Brainscape's Knowledge GenomeTM

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


See full index

A Level Biology > Topic 6A - Stimuli And Responses > Flashcards

Topic 6A - Stimuli And Responses Flashcards

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

What is a taxis response

A

A directional response in the direction of a stimuli. E.g light

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

What is a kinetic response

A

A non directional movement in response to a stimulus. E.g. the intensity of a stimulus affects the response

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

What’s the difference between positive taxis and negative taxis response

A

Positive - moves toward the stimulus
Negative - moves away from the stimulus

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

What are the 3 neurones and what are there functions

A
  1. Sensory - transmit electrical impulse from receptors to the CNS
  2. Motor - transmit electrical impulse from the CNS to the effector
  3. Relay - transmit electrical impulse between sensory neurone and motor neurone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the pathway of nervous communication

A

Stimulus —> receptor —> CNS —> effector —> response

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

What is a simple reflex

A

A rapid, involuntary response to a stimulus

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

What is the purpose of simple reflexes

A

Protection - help organism avoid damage to the body as response happens so quickly

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

What is a tropism

A

A response of a plant to a directional stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a positive and negative tropism

A

Positive - growth in response to a stimulus
Negative - growth away from the stimulus

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

What are the 2 types of tropism

A

Phototropism
Gravitropism

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

What is phototropism? What are the 2 types of phototropism?

A

Growth in response to light

Positive phototropism (growth towards light)
Negative phototropism (growth away from light)

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

What is gravitropism? What are the 2 types of gravitropism?

A

Growth in response to gravity

Positive gravitropism (grow downwards)
Negative gravitropism (grow upwards)

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

Which hormones speed or slow down plant growth

A

Auxins

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

Where are auxins produced?

A

In the tips of shoots (diffuse backwards to stimulate the cell just behind the tip to elongate)

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

What is indoloaecetic acid? Why does it move around the plant? How does it move across?

A

Important Auxin produced in the tips of shoots and roots.
It’s moved around the plant to control tropisms.
Moves via diffusion and active transport over short distances.

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

What is the resting potential? How is it generated

A

Is the potential difference when a cell is at rest
It is generated by ion pumps and ion channels

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

What is the generator potential

A

Change in potential difference due to a stimulus

18
Q

What is an action potential? How is it generated?

A

An electrical impulse
If a generator potential is big enough

19
Q

What is a pacinian corpuscles? Where are they found?

A

Nerve endings in skin, responsible for sensitivity to deep pressure touch and high frequency vibrations.
Are at the end of a sensory neurone wrapped in layers of lamellae

20
Q

How does a pacinian corpuscle convert mechanical pressure into a nervous impulse

A

Mechanical pressure stimulates the layers of lamellae to stretch and become deformed.
This causes the axon membrane to also stretch.
The stretch mediated channels are open and sodium ions diffuse into the cell creating a generator potential.
If generator potential reaches the threshold then it causes an action potential.

21
Q

What are photoreceptors?

A

A receptor in the eye that detects light.

22
Q

How is something seen?

A

Light enters the eye through the pupil, the light rays are focused by the lens onto the retina. The retina contains photoreceptors.

23
Q

Where are rods located

A

Periphery and the retina

24
Q

How do photoreceptors work

A

Light enters the eye and hits the photoreceptors
It’s absorbed by light sensitive pigments, which causes a chemical change and alters the membrane permeability to sodium ions
This creates a generator potential, if it reaches the threshold then an action potential is sent along the bipolar neurone.
The bipolar neurones connect the photoreceptors to the optic nerve which takes impulses to the brain.

25
Q

What is the structure of rods

A

Many rods to 1 bipolar neurone

26
Q

What is the function of rods

A

See black and white (works in dim light)
High sensitivity
Low acuity

27
Q

Where are cones located

A

Fovea

28
Q

What are the different types of cones

A

Red
Green
Blue

29
Q

What is the function of cones

A

Color vision
Low sensitivity
High acuity

30
Q

How are we able to see in high visual sensitivity

A

Dim light stimulates each rod cell and rhodopsin breaks down
Several rods are connected to one bipolar neurone so there is a spatial summmation of ACh
This leads to a generator potential
The threshold is passed and impulses move along the shared bipolar neurone
Impulses reach the brain

31
Q

Why are rods very sensitive to light

A

Many rods join one bipolar neurone, therefore many weak generator potentials combine to reach the threshold and trigger an action potential

32
Q

Why are cones less sensitive to light

A

One cone joins one bipolar neurone, therefore it takes more light to reach the threshold and trigger an action potential

33
Q

What is visual acuity

A

The ability to tell apart 2 points that are close together

34
Q

Why do rods have low visual acuity

A

Many rods join the same bipolar neurone, this means light from 2 points close together cant be told apart
(Brain doesn’t get seperate information about the 2 points)

35
Q

Why do cones have a high visual acuity

A

Because one cone joins one bipolar neurone and they are close together.
(When light from 2 points hits 2 different cones, 2 action potentials are generated and sent to the brain)

36
Q

What does the term myogenic means

A

Heart will beat without an external stimulus

37
Q

How are heartbeats controlled? (4)

A
  1. SAN sends electrical impulse across heart
  2. AVN delays the impulse by 0.1 second to allow the atria to finish contracting
  3. The bundle of HIS takes the electrical impulse to the base of ventricles
  4. The bundle splits into punkijne fibres which causes the ventricles to contract
38
Q

What is a parasympathetic neurone

A

Neurone that sends low frequency of impulses

39
Q

What is a sympathetic neurone

A

Neurone that sends high frequency impulses

40
Q

Where are impulses sent when wanting to reach the heart

A

Medulla oblongata

41
Q

How is heart rate slowed down?

A

Barrow receptors detect high blood pressure
Chemoreceptors can detect high blood pH

Impulses are sent down the sensory neurone to the medulla oblongata
Low frequency impulses are sent along the parasympathetic neurone to the heart.
This stimulates ACh to be released which binds to receptors in the heart.
Heart rate slows down

42
Q

How does heart rate increase?

A

Barrow receptors detect low blood pressure
Chemoreceptors detect low blood pH

Impulses sent along sensory neurone to medulla oblongata
High frequency impulses are sent along SYMPATHETIC neurone to the heart
This stimulates noradrenaline to be realeased which binds to receptors in the heart
Heart rate increases

A Level Biology (20 decks)

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