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Biology > Stimuli and responses > Flashcards

Stimuli and responses Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a taxis?

A

A taxis is a directional response where the direction of the stimulus determines the direction of movement.

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2
Q

Give an example of a taxis.

A

Negative phototaxis occurs when organisms move away from a light source.

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3
Q

What is kinesis?

A

Kinesis is a random (non-directional) response where the intensity of the stimulus affects the speed of movement.

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4
Q

Give an example of kinesis.

A

Woodlice move slower in a favourable environment (e.g., damp) and faster in an unfavourable one.

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5
Q

What is a stimulus?

A

A stimulus is a change in the internal or external environment of an organism.

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6
Q

What do the prefixes ‘photo-‘, ‘geo-‘, ‘chemo-‘, and ‘rheo-‘ mean?

A

Photo- means light, geo- means gravity, chemo- means chemical, and rheo- means movement.

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7
Q

What is a tropism?

A

A tropism is the growth movement of part of a plant in response to a directional stimulus.

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8
Q

What is phototropism?

A

Phototropism is the growth of a plant toward or away from light.

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9
Q

What is gravitropism (geotropism)?

A

Gravitropism is the growth of a plant upwards or downwards in response to gravity.

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10
Q

What are growth factors in plants?

A

Growth factors are hormone-like chemicals that regulate plant growth by speeding up or slowing down growth.

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11
Q

What is auxin?

A

Auxin is a plant hormone that stimulates growth by cell elongation.

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12
Q

How do high concentrations of auxin affect shoots and roots?

A

High concentrations of auxin stimulate growth in shoots but inhibit growth in roots.

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13
Q

What is IAA and where is it produced?

A

IAA (indoleacetic acid) is an auxin produced in the tips of shoots and roots in plants.

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14
Q

How does IAA cause phototropism in shoots?

A

IAA moves to the shaded side of shoots, causing cells to elongate and the shoot to bend toward light.

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15
Q

How does IAA cause gravitropism in roots?

A

IAA moves to the underside of roots, inhibiting growth and causing the root to bend downwards.

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16
Q

What are the structures of a neurone?

A

Neurones consist of dendrites, cell body, axon, myelin sheath, nodes of Ranvier, and axon terminal.

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17
Q

What is the function of dendrites?

A

Dendrites branch out from the cell body and carry impulses from neighbouring neurones.

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18
Q

What is the function of the cell body?

A

The cell body contains the nucleus and genetic material of the neurone.

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19
Q

What is the function of the axon?

A

The axon carries electrical impulses away from the cell body and down the length of the neurone.

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20
Q

What is the function of the myelin sheath?

A

The myelin sheath is a fatty layer that insulates the axon and speeds up electrical transmission.

21
Q

What are nodes of Ranvier?

A

Nodes of Ranvier are gaps in the myelin sheath that speed up transmission by forcing impulses to jump across the gap.

22
Q

What is the function of the axon terminal?

A

The axon terminal transmits impulses to neighbouring neurones across a synapse.

23
Q

What are the three main types of neurones?

A

The three types are sensory neurones, motor neurones, and relay neurones.

24
Q

What is the role of sensory neurones?

A

Sensory neurones transmit impulses from receptors to the central nervous system (CNS).

25
Q

What is the role of motor neurones?

A

Motor neurones transmit impulses from the CNS to effectors such as muscles.

26
Q

What is the role of relay neurones?

A

Relay neurones transmit impulses between sensory and motor neurones.

27
Q

What is the central nervous system (CNS)?

A

The CNS consists of the brain and spinal cord.

28
Q

What is the peripheral nervous system?

A

The peripheral nervous system connects the CNS to the rest of the body via neurones.

29
Q

What is the role of the somatic nervous system?

A

The somatic nervous system controls conscious activities such as running.

30
Q

What is the role of the autonomic nervous system?

A

The autonomic nervous system controls unconscious activities such as digestion.

31
Q

What is the sympathetic nervous system?

A

The sympathetic nervous system prepares the body for action (‘fight or flight’).

32
Q

What is the parasympathetic nervous system?

A

The parasympathetic nervous system calms the body down (‘rest and digest’).

33
Q

What is a reflex arc?

A

A reflex arc is the pathway of information in a reflex, which allows for rapid responses without conscious thought.

34
Q

What are the steps in a reflex arc?

A
  1. Receptors detect stimulus, 2. Sensory neurone transmits impulse, 3. Relay neurone connects to motor neurone, 4. Motor neurone sends impulse to effector.
35
Q

What is an action potential?

A

An action potential is a reversal of charge across the axon membrane (+40mV).

36
Q

What is the all-or-nothing principle?

A

An action potential is only generated if the stimulus reaches the threshold value; it is always the same size.

37
Q

What is a generator potential?

A

A generator potential is the nervous impulse produced by a sensory receptor when a stimulus is detected.

38
Q

What is the Pacinian corpuscle?

A

The Pacinian corpuscle is a sensory receptor that responds to mechanical stimuli (pressure).

39
Q

How does a Pacinian corpuscle generate an action potential?

A
  1. Pressure deforms the lamellae, 2. Stretch-mediated sodium channels open, 3. Sodium ions enter the neurone, 4. If threshold is reached, an action potential is generated.
40
Q

What happens to light entering the eye?

A

Light enters through the pupil, focused by the lens onto the retina, where photoreceptors detect light.

41
Q

What is the fovea?

A

The fovea is a part of the retina where many photoreceptors are concentrated.

42
Q

What is the difference between rods and cones?

A

Rods detect black and white light in low light intensity; cones detect colour and work in bright light.

43
Q

What is visual sensitivity in rods?

A

Rods are very sensitive to light because many rods join one neurone, allowing generator potentials to combine.

44
Q

What is visual acuity in cones?

A

Cones provide high visual acuity because each cone connects to one neurone, allowing close points to be seen as separate.

45
Q

How do rods produce action potentials?

A
  1. Rhodopsin breaks down in low light, 2. Sodium ions enter rod cells, 3. Membrane depolarises, 4. Generator potential triggers an action potential.
46
Q

What is the SAN and its role in heart rate control?

A

The sinoatrial node (SAN) sets the rhythm of the heart by sending out regular action potentials.

47
Q

How does the medulla oblongata control heart rate?

A

The medulla sends impulses to the SAN via the sympathetic or parasympathetic nervous system.

48
Q

How does the heart respond to high blood pressure?

A

Receptors send impulses to the medulla, which uses the parasympathetic nervous system to decrease heart rate.

49
Q

How does the heart respond to low blood pressure?

A

Receptors send impulses to the medulla, which uses the sympathetic nervous system to increase heart rate.

Biology (13 decks)

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