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AQA GCSE BIOLOGY PAPER 1 > B2 - Cell Division > Flashcards

B2 - Cell Division Flashcards

1
Q

What part of the cell contains chromosomes?

A

The nucleus

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2
Q

What do chromosomes carry?

A

The genes

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3
Q

What are genes

A

Sections of the DNA which contain the instructions for making new cells

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4
Q

How many chromosomes do humans have?

A

46 chromosomes

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5
Q

How many chromosomes does a haploid cell have?

A

23 chromosomes

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6
Q

How many chromosomes does a diploid cell have?

A

46 chromosomes

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7
Q

What are gametes, and give two examples.

A

Sex cells - egg cells and sperm cells

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8
Q

What is the name of the series of stages cells undergo to divide?

A

The Cell Cycle

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9
Q

What process is involved in the cell cycle?

A

Mitosis

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10
Q

What is the product of mitosis?

A

Two identical cells

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11
Q

What is asexual reproduction?

A

Reproduction with a single parent

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12
Q

Why is there no genetic variation in asexual reproduction?

A

Genes of the cell is taken from a single parent therefore there will be no variation.

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13
Q

At what time in your life is the cell cycle the shortest?

A

When a baby is developing in the womb.

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14
Q

At what point is the cell cycle the longest?

A

Old age

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15
Q

When does the cell cycle in a person begin to slow down?

A

After puberty

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16
Q

What cells continue to divide (fairly) rapidly throughout your life?

A

Cells in the hair, the skin, the blood, and the lining of the digestive system

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17
Q

Which stage is the longest stage in the cell cycle?

A

The first stage

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18
Q

What happens in stage 1 of the cell cycle?

A

Cells grow bigger
Mass increases
Continue with normal cell activities

Replicates their DNA
Forms two copies of each chromosome
Ready for division

Increase the number of sub-cellular structures:
• Mitochondria
• Ribosomes
• Chloroplasts (plants)

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19
Q

What happens in stage 2 of the cell cycle?

A

Mitosis
One set of chromosomes is pulled to each end of the dividing cell
Nucleus divides

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20
Q

What happens in stage 3 of the cell cycle?

A

Cytoplasm and cell membranes divide to form two identical daughter cells

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21
Q

About how many body cells die every minute?

A

300 million

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22
Q

What is a stem cell?

A

An undifferentiated cell

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23
Q

What happens to a cell to become differentiated?

A

Some of the genes are switched off, except those that will be used for its specific function

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24
Q

What are two places stem cells can be taken from in humans?

A

Embryo

Adult bone marrow

25
Q

Where are stem cells found in plants?

A

Tips of the roots and shoots - meristems

26
Q

Why aren’t nerve cells replaced when they are damaged?

A

They do not divide

They are not replaced by stem cells

27
Q

In a mature animal, what is cell division mostly for?

A

Repair and replacement of damaged cells

28
Q

How many times can a plant cell differentiate?

A

As many as they want

29
Q

How often does mitosis take place in the meristems?

A

Almost continuously

30
Q

How do plant cells grow?

A

They elongate

31
Q

Producing identical offspring is known as what?

A

Cloning

32
Q

How does cloning a plant work?

A

Under the right conditions, a plant cell will become unspecialised.
These cells then undergo mitosis
More undifferentiated cells are therefore made
Under new conditions, the now-stem cell will differentiate into a different cell
Necessary plant tissues such as:
Xylem, phloem, photosynthetic cells, and root hair cells
can be made.
The new plant will be identical to the original

33
Q

Why is it difficult to clone animals?

A

Most stem cells differentiate early i embryo development.

They cannot be reverted.

34
Q

Egg and sperm cells fuse to form a?

A

Zygote

35
Q

The zygote divides and becomes what?

A

A hollow ball of cells called an embryo

36
Q

What are found in the inner cells of the embryo

A

Embryonic stem cells

37
Q

What do embryonic stem cells do?

A

Differentiate to form all the specialised cells in the body

38
Q

Why can spinal injuries cause paralysis?

A

Spinal nerves cannot repair themselves

39
Q

What breakthrough occurred in 1998?

A

Two scientists managed to culture human embryonic stem cells, capable of forming other cells

40
Q

What happened in 2010?

A

The first trials testing the safety of injecting nerve cells into the spinal cords of paralysed human patients were carried out.

41
Q

What happened in 2014?

A

Doctors transplanted embryonic stem cells into the eyes of people going blind as a result of macular degeneration
It was a small study to check the safety of the technique.

42
Q

What happened as a result of the test in 2014?

A

The patients found that they could see better

43
Q

How can cloning be used to save rare plants from extinction?

A

They can produce a large number of one plant very quickly, economically, safely and reliably.

44
Q

Where may embryonic stem cells come from?

A

Aborted embryos

Spare embryos from fertility treatments

45
Q

What ethical issues surround the use of embryonic stem cells?

A

The embryo cannot give permission - this is a violation of human rights

46
Q

What is a religious reason against using embryonic stem cells?

A

Some religions cannot accept any interference with the process of human reproduction

47
Q

Describe the progress of developing the use of embryonic stem cells

A

Slow, expensive, difficult, hard to control

48
Q

What is a health issue with adult stem cells?

A

They may be infected with viruses - they can therefore be transferred between people

49
Q

What is another issue with the use of adult stem cells?

A

They may trigger an immune response.

50
Q

How must patients combat immune responses?

A

Immunosuppressant drugs which stop their body from rejecting new cells

51
Q

What are two other places that scientists have recently discovered to host embryonic stem cells?

A

Umbilical cord

Amniotic fluid

52
Q

What is therapeutic cloning?

A

Using cells from an adult to produce a cloned early embryo of themselves.

53
Q

What would therapeutic cloning provide?

A

A source of perfectly matched embryonic stem cells.

54
Q

What medical treatments could therapeutic cloning be used for?

A

Growing new organs for the original donor

55
Q

Why would the new organs not be rejected by the body?

A

They have been made by the body’s own cells and have the same genes

56
Q

Where have scientists discovered stem cells in adults?

A

The tubes that connect the liver and the pancreas to the small intestine

57
Q

What have these stem cells been successfully turned into?

A

Special insulin-producing cells

58
Q

In the UK, stem cell research is being carried out into potential therapies to treat what?

A 
Spinal cord after injuries
Diabetes
Heart after damage
Eyesight
Damaged bone and cartliage

AQA GCSE BIOLOGY PAPER 1 (8 decks)

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