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biology > 14 response to stimuli > Flashcards

14 response to stimuli Flashcards

1
Q

what is a stimulus?

A

a detectable change in environment, either external or internal

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2
Q

what is an effector?

A

responds to stimulation by the nerve cells

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3
Q

give an example of an effector

A

muscle
gland
organ
cell

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4
Q

why do organisms respond to changes in their environment?

A

to increase survival and reproduction by:
1. DISPERSING TO FIND NEW MATES
2. avoiding harmful environments
3. stay in favourable environment

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5
Q

is instinctive behaviour learned or inherited?

A

inherited

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6
Q

what are the types of simple responses to stimuli?

A

kinesis
taxes
reflex action

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7
Q

what is kinesis?

A

random movement responding to a change in stimulus by increasing or decreasing activity
change in rate of movement

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8
Q

give an example of kinesis

A

woodlice move around more when humidity is dry and the rate of movement is related to the intensity of the stimulus

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9
Q

what experiment would you use to investigate kinesis?

A

choice chamber

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10
Q

what statistical test would be used for a choice chamber?

A

chi squared

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11
Q

how do you calculate degree of freedom and what is the dof for a basic choice chamber?

A

n-1 so 3 for choice chamber

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12
Q

what is taxes?

A

directional movement towards or away from a stimulus

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13
Q

what are the types of taxes?

A

positive and negative

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14
Q

what is positive taxes?

A

movement towards the stimulus

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15
Q

what is negative taxes?

A

movement away from the stimulus

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16
Q

give an example of negative taxes

A

earthworms move away from light to find food and avoid predators

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17
Q

what are the types of tropism?

A

positive and negative

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18
Q

what is positive tropism?

A

growth towards a stimulus

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19
Q

what is negative tropism?

A

growth away from a stimulus

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20
Q

what does the prefix ‘halo’ mean?

A

salt

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21
Q

what does the prefix ‘geo’ mean?

A

gravity

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22
Q

what does the prefix ‘photo’ mean?

A

light

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23
Q

what does the prefix ‘hydro’ mean?

A

water

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24
Q

give an example of positive phototropism

A

plant shoots grow towards light

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25
Q

give an example of negative phototropism

A

plant root grow away from llight

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26
Q

what is a similarity between tropism and taxes?

A

both are directional

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27
Q

what is a difference between tropism and taxes?

A

tropism is part of the organism whereas taxes is al of the organism

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28
Q

what do plant growth factor do?

A

regulate growth in response to stimuli

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29
Q

give 2 examples of plant growth factors

A

gibrellins and indole acetic acid

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30
Q

what do gibrellins do?

A

promotes seed germination

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31
Q

where does mitosis occur in plants?

A

tip of shoots
tip of roots

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32
Q

what does IAA stand for?

A

indole acetic acid

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33
Q

what does IAA do in the shoots of plants?

A

promotes cell elongation

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34
Q

what des IAA do in the roots?

A

inhibits cell elongation

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35
Q

explain what happens with IAA in the shoots of plants and light

A
  1. IAA synthesised in shoot tips
  2. IAA diffuses into elongation region
  3. light causes IAA to move to shady side
  4. high conc of IAA on shady side
  5. causes greater cell elongation on shady side and for shoot to grow faster and bend towards light
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36
Q

explain what happens with IAA in the roots of plants and light

A
  1. IAA synthesised in root tips
  2. IAA diffused into elongation region
  3. light causes IAA to move to shady side
  4. high conc of IAA on shady side
  5. cell elongation inhibited on shady side so roots grow away from light and towards gravity
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37
Q

where is IAA synthesised?

A

in the root tips and shoot tips

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38
Q

what is tropism?

A

a growth movement of part of a plant in response to a DIRECTIONAL STIMULUS

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39
Q

what is a reflex arc?

A

an example of behaviour that a certain stimulus produces a specific short lived response

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40
Q

are reflex arcs learnt?

