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8A Flashcards

1
Q

Light sensitive cells located in

A

Retina

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2
Q

Photoreceptor in light-sensitive cells

A

Membrane bound organelles in the outer segment

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3
Q

Pigment forming photoreceptor in mammal eye

A

Rhodopsin

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4
Q

Describe effect of light intensity on light sensitive cells (graph with light intensities)

A

More flash intensity— more -ve mv
More intense flash—longer to return from -ve
More intense light—cell hyperpolarised faster

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5
Q

How does increasing hyperpolarisation of light sensitive cells result in impulses that can be interpreted by the brain (4 points)

A

1-Greater hyperpolarisation—less neurotransmitter released by rod cell
2-Greater #of action potentials generated in sensory neuron/bipolar cell
3-increased frequency of action potentials is interpreted as more intense light
4-by visual cortex/occipital lobe

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6
Q

Describe effect of multiple sclerosis on speed of conduction of nerve impulse

A

1-No significant difference in conduction speed from spinal cord to biceps
2-conduction speedfrom brain to biceps slower for people with multiple sclerosis
3-use of data manipulation

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7
Q

In multiple sclerosis, the immune system destroys the myelin sheath
Ecplain effect of ms on conduction of an impulse

A

1-conduction speed faster in myelinated neurons
2-bc in myelinated action potentials jump bw gals of m sheath / saltatory conduction
3- myelin removed, action potentials have to move along the whole axon slowing speed of conduction

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8
Q

Using the graph compare response of adp1 and tom1 mutants with response to C elegans

A

1-more worms with adp-1 mutants swim backward following tapping than wt
2-fewer tom1 mutants swim backward following tapping than wt
3-use data to support point 1-2
4-idea that adp1 mutation slows habituation

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9
Q

Describe the role of ion transport in maintaining resting potential of a neuron

A

1-active transport by Na/K pump
2- Na out of axon K into axon
3-passive diffusion of K out of axon
4-inside of membrane -ve compared to outside
5-membrane voltage stays at the same value

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10
Q

How does ttx inhibit nerve impulse

A

1-binds/inhibits voltage dependant Na channels
2-blocking rapid diffusion of Na into axon
3-reducing depolarization of axon
4-below the should for action potential to be triggered

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11
Q

Why does maintaining a resting potential require ATP?

A

1-ATP used by Na/K pump
2- to move Na and K ions across the membrane
3-to establish concentration gradients from Na and K ions

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12
Q

How is -70mv resting potential maintained

A

1-Na/K pump
2- Na channels closed
3-membrane relatively permeable to K
4-At rest high K in axon and high Na outside axon

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13
Q

How does change in pressure receptors cause action potential

A

1-pressurr deforms cell membranes in Pacinian corpuscle (pressure receptors)
2-influx of sodium ions into axon
3-depolarisation of axon moving though the axon in an action potential

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14
Q

Explain why amount of pressure doesn’t change the membrane potential after a medium or high pressure

A

1-theshold has been reached
2-results in action potential
3-action potentials are an all or nothing response since they either occur fully or not at all

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15
Q

Why does myelinated axon conduct impulses faster than unmyelinated?

A

1-myelin sheath is an insulator
2-therefore action potential only occurs at nodes of Ranvier
3-therefor nerve impulse “jumps” from one node to the next: saltatory conduction

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16
Q

Show how damage to myelin sheath can lead to muscle weakness

A

1-myelin sheath destroyed–transmission of nerve impulse impaired
2-fewer impulses reach muscle
3-fewer muscle fibers stimulated to contract—muscle weakness

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17
Q

Is it valid to say there is a relationship bw quantity of myelin in brain of person and whether or not they had demetia

A

1-all types of demetia lower level of myelin vs control
2-no relationship between amount of myelin in brain and type of demetia
3-no overlap of any SD of demetia vs control suggesting validity

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18
Q

Habituation crabs experiment comment on results

A

1- male and female crabs respond differently to the predator
2-female crabs showed greater habituation than male crabs
3-after 10 exposures there seems to be variability in the data

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19
Q

What statistical test to be used to compare increase of predator vs percentage of crabs running home

A

Correlation coefficient

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20
Q

Effect of light absorbtion on rod cells and bipolar cells

A

Rod cell: hyperpolarized
Bipolar neuron: depolarised

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21
Q

Describe effect of light intensity on mean potential differences of bipolar neurons

A

1-light intensity increases–mean potential difference increases
2-mean potential difference stays the same after 12

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22
Q

Two reasons why people might object to the use of mammalian retinas in investigation

A

-Removing retina from mammals can cause blindness/harm
-using anaesthetic causes harm to mammals
-not ethical

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23
Q

Response of muscles in eye to increasing light intensity

A

Circular contract, radial relax

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24
Q

Describe changes in whale heart beat when diving

A

1-heart rate increases when diving
2-the longer the whale is diving the lower the heart rate
3-dif bw maximum heart rate at surface and min heart rate in dive increases as dive duration increases

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25
Q

Describe the role of rhodopsin in rod cells

A

1-rhodopsin is the photoreceptor
2-when light is absorbed, cis retinal becomes trans retinal
3-causes sodium channels to close
4-membrane becomes hyperpolarized

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26
Q

Explain why membrane potential changes bw -70 and +40 mb on the graph

A

1-Stimulus initiates change in voltage
2-Na channels open, Na moves in, less negative
3-if above threshold potential depolarization initiated

27
Q

The protein coded for by the tom1 gene is involved in neurotransmitter release from a sensory neuron.

