejected

• treats less diseases
• can be painful
• may be risky