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Biology > 14. RESPONSE TO STIMULI > Flashcards

14. RESPONSE TO STIMULI Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define stimulus.

A

A change in the environment.

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2
Q

How are stimuli detected?

A

By receptors in sensory organs.

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3
Q

State the pathway of a response from a stimuli.

A

stimulus → receptor → coordinator → effector → response

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4
Q

Define a taxis.

A

A directional motile response

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5
Q

State what positive taxis is.

A

Movement of the organism towards a (favourable) stimulus.

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6
Q

State what negative taxis is.

A

Movement of the organism away from an (unfavourable) stimulus.

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7
Q

What stimuli are phototaxis in response to?

A

Light

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8
Q

What stimuli are chemotaxis in response to?

A

Chemicals

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9
Q

Define kinesis

A

A non-directional motile response

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10
Q

How does an organism’s movement change in response to a stimuli in kinesis?

A

The organism changes the speed at which it moves, and the rate at which is changes direction (turns)

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11
Q

Describe how an organism changes its speed and the rate at which it turns in kinesis when it experiences a favourable stimuli

A

It slows down and decreases the rate at which it turns

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12
Q

Describe how an organism changes its speed and the rate at which it turns in kinesis when it experiences an unfavourable stimuli

A

It speeds up and increases the rate at which it turns

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13
Q

What is a tropism?

A

A tropism is a directional plant growth response to a stimuli

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14
Q

Which stimuli is phototropism in response to?

A

Light

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15
Q

Which stimuli is gravitropism in response to?

A

Gravity

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16
Q

Which stimuli is hydrotropism in response to?

A

Water

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17
Q

Give an example of a plant growth factor.

A

Indoleactic acid (IAA).

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18
Q

What group of plant hormones does IAA belong to?

A

Auxins

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19
Q

Where is IAA produced?

A

Tips of shoots and roots (meristems)

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20
Q

How does IAA travel down the meristem?

A

Diffusion

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21
Q

Where will there be a higher concentration of IAA in shoots?

A

On the shaded side

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22
Q

Describe the effect of IAA on cells in shoots

A

Stimulates cell elongation

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23
Q

Describe the effect of IAA on the direction of growth of shoots

A

Causes shoots to grow towards the light (positive phototropism)

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24
Q

Where will there be a higher concentration of IAA in roots?

A

At the bottom / the side towards gravity

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25
Q

Describe the effect of IAA on the cells in roots

A

Inhibits cell elongation

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26
Q

Describe the effect of IAA on the direction of growth of roots

A

Causes shoots to grow towards the gravity (positive gravitropism)

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27
Q

Name the two structural divisions of the nervous system.

A

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

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28
Q

Which two types of neurones exist within the peripheral nervous system?

A

Sensory neurones and motor neurones.

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29
Q

State the function of the sensory neurones.

A

Carries nerve impulses from receptors towards the CNS.

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30
Q

State the function of the motor neurones.

A

Carries nerve impulses away from the CNS to effectors.

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31
Q

Which two functional systems exist within the motor nervous system?

A

The voluntary and the autonomic nervous system.

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32
Q

What is the voluntary nervous system?

A

Carries nerve impulses to body muscles under voluntary (conscious) control.

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33
Q

What is the autonomic nervous system?

A

Carries nerve impulses to glands, smooth muscle and cardiac muscle under involuntary (subconcious) control.

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34
Q

Name the two divisions of the autonomic nervous system.

A

Sympathetic and parasympathetic nervous system.

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35
Q

The sympathetic nervous system is associated with which types of responses?

A

Fight or flight, preparing for action and energy release

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36
Q

The parasympathetic nervous system is associated with which types of responses?

A

Rest and recouperation, calm and self maintenance functions

37
Q

Why are the sympathetic and parasympathetic nervous system antagonistic?

A

The responses they produce oppose one another and occur exclusively.

38
Q

Name the two control centres in the nervous system

A

Brain and spinal cord

39
Q

Name the three types of neurones within a reflex arc

A

Sensory neurone, relay neurone and motor neurone.

40
Q

Why is it important that reflexes are innate, rapid and involuntary?

A

To minimise damage from dangerous stimuli.

41
Q

As well as minimising harm from dangerous stimuli, describe two other functions of reflexes

A

Maintain posture and coordinating homeostasis

42
Q

State the sequence of the main stages of a spinal reflex arc.

A

Stimulus → receptor → sensory neurone → intermediate neurone → motor neurone → effector → response

43
Q

How many neurones are there in a simple reflex?

A

3

44
Q

Receptors are examples of transducers. Define what a transducer is.

A

Converts energy from one form to another.

45
Q

Give an example of a receptor found in the skin.

A

Pacinian corpuscle

46
Q

State the function of the Pacinian corpuscle.

A

Detects changes in mechanical pressure.

47
Q

Why would a generator potential not always cause an action potential?

