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Biology > SB2 - Cells & control > Flashcards

SB2 - Cells & control Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are organisms made up of many cells called?

A

Multicellular organisms

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2
Q

What do multicellular organisms need in order to grow?

A

New cells

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3
Q

When do cells divide?

A
  • When an organism grows
  • When an organism becomes damaged & needs new cells for repair
  • When organisms reproduce asexually
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4
Q

What is the cell cycle?

A

The events that lead to cell division & DNA replication

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5
Q

What is Mitosis?

A

A type of cell division which produces daughter cells identical to the parent

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6
Q

What are the phases of the cell cycle?

A
  • Interphase
  • Mitosis
  • Cytokinesis
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7
Q

What is interphase

A
  • The cell grows, organelles (such as ribosome and
    mitochondria) grow and increase in number
  • The synthesis of proteins occurs
  • DNA is replicated (forming the characteristic ‘X’ shape) and energy stores are increased
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8
Q

What are the substages of mitosis?

A
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis
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9
Q

What is Prophase?

A

The nucleus starts to break down and spindle fibres appear

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10
Q

What is Metaphase?

A

The chromosomes are lined up in the spindle fibres across the middle of the cell

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11
Q

What is Anaphase?

A

The chromosome copies are separated and moved to either end of the cell on the spindle fibres

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12
Q

What is Telophase?

A

A membrane forms around each set of chromosomes to form nuclei

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13
Q

What is Cytokinesis?

A

Two identical daughter cells form when the cytoplasm and cell membranes divide

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14
Q

How many daughter cells does mitosis produce?

A

2 genetically identical diploid cells

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15
Q

Where is a diploid number of chromosomes found in the body?

A

Body cells (46)

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16
Q

Where is a haploid number of chromosomes found in the body?

A

Gametes (23)

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17
Q

What is a gene?

A

A short section of DNA that codes for a protein and as a result controls a characteristic- therefore each chromosome carries many genes

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18
Q

How does cancer occur?

A

As a result of small changes in cells, that lead to uncontrolled cell division

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19
Q

What is a tumour?

A

The group of cells that results from this uncontrolled division

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20
Q

How does growth occur in animals?

A

Via cell division and differentiation

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21
Q

What is differentiation?

A

The process by which a less specialised cell becomes more specialised for a particular function

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22
Q

How does growth occur in plants?

A

Via cell division, differentiation and elongation

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23
Q

How can plant cells grow in a specific direction?

A

By absorbing water into their vacuoles
—> Controlled by auxins

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24
Q

At what time can plants differentiate?

A

Many types of cells retain the ability to differentiate throughout life

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25
Q

What are the types of stem cells?

A
  • Embryonic
  • Adult
  • Meristem
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26
Q

What can embryonic stem cells differentiate into?

A

Any type of body cell

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27
Q

When do embryonic stem cells form?

A

When an egg and sperm cell fuse to form a zygote

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28
Q

How can scientists clone embryonic stem cells?

A

By culturing them

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29
Q

What can Adult stem cells differentiate into?

A

Many types of cells (including blood cells)

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30
Q

What can meristem cells differentiate into?

A

Any type of plant, and have this ability throughout the life of the plant

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31
Q

Where are meristem cells found?

A

Root shoot and tips

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32
Q

What is therapeutic cloning?

A

Involves an embryo being produced with the same genes as the patient.

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33
Q

Describe how therapeutic cloning works

A

The embryo produced could then be harvested to obtain the embryonic stem cells
—> Could be grown into any cells the patient needed

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34
Q

What is an advantage of therapeutic cloning?

A

They would not be rejected as they would have the exact same genetic make-up as the individual

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35
Q

What are the benefits with the use of stem cells in medicine?

A
  • Can be used to replace damaged or diseased body parts
  • Research into the process of differentiation
  • Unwanted embryos from fertility clinics
    could be used
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36
Q

What are the problems with the use of stem cells in medicine?

A
  • People may have religious or ethical objections
  • If growing cells are contaminated w/ virus - can pass onto individual
  • Don’t completely understand the process of differentiation
  • People may have religious or ethical objections
  • Removal of stem cells = destruction of the embryo
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37
Q

Why may people have religious or ethical objections when using embryonic stem cells?

