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GCSE - Biology > Topic 2 - Cells And Control > Flashcards

Topic 2 - Cells And Control Flashcards

1
Q

What is the cell cycle?

A

Series of events taking place in a cell

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2
Q

Name some parts of the cell cycle

A

Cell growth
DNA replication
Cell division

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3
Q

State the three stages of the cell cycle

A

Interphase
Mitosis
Cytokinesis

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4
Q

What is interphase

A

Involves cell growth, synthesis of new organelles and DNA replication

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5
Q

What is the longest stage of the cell cycle?

A

Interphase

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6
Q

What does DNA replication involve?

A

Double helix unzips
DNA bases align next to complementary bases on strands
Complementary base pairs join
2 identical DNA molecules form

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7
Q

What’s a chromosome?

A

A DNA molecule tightly coiled around proteins

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8
Q

What happens to chromosomes during DNA replication?

A

DNA in arm of each chromosome is replicated

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9
Q

What are the arms of the chromosomes called?

A

Chromatids

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10
Q

What is mitosis?

A

Form of cell division - forms 2 diploid daughter cells

Genetically identical to parent cell

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11
Q

Why is mitosis important in organisms?

A

Asexual reproduction
Growth
Repair of damaged cells
Cell replacement

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12
Q

State the 4 stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

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13
Q

Outline prophase

A

DNA condenses
Chromosomes become visible
Nuclear membrane disappears

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14
Q

Outline metaphase

A

Chromosomes line up along cell equator

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15
Q

Outline anaphase

A

Spindle fibres attach to each chromosome
Arms of each chromosome pulled to opposite poles
Chromatids separated

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16
Q

Outline telophase

A

Nucleus of cell divides

New membrane forms around each set of chromosomes

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17
Q

What does cytokinesis involve?

A

Division of cell membrane and cytoplasm

2 genetically identical daughter cells produces

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18
Q

A cell divides by mitosis once every 2 minutes. Calculate the number of identical cells present after 10 minutes

A

10/2=5
5 cell divisions taken place
2⁵ = 32 cells

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19
Q

What is cancer

A

Non communicable disease
Uncontrolled cell division (due to damaged DNA) results in formation of primary tumour
Tumour cells break off and spread to other tissues forming secondary tumours

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20
Q

What are percentile charts?

A

Chart used to monitor growth

Measurements can be compared to expected values at certain age

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21
Q

What does the 95th percentile mean?

A

95% of measurements will be below the value of the 95th percentile

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22
Q

What can doctors determine from percentile charts? (3)

A

Slower growth than normal (below bottom line)
Faster growth than normal (above top line)
Abnormal growth (irregular growth patterns)

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23
Q

Describe growth in animals

A

Cell division occurs in all body cells at slower rate in adults than younger animals - growth stops + cell division only required for repairs

Most cells differentiate at early stage + become specialised.

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24
Q

Describe growth in plants

A

Cell division only occurs in meristematic tissue. Rate remains same through life.
Meristematic stem cells can differentiate into any cell type.
Cell elongation occurs in all cells. They expand and enlarge = growth

