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Biology Unit 2 GCSE > 2.) Topic 2 Cell Division And Stem Cells > Flashcards

2.) Topic 2 Cell Division And Stem Cells Flashcards

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1
Q

What are chromosomes

A

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.

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2
Q

Just before cell division what does the DNA do?

A

It coils up tightly

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3
Q

How many chromosomes does the human body contain?

A

46 in total (23 pairs)

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4
Q

W cells divide [3]hen do

A

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

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5
Q

What are gametes and what are special about them

A

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

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6
Q

Where is sperm and egg produced

A

Sperm is produced in the testes

Egg is produced in the ovaries

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7
Q

What is mitosis

A

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

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8
Q

Why is mitosis important (4)

A

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

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9
Q

How is a zygote fomed

A

When a male gamete fuses with a female gamete

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10
Q

In which type of cell division are gametes formed?

A

By a type of cell division called meiosis

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11
Q

What is meiosis

A

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).

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12
Q

Are all gametes genetically different from each other?

A

Yes

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13
Q

Why is meiosis important

A

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

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14
Q

What causes meiosis to take place?

A

Sexual reproduction

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15
Q

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?

A 
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
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16
Q

What is cancer a result of?

A

Uncontrolled mitosis

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17
Q

What type of disease is cancer

A

A non-communicable disease

18
Q

What can uncontrolled mitosis lead to the formation of?

A

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

19
Q

What does cell differentiation produce?

A

Specialised cells with specialised functions

20
Q

What are stem cells?

A

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

21
Q

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

A

No it can’t

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

22
Q

What do stem cells form when they divide

A

One of the daughter cells becomes a tissue cell

23
Q

What are meristems?

A

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

24
Q

What are embryonic stem cells?

What is their function?

A

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

25
Q

What is an embryo

A

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

26
Q

What are adult stem cells?

A

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

27
Q

Where can adult stem cells be found?

A 
Brain
Eyes
Skin
Muscle
Blood
Heart
Liver
Bone marrow
28
Q

What are the uses of stem cell technology

[2]

A

Can lead to treatment or a cure for many diseases

Can be used to replace damaged tissues e.g. trachea

29
Q

What are the advantages of using stem cells

A

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

30
Q

What are the disadvantages of using stem cells

A

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

31
Q

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

A

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

32
Q

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

A

Avoids ethical issues e.g. killing of unborn children

33
Q

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

A

Mitosis

34
Q

What does ‘undifferentiated’ mean [1]

A

Unspecialised

The process by which stem cells become specialized

35
Q

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

A

Advantage - Risk of rejection is virtually non-existent

Disadvantage - Can only differentiate into into a certain number of types of cells

36
Q

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

A

Pancreas

37
Q

Why is meiosis important for sexual reproduction? x2

A

Increases genetic variation

Ensures that the resultant zygote has a full set of chromosomes

38
Q

In plants, where can stem cells be found

A

In meristematic tissue in the root and shoot tips

39
Q

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

A

Donor stem cells removed from embryos grown in vitro

Patients own stem cells removed from the umbilical blood before birth

40
Q

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

A

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

41
Q

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

A

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

42
Q

What is a protein

A

A large molecule synthesized from amino acids monomers

Biology Unit 2 GCSE (9 decks)

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