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AQA Biology > NOT DONE 6.1 Internal & External Stimuli > Flashcards

NOT DONE 6.1 Internal & External Stimuli Flashcards

1
Q

What are plant growth factors?

A

Chemicals that regulate plant growth response to directional stimuli

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2
Q

Where are plant growth factors produced?

A

Planting growing regions

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3
Q

How do plant growth factors move around plant?

A

Diffuse from cell to cell
Mass transport in phloem

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4
Q

Why do shoots show positive phototropism?

A

IAA diffuses to shaded side of shoot tip
Causes active transport of H+ ions into cell wall
Disruption of H bonds between cellulose molecules make cell more permeable to water
Cells on shared side elongate faster due to higher turgor pressure
Shoot bends towards light

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5
Q

Why do roots show positive gravitropism?

A

Gravity causes IAA to accumulate on lower side of root
IAA inhibits elongation of root cells
cells on upper side of root elongate faster
Root tip bends downwards

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6
Q

What’s the acronym for contrasting mammalian hormones and plant growth factors?

A

CASTS
Concentration
Action
Synthesis
Transport
Speed

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7
Q

Compare concentration of mammalian hormones and plant growth factors.

A

MH response not always dependent on concentration
PGF response proportional to concentration

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8
Q

Compare action of mammalian hormones and plant growth factors.

A

MH bind to complementary proteins in/on target cells
PGF can affect all cells

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9
Q

Compare synthesis of mammalian hormones and plant growth factors.

A

MH specialised glands
PGF various tissues in growing regions

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10
Q

Compare transport of mammalian hormones and plant growth factors.

A

MH circulatory system
PGF diffusion or phloem translocation

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11
Q

Compare speed of mammalian hormones and plant growth factors.

A

MH faster acting (homeostasis)
PGF slower acting (plant growth)

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12
Q

Define taxis.

A

Directional movement in response to external stimulus

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13
Q

Define kinesis.

A

Non directional response to presence and intensity of external stimulus

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14
Q

What is the importance of taxis and kinesis?

A

Maintain mobile organism in optimum environment

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15
Q

Why do many organisms respond to temperature and humidity with kinesis rather than taxis?

A

Less directional stimuli
Often no clear gradient from one extreme to other

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16
Q

How could a student recognise kinesis in an organisms movement?

A

Organism crosses division between two environments and turning increases to return to favourable
Organism moves distance into unfavourable and turning slowly decreases to lead to new environment

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17
Q

Outline events in a simple reflex arc.

A

Receptor detects stimulus
Sensory neuron
Relay neuron in CNS coordinated response
Motor neuron
Response by effector

18
Q

What is the importance of a simple reflex?

A

Rapid response to potentially dangerous stimuli since only 3 neurons involved

19
Q

What stats test could be used to determine whether factor has significant effect on organism movement in choice chamber or not?

A

Chi squared

20
Q

What features do all sensory receptors have?

A

Establiish a generator potential
Respond to specific stimuli

21
Q

What is a Pacinian corpuscle?

A

A type of receptor found in the skin that responds to changes in pressure.

22
Q

Describe the structure of a Pacinian corpuscle.

A

Single nerve fibre surrounded by layers of connective tissue separate by viscous gel and contained by a capsule

23
Q

What do Pacinian corpuscles have on the plasma membrane?

A

Stretch-mediated Na+ channels

24
Q

What do Pacinian corpuscles have along the base layer of tissue?

A

A capillary

25
Q

How does a Pacinian corpuscle respond to pressure?

A

Pressure deforms membrane, causing stretch-mediated Na+ ion channels to open
If Na+ influx raises membrane to threshold potential, a generator potential is produced
Action potential moves along sensory neuron

26
Q

Name the two types of photoreceptor cell located in the retina.

A

Cone cells
Rod cells

27
Q

Where are rod cells located in the retina?

A

Evenly distributed around periphery
Not in central fovea

28
Q

Where are cone cells located in the retina?

A

Mainly central fovea

29
Q

What’s the acronym for contrasting mammalian hormones and plant growth factors?

A

PACL
Pigment
Visual Acuity
Colour sensitivity
Light sensitivity

30
Q

Compare pigment of rod cells and cone cells.

A

ROD: Rhodopsin
CONE: 3 types of iodopsin

31
Q

Compare visual acuity of rod cells and cone cells.

A

ROD: Low resolution as many rod cells synapse with 1 neuron
CONE: High resolution as 1 cone cell synapses with 1 neuron (no retinal convergence)

32
Q

Compare colour sensitivity of rod cells and cone cells.

A

ROD: Monochromatic (all wavelengths of light detected) so can’t detect different colours
CONE: Tricolour (red/blue/green wavelengths absorbed by different types of iodopsin) so can detect different colours

33
Q

Compare light sensitivity of rod cells and cone cells.

A

ROD: Very sensitive
CONE: Less sensitive

34
Q

What is retinal convergence?

A

The sharing of a single nerve fiber by several rod cells in the retina

35
Q

Outline the pathway of light from a photoreceptor to the brain.

A

Photoreceptor
Bipolar neuron
Ganglion cell of optic nerve
Brain

36
Q

Define myogenic.

A

Contraction of heart initiated within muscle rather than by nerve impulses

37
Q

Name the two nodes involved in heart contraction.

A

Sinoatrial node (SAN)
Atrioventricular node (AVN)

38
Q

Where is the Sinoatrial node (SAN) located?

A

Within the wall of the right atrium

39
Q

Where is the Atrioventricular node (AVN) located?

A

Near lower end of right atrium in the wall that separates the 2 atria

40
Q
A

AQA Biology (35 decks)

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