A

no

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41
Q

explain the advantages of simple reflex arcs

A
  1. rapid
  2. protect against damage to body tissue
  3. don’t have to be learnt
  4. help escape from predators
  5. enable homeostatic control
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42
Q

what is a receptor called that is found deep in the skin?

A

pacinian corpuscle

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43
Q

what is the pacinian corpuscle an example of?

A

pressure receptor/mechanoreceptor

44
Q

what is a pressure receptor?

A

a receptor that responds to mechanical stimuli

45
Q

what are 5 places the pacinian corpuscle is found?

A
  1. fingers
  2. soles of feet
  3. external genitalia
  4. joints
  5. ligaments
46
Q

describe the structure of a pacinian corpuscle

A

unmyelinated axon layered with lamellae with a myelinated axon coming from it

47
Q

what is the lamellae in the pacinian corpuscle filled with?

A

viscus gel/jelly

48
Q

what is the lamellae that surrounds the axon of a pacinian corpuscle sometimes referred to as?

A

capsule

49
Q

what are pacinian corpuscles only specific to?

A

pressure

50
Q

what do pacinian corpuscles generate rather than an action potential?

A

generator potential

51
Q

how do pacinian corpuscles activate a generator potential?

A
  • pressure on skin causes deformation to lamellae
  • which deforms and opens the stretch mediated sodium ion channel proteins
  • sodium ions diffuse in
  • depolarisation leads to generator potential
52
Q

what do you call the sodium ion channel proteins that are embedded in the pacinian corpuscles?

A

stretch mediated

53
Q

what happens if the generator potential reaches threshold?

A

an action potential is created causing a nerve impulse

54
Q

what happens when the pressure increases on the skin in relation to pacinian corpuscles?

A

more stretch mediated sodium ion channel proteins open and more sodium ions enter
larger generator potential
generator potential reaches threshold causing depolarisation

55
Q

what type of organ is the eye?

A

sense organ

56
Q

how many types of receptor cells does the eye have?

A

two

57
Q

what do the receptor cells in the eye respond to?

A

light intensity and wavelength

58
Q

what are the locations for the receptor cells in the eye?

A

macula
fovea

59
Q

where are the macula and the fovea in the eye located?

A

retina

60
Q

what type of receptor are the receptors in the eye?

A

photo-receptor

61
Q

what are the two types of photo-receptors called?

A

rods and cones

62
Q

where are the rods and cones located in the eye?

A

rods- macula
cones- fovea

63
Q

how are the rods and cones distributed in the eyes?

A

rods- evenly distributed in the macula
cones- densley packed in the fovea

64
Q

explain the sensitivity of rods and cones

A

rods- sensitive to all wavelengths of of light
cones- each type of cone sensitive to a specific wavelength

65
Q

what is rhodopsin and iodopsin?

A

pigments
rhodopsin: light sensitive
iodopsin: sensitive to three types

66
Q

what does low visual acuity mean?

A

image being unclear

67
Q

what does high visual acuity mean?

A

having a sharp and clear image

68
Q

what causes low visual acuity?

A

retinal convergence due to several rods sharing a single bipolar neuron

69
Q

what causes high visual acuity?

A

each cone is connected to a single bipolar neuron

70
Q

what are the pigments called in rods and cones?

A

rods- rhodopsin
cones- iodopsin

71
Q

how do light sensitive pigments produce a generator potential?

A

photons break the pigments down which alter the chemical structure

72
Q

explain the relationship between bipolar neurons and rod cells

A

multiple rod cells synapse with one bipolar neuron

73
Q

explain the relationship between bipolar neurons and cone cells

A

each cone cell synapses with a single bipolar neuron

74
Q

what type of summation do rods and cones have?

A

rods- spatial summation
cones- temporal summation

75
Q

why do rods have spatial summation?

A

because of retinal convergence

76
Q

how does spatial summation lead to activating an impulse?

