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A2 AQA Biology - Burnley College (2024-25) > Organisms Respond to their Environment (3.6) > Flashcards

Organisms Respond to their Environment (3.6) Flashcards

1
Q

Survival & Response (AO1)

Organisms [1] their chance of survival by responding to [2] in their environment.

A

[1] increase

[2] changes

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2
Q

Survival & Response (AO1)

List two simple responses by small organisms such as insects

A

Taxis

Kinesis

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3
Q

Survival & Response (AO1)

Function of taxis and kinesis for mobile organisms?

A

1. Keep organisms in a favourable environment.
(e.g. more food, more mates, less predators, less desiccation)

2. Increase chances of survival

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4
Q

Survival & Response (AO1)

Define taxis

A

Directional movement in response to a stimulus

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5
Q

Survival & Response (AO1)

Positive taxis

A

Directional response with movement towards the stimulus

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6
Q

Survival & Response (AO1)

Negative taxis

A

Directional response with movement away from the stimulus

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7
Q

Survival & Response (AO1)

Define kinesis

A

Random OR non-directional movements in response to the stimulus

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8
Q

Survival & Response (AO2)

A

Behaviour:
(Positive photo) taxis;

Advantage:
Avoid competition / to find a mate / increase dispersal / to avoid predators;

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9
Q

Survival & Response (AO2)

A

1. Kinesis;

2. Movement is random / non-directional

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10
Q

Survival & Response (AO2)

A

Taxis

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11
Q

Survival & Response (AO1)

Give one similarity and one difference between a taxis and a tropism.

A

Similarity − directional response to a stimulus / movement towards OR away from a stimulus;

Difference − in taxis whole organism moves whereas tropism a growth response in part of the plant (e.g. shoot or root tips).

OR

Difference - taxis occurs in animals whereas tropisms occurs in plants

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12
Q

Survival & Response (Maths)

A

11.1%

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13
Q

Survival & Response (AO2)

A

Taxis

B moves towards stimulus / light

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14
Q

Survival & Response (AO2)

A

kinesis;

random / non-directional movements;

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15
Q

Survival & Response (AO1)

In flowering plants, specific [1] factors move from growing regions to other tissues, where they regulate growth in response to directional [2].

A

[1] growth

[2] stimuli

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16
Q

Survival & Response (AO1)

Which organisms demonstrate tropisms?

A

Plants

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17
Q

Survival & Response (AO1)

Define tropism

A

Response of a plant to a directional stimulus

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18
Q

Survival & Response (AO1)

Stimuli that cause tropisms

A

Light
Gravity
Water
Salinity

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19
Q

Survival & Response (AO1)

Positive phototropism

A

Directional response of shoot tips towards light

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20
Q

Survival & Response (AO1)

Directional response of root tips away from light

A

negative phototropism

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21
Q

Survival & Response (AO1)

Positive gravitotropism

A

Directional response of root tips towards gravity

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22
Q

Survival & Response (AO1)

Auxis are a family of growth factors that cause tropisms. Which specific auxin must you know.

A

IAA

Full name: Indoleacetic acid

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23
Q

Survival & Response (AO1)

Where is IAA synthesised?

A

Shoot tips &
root tips

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24
Q

Survival & Response (AO1)

How does IAA move into the growing region of the shoot or root tip?

A

Diffusion

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25
Q

Survival & Response (AO1)

Where does IAA build up in the shoot tips in response to light?

A

On the shaded side

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26
Q

Survival & Response (AO1)

Effect of IAA in the shoot tips

A
  1. Stimulates elongagation of cells on the shaded side;
  2. Causes shoot to bend towards the light;
    (this is a positive phototropism)
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27
Q

Survival & Response (AO1)

Where does IAA build up in the root tips in response to gravity?

A

On the side closest to gravity / on the underside

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28
Q

Survival & Response (AO1)

Effect of IAA in the root tips

A
  1. Inhibits elongagation of cells on the underside;
  2. Cells on opposite side (away from gravitiy) can elongate and cause the root tip to bend towards gravity;
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29
Q

Survival & Response (AO2)

A

1. Tip produces/synthesises IAA;

2. IAA diffuses (into growing region of shoot);

3. Stimulates elongation of cells on one side (than other);

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30
Q

Survival & Response (AO2)

A

1. Tip produces IAA;

2. Affects concentration of IAA

OR Affects (shoot) length/growth/elongation;

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31
Q

Survival & Response (Maths)

A

0.4cm^3 stock IAA + 39.6cm^3 water

Step by step working:
C1 x V1 = C2 x V2
C1 = stock concentration
V1 = volume of stock
C2 = desired concentration
V2 = desired volume
1 x V1 = 0.01 x 40
V1 = 0.4cm^3 of IAA stock + 39.6cm^3 of water

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32
Q

Survival & Response (AO2)

A

1. Grow in direction of / towards (pull of) gravity;

Accept: tropism for growth

Accept: positively geotropic / gravitropic

2. Grow away from salt;

3. Salt has more effect than gravity;

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33
Q

Survival & Response (AO2)

A

1. Seedlings / root tips respond to light;

2. Only measuring the effect of gravity;

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34
Q

Survival & Response (AO2)

When a young shoot is illuminated from one side, IAA stimulates growth on the shaded side.