Suggest how this gene could produce the results observed for the Tom 1 gene (5points)

A

1-sensible function of tom1 protein–reduced activity of Ca2+ channels
2-mutation results in less neurotransmitter being released
3-from sensory neuron
4-fewer action potentials stimulated in post synaptic membrane
5-of motor neurons

28
Q

Suggest how adp1 gene mutation affects the transmission of nerve impulses at synapses

A

1-Ca channels remain responsive
2-idea of neurotransmitter remaining in synapse longer
3-resultijg in prolonged depolarization of post synaptic membrane

29
Q

Suggest how a change in activity of na channels can result in an increase in electrical activity in the brain of a person with epilepsy

A

1-more Na channels open
2-allows membrane to depolarise
3-more easy to reach threshold/generate action potential
4-in large number of neurons

30
Q

Explain how ca2+ is involved in synaptic transmission

A

1-impulse reaches pre-synaptic membrane
2-Ca2+ channels open and Ca2+ diffuses in
3-causing vesicles to fuse with the membrane
4-release of neurotransmitter into synaptic cleft

31
Q

Suggest two reasons why impulses only travel in one direction across a synapse

A

1-neurotransmitters only found in presynaptic knob
2-idea that receptors only found in post-synaptiv membrane

32
Q

Effect of acetylcholine in excitatory and inhibitory synapses of post synaptic cells

A

1-Acetylcholine depolarise post synaptic cell at an excitatory synapse but hyperpolarized post synaptic cell at inhibitory synapse
2-acetylcholine faster effect at excitatory synapse
3-Acetylcholine shows a greater change in membrane potential in excitatory synapse

33
Q

Describe how an action potential is produced and resting potential restored in an axon

A

1-voltage gated Na channels open
2-Na diffuses into axon
3-axon depolarised
4-voltage gated Na channels close
5-voktage gated K channels open
6-K diffuse out of axon–REPOLARISING
7-K diffuses back into axon through non gated K channels restoring resting potential (or Na K pump restores resting potential)

34
Q

Where in rod cell is opsin gene transcribed

A

Nucleus

35
Q

What happens to rod cell membrane when light bleaches the light sensitive pigment

A

Na channels close, rod cell membrane hyperpolarized

36
Q

Describe the role of ATP in response of rod cells to light (3marks)

A

1-atp provides anergy
2-synthrsis of rhodopsin
3-rejoining retinal to opsin
4-converting trans retinal to vis retinal
5- used by Na pump to actively pump na ions

37
Q

How to improve experiment with cuttlefish

A

Repeat experiment
Higher sound intensity above 165
Smaller intervals for both

38
Q

Using table and your own knowledge show how cuttlefish become habituated to sound (4)

A

1- use sound frequency bw 100-200
2- use sound intensity 140-165
3-use a group of cuttlefish
4- testing cuttlefish with sound at regular intervals
5-idea of observing strength of flight response
6-reduced response shows that habituation has occured

39
Q

Using info in graph compare speed of conduction in myelinated and unmyelinated neurons (2)

A

1-as diameter increases, speed increases for both
2-above 1μm myelinated neurons have faster speed of conduction than unmyelinated
3- diameter has greater effect on speed of conduction of myelinated neuron
4- linear relationship in myelinated but nonlinear in unmyelinated

40
Q

Explain why speed of conduction in myelinated neuron with diameter of 1.5 μm is higher than unmyelinated neuron with the same diameter (3)

A

1-idea that myelin sheath insulates axon
2- breaks in myelin nodes of Ranvier
3- action potentials pnlynpccur at nodes
4- nerve impulse jumps from node to node/ saltatory conduction
5- in unmyelinated fibers action potential has to generated all along axon

41
Q

Why is habituation of prairie dogs to humans on trails important

A

1- don’t waste energy running from humans
2- more energy to run from predators
3-warning signal not ignored if predator

42
Q

Discuss issues relating to using rat brains in study (2)

A

1- rats are living organisms – harming wrong
2-need to carry out research not on humans
3- brain of rat similar to humans
4- rats can’t consent

43
Q

State two factors determining how quickly animal become habituated

A

1- time between each stimulus
2- duration of each stimulus
3- strength of stimulus