A

The generator potential has to reach threshold for an action potential to be initiated.

48
Q

Where are Pacinian corpuscle most abundant?

A

On the fingers, soles of the feet and external genitalia.

49
Q

Pacinian corpuscle contains a specific type of sodium ion channel in its CSM. What are they called?

A

Stretch-mediated sodium ion channel

50
Q

Why are these sodium ion channels referred to as ‘stretch-mediated’?

A

Their permeability to sodium changes when they are deformed.

51
Q

What happens to the lamellae in the pacinian corpuscle when pressure is applied?

A

It deforms

52
Q

What happens to the stretch mediated sodium ion channels in the pacinian corpuscle membrane when pressure is applied?

A

They widen, open, and sodium ions diffuse into the neurone.

53
Q

The ending of the sensory neurone at the centre of the Pacinian corpuscle becomes depolarised. What does this mean?

A

The influx of sodium ions changes the potential difference across the membrane, producing a generator potential.

54
Q

If the generator potential in the pacinican corpuscle reaches threshold, what will happen?

A

An action potential will be propogated down the sensory neurone

55
Q

Where are photoreceptors found in the eyes?

A

The retina

56
Q

Name the two main types of photoreceptors

A

Rod cells and cone cells.

57
Q

What does the break down of the photosensitive pigments inside photoreceptors cause?

A

A depolarisation called a generator potential

58
Q

When will the generator potential produced from a photoreceptor initiate an action potential?

A

When the generator potential reaches threshold

59
Q

Name the photosensitive pigment inside rod cells

A

Rhodopsin

60
Q

Why is Rhodopsin sensitive to light?

A

Because it’s broken down in low light intensities

61
Q

When are rod cells mostly utilised to produce images

A

In low light intensities / at night

62
Q

Is the image produced from rod cells colour or black and white?

A

Black and white

63
Q

Name the photosensitive pigment inside cone cells

A

Iodopsin

64
Q

Name the three different types of cone cells

A

Blue light cones, green light cones and red light cones

65
Q

Why can we see more than three colors, even though there are only three types of cone cell?

A

Because the wavelengths absorbed by the cones overlap

66
Q

When are cone cells mostly utilised to produce images

A

In high light intensities / in the day

67
Q

Define visual acuity

A

Visual acuity is the clearness and sharpness of your vision

68
Q

Which type of photorecetor produce a high visual acuity but a low visual sensitivity?

A

Cone cells

69
Q

Why do cone cells produce a high visual acuity but a low visual sensitivity

A

Each cone cell synapses with a separate neurone so there is no retinal convergence, and no summation of impulses

70
Q

Which type of photorecetor produce a low visual acuity but a high visual sensitivity?

A

Rod cells

71
Q

Why do rod cells produce a low visual acuity but a high visual sensitivity

A

Multiple rod cells synapse with one neurone so there is retinal convergence, and spatial summation of impulses to overcome the threshold potential.

72
Q

Where in your field of vision is your visual acuity the highest?

A

In the centre (the fovea)

73
Q

Why is your visual acuity the highest in the centre?

A

Because cone cells are concentrated in the fovea

74
Q

Where are rods found in your retina?

A

Around the edges of the fovea

75
Q

What is the blind spot?

A

Where the optic nerve connects to your retina, so there are no photoreceptors here

76
Q

Which part of the brain controls heart rate?

A

Medulla

77
Q

How would the medulla increase the heart rate?

A

It would increase the impulses sent through the parasympathetic nerves

78
Q

How would increased impulses sent through the parasympathetic nerves decrease heart rate?

A

It would decrease impulses sent from the SAN

79
Q

How would the medulla decrease the heart rate?

A

It would increase the impulses sent through the sympathetic nerves

80
Q

How would increased impulses sent through the sympathetic nerves decrease heart rate?

A

It would increase impulses sent from the SAN

81
Q

Name the two stimuli that can cause a change in heart rate

A

Changing blood pressure and changing carbon dioxide concentration

82
Q

Name the receptors that detect a change in blood pressure

A

Baroreceptors

83
Q

Name the receptors that detect a change in carbon dioxide concentration

A

Chemoreceptors

84
Q

Where in the body are baroreceptors and chemoreceptors found?

A

Aorta

85
Q

When baroreceptors and chemoreceptors detect a change, what do they send impulses to?

A

The medulla

86
Q

If the blood pressure increased, how would the heart rate change as a response to this?

A

It would decrease (to decrease the blood pressure)

87
Q

If the blood pressure decreased, how would the heart rate change as a response to this?

A

It would increase (to increase the blood pressure)

88
Q

If the carbon dioxide concentration of the blood increased, how would the heart rate change as a response to this?

A

It would increase (to increase carbon dioxide excreted)

89
Q

If the carbon dioxide concentration of the blood decreased, how would the heart rate change as a response to this?

A

It would decrease

Biology (26 decks)

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