Cell division 2.0

Question 1

what are a risk factor?

Answer 1

Something that increases the likelihood of developing a disease

Question 2

life factors that may result in an increased chance of cancer: (5)

Answer 2

-viruses linked with cancer, such as the human papilloma virus (HPV), being spread from person to person through sexual intercourse

-the chemical carcinogens in cigarette smoke increasing the risk of lung cancer

-alcohol intake is linked with certain cancers

-exposure to ultraviolet radiation, part of which is ionising, during sunbathing or outdoor activities, leading to the development of skin cancers

-diet, including fat and salt intake, increases the risk of cancer

Question 3

Industrial and environmental factors at work: (2)

Answer 3

-exposure to ionising radiation increases the risk factor
-exposure to chemical carcinogens

Question 4

-how do animal and plant cells produced via sexual reproduction start life as?
what must these cells do?

Answer 4

-a single cell, a fertilised egg or zygote.
-divide by mitosis to produce a multicellular organism.

Question 5

where does mitosis occur in plants?
-where are they found?

Answer 5

meristems
-the tips of roots and shoots

Question 6

what is cell elongation?
-where does it occur?
-which group does it not occur to?

Answer 6

-plant cells becoming longer as they grow.
-occurs throughout the plant, not just in the meristems.
-animals.

Question 7

what is differentiation/ when cells differentiate? and how?

Answer 7

-unspecialised cells become specialised cells
-by developing features that enable them to fulfil specific roles

Question 8

what is the growth of babies measured in? (3)

Answer 8

-Mass (kg)
-Length (cm)
-Head circumference (cm)

Question 9

how can the growth of babies be monitored?

Answer 9

percentile growth charts

Question 10

what would a change in position on a percentile chart be an indicator of?

Answer 10

-a health problem

Question 11

what are stem cells?

Answer 11

cells that have not undergone differentiation

Question 12

what are the two types of stem cells?

Answer 12

embryonic and adult stem cells

Question 13

what will happen if embryonic stem cells are removed from the embryo?

Answer 13

they will differentiate into any cell type.

Question 14

why are adult stem cells limited?

Answer 14

they can differentiate into related cell types only

Question 15

what are meristems?

Answer 15

regions in plants in which cell division occurs

Question 16

what can cells of meristems do?

Answer 16

-can differentiate to produce all types of plant cells at any time during the life of the plant

Question 17

where are meristems located?

Answer 17

close to the tip of the shoot, and the tip of the root.

Question 18

what happens in a growing shoot?

-what happens as the cells become older?

Answer 18

-new cells are being produced continuously near the tip.

-they become differentiated. (They enlarge and develop a vacuole)

Question 19

what can stem cells do?

Answer 19

divide to produce new cells, which can then divide into different cell types

Question 20

why are stem cells beneficial for use in medicine? (2)

Answer 20

-have the potential to be transplanted into patients to treat medical conditions and disease.
-they could be used to replace cells that have been damaged or destroyed,

Question 21

discuss the benefits and drawbacks of using embryonic stem cells: (3)

Answer 21

-embryonic stem cells can differentiate into a wider range of cell types,
-difficult to obtain; The best source is a five-day-old embryo
-there are clinical, ethical and social issues with their use.

Question 22

discuss the usage of adult stem cells and an example of how they’re used: (3)

Answer 22

-adult stem cells will differentiate into a narrower range of cell types.
-one marrow transplants are an example of adult stem cell transplant.
-bone marrow cells will differentiate into different types of blood cell.

Question 23

what do stem cells have great potential for? (3)

Answer 23

-treating patients with currently untreatable conditions
-growing organs for transplants
-medical research

Question 24

discuss the ‘clinical issues’ associated with the usage of stem cells: (5)

Answer 24

-There is no guarantee of how successful these therapies will be, for example in the use of stem cells in healing damage caused by Parkinson’s disease.

-The difficulty in finding suitable stem cell donors.

-The difficulty in obtaining and storing a patient’s embryonic stem cells.

-Mutations have been observed in stem cells cultured for a number of generations, and some mutated stem cells have been observed to behave like cancer cells.

-Cultured stem cells could be contaminated with viruses which would be transferred to a patient.

Question 25

discuss the ‘ethical issues’ associated with the usage of stem cells: (4)

Answer 25

-A source of embryonic stem cell is unused embryos produced by in vitro fertilisation

-For therapeutic cloning, is it right to create embryos for therapy, and destroy them in the process?

-Embryos could come to be viewed as a commodity, and not as an embryo that could develop into a person.

-At what stage of its development should an embryo be regarded as, and treated as, a person?

Question 26

discuss the ‘social issues’ associated with the usage of stem cells: (4)

Answer 26

-Educating the public about what stem cells can, and can’t do, is important.

-Whether the benefits of stem cell research use outweigh the objections.

-Much of the research is being carried out by commercial clinics, so reported successes are not subject to peer review.

-Patients could be exploited by paying for expensive treatments and being given false hope of a cure as stem cell therapies are only in their developmental stages.