Explain why growth on the shaded side helps to maintain the leaves in a favourable environment (2 marks).

A

1. Causes plant to bend / grow towards light / positive phototropism;

2. Light energy required for photosynthesis;

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35
Q

Survival & Response (AO1)

TRUE or FALSE:

IAA is only produced in the light

A

FALSE

IAA is produced in the light AND dark

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36
Q

Survival & Response (AO1)

Draw out a simple reflex arc
(include the neurons and an effector)

A
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37
Q

Survival & Response (AO1)

Which neuron in the simple reflex arc contains receptors to the stimulus?

A

Sensory

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38
Q

Survival & Response (AO1)

Suggest two advantages of simple reflexes

A
  1. Rapid;
  2. Protect against damage to body tissues;
  3. Do not have to be learnt / innate behaviour / involuntary;
  4. Help escape from predators;
  5. Enable homeostatic control;
  6. Finding suitable conditions / keep organism in favourable environment;
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39
Q

Survival & Response (AO1)

Give two types of cell that act as effectors.

A

Muscles

Glands
(which produce hormones)

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40
Q

Survival & Response (AO1)

A

Only 3 neurones

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41
Q

Survival & Response (AO1)

What is found between the sensory neuron and relay neuron

42
Q

Nerve impulses (AO1)

Draw out and annotate a myelinated motor neuron

43
Q

Nerve impulses (AO1)

What is found on the cell surface membrane of the dendrites?

44
Q

Nerve impulses (AO1)

Organelles in the cell body of a neuron

A

Nucleus
Golgi apparatus / body
Ribosomes / Rough ER
Mitochondria

45
Q

Nerve impulses (AO1)

Specialised cell that produces the myelin sheath

A

Schwann cell

46
Q

Nerve impulses (AO1)

Biological molecule found in myelin sheath

A

phospholipids

Myelin also contains cholesterol, so similar to cell surface membrane.

47
Q

Nerve impulses (AO1)

Released by axon terminals

A

neurotransmitters

e.g. acetylcholine, dopamine, serotonin

48
Q

Nerve impulses (AO1)

Process at nodes of ranvier

A

saltatory conduction

49
Q

Nerve impulses (AO1)

Stages of an action potential

A
  • Resting potential,
  • (Threshold potential),
  • Depolarisation,
  • Repolarisation,
  • Hyperpolarisation,
  • Re-establish resting potential.
50
Q

Nerve impulses (AO1)

Resting potential in mV

A

-70mV

This means inside of axon is LESS positive than outside

51
Q

Nerve impulses (AO1)

Channel proteins found in axon cell surface membrane

A

Voltage-gated sodium ion channels

Voltage-gated potassium ion channels

52
Q

Nerve impulses (AO1)

Explain how a resting potential is maintained across the axon membrane in a neurone (3 marks).

A

1. Sodium ions actively transported OUT and potassium ions IN;

2. LESS permeable to sodium ions as voltage-gated channels closedOR membrane MORE permeable to potassium ions as some voltage-gated channels open;

3. Higher concentration of potassium ions inside AND higher concentration of sodium ions outside the axon

53
Q

Nerve impulses (AO1)

The sodium potassium ion pump establishes an ________________ gradient.

A

electrochemical gradient

i.e., higher sodium ion concentration outside the axon, lower inside.

54
Q

Nerve impulses (AO1)

Threshold potential in mV

55
Q

Nerve impulses (AO1)

Channel open at -55mV

A

Voltaged-gated sodium ion channels

56
Q

Nerve impulses (AO1)

The all-or-nothing principle

A

An action potential is only generated/produced when threshold stimulus is reached (-55mv)

OR

An action potential is not generated/produced until/unless threshold stimules is reached (-55mv);

If stimulus reached, voltage-gated sodium ion channels open

57
Q

Nerve impulses (AO1)

Sodium and potassium ions can only cross the axon membrane through channel proteins. Explain why (2 marks).

