F214 COMMUNICATION AND HOMEOSTASIS REVISION PACK ANSWERS

F214 COMMUNICATION AND HOMEOSTASIS REVISION PACK ANSWERS

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  • Created on: 31-12-12 23:06
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1. (a) islets of Langerhans; 1
(b) glucagon; 1
(c) 1 fall detected by, pancreas / islets of Langerhans / alpha cells / beta cells;
2 fall inhibits insulin, secretion / production;
3 stimulates, secretion / production, of glucagon (by alpha cells);
4 into blood;
5 binds to receptor on, liver cell / hepatocyte;
7 stimulates conversion of glycogen to glucose / glycogenolysis;
8 gluconeogenesis / detail of gluconeogenesis;
9 glucose into blood stream; 6
[8]
2. (a) A axon terminal / synaptic knob / synaptic bulb;
B cell body / centron; 2
(b) at X:
sodium channels open and sodium ions move into neurone;
potential difference rises from ­70mV to 30mV;
at Y:
potassium channels open and potassium ions move out of neurone;
potential difference falls from 30mV to ­76mV;
AVP;; e.g. ref. to voltage gated channels
ref to movement by diffusion / passively
ref to electrochemical gradient 4
(c) effect:
myelinated fibres conduct more quickly than unmyelinated / AW;
ref. to one set of comparative figures from table;
explanation - max 4
myelin sheath acts as (electrical) insulator;
lack of sodium and potassium gates in myelinated region;
depolarisation occurs at nodes of Ranvier only;
(so) longer local circuits;
(action potential) jumps from one node to another / saltatory conduction; 5
[11]
3. (i) A 3
B 2
C 1; 1
(ii) A 1 (voltage gated) sodium channels open;
2 sodium (ions) enter (axon);
3 positive feedback/more sodium channels open;
4 depolarisation/description of depolarisation;
5 sodium channels close;
6 ref to +40 mV;
JFS School 1

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B 7 (voltage gated) potassium channels open;
8 potassium (ions) move out (of axon);
9 positive feedback/more potassium channels open;
only award marking points 3 or 9, not both
10 repolarisation/description of repolarisation;
11 beyond -65 mV/hyperpolarisation/AW;
C 12 Na/K pump (helps to), restore/maintain, resting potential;
13 membrane more permeable to potassium ions
(at resting potential);
14 (many) potassium channels open (at resting potential); max 5
[6]
4.…read more

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D1 high(est) incidence of torpor/AW;
D2 low(est) oxygen consumption/AW;
D3 high(est) body mass/AW;
D4 data quote; 3 max
explanation
E1 less food used;
E2 (for) less respiration/lower BMR/lower body temperature;
E3 more food stored;
E4 as fat;
E5 (food store/fat) for, migration/flight; max 4
(c) flying, easier/uses less energy (with incomplete feathers if mass low);
can, escape predators/find food, (by flying);
food used for feather growth;
therefore, fat stores used/less food stored;
incomplete/missing feathers may reduce body mass; max 2
(d) yes
(autumn) high(est) mass…read more

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S dorsal root ganglion ;
T relay / intermediate / bipolar / internuncial, neurone ; 2
(ii) 1 rapid / fast acting ;
2 short lived ;
3 automatic / involuntary / no conscious thought / brain not involved ;
4 not learned / innate / genetic / inborn / instinctive ;
5 response the same each time / stereotypical ;
6 AVP ; e.g.…read more

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AW ;
8 ref to nodes of Ranvier ;
9 synapse with, motor / effector / efferent, neurone ;
10 ref to, calcium ions / calcium channels ;
11 vesicles of neurotransmitter fuse with presynaptic membrane ;
12 named neurotransmitter ;
13 secretion / exocytosis (from presynaptic membrane) ; R release
14 diffusion across synaptic cleft ;
15 receptors on postsynaptic membrane ;
16 depolarisation / AW, (of postsynaptic membrane / motor neurone) ;
17 ref to, neuromuscular junction / motor end plate ;
18…read more

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A islet of Langerhans / and cells ;
B (branch of pancreatic) duct ; 2
(ii) endocrine ductless gland ;
hormones / named hormone ; e.g. insulin / glucagon
into blood ;
exocrine enzymes / pancreatic juice / HCO3­ ;
amylase / trypsin / chymotrypsin / lipase / carboxypeptidase ;
into duct ;
if answers are interchanged then mark to 2 max 4 max
[6]
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R reference to rejection
better for people who have developed a tolerance for animal insulin / less needed ;
R immune
acceptable to people who have ethical, moral or religious objections ; A
vegetarians
no risk of, infection / contamination ;
[3]
16. thick axons transmit impulses quicker than thin ones / AW ;
myelinated fibres quicker than unmyelinated / AW ;
invertebrates have slower speed of impulse / ora ;
ref to one set of comparative figures from table ;
[2]
17.…read more

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