grey matter Flashcards

1
Q

describe the role of sodium ions in the functioning of a mammalian rod cell

A

sodium ions pumped out of the rod cell

in the light sodium ions do not move back into rod cell

in the dark sodium ions can move back into the rod cell

in the light the rod cell is hyper polarised
in the dark the rod cell is depolarised

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2
Q

other affects of IAA

A

alters pH of cell wall

makes cellulose cell wall more plastic

effect on transcription

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3
Q

cells in the tip of the oat coleoptile release IAA
explain how the IAA affects the growth of the coleoptile

A

IAA diffuses from the tip of the coleoptile

can be taken up by cells in the zone of elongation

causes cells to elongate

leads to lowering of the pH in the cellulose cell wall

causes the coleoptile to grow towards the light/ increase in height

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4
Q

give one example of a growth response of a plant that is affected by phytochrome

A

seed germination
flowering

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5
Q

explain the effect of increasing light intensity on the current produced by a rod cell

A

decreases current

rhodopsin is broken down/ opsin is released

more opsin binds to channel proteins in outer segment

sodium voltage gated channels close

stopping the influx of sodium ions/ making the membrane impermeable to sodium ions

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6
Q

describe the role of IAA in the phototropic response of plants

A

produced in the tip of the shoot

accumulates on the dark side of the shoot

stimulates cell elongation

causing shoot to grow towards the light source

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7
Q

the non protein part of the light absorbing pigment in the rod cells of the retina is called

A

retinal

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8
Q

explain the electrical changes in an axon that allow nerve impulses to be detected

A

potential difference across axon changes (from -70 to +40)

due to increased permeability to Na+/ Na+ channels open

Na+ move into the axon/ cause depolarisation

followed by an increased permeability to K+/ K+ channels open

K+ move out of the axon/ cause re polarisation of the membrane

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9
Q

give 3 similarities between IAA and animal hormones

A

chemicals
produced in cells
move away from production site
long term effect
involved in gene activation

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10
Q

give the name of the light absorbing part of rhodopsin

A

retinal

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11
Q

the cell that links a rod cell to a sensory neurone is

A

a bipolar neurone

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12
Q

describe the roles of the circular and radial muscles in pupil dilation

A

muscles work antagonistically
circular muscle relaxes
radial muscle contracts

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13
Q

describe the role of dendrites in a neurone

A

form synapses/ connections w other neurones

integrate/ receive impulses from other neurones

involved in summation

propagate a signal/ initiate an action potential to the cell body/ axon

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14
Q

describe how ions and neurotransmitter molecules are involved in the transmission of an impulse

A

Ca2+ enter presynaptic neurone so vesicles w neurotransmitter can move towards/ fuse w presynaptic membrane

neurotransmitter molecules diffuse along synapse

neurotransmitter binds w receptors on postsynaptic membrane

Na+ diffuse into post synaptic cell leading to a depolarisation/ action potential

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15
Q

similarities between sensory and motor neurone structure

A

both have:

axon

cell body containing nucleus

dendrites at one end of neurone and terminal branches at other end

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16
Q

difference between sensory and motor neurone structure

A

motor neurone cell body is at one end of the axon

sensory neurone cell body is located along the axon

17
Q

describe the post synaptic receptor’s role in synaptic transmission

A

neurotransmitter attaches to it
Na+ enter post synaptic neurone
depolarising it

18
Q

Explain why a myelinated axon conducts impulses faster than a non myelinated axon

A

Action potential/ depolarisation only occurs at nodes

Nerve impulse jumps from node to node/ salta Tory conduction

Action potential/ impulse doesn’t travel along whole length

19
Q

Explain how a lower temperature can effect the speed of an action potential

A

Slower diffusion/ movement down conc grad
Of ions/ K+/ Na+