A

1. Cannot pass through phospholipid bilayer
(via simple diffusion)

2. because they are NOT lipid soluble

OR because they are charged;

58
Q

Nerve impulses (AO2)

A scientist investigated the effect of inhibitors on neurones. She added a respiratory inhibitor to a neurone. The resting potential of the neurone changed from –70 mV to 0 mV.

Explain why (3 marks).

A

1. No/less ATP produced;

2. No/less active transport
OR fewer sodium ions moved out.
OR Sodium/potassium pump inhibited;

3. Electrochemical gradient not maintained

OR same concentration of sodium and potassium ions either side of axon membrane

59
Q

Nerve impulses (AO1)

60
Q

Nerve impulses (AO1)

Sodium ions diffusing into the axon via open voltage-gated channels leads to___________________.

A

depolarisation

61
Q

Nerve impulses (AO1)

Why does the graph increase from -55mV to +40mV?

A

1. Voltage-gated sodium ion channels are open

2. Sodium ions diffuse into the axon via faciliated diffusion (DOWN an electrochemical gradient)

3. Inside of the axon MORE positive

62
Q

Nerve impulses (AO1)

What happens at +40mV?

A

Voltage-gated sodium ion channels CLOSE

AND

Voltage-gated potassium ion channels OPEN

63
Q

Nerve impulses (AO1)

Why does the graph decrease after +40mV during repolarisation?

A

1. Voltage-gated potassium ion channels are open (& voltage-gated sodium ion channels are closed).

2. Potassium ions rapidly diffuse OUT of the axon via faciliated diffusion (DOWN an electrochemical gradient)

3. Inside of the axon LESS positive

64
Q

Nerve impulses (AO1)

Hyperpolarisation in mV

65
Q

Nerve impulses (AO1)

What causes hyperpolarisation?

A

1. Voltage-gated potassium ion channels stay open;

2. Potassium ions diffuse out of axon;

3. Inside of axon becomes even LESS positive (decreasing from -70mV to -90mV).

66
Q

Nerve impulses (AO1)

Channels closed at -90mV

A

Voltage-gated potassium ion channels (close at -90mV)

Voltage-gated sodium ion channels (already closed during repolarisation)

67
Q

Nerve impulses (AO1)

Explain how the resting potential is re-established (2 marks).

A

1. Sodium potassium pump uses energy from ATP hydrolysis;

2. Sodium ions actively transported OUT and potassium ions IN.

Both ions move AGAINST their concentraton gradient from low to high.

68
Q

Nerve impulses (AO1)

Explain why the speed of transmission of impulses is faster along a myelinated axon than along a non-myelinated axon (3 marks).

A

1. Myelination provides insulation;

2. In myelinated axon saltatory conduction occurs

OR In myelinated axon depolarisation only occurs at nodes of Ranvier;

3. In non-myelinated axon, depolarisation occurs along whole length of axon;

69
Q

Nerve impulses (AO1)

Refractory period

A

1. Time during which a new action potential cannot be generated;

2. It lasts from the threshold potential until the resting potential has been re-established;

70
Q

Nerve impulses (AO1)

Importance of the refractory period

A

1. Action potentials occur in one direction

2. Each impulse / action potential is discrete

3. Number of action potential is limited

71
Q

Nerve impulses (AO1)

Factors affecting speed of impulse conductance along an axon

A

Myelination

Temperature

Axon diameter

72
Q

Nerve impulses (AO1)

Explain how myelination affects conductance of an impulse

A

Insulates axon;

Depolarisation only occurs at nodes of Ranvier;

Leads to salatory conduction (action potential ‘jumps’ between nodes of Ranvier);

Impulse / action potential moves FASTER along axon;

73
Q

Nerve impulses (AO1)

Explain how increasing temperature affects conductance of an impulse

A

More kinetic energy;

Faster rate of diffusion of sodium and potassium ions DOWN electronchemical gradient;

Faster rate of diffusion of sodium ions within axon;

Impulse / action potential moves FASTER along axon;

74
Q

Nerve impulses (AO1)

Explain how increasing axon diameter affects conductance of an impulse

A

1. Larger surface area so more cell-surface membrane for voltage-gated sodium/potassium ion channel proteins;

2. Less resistance to flow ions within the axon;

75
Q

Nerve impulses (AO2)

Multiple sclerosis is a disease in which parts of the myelin sheaths surrounding neurones are destroyed.

Explain how this results in slower responses to stimuli (2 marks).

