Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology A-level > 6A Stimuli and Responses > Flashcards

6A Stimuli and Responses Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

How do animals responding to their environment help them?

A

They increase their chances of survival

They also respond to changes in their internal environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do receptors do?

A

They detect stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do effectors do?

A

They produce a response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give some examples of receptors in humans

A

They can be cells or proteins on cell surface membranes

Loads of different types of receptors detect different stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What can effectors be?

A

They can be muscle cells & cells found in glands

e.g. the pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does the nervous system send info?

A

As electrical impulses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the nervous system made up of?

A

It is a complex network of cells called neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 3 main types of neurones?

A
  • Sensory neurones
  • Motor neurones
  • Relay neurones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do sensory neurones do?

A

They transmit electrical impulses from receptors to CNS - the brain & spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do motor neurones do?

A

They transmit electrical impulses from the CNS to effectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do relay neurones do?

A

They transmit electrical impulses between sensory neurones & motor neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What can electrical impulses also be called?

A
  • Nerve impulses

- Action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What sorts of stimuli do plants respond to?

A

They respond to changes in their environment:

  • Light
  • Gravity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why do plants grow towards light?

A

To maximise light absorption for photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why do plants grow according to gravity?

A

They can sense gravity, their roots & shoots then grown in the right direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do climbing plants respond to stimuli?

A

They have a sense of touch, so they can find things to climb up & reach the sunlight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a tropism?

A

A plant’s growth response to an external (directional) stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do plants respond to stimuli in general?

A

By regulating their growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a positive tropism?

A

Growth of the plant towards the stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a negative tropism?

A

Growth of the plant away from the stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is phototropism?

A

The growth of a plant in response to light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How do shoots respond in phototropism?

A

Shoots are positively phototropic & grow towards light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do roots respond to phototropism?

A

They are negatively phototropic & grow away from light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is gravitropism?

A

The growth of a plant in response to gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How do shoots respond to gravitropism?

A

Shoots are negatively gravitropic & grow upwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How do roots respond to gravitropism?

A

Roots are positively gravitropic & grow downwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How do plant responses occur?

A

They are brought around by growth factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are growth factors?

A

They are hormone-like chemicals that speed up or slow down plant growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Where are growth factors produced?

A

They are produced in the growing regions of the plant (e.g. shoot tips, leaves) & they move to where they’re needed in the other parts of the plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Give an example of a growth factor in plants

A

Auxins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What do auxins do?

A

They stimulate the growth of shoots by cell elongation

This is where cell walls become loose & stretchy, so the cells get longer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How do high concentrations of auxins affect the roots?

A

These auxins inhibit growth in roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is IAA?

A

Indoleacetic Acid - it is an important auxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Where is IAA produced?

A

In the tips & shoots in flowering plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Why and how is IAA moved around a plant?

A

It is moved around the plant to control tropisms

It moves by diffusion & active transport over short distances, via the phloem over long distances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What happens if the concentrations of IAA are uneven in the plant?

A

Growth is uneven

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

How does an uneven distribution of IAA occur?

A

The movement of it through the plant means there are varying concentrations around the plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

In phototropism, how does IAA move?

A

IAA moves to the more shaded parts of the shoots and roots , so theres uneven growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

In gravitropism, how does IAA move?

A

IAA moves to the underside of shoots & roots, so there’s uneven growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How does IAA act in shoots for photoropism?

A

IAA concentration increases on the shaded side - cells elongate & the shoot bends towards the light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

How does IAA act in roots for phototropism?

A

IAA conc. increases on the shaded side - growth is inhibited so the root bends away from the light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How does IAA act in the shoots for gravitropism?

A

IAA conc. increases on the lower side - cells elongate so the shoot grows upwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How does IAA act in the roots for gravitropism?

A

IAA increases on lower side, growth is inhibited so the root grows downwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How do simple organisms respond?

A

They use simple responses to keep simple organismsin a favourable environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Give two examples of simple mobile organisms?

A

Woodlice and earthworms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What are the two types of simple responses?

A
  • Tactic (taxes)

- Kinetic (kineses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What are tactic responses?

A

The organism moves towards or away from a directional stimulus

e.g. light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What are kinetic responses?

A

The organisms’ movement is affected by a non-directional stimulus

e.g. humidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Give an example of a tactic response

A

Woodlice - they show a tactic response to light (phototaxis)

They move away from a light source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is phototaxies?

A

A tactic response to light

51
Q

How does a phototactic response help woodlice?

A

Concealed under stones during the day = safe from predators

Damp conditions = reduces water loss

52
Q

What muscles control the regular beating of the heart?

A

The cardiac muscles

53
Q

The cardiac muscle is ‘myogenic’ - what does this mean?

A

It can contract and relax without receiving signals from nerves

This patter of contractions controls the regular heartbeat

54
Q

What are the key areas of the heart in the control of heart rate?

A
  • Sionoatrial node
  • Atrioventricular node
  • Bundle of His
  • Purkyne tissue
  • L&R atrium
  • L&R ventricle
55
Q

What are the stages in producing a heart beat?