A

generator potentials combine to reach threshold

77
Q

why do cones have temporal summation?

A

because each cone cell must release enough neurotransmitter to reach threshold

78
Q

when are cone cells most likely to reach threshold?

A

in bright light

79
Q

what does myogenic mean?

A

it can initiate it’s own contraction

80
Q

the heart can initiate its own contraction, what do you call this?

A

myogenic

81
Q

what nodes are there in the heart?

A

sinoatrial node
atrio-ventricular node

82
Q

what is responsible for the initial stimulus of the heart

A

sino atrial node

83
Q

describe how the heart controls the regular contractions in the atria and ventricles

A
  1. sinoatrial node sends electrical activity over both atria
  2. atria contract
  3. layer of non conductive tissue prevents wave reaching ventricles causing 0.1 second delay
  4. atrio-ventricular node sends a wave of electrical activity down the bundle of His and up the purkinje fibres
  5. ventricles contract from apex upwards
84
Q

why can heart rate be altered?

A

in response to the changing demands of respiring tissues for oxygen

85
Q

in what situation may respiring tissues demand more oxygen?

A

exercise
fight or flight response

86
Q

what controls heart rate?

A

autonomic nervous system

87
Q

what 2 branches does the autonomic nervous system have?

A

sympathetic
parasympathetic

88
Q

what does the sympathetic branch and the parasympathetic branch do to effectors?

A

sympathetic: stimulates effectors
parasympathetic: inhibits effectors

89
Q

what is the neurotransmitter involved in the sympathetic branch?

A

noradrenaline

90
Q

what is the neurotransmitter involved in the parasympathetic branch?

A

acetylcholine

91
Q

what is the word you would use to compare the sympathetic and the parasympathetic branch?

A

antagonistic

92
Q

what in the brain controls heart rate?

A

medulla oblongata

93
Q

what part of the medulla is important in heart rate?

A

cardio regulatory centre

94
Q

what are the 2 parts of the cardio regulatory center?

A

acceleratory centre
inhibitory centre

95
Q

which branch is the acceleratory centre associated with?

A

sympathetic

96
Q

which branch is the inhibitory centre associated with?

A

parasympathetic

97
Q

where do the para/sympathetic nerves take the inhibitory and acceleratory to?

A

sinoatrial node

98
Q

what are the 2 receptors important in the control of heart rate?

A

baro receptors
chemo receptors

99
Q

where are the baro receptors and chemoreceptors located?

A

in the aorta and carotid arteries

100
Q

what do baro receptors respond to?

A

blood pressure

101
Q

what do chemo receptors respond to?

A

pH levels

102
Q

describe the process with receptors if blood pressure increases above normal

A
  1. baro receptors detect this in the aorta and the carotid arteries
  2. more frequent impulses sent to medulla oblongata
  3. more frequent impulses sent to SA node from the inhibitory centre through the parasympathetic nerve
  4. decreases frequency of impulses from SA node across atria
  5. heart rate decreases
103
Q

describe the process with receptors if blood pressure decreases below normal

A
  1. baro receptors detect this in the aorta and carotid arteries
  2. more frequent impulses sent to the medulla oblongata
  3. more frequent impulses sent to to SA node from acceleratory centre through sympathetic nerve
  4. increases frequency of impulses from SA node across atria
  5. heart rate increases
104
Q

what affects the pH of blood?

A

changes in CO2 levels

105
Q

how do CO2 levels affect pH levels in the blood?

A

forms a weak acid in solution and decreases blood pH
(more acidic)

106
Q

describe the process with receptors if CO2 levels rise and pH decreases below normal

A
  1. detected by chemo receptors in the aorta and carotid arteries
  2. more frequent impulses sent to medulla oblongata
  3. more frequent impulses sent to SA node from acceleratory centre through sy
    mpathetic nerve
  4. more frequent impulses from SA node across atria
  5. heart rate increases

biology (23 decks)

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