A

1. Less / no saltatory conduction / action potential / impulse unable to ‘jump’ from node to node;

2. More depolarisation over length of membranes;

76
Q

Nerve impulses (AO1)

77
Q

Receptors (AO1)

Receptor to detect change in pressure

A

Pacinian corpuscle

78
Q

Receptors (AO1)

A

P = capsule/lamella(e)

Q = Axon (membrane) / (sensory) neurone

R = Schwann cell(s) / Myelin sheath

79
Q

Receptors (AO1)

Channel proteins in Pacinian corpuscle

A

Stretch-mediated sodium ion channel proteins

80
Q

Receptors (AO1)

Describe how stimulation of a Pacinian corpuscle produces a generator potential (3 marks).

A

1. Increased pressure deforms membrane/lamella(e)

2. This opens the stretch-mediated sodium ion channels (in the membrane);

OR (Increased pressure) deforms/changes sodium ion channels;

3. Sodium ion channels open;

4. Sodium ions diffuse in;

5. Depolarisation (leading to generator potential);

81
Q

Receptors (AO1)

TRUE or FALSE:

The generator potential must exceed the threshold stimulus to trigger an action potential in the sensory neuron

82
Q

Receptors (AO1)

[1] pressure leads to more stretch-mediated sodium [2] channels opening. This leads to [3] and makes it more likely the generator potential produced exceeds the [4] stimulus for an action potential.

This is an example of the [5] principle.

A

[1] Increased
[2] ion
[3] depolarisation
[4] threshold
[5] all or nothing

83
Q

Receptors (AO1)

TRUE or FALSE:

A new generator potential in the axon of the Pacinian corpuscle can be produced during the refractory period.

A

FALSE

The resting potential inside the axon must be re-established

84
Q

Receptors (AO1)

Example of photoreceptors

A

Rods & cones

85
Q

Receptors (AO1)

Photoreceptors location

A

Macula
(middle of retina)

86
Q

Receptors (AO1)

Cone location

A

Fovea
(the centre of the macula)

87
Q

Receptors (AO1)

Rod location

A

Edges of the macula
(not present in the fovea)

88
Q

Receptors (AO1)

Rods and cones convert [1] energy into electrical energy in the form of [2].

A

[1] light

[2] action potentials / nerve impulses

89
Q

Receptors (AO1)

Sensivity of rods

A

High sensivity to low light intensity

90
Q

Receptors (AO1)

In rods, light breaks down the pigment [1] and this leads to the release of [2]. This leads to a [3] potential in the [4] neurone.

A

[1] rhodopsin
[2] neurotransmitter
[3] generator
[4] bipolar

91
Q

Receptors (AO1)

Retinal convergence

A

Several rod cells connected to a single bipolar neurone

92
Q

Receptors (AO1)

Spatial summation

A

Release of neurotransmitter from one rod cell leads to generator potential below threshold stimulus in the bipolar neurone

Neurotransmitter released from several/additional rods cells connected to same bipolar neurone helps exceed the threhold and trigger an action potential

93
Q

Receptors (AO1)

Photoreceptor with low visual acuity

94
Q

Receptors (AO1)

Acuity

A

How clear / detailed the image is

95
Q

Receptors (AO1)

Photoreceptor with high visual acuity

96
Q

Receptors (AO1)

Types of cone cells

A

3 cone cells specific to different wavelengths of light: red, blue & green.

97
Q

Receptors (AO1)

Sensivity of cones

A

Low sensitivity to low light intensity

98
Q

Receptors (AO1)

In cones, high intensity light breaks down the pigment [1] and this leads to the release of [2]. This leads to a [3] potential in the [4] neurone.

A

[1] iodopsin
[2] neurotransmitter
[3] generator
[4] bipolar

99
Q

Receptors (AO1)

Each [1] cell is connected to a single [2] neurone. This sends [3] impulses to the visual cortex via the optic nerve.

A

[1] cone
[2] bipolar
[3] separate

100
Q

Receptors (AO2)

The fovea of the eye of an eagle has a high density of cones. An eagle focuses the image of its prey onto the fovea.

Explain how the fovea enables an eagle to see its prey in detail.

Do not refer to colour vision in your answer (3 marks).

A

1. Each cone cell is connected to a single bipolar neurone

OR no retinal convergence;

2. Cones send separate (sets of) impulses to brain / optic nerve;

3. Produces high visual acuity;

101
Q

Receptors (AO2)

The retina of an owl has a high density of rod cells.

Explain how this enables an owl to hunt its prey at night.

Do not refer to rhodopsin in your answer (3 marks).

A

1. High sensitivity to low light intensity

2. Retinal converage OR several rods connected to a single bipolar neurone;

3. Enough neurotransmitter released to reach/overcome threshold

OR spatial summation to reach/overcome threshold;

102
Q

Receptors (AO2)

A

no photoreceptor cells at Y
OR no rods and cones;

A2 AQA Biology - Burnley College (2024-25) (5 decks)

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