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HCHS GCSE Science 3 - Biology > Section 2 - Cells and Control > Flashcards

Section 2 - Cells and Control Flashcards

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1
Q

What are chromosomes?

A

Coiled up lengths of DNA molecules.

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2
Q

How many of each chromosome do body cells normally have? What is the name given to this type of cell?

A

One pair. Diploid cells.

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3
Q

What is mitosis?

A

When a cell divides to make two identical copies of itself.

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4
Q

What do multicellular organisms use mitosis for?

A

Growth or the replacement of damaged cells.

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5
Q

In some multicellular organisms and most monocellular organisms, what can mitosis be used for?

A

Asexual reproduction.

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6
Q

What are the stages of the cell cycle?

A 
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
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7
Q

What occurs in the Interphase?

A

The cell is preparing to divide, for this it must grow and increase the number of subcellular structures like mitochondria and ribosomes. The DNA is spread out in long strings and is copied to form X shaped chromosomes. both sides of the chromosome is identical.

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8
Q

What occurs in the Prophase?

A

The chromosomes condense, the nucleus membrane breaks down and the chromosomes lie free in the cytoplasm.

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9
Q

What occurs in the Metaphase?

A

The chromosomes line up along the centre of the cell.

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10
Q

What occurs in the Anaphase?

A

Cell fibres pull the chromosomes apart, the two arms of the chromosomes go to opposite sides of the cell.

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11
Q

What occurs in the Telophase?

A

Membranes form around both sets of chromosomes, these become the nuclei of the new cells.

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12
Q

What occurs in Cytokinesis?

A

Before the Telophase ends, the cell membrane divides to form two separate cells.

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13
Q

What is cell differentiation?

A

The process by which a cell changes to become speacialised for it’s job.

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14
Q

What is cell elongation?

A

Where the plant cell expands and becomes bigger in order to make the plant grow.

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15
Q

In animals, how does growth occur?

A

By cell division.

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16
Q

In plants, how does growth occur?

A

By cell division and elongation.

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17
Q

How does the rate of mitosis change in animals over time?

A

When young, the rate of mitosis is rapid, so that the child grows, though once it reaches adulthood it slows greatly and is used mainly to repair damage.

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18
Q

How does the rate of mitosis change in plants over time?

A

It doesn’t, most growth is due to cell elongation and the cells continue dividing regardless.

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19
Q

Where does growth occur in plants?

A

In the tips of roots and shoots, known as meristems.

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20
Q

What is a cancer?

A

A mass of abnormal cells that invade and destroy surrounding tissues.

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21
Q

How does cancer occur?

A

A change in the genes of a cell making it divide uncontrollably.

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22
Q

How can growth be measured?

A

Percentile charts.

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23
Q

What measurements are usually taken of babies to assess their health.

A

Length, mass and head circumference.

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24
Q

For what reasons would doctors investigate a baby for according to a percentile chart?

A

If the baby was above the top percentile, bellow the bottom, increases or decreases by two or more percentiles over time or if their growth pattern is inconsistent.

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25
Q

What are stem cells?

A

Undifferentiated cells.

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26
Q

Where in humans can stem cells be found?

A

In embryos or in certain places like bone marrow in adults.

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27
Q

What do stem cells do?

A

They divide and speacialise to make any cell that is necessary.

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28
Q

Where in plants can stem cells be found?

A

In the meristems.

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29
Q

What are uses of stem cells in medicine?

A

Organ transplant, cancer research.

30
Q

What are the risks of using stem cells in surgery?

A

Tumor development, Disease transmission and rejection.

31
Q

What is the central nervous system?

A

The brain and spinal cord.

32
Q

What is the spinal cord?

A

A long column of neurones that relay information between the brain and the rest of the body.

33
Q

What are the different parts of the brain?

A

Cerebrum
Cerebellum
Medulla oblongata

34
Q

What is the cerebrum? What does it do?

A

The largest part of the brain, is separated in two halves known as cerebral hemispheres, the right hemisphere controls movement on the left side and the left hemisphere controls movement on the right. Different parts are responsible for different things, such as movement, intelligence, memory, language and vision.

35
Q

What does the cerebellum do?

A

It is responsible for muscle coordination and balance.

36
Q

What does the medulla oblongata do?

A

Controls unconscious activities like breathing and heart rate.