A

As it is seen as interference with
the natural process of reproduction

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38
Q

Why might not understanding the process of differentiation be a problem when using embryonic stem cells?

A

It is hard to control stem cells to form the cells we desire

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39
Q

What makes up our CNS?

A
  • The brain
  • Spinal cord
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40
Q

What is the CNS responsible for?

A

Controlling consciousness, movements thoughts and emotions, among other things

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41
Q

Where is the cerebral hemispheres located?

A

On the left & right hand sides

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42
Q

What are the functions of the cerebral hemispheres?

A
  • Consciousness
  • Memory
  • Intelligence
  • Visual & sensory processing
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43
Q

Where is the cerebellum located?

A

Bottom of the brain, on the rear side

44
Q

What are the functions of the cerebellum?

A

Fine movements of muscles
—> Ensuring movements are smooth

45
Q

Where is the medulla oblongata located?

A

In the brainstem, at the base of the brain

46
Q

What are the functions of the medulla oblongata?

A
  • Breathing
  • Digestion
  • Swallowing
  • Sneezing
47
Q

What scans can we use to look inside the brain?

A
  • PET
  • CT
48
Q

What are CT scans?

A

Fire X-Ray radiation at the brain from several different angles to generate a 3D image of the brain

49
Q

What are CT scans useful for?

A
  • Examining bleeding
  • Damage to brain structures
50
Q

Why are CT scans not recommended for pregnant women and children?

A

As it exposes the patient to higher doses of radiation than a normal X-ray

51
Q

How do PET scans work?

A

A radioactive ‘tracer’ is injected into the blood before the scan.
—> Scan itself is sensitive to the tracer - areas where the tracer builds up will be highlighted more brightly on the resulting scan.

52
Q

Why will the tracer in a PET scan build up in certain areas?

A

As they will also be areas with greater blood flow

53
Q

What are PET scans useful for?

A

Identifying cancerous tumours

54
Q

Why is Investigating brain function and treating brain damage difficult?

A
  • It is complex and delicate
  • It is easily damaged
  • Drugs given to treat diseases cannot always reach the brain
  • It is not fully understood which part of the brain does what.
55
Q

Why can’t certain drugs reach the brain when treating diseases?

A

Because of the membranes that surround it

56
Q

Why might brain tumours be difficult to remove?

A
  • Can push against other structures and blood vessels in the brain
  • Can be buried deep in the brain or spinal cord - difficult to remove
57
Q

What is the eye?

A

A sense organ containing receptors sensitive to light intensity and colour

58
Q

Name some structures in the eye

A
  • Retina
  • Cornea
  • Iris
  • Ciliary muscles
  • Lens
  • Suspensory ligaments
59
Q

What is the Retina?

A

Layer of light sensitive cells found at the back of the eye

60
Q

What does the Retina contain?

A
  • Rod cells
  • Cone cells
61
Q

What are cone cells sensitive to?

A

Colour

62
Q

What are rod cells sensitive to?

A

Light

63
Q

What is the Cornea?

A

The see-through layer at the front of the eye

64
Q

What is the purpose of the cornea?

A

Allows light through Curved surface bends and focuses light onto the retina

65
Q

What is the Iris?

A

Muscles that surrounds the pupil.

66
Q

What is the purpose of the iris?

A

Contracts or relaxes to alter the size of the pupil

67
Q

How does the Iris react to bright light?

A

The circular muscles contract and radial muscles relax
—> To make the pupil smaller- avoiding damage to the retina

68
Q

How does the Iris react to dim light?

A

The circular muscles relax and the radial muscles contract
—> To make the pupil larger- so more light can enter to create a better image

69
Q

What is the ciliary muscle and the suspensory ligaments?

A

Hold the lens in place

70
Q

What is the ROLE of the ciliary muscle and the suspensory ligaments?

A

They control its shape and allow us to focus on objects nearer or further away

71
Q

What is the Lens?

A

Transparent, curved surface on the front of the eye

72
Q

What is the purpose of the Lens?

A

Reflects light onto the retina

73
Q

What is accommodation?

A

The process of changing the shape of the lens to focus on near or distant objects

74
Q

Describe how eyes focus on a near object?

