2.) Topic 2 Cell Division And Stem Cells

Question 1

What are chromosomes

Answer 1

A chromosome is a linear DNA molecule tightly coiled around proteins. It carries genetic information in the form of genes. Genes also exist in pairs, and each gene creates a code that makes a specific protein.

Question 2

Just before cell division what does the DNA do?

Answer 2

It coils up tightly

Question 3

How many chromosomes does the human body contain?

Answer 3

46 in total (23 pairs)

Question 4

W cells divide [3]hen do

Answer 4

When:
An organism grows
Organisms need to replace worn-out cells
Organisms need to repair damaged tissue

Question 5

What are gametes and what are special about them

Answer 5

Sex cells. They contain half the number of chromosomes of a normal human cell

Question 6

Where is sperm and egg produced

Answer 6

Sperm is produced in the testes

Egg is produced in the ovaries

Question 7

What is mitosis

Answer 7

Mitosis is the division of a mother cell to produce two genetically identical daughter cells with a full set of chromosomes (46 chromosomes). It involves one division

Question 8

Why is mitosis important (4)

Answer 8

It is important because it allows an organism to grow, repair damaged tissues, replace old cells and asexually reproduce

Question 9

How is a zygote fomed

Answer 9

When a male gamete fuses with a female gamete

Question 10

In which type of cell division are gametes formed?

Answer 10

By a type of cell division called meiosis

Question 11

What is meiosis

Answer 11

Meiosis is a type of cell division that creates four genetically different daughter cells known as gametes. Meiosis involves two divisions and produces cells with half the number of chromosomes (23 chromosomes).

Question 12

Are all gametes genetically different from each other?

Answer 12

Yes

Question 13

Why is meiosis important

Answer 13

For genetic variation and ensuring that the resultant zygote has a full set of chromosomes

Question 14

What causes meiosis to take place?

Answer 14

Sexual reproduction

Question 15

Comparing mitosis and meiosis x6

How many cell divisions are there?

How many cells are produced?

How many chromosomes are present?

What is it used for?

Where in the body does it happen?

Are the cells produced different or the same?

Answer 15

Mitosis                                                    
The cells divides ONCE         
2 daughter cells produced     
46 chromosomes present   
Produce new body cells     
All parts of the body in        
non-reproductive cells                        
Genetically identical 

Meiosis
The cell divides TWICE 
4 gamete cells produced     
23 chromosomes present 
How gametes are made
Happens in the testes and ovaries  
Genetically different

Question 16

What is cancer a result of?

Answer 16

Uncontrolled mitosis

Question 17

What type of disease is cancer

Answer 17

A non-communicable disease

Question 18

What can uncontrolled mitosis lead to the formation of?

Answer 18

A primary tumour and these tumour cells can break off and and spread to other tissues forming secondary tumours

Question 19

What does cell differentiation produce?

Answer 19

Specialised cells with specialised functions

Question 20

What are stem cells?

Answer 20

Unspecialised cells which have the capability to develop into different types/other cells

Question 21

When a cell becomes specialised, can it change into anther type of cell and give an example

Answer 21

No it can’t

E.g. you cannot use a muscle cell to try and grow skin cells

Question 22

What do stem cells form when they divide

Answer 22

One of the daughter cells becomes a tissue cell

Question 23

What are meristems?

Answer 23

The source of stem cells in plants are called meristems and they are the growing points in the tips of shoots and roots

Question 24

What are embryonic stem cells?

What is their function?

Answer 24

Unspecialised and capable of differentiating into any cell type, enable the growth and development of tissues in embryos

Question 25

What is an embryo

Answer 25

When a fertilised egg divides to form a ball of cells. These are called embryos

Question 26

What are adult stem cells?

Answer 26

Can develop into a limited range of cell types, enable the replacement of dead or damaged cells

Question 27

Where can adult stem cells be found?

Answer 27

``` Brain Eyes Skin Muscle Blood Heart Liver Bone marrow ```

Question 28

What are the uses of stem cell technology | [2]

Answer 28

Can lead to treatment or a cure for many diseases | Can be used to replace damaged tissues e.g. trachea

Question 29

What are the advantages of using stem cells

Answer 29

Used to treat damage or disease e.g. type 1 diabetes and heart disease Used to treat disease that would otherwise be untreatable Not rejected by the body No need to find a donor No need for tissue typing Can be used to grow organs for transplants

Question 30

What are the disadvantages of using stem cells

Answer 30

May become contaminated during preparation and when transplanted may transmit infections to the patient No guarantee that the treatment will work Transplanted stem cells can cause tumours Long term risks are unknown Potential side effects

Question 31

Suggest why some people support embryonic stem cell research, whereas others do not [2]

Answer 31

Some people support it because it can be used as a cure for many diseases. However some people do not because they believe it destroying a human life by destroying an embryo

Question 32

State one advantage of using stem cells over the use of embryonic stem cells [1]

Answer 32

Avoids ethical issues e.g. killing of unborn children

Question 33

What type of cell division would happen embryonic stem cells [1]

Answer 33

Mitosis

Question 34

What does 'undifferentiated' mean [1]

Answer 34

Unspecialised | The process by which stem cells become specialized

Question 35

State an advantage and disadvantage of using adult stem cells rather than embryonic stem cells [2]

Answer 35

Advantage - Risk of rejection is virtually non-existent | Disadvantage - Can only differentiate into into a certain number of types of cells

Question 36

If a treatment for diabetes were developed, which organ would need to be treated? [1]

Answer 36

Pancreas

Question 37

Why is meiosis important for sexual reproduction? x2

Answer 37

Increases genetic variation | Ensures that the resultant zygote has a full set of chromosomes

Question 38

In plants, where can stem cells be found

Answer 38

In meristematic tissue in the root and shoot tips

Question 39

Where can embryonic stem cells be collected from? [2]

Answer 39

Donor stem cells removed from embryos grown in vitro Patients own stem cells removed from the umbilical blood before birth

Question 40

Describe the potential uses of stem cells in medicine (4)

Answer 40

Treat diseases e.g. heart disease, type 1 diabetes Used to repair damages tissue e.g. brain damage Used in scientific research Growing organs for transplants

Question 41

What are the ethical issues related to the use of stem cells in medicine? [3]

Answer 41

Embryos used to provide stem cells are destroyed - human life destroyed Could lead to the 'farming' of embryos for stem cells May lead to the reproductive cloning of humans

Question 42

What is a protein

Answer 42

A large molecule synthesized from amino acids monomers