A

1 - Starts w sinoatrial (SAN) node
2 - SAN is like a pacemaker - sends out waves of elec. activity to the atria walls
3 - Causes R&L atria (A) to contract at same time
4 - Band of non-conducting collagen tissue prevents waves of elec. activity from passing from A to ventricles (V)
5 - Instead waves of elec. activity passed form SAN to AVN
6 - AVN passes waves of elec. activity to bundle of His - slight delay before AVN reacts
7 - Bundle of His splits into finer muscle fibres in R&L ventricle walls called purkyne fibres
8 - Purkyne fibres carry elec. activity into muscular walls of heart, causing them to contract simultaneously from the bottom up

56
Q

How does the SAN set the rhythms for the heartbeat?

A

Sets the rhythms by sending out regular waves of electrical activity to the atrial walls

57
Q

Why is there a slight delay before the AVN reacts when controlling heart beat?

A

Slight delay so to make sure atria have emptied before ventricles contract

58
Q

What is the bundle of His?

A

A group of muscle fibres responsible for conducting the waves of elec. activity between the ventricles & apex of heart

59
Q

What is the apex of the heart?

A

The bottom of the heart

60
Q

What does the control of heart rate involve?

A

The brain & autonomic nervous system

61
Q

Why are receptors specific?

A

The only detect one stimulus

62
Q

Where are the 2 types of receptors?

A
  • Proteins on cell surface

- Some receptors are cells

63
Q

What is a nervous system receptor like in its resting state?

A
  • Difference in charge between inside and outside of cell

- This creates a potential difference across the membrane

64
Q

What happens when the nervous system receptor detects a stimulus?

A
  • Cell membrane becomes more permeable so more ions move in and out
  • This alters the potential difference (this is called the generator potential)
65
Q

What happens when there is a bigger stimulus nervous system receptor?

A
  • Excites the membrane more

- Bigger generator potential produced

66
Q

What happens when the generator potential reaches a threshold?

A

Action potential occurs

67
Q

How is the strength of the stimulus measured?

A

Frequency of action potentials

68
Q

What are pacinian corpuscles?

A

Mechanoreceptors - detect pressure and vibrations

69
Q

Where are pacinian corpuscles found?

A

In your skin

70
Q

What do pacinian corpuscles contain?

A

Sensory nerve endings which are wrapped in lamellae

71
Q

What happens when pacinian corpuscles is stimulated?

A

1) Lamellae are deformed and press on sensory nerve ending
2) The sensory nerve endings stretch which deforms the stretch mediated sodium ion channels
3) This creates a generator potential where if threshold is met makes a action potential

72
Q

What are photoreceptors?

A

Light receptors in your eye

73
Q

Where does light enter the eye?

A

Pupil

74
Q

What does iris in the eye do?

A

Its muscles control the amount of light that enters the pupil

75
Q

What does the retina do?

A
  • Its where light rays are focused

- Contains photoreceptors that detect light

76
Q

What is the fovea?

A

Area of the retina where there are lots of photoreceptors

77
Q

Where are nerve impulses from the photoreceptor cells carried to?

A

They are carried from the retina to the brain by optic nerve (bundle of neurons)

78
Q

What is the blind spot?

A
  • Part where the optic nerve leaves the eye

- Has no photoreceptors so is not sensitive to light

79
Q

What do photoreceptors do?

A

Convert light into an electrical impulse

80
Q

How do photoreceptors create an electrical impulse?

A

1) Light hits photoreceptors and is absorbed by light sensitive optical pigments
2) Light bleaches the pigments, causing a chemical change
3) This alters membrane permeability to sodium ions
4) Generator potential created and if threshold met nerve impulse sent along bipolar neuron

81
Q

What do bipolar neurons do?

A

Connect photoreceptors to optic nerve

82
Q

What are the 2 types of photoreceptors?

A

Rods and cones

83
Q

Where are rods found?

A

Peripheral parts of the retina

84
Q

Where are cones found?

A

Found packed together in the fovea

85
Q

What are the parts of the eye?

A
  • Pupil
  • Iris
  • Retina
  • Fovea
  • Blind spot
  • Optic nerve
86
Q

Why are rods and cones sensitive to different wavelengths of light?

A

Have different optical pigments

87
Q

What do rods give information for?

A

Black and white

88
Q

What are the 3 types cones?

A
  • Red sensitive
  • Green sensitive
  • Blue sensitive
89
Q

What are rods sensitivity like?

A
  • Very sensitive to light (work best in dim light)

- Many rods join one neuron so weak generator potentials can reach the threshold

90
Q

What are cones sensitivity like?

A
  • Less sensitive than rods (work best in bright light)

- One cone joins one neuron

91
Q

What is the visual acuity like in rods?

A
  • Low visual acuity

- Many rods join same neuron (light from 2 points cant be told apart)

92
Q

What is visual acuity?

A

Ability to tell apart points that are close together

93
Q

What is the visual acuity like in cones?

A
  • High visual acuity

- One cone joins one neuron so can tell cones apart as they have different action potentials

94
Q

What can be used to investigate animal responses?

A

A choice chamber experiment

95
Q

What is a choice chamber?

