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Biology Unit 5 > 10 Coordination > Flashcards

10 Coordination Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

EQ

A myelinated axon conducts impulses faster than a non-myelinated axon. Explain this difference. (3)

A
  1. (In myelinated) action potential/depolarisation
    only at node(s);
  2. (In myelinated, nerve impulse) jumps from node
    to node/saltatory;
  3. (In myelinated) action potential/impulse does
    not travel along whole length;
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2
Q

EQ

Explain the shape of the curve for sodium ions between 0.5 ms and 0.7 ms (rapid increase) (3)

A

(Ion) channel proteins open;
Sodium in;
Changes membrane potential/makes inside of axon less
negative/positive/depolarisation/ reaches threshold;
More channels open/positive feedback;

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3
Q

EQ

During an action potential, the membrane potential rises to +40 mV and then falls. Use
information from the graph to explain the fall in membrane potential. (3)

A

Potassium channels open;
Potassium out;
Sodium channels close;

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4
Q

EQ

After exercise, some ATP is used to re-establish the resting potential in axons. Explain
how the resting potential is re-established.. (2)

A

Pump/active transport/transport against concentration
gradient;
Of sodium from axon/sodium out/of potassium in;

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5
Q

EQ

Describe how hormones are different in the cells they affect. (1)

A

Hormones have widespread effect / affect different organs /
affect different parts of the body / affect distant organs / only
affect cells with right receptor;

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6
Q

EQ

Describe how hormones and local chemical mediators reach the cells they affect. (2)

A
  1. Hormones in blood;
  2. Local chemical mediators spread by diffusion / spread
    directly;
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7
Q

EQ

Synapses are unidirectional. Explain how acetylcholine contributes to a synapse being
unidirectional. (2)

A
  1. (Acetylcholine) released from/in presynaptic side;
  2. Diffusion from higher concentration/to lower concentration;
  3. Receptors in postsynaptic (side) / binds on postsynaptic
    (side) ;
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8
Q

EQ

The black mamba’s toxin kills prey by preventing their breathing. It does this by
inhibiting the enzyme acetylcholinesterase at neuromuscular junctions. Explain how
this prevents breathing. (3)

A 
1. Acetylcholine not broken
down / stays bound to
receptor;
2. Na+ ions (continue to) enter /
(continued) depolarisation /
Na+ channels (kept) open /
action potentials/impulses
fired (continuously);
3. (Intercostal) muscles stay
contracted / cannot relax;
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9
Q

EQ

Serotonin is a neurotransmitter released in some synapses in the brain. It is
transported back out of the synaptic gap by a transport protein in the pre-synaptic
membrane.
7 (a) Serotonin diffuses across the synaptic gap and binds to a receptor on the post-synaptic
membrane.
Describe how this causes depolarisation of the post-synaptic membrane. (2)

A
  1. Causes sodium ion channels to
    open;
  2. Sodium ions enter (cell and
    cause depolarisation);
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10
Q

EQ

It is important that a neurotransmitter such as serotonin is transported back out of
synapses. Explain why. (2)

A
  1. (If not removed) keeps binding (to
    receptors);
  2. Keeps causing action
    potentials/depolarisation (in postsynaptic
    membrane);
  3. Prevents information being
    carried across synapse/described
    consequence;
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11
Q

EQ

What conclusion can be made from the results for treatment B? (1) (grows horizontally, 0 degree curvature)

A 
1. (Cells in) root tip detect
gravity / respond to gravity;
OR
2. IAA/auxin is produced in the
root tip;
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12
Q

EQ

(low on top, high on bottom)

Explain how this distribution of IAA causes the root to bend (2)

A 
1. Greater (elongation) growth on top
of root/less growth on bottom of
root;
2. (IAA) at bottom of root/where IAA
concentration high inhibits
expansion/elongation (of cells);
3. (IAA) at top of root/where IAA
concentration low leads to
expansion/elongation (of cells);
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13
Q

EQ

When a young shoot is illuminated from one side, IAA stimulates growth on the shaded
side. Explain why growth on the shaded side helps to maintain the leaves in a
favourable environment. (2)

A
  1. Causes plant to bend/grow towards light / positive
    phototropism;
  2. (Light) required for photosynthesis;
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13
Q

EQ

The pea seedlings were kept in the dark after each treatment. Explain why this was
necessary. (1)

A 
1. (Seedlings) respond to light /
are phototropic;
OR
2. (Only) measuring the effect
of gravity / response to
gravity;
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14
Q

EQ

Name the process by which IAA moves from the growing regions of a plant shoot to
other tissues. (1)

A

Diffusion;

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16
Q

EQ

Suggest how indoleacetic acid (IAA) could have caused the results for:

treatment A (grows downwards, 60 degree curvature)

treatment B (upper half of root tip removed, grows downwards, 30 degree curvature)

A 
) 1. IAA/auxin moves to lower
side / more IAA/auxin on
lower side;
2. Lower side grows
less/slower / upper side
grows more /faster / inhibits
growth on lower side;
  1. Less IAA/auxin (produced);
  2. Lower side grows
    more/faster / less inhibition
    of growth on lower side;
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17
Q

Name 2 differences between nervous and hormonal system.

A

Slow, long-lasting, widespread, blood plasma

Rapid, short-lived, localised, nerve cells

18
Q

Chemical mediators

2 examples?

A

Released by infected/injured cells
Spread by diffusion
Cause inflammation

Histamine and prostaglandins

19
Q

Name 3 external stimuli and why they are needed in plants.