A

● The ciliary muscles contract
● The suspensory ligaments loosen
● The lens is then thicker and more curved- this refracts the light more

75
Q

Describe how eyes focus on a distant object?

A

● The ciliary muscles relax
● The suspensory ligaments tighten
● The lens then becomes thinner - light is refracted less

76
Q

Name some eye defects

A
  • Myopia
  • Hyperopia
  • Cataracts
  • Colour blindness
77
Q

What is Myopia?

And why might people have this?

A

Short-sightedness
—> lens is too curved, so distant objects appear blurry

78
Q

What is Hyperopia?

And why might people have this?

A

Long sightedness
—> Lens is too flat, so it cannot refract light enough

79
Q

How can myopia and hyperopia be treated?

A
  • Spectacle lenses
  • Contact lenses
  • Laser eye surgery
  • Replacement lens
80
Q

How can spectacle lenses be used to treat myopia?

A

Concave lenses = spreads out the light to treat myopia

81
Q

How can spectacle lenses be used to treat hyperopia?

A

Convex lenses = brings the rays together to treat hyperopia

82
Q

How can laser eye surgery be used to treat myopia or hyperopia?

A

Lasers can be used to either reduce the thickness of the cornea or change its curvature

83
Q

How can a replacement lens be used to treat hyperopia?

A

Either by:
* Replacing the lens with an artificial one made of clear plastic

  • Adding the plastic on top of the natural lens
84
Q

What are the risks of replacement lens?

A
  • Damage to retina
  • Cataracts developing
85
Q

What are cataracts?

A

Clouding of the lens of the eye

86
Q

How are cataracts fixed?

A

By replacing the lens of the eye in surgery w/ a plastic one

87
Q

What is colour blindness?

A

The inability to see certain colours

88
Q

Why does colour blindness occur?

A

As people with the condition do not have enough cone cells in their retina
—> Usually genetic

89
Q

Can colour blindness be corrected?

A

No

90
Q

What is are reflexes?

A

Automatic responses which take place before you have time to think

91
Q

Why are reflexes important?

A

They prevent the individual from getting hurt

92
Q

What are synapses?

A

Gaps between two neurons

93
Q

What are motor neurones?

A

A type of neuron that carries impulses to effectors

94
Q

What are relay neurones?

A

A short type of neurone found in the spinal chord and brain
—> Relay neurones link sensory, motor & other relay neurones together

95
Q

What are sensory neurones?

A

A neurone that carries impulses from receptor cells towards the CNS

96
Q

What is a reflex arc?

A

A neurone pathway consisting of a sensory neurone passing impulses to a motor neurone which allows reflexes to occur

97
Q

Describe the reflex arc?

A
  1. A stimulus is detected by receptors
  2. Impulses are sent along a sensory neuron
  3. In the CNS the impulse passes to a relay neuron
  4. Impulses are sent along a motor neuron
  5. The impulse reaches an effector resulting in the appropriate response
98
Q

What happens when an impulse reaches the end of the 1st neuron?

A

A neurotransmitter is released into the synapse

99
Q

Describe how impulses are transmitted between synapses

A

● When the impulse reaches the end of the first neuron -
neurotransmitter is released into the synapse

● This neurotransmitter diffuses across the synapse

● When the neurotransmitter reaches the second neuron, it triggers the impulse to begin again in the next neuron

100
Q

Why are there different speeds & frequencies of impulses?

A

Different neurotransmitters have different effects on the frequency and speed of the impulse in the second neuron

101
Q

Why are synapses useful?

A
  • As neurotransmitters are released from axon terminals so impulses only flow in one direction
  • Allow fresh impulses to be generated - original impulse will not lose ‘strength’
102
Q

What is myelin sheath?

A

A fatty substance which surrounds and insulates neuron axons

103
Q

What is a benefit of myelin sheath?

A

Nerve transmission will travel faster

104
Q

What is Myelin sheath produced by?

A

Schwann cells

105
Q

How does the nervous system coordinate actions in response to stimuli?

A
  1. Receptor cells convert a stimulus into an electrical impulse
  2. This electrical impulse travels along sensory neurons to the CNS
  3. The information is processed & the appropriate response is coordinated, resulting in an electrical impulse being sent along motor neurones to effectors
  4. The effectors carry out the response

Biology (11 decks)

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