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25
What are stem cells?
Cells that are unspecialised and capable of differentiating into a range of different cell types.
26
What is meant by differentiation?
Process where stem cells become specialised
27
Why is cell differentiation important?
Enables formation of specialised tissues with specific funtions
28
What are embryonic stem cells?
Stem cells found in very early embryos that are unspecialised and capable of differentiating into any cell type
29
What is the function of embryonic stem cells?
Enable growth and development of tissues in human embryos
30
What are adult stem cells?
Stem cells that can differentiate into a limited range of cell types
31
Give an example of an adult stem cell
Bone marrow stem cells
32
What’s the primary function of adult stem cells?
Replacement of dead cells | Eg replacement of red blood cells which only live for 120 days
33
Where are stem cells found in plants?
Meristems
34
Where is meristem tissue found?
In regions of the plant where cells are continuously dividing - eg root tips, shoot tips
35
What are meristematic stem cells?
Stem cells found in meristems that are unspecialised and capable of differentiating into any cell type during the plants life
36
How can stem cells be used in medicine?
Stem cells collected Stimulated to differentiate into specific cell types Specialised cells transplanted into patient Used to treat damage or disease
37
Where can embryonic stem cells be collected from?
Donor stem cells removed from embryos grown in vitro | Patients own stem cells removed from the umbilical blood before birth
38
What are the benefits of using stem cells in medicine? (4)
Treat damage or disease eg: heart disease Treat diseases that would otherwise be untreatable Used in scientific research Growing organs for transplants
39
What are the risks of stem cell use in medicine? (6)
Transplanted stem cells could cause tumours Finding suitable donors is difficult May be rejected by body Potential side effects Long term risks unknown May become contaminated during prep and transmit infections to patient
40
What are the ethical issues related to the use of stem cells in medicine? (2)
The embryos that were used to provide stem cells are destroyed which is seen as unethical and a waste of human life May lead to reproductive cloning of humans
41
What is the central nervous system?
Brain and spinal cord
42
What is the spinal cord?
A long thin structure composed to neurones that extends from medulla oblongata down spine
43
What’s the function of the spinal cord?
Connects peripheral NS to brain
44
Describe structure of brain
3 main regions: Cerebrum Cerebellum Medulla oblongata
45
Describe the structure of the cerebrum
Largest region of brain | Divided into 2 hemispheres
46
What is the function of the cerebrum?
``` Involved in: Intelligence Language Memory Emotion Visual and sensory processes ```
47
What is the function of each cerebral hemisphere?
Left receives sensory info from right side of body and controls muscle coordination on right Right received sensory info from left side of body and controls muscle coordination on left
48
Where is the cerebellum located?
Lower region of brain
49
What’s the function of the cerebellum?
Involved in: Coordination of muscles Voluntary movement - walking Non voluntary movement - balance
50
What’s the function of the medulla oblongata?
Controls automatic processes in the body eg: breathing rate, heart rate
51
What methods, other than surgery, are used by doctors to observe the brain?
CT scan | PET scan
52
What is a CT scan?
Procedure that uses X rays to produce 3D cross-sectional images of the brain
53
Describe how CT scans are useful to investigate brain function
Show damaged regions of brain (areas of swelling/bleeding) | Observations of symptoms can enable scientists to determine function of damaged region
54
What does a PET scan involve?
Radioactive substance injected into patients bloodstream and taken up by tissues in brain. Radiated emitted by tissues detected, enabling identification of active and inactive brain regions.
55
Describe how PET a scans are useful to investigate brain function
Show which areas are active/not | Comparisons between healthy and brain damaged allow determine functions of inactive regions
56
Why is it difficult to treat damage to the CNS?
Damage to neurones is permanent and can’t be repaired (nerve cells don’t divide by mitosis). Hard to reach some areas of brain. Risk of further damage to other areas in surgery.
57
What is the function of the nervous system?
Allows an organism to rapidly react to environmental and internal changes
58
What are neurones?
Nerve cells adapted to quickly transmit nerve impulses. The functional units of the NS.
59
What is the function of the axon?
Carries impulses away from the cell body | Enables transmission of nerve impulses over long distances
60
What’s the function of the dendrites and dendrons?
Carry impulses towards cell body | Provide large surface area to receive impulses
61
What’s the role of the myelin sheath?
Electrically insulating layer | Surrounds axon and increases speed of impulses
62
Outline the function of a sensory neurone
Carries impulses from receptors to the CNS
63
Describe the structure of a sensory neurone
Long dendron carries impulses from receptor to cell body Cell body found halfway down neurone Short axon carries impulses from cell body to CNS
64
Outline the function of a motor neurone
Carries impulses from CNS to effectors
65
Describe the structure of a motor neurone
Short dendrites carry impulses from CNS to cell body Cell body found at one end of the neurone Long axon carries impulses from cell body to effectors
66
Outline function of relay neurone
Carries impulses from sensory neurones to motor neurones within CNS
67
Describe structure of relay neurone
Short dendrites carry impulses from sensory neurones to cell body Short axon carries impulses from cell body to motor neurones
68
Describe how the CNS coordinates a response to a stimulus
Stimulus Sensory receptor detects stimulus Sensory receptor sends impulses along sensory neurone to CNS CNS coordinates response CNS sends info to effector along motor neurone Effector produces a response to the stimulus
69
What is a synapse?
A small gap between neurones across which a nerve impulse is transmitted via neurotransmitters
70
How are nerve impulses transmitted across a synapse?
Nerve impulses reach presynaptic neurone Triggers release of neurotransmitters Neurotransmitters diffuse across synapse Bind to receptors on postsynaptic neurone Stimulates impulse in postsynaptic neurone
71
Why do synapses slow down the transmission of nerve impulses?
Takes time for the neurotransmitters to diffuse across the synapse and bind to receptors on the postsynaptic neurone
72
What is a reflex?
Automatic response to a stimulus by the body Involuntary - doesn’t involve conscious part of brain Protective mechanism eg a withdrawal reflex is initiated when a hot object is touched to prevent burns
73
Describe the reflex arc
Stimulus -> sensory receptor -> sensory neurone -> relay neurone -> motor neurone -> effector -> response

GCSE - Biology (7 decks)

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