A

Light - photosynthesis
Water - photosynthesis/plant support
Gravity - anchoring

20
Q

Effect of IAA (shoots)

A
  1. Cells in the shoot tip produce IAA
  2. Light causes IAA to move to shaded side, greater concentration
  3. IAA causes elongation of cells
  4. Shaded side grows faster causing shoot to bend towards light.
21
Q

Effect of IAA (roots)

A
  1. Cells in the root tip produce IAA
  2. Gravity causes IAA to move to lower side, greater concentration
  3. IAA inhibits elongation of cells
  4. lower side grows slower.
22
Q

Why does the cell body contain nucleus and RER?

What do dendrons do?

What does the axon do?

Give 2 functions of Schwann cells

A

To produce proteins/neurotransmitter

Carry nerve impulse to cell body

Carry nerve impulse away from cell body

Protection/insulation of axon, phagocytosis

23
Q

Define nerve impulse

A

a temporary reversal of the electrical p.d. across the axon membrane. (also action potential).

24
Q

Give 3 ways in which movement of ions across the axon membrane is controlled.

A

Plasma membrane
Channel proteins
Na-K pumps

25
Q

Resting potential:

inside/outside?
charge?
state?

ESTABLISHING RESTING POTENTIAL

Chemical gradient (4)

Electrical gradient (2)

A

INSIDE = NEGATIVE, OUTSIDE=POSITIVE
Charge = -65mV
Axon polarised

  1. Na-K pump AT Na ions out, AT K ions in (Na:K=3:2)
  2. Outside more positive than inside
  3. Through channel proteins Na ions diffuse in, K ions diffuse out (axon 100x more permeable to K)
  4. Outside even more positive
  5. Diffusion of K stops because attracted to -ive inside, repelled by +ve outside
  6. Equilibrium - gradients balanced, no net movement of ions
26
Q

Action potential:

inside/outside?
charge?
state?

When NI reaches end of axon? (2)
At +40mV? (4)
Resting potential re-established?

A

INSIDE = POSITIVE, OUTSIDE = NEGATIVE
Charge = +40mV.
Depolarised

  1. NI reaches end of axon:
  2. Na channels open, Na ions diffuse in = depolarisation
  3. More Na channels open
  4. At +40mV:
  5. Na channels close
  6. K channels open, K ions diffuse out = repolarisation
  7. More K channels open (K ions cause temporary overshoot = hyperpolarisation)
  8. K channels close
  9. Na-K pump re-establishes resting potential by AT Na ions out
27
Q

How does an action potential pass along an unmyelinated axon? (3)

A

Depolarisation establishes localised electrical circuits
Causes depolarisation further along axon
Behind new region repolarisation

28
Q

Factors affecting speed of action potential passage:

Myelin sheath (1)
Diameter of the axon (2)
Temperature (3)

A

Myelinated = faster

Greater diameter = faster
Leakage of ions less likely

Higher temperature = faster
Enzymes work faster, more e-s complexes, more collisions
Enzymes control respiration which provides ATP for active transport

29
Q

Refractory period

Describe it

Purposes? (3)

A

When depolarisation in one region, no depolarisation in any other region

Ensures action potential propagated in one direction only
Produces discrete impulses:
Limits the number of action potentials

30
Q

All-or-nothing principle:

Define threshold value

All:?
Nothing?

A

= level of stimulus that must be exceeded to generate action potential and therefore nerve impulse

any stimulus above = one action potential
any stimulus below = no action potential

31
Q

How do organisms perceive the size of a stimulus? (2)

A

Number of impulses in given time

Different neurones have different threshold values

32
Q

Define Neurotransmitter

A

= chemical form of nerve impulse

33
Q

Define synaptic cleft

A

= small gap that separates neurones

34
Q

Define presynaptic neurone

A

= neurone that releases neurotransmitter.

35
Q

Define synaptic knob

A

= portion at end of presynaptic neurone axon (many mitochondria and RER for neurotransmitter production)

36
Q

Define synaptic vesicles

A

=store neurotransmitter.

37
Q

Define postsynaptic neurone

A

= neurone that receives neurotransmitter - has receptors on membrane that it binds to.

38
Q

Function of synapses? (2)

A

Transmit single nerve impulse to multiple neurones (one stimuli, multiple responses)
Combine multiple impulses to single neurone (multiple stimuli, single response)

39
Q

Features of synapses:

Unidirectionality?

Summation? (3)

Inhibition (inhibitory synapses)? (2)

A

Nerve impulse passes in one direction (presynaptic to postsynaptic)

  • Resolves insufficient quantity of neurotransmitter to exceed threshold value on postsynaptic neurone and generate action potential.
  • Spatial summation - multiple presynaptic neurones combined
  • Temporal summation - single presynaptic neurone releases lot of neurotransmitter over short period of time (high-frequency)

Cl channels ions open, Cl ions diffuse in =hyperpolarisation
Less likely action potential generated

40
Q

Define cholinergic synapse

A

a synapse in which the neurotransmitter is acetylcholine.

41
Q

Transmission across a cholinergic synapse (6)

Why do acetyl and choline diffuse back across synaptic cleft into presynaptic neurone to be stored in vesicles?

A
  1. Nerve impulse reaches reaches end of axon
  2. Influx of calcium ions into pre-synaptic membrane
  3. Synaptic vesicles fuse with membrane and release acetylcholine
  4. Acetylcholine diffuses across synapse and binds to receptors on postsynaptic membrane
  5. Action potential/depolarisation of postsynaptic membrane
  6. Influx of sodium ions;

To prevent continuous generation of action potential in postsynaptic neurone.

Biology Unit 5 (9 decks)

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