37
Q

What are the two scanners used to detect brain activity?

A

CT scanners & PET scanners.

38
Q

How do CT scanners work?

A

They use X-rays to produce an image of the brain, it shows the main structures of the brain but it doesn’t show their functions, it can show diseased or damaged brain structures which can be used to detect what that structure did from the loss of function in the patient.

39
Q

How do PET scanners work?

A

They use radioactive chemicals to show which parts of the brain are active, they are very detailed and can be used to investigate both structures and their functions in real time. They can also show disorders in brain activity by abnormally high or low areas of activity.

40
Q

Why is treating problems in the central nervous system difficult?

A

Damage to the CNS is difficult to repair as the neurones in the CNS don’t readily repair, nor have scientists figured out a way to repair CNS damage.
It is difficult to conduct surgery on the brain.
Treatment may lead to permanent damage to the CNS.

41
Q

What is the signal path for stimulus and response?

A 
Stimulus
Receptor
Sensory neurone
CNS
Motor neurone
Effector
Response
42
Q

How do neurones work?

A

They rapidly transmit information as electrical signals.

43
Q

What is the basic structure of a neurone?

A

The cell has a cell body, containing the nucleus and other subcellular structures, but it also has ling extensions that connect to other neurones, dendrites and dendrons carry impulses towards the cell body, while axons carry signals away from the cell body, some axons have myelin sheaths which acts as an insulator and speeds up the impulse.

44
Q

What are the three types of neurone?

A

Sensory
Motor
Relay

45
Q

What is the structure of a sensory neurone?

A

One long dendron from receptor cells to the cell body, with a short axon leading to the CNS.

46
Q

What is the structure of a motor neurone?

A

Many short dendrites leading from CNS to cell body, one long axon leading to effector cells, m\ny motor neurones have a myelin sheath but there are unmyelinated ones.

47
Q

What is the structure of a relay neurone?

A

Many short dendrites leading from sensory neurones to cell body, an axon leads to motor neurones.

48
Q

What are synapses?

A

The connection between neurones.

49
Q

How are nerve signals transmitted between neurones?

A

By chemical neurotransmitters which diffuse across the gap.

50
Q

What is the name of the signal path for reflexes?

A

The reflex arc.

51
Q

Why are reflexes quicker than normal reactions?

A

Because they aren’t conscious actions and the brain spends no time thinking about them.

52
Q

What are the parts of the eye?

A 
The cornea
The iris
The lens
The retina
Rods
Cones
The optic nerve
53
Q

What does the cornea do?

A

Refracts light into the eye.

54
Q

What does the iris do?

A

Controls how much light enters the pupil.

55
Q

What does the lens do?

A

Focuses light onto the retina.

56
Q

What is the retina?

A

The light sensitive part of the eye, it is made up of rods and cones.

57
Q

What do the rods do?

A

They allow sight in dim light.

58
Q

What do the cones do?

A

They allow sight in colour.

59
Q

What does the optical nerve do?

A

Caries the signal from the eye to the brain.

60
Q

What happens to the lens when looking at distant objects?

A

The ciliary muscle relaxes, pulling the suspensory ligaments tight, this stretches the lens to a less round shape refracting the light less.

61
Q

What happens to the lens when looking at close objects?

A

The ciliary muscle contracts, slackening the suspensory ligaments, the lens becomes more rounded, refracting more light.

62
Q

List two vision problems.

A

Cataracts and colour blindness.

63
Q

How can cataracts be cured?

A

Replacing the faulty lens with an artificial one.

64
Q

What does the myelin sheath do?

A

Speeds up signal transfer through the axon.

65
Q

What’s wrong with the eye if someone is short-sighted?

A

The lens is the wrong shape and refracts the light too much or the eye is too long and so light focuses in front of the retina instead of on.

66
Q

What’s wrong with the eye if someone is long-sighted?

A

The lens is the wrong shape and refracts the light too little or the eye is too short and so light focuses behind the retina instead of on.

67
Q

What type of lens is used to correct short-sightedness?

A

A concave lens.

68
Q

What type of lens is used to correct long-sightedness?

A

A convex lens.

69
Q

What is colour blindness caused by?

A

When certain cone cells in the eye don’t function correctly.

70
Q

What is a cataract?

A

A cloudy patch on the lens.

HCHS GCSE Science 3 - Biology (9 decks)

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