A

A container with different compartment, in which you can create different environmental conditions

Can be used to investigate how animals (such as woodlice) respond to conditions like light intensity/humidity in the lab

96
Q

What are the two different systems that the nervous system is split into?

A
  • The central nervous system (CNS)

- The peripheral nervous system

97
Q

What is the CNS made up of?

A

It’s made up of the brain & spinal cord

98
Q

What is the peripheral nervous system?

A

It is made up of the neurons that connect the CNS to the rest of the body - it is made up of two different systems

99
Q

What are the two systems that make up the peripheral nervous system?

A
  • The somatic nervous system

- The autonomic nervous system

100
Q

What does the somatic nervous system do?

A

It controls concious activities

e.g. running & playing video games

101
Q

What does the autonomic nervous system do?

A

It controls unconcious activities (remember as it sounds like ‘automatic’)

e.g. digestion

This also has two divisions

102
Q

What are the two divisions of the autonomic nervous system?

A
  • The sypathetic nervous system

- The parasympathetic nervous system

103
Q

What does the sympathetic nervous system do?

A

It gets the body ready for action - it’s the ‘fight or flight’ system

Remember it like a sympathetic friend who reacts to your actions

104
Q

What does the parasympathetic nervous system do?

A

It calms the body down - the ‘rest and digest’ system

105
Q

What is a reflex arc?

A

Where the body responds to a stimus without making a concious decision to respond

106
Q

What makes a reflex arc so fast?

A

You don’t have to spend time deciding how to respond, info travells from receptors to effectors

Simple reflxes help organisms protect the body because they’re rapid

107
Q

What would be the process of the hand-withdrawl in response to heat?

A
  • Thermoreceptors in the skin detect the heat stimulus
  • The sensory neuron carries impulses to the relay neuron
  • The relay neuron connects to the motor neuron
  • The motor neuron sends impulses to the effector (your biceps muscle)
  • Your muscle contracts to withdraw your hand & stop it being damaged
108
Q

What is nervous system communication like?

A
  • Localised
  • Short-lived
  • Rapid
109
Q

What makes nervous system communications localised?

A

When an elcetrical impulse reaches the end of a neurone, neurotransmitters are secretly directed onto target cells

This makes the nervous response loaclised

110
Q

What makes nervous system communications short-lived?

A

Neurotansmitters are quickly removed once they’ve doen their job, so the response is short-lived

111
Q

What makes nervous system communications rapid?

A

Electrical impulses are really fast, so the response is rapid

This allows animals to react quickly to stimuli

112
Q

What do baroreceptors detect?

A

They detect changes in blood pressure

113
Q

What do chemoreceptors detect?

A

They detect chemical changes in the blood

114
Q

What are the receptors called that cause HR to speed up/slow down?

A
  • Baroreceptors

- Chemoreceptors

115
Q

Explain the process or receptors respondign to high blood pressure

A
  • BARORECEPTORS detect HIGH blood pressure
  • Impulses sent to medulla, send impulses along the PARASYMPATHETIC neurones - these secrete ACETYLCHOLINE, which binds to receptors on SAN
  • Effector: cardiac muscles
  • The heart rate SLOWS DOWN to reduce blood pressure back to normal
116
Q

Explain the process or receptors respondign to low blood pressure

A
  • BARORECEPTORS detect LOW blood pressure
  • Impulses sent to medulla, send impulses along the SYMPATHETIC neurones - these secrete NORADRENALINE, which binds to receptors on SAN
  • Effector: cardiac muscles
  • The heart rate SPEEDS UP to reduce blood pressure back to normal
117
Q

Explain the process or receptors respondign to high blood O2, low CO2 or high pH levels

A
  • CHEMORECEPTORS detect chemical changes in blood
  • Impulses are sent to medulla, send impulses along PARASYMPATHETIC neurones - these secrete ACETYLCHOLINE, which binds to receptors on SAN
  • Effector: cardicac muscles
  • HR DECREASES to return O2, CO2 & pH levels to normal
118
Q

Explain the process or receptors respondign to low blood O2, high CO2 or low pH levels

A
  • CHEMORECEPTORS detect chemical changes in blood
  • Impulses are sent to medulla, send impulses along SYMPATHETIC neurones - these secrete NORADRENALINE, which binds to receptors on SAN
  • Effector: cardicac muscles
  • HR INCREASES to return O2, CO2 & pH levels to normal
119
Q

What is the SAN controlled by?

A

The medulla oblongata

120
Q

How does the SAN cause the cardiac muscles to contract?

A

It generates electrical impulses - this is controlled by the medulla oblongata

121
Q

Why do animals alter their HR?

A

To respond to their internal stimuli

e.g. to prevent fainting due to low blood pressure/to make sure the heart rate is high enough to supply the body with enough oxygen

122
Q

What are the (blood) pressure receptors for HR called?

A

They’re called baroreceptors

They’re located in the aorta & cartiod arteries - stimulated by high & low blood pressure

123
Q

What are the chemical receptors for HR called?

A

They’re called chemoreceptors

They’re loacated in the aorta, cartiod arteries & medulla - they monitor O2 levels in the blood & also CO2 and pH levels

Biology A-level (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions