F214 A2 Biology Communication and homeostasis

Notes for F214 A2 Biology Communication and homeostasis

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  • Created on: 15-10-12 16:27
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1. The pancreas contains endocrine tissue. The figure below shows an
electronmicrograph of a section of pancreatic endocrine tissue.
nucleus rough endoplasmic reticulum cell membrane beta cell secretory vesicle
alpha cell secretory vesicle mitochondrian x 30000
(a) Name the endocrine tissue shown in the figure.
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[1]
(b) Name the hormone present in the secretory vesicles of alpha cells.
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[1]
JFS School 1

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During vigorous exercise, the blood glucose concentration falls.
Describe the changes that take place to make sure that the blood glucose
concentration does not fall to a dangerous level.
In your answer, you should use appropriate technical terms, spelled correctly.
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Fig. 1 is a diagram of a neurone.
A B C D
direction
of impulse indicates
long distance
Fig. 1
Name the structures A and B.
A ......................................................................................................................
B ......................................................................................................................…read more

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Fig. 2 shows a recording of the potential difference across the membrane of an axon as
an action potential is transmitted.
+40
+30
+20
+10
0
membrane ­10 X Y
potential / ­20
mV ­30
­40
­50
­60
­70
­80
­90
0 1 2 3 4 5
time / ms
Fig. 2
(b) Describe the events taking place in the neurone during stages X and Y.
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The table below shows how the speed of conduction of an action potential varies with
the diameter of myelinated and non-myelinated axons in different organisms.
organism type of axon axon diameter / µm speed of conduction
/ ms-1
crab non-myelinated 30 5
squid non-myelinated 500 25
cat myelinated 20 100
frog myelinated 16 32
(c) Describe the effect of myelination on the rate of conduction of an action potential
and explain how this effect is achieved.…read more

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Fig.1 represents some of the changes that occur across the membrane of the axon.
Three protein complexes are shown to be present in the membrane:
· sodium channels
· potassium channels
· sodium-potassium pumps.…read more

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Fig.2 shows the change of membrane potential associated with an action potential.
+40
membrane
potential / mV A
B
C
­65
0 1 2
time / milliseconds
Fig.2
(a) (i) State which of the three diagrams of the axon membrane in Fig. 1 match up
to the phases labelled in Fig. 2. Write your answers in the table below.…read more

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With reference to Fig. 1, explain the changes in membrane potential in
Fig. 2.
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[5]
[Total 6 marks]
4. In this question, one mark is available for the quality of spelling, punctuation and
grammar.
In order to transfer information from one point to another in the nervous system, it is
necessary that action potentials be transmitted along axons. In humans, the rate of
transmission is 0.…read more

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Explain how action potentials are transmitted along a nonmyelinated neurone and
describe which parts of this process are different in myelinated neurones.
No credit will be given for reference to events at the synapse.
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Hummingbirds are very small. Typically their mass is between 3 and 5 g. They are able
to hover at a fixed point in the air by beating their wings very rapidly. The rufous
hummingbird, Selasphorus rufus, is a migratory species. It breeds in Canada and
Alaska in the summer, migrates south to Mexico in the autumn and returns to high
latitudes in spring after completing its annual moult (loss of feathers, which are then
re-grown).…read more

Comments

Ibzay101010

Do you happen to have any of the answers for these?

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