44
Q

Note

A

Dendrites feel impulse
Impulse moves away from dendrites

45
Q

Explain role of acetylcholine in transmission of nerve impulse (2)

A

1- to transmit nerve impulse across synapse
2- bc action potential cannot cross gap
3- detail: vesicles, receptors on post synaptic cell, exocytosis
4- initiated action potential in post synaptic cell

46
Q

Some pesticides are inhibitors of acetylcholinesterase
Suggest how these pesticides could affect nervous system of insect and person spraying (2)

A

1- acetylcholinesterase needed to release acetylcholine from receptors/ conc remains high in synaptic cleft
2- idea of continuous action potentials
3- presynaptic cell will run out of acetylcholine

47
Q

Suggest how plants can be genetically modified to resist insect damage

A

1- gene resisting insect
2- coding for tough cell wall or toxin
3- idea that gene isolated from plant
4- gene gun introducing gene to plant cell
5- idea of testing plants for gene

48
Q

Describe how light is detected in animals (6)

A

1- rhodopsin in rod cells
2- rhodopsin absorbs light
3- cis retinal–trans retinal
4- rhodopsin splits into retinal and opsin
5- cells become less permeable to sodium
6- resulting in hyperpolarization
7- stimulus large enough–action potential
8- nerve impulse along optic nerve to brain

49
Q

Looking at table explain how distribution of these ions is maintained

A

1- pump/active transport
2- Na move out/ K into cell
3- membrane permeable to K
4- impermeable to Na
5- membrane not permeable to organic anions

50
Q

Suggest how metaflumizone makes ants immobile (3)

A

1- metaflumizone closes or blocks Na ion channels
2- no influx of sodium ions
3- no depolarization/action potential
4- no stimulation/contraction of muscles

51
Q

Describe valid lab investigation to find min concentration of metaflumizone to make ants immobile (4)

A

1- range of 5 concentration
2- standardisation of ants (species)
3- method to assess mobility (observing immobility)
4-large sample size
5- named variable stated (time/solution volume)
6- repeat with a narrower range of concentrations

52
Q

Some ants are resistant to metaflumizone suggest how this happens (3)

A

1- mutation in DNA
2- different protein produced
3- enzyme breaks down metaflumizone
4- metaflumizone no longer blocks channel

53
Q

Explain the role of the synaptic bulb on the stimulation of the effector cell (3)

A

1- action potential causes influx of Ca2+
2- vesicles fuse with pre-synaptic membrane
3- neurotransmitter released and attached to receptors on effector cell

54
Q

Using table suggest how aging affects vision in low light

A

1- pupil size smaller in older people
2- radial fibers in iris contract less in older people

55
Q

Explain advantage to rat of having increased rod cells when length of day is short

A

1- rat will have more hours of darkness
2- rod cells work well on low light levels
3- rats need to see to find food and avoid predators

56
Q

Using table describe the effect of temp on refractory period (2)

A

1- idea that an increase in tekp reduces duration
2- data manipulation
3- reference to overlapping SD
4- idea that as temp increases range decreases

57
Q

Use info in table to suggest how carbamazepine can be used to treat shaking caused by over active neurons in the brain in epilepsy patients

A

1- binds to blocks Na channels
2- no na diffuses in
3- no depolarization
4- no action potential in motor neurons
5- reduced muscle contraction

58
Q

Describe how GALC gene is transcribed

A

1- DNA unwinds
2- mononucleotides line up against their complimentary bases
3- on the template stand
4- phosphodiester bonds form form bw adjacent mononucleotides
5- reference to RNA polymerase or DNA helicase
6- mRNA formed

59
Q

How is a nerve impulse affected by Krabbe disease causing loss of myelin sheath (2)

A

Slows speed of impulse
Idea that impulse cannot jump from node to node

60
Q

Pyrethrin binds to insect neuron protein channels delaying their closure. Why does it not affect animal neurons

A

1- protein channels different
2- pyrethrin cannot bind
3- idea of dilution on mammals

61
Q

Why does people who absorb insecticides have pupils with small diameter

A

1- circular muscles contract
2- radial muscles relax

62
Q

Compare the effect of insecticides on the survival of each species of sand fly

A

1- increased conc kills more flies
2-organichloride kills more species b at lower conc
3- pyrethrin kills more species a at lower conc
4- 100% killed at lower conc of pyrethrin than organichloride

63
Q

During action potential the distribution of Na and K changes. Explain how proteins in cell membrane enable conc of these ions to return to resting potential

A

1- proteins act as channels
Repolarization
2- Na channels close
3- Na cannot enter neuron
Resetting after hyperpolarization
4- k channels close
5- na k pump imports 2k for 3na

64
Q

Describe how arrival of nerve impulse causes release of neurotransmitter

A

1- Ca enters presynaptic knob
2- vesicles containing neurotransmitter
3- fuse with pre-synaptic membrane releasing neurotransmitter into synaptic cleft

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