1112-Level O Biology Basic Questions
Chapter 19
Control, coordination and homeostasis
Part A
1-
Discuss the ways in which the structures of different parts of a nephron are adapted to their functions.
2-
The table shows information about the relative thickness of the medulla of the kidneys, the percentage
of the loops of Henle which are long rather than short, and the relative concentration of the urine for
three mammals.
Discuss these data.
3-
Discuss the roles of active transport in the reabsorption of glucose and water in a kidney nephron.
4-
Compare the mechanisms for controlling blood glucose levels and water content in body fluids.
5-
Most vertebrates use hormones similar to mammalian ADH, to help with water regulation. These
hormones do not always work in the same way as described in this chapter. Suggest how each of the
following might help the animal to conserve water.
a-
In reptiles and amphibians the hormones not only increase the permeability of the distal tubules
and collecting ducts to water, but also reduce glomerular filtration rate.
b-
In some amphibians the hormone increases the permeability of the outer surface of the skin to
sodium ions.
c-
In toads the hormone increases the permeability of the walls of the urinary bladder to water.
6-
Discuss the ways in which the structure of a motor neurone is related to its function.
7-
Compare and contrast the ways in which the nervous system and the endocrine system bring about
communication between different parts of the mammalian body.
8-
Compare and contrast animal hormones with plant growth substances.
To answer the following questions, you will need to bring together information from the other areas of your
course, as well as from this chapter.
9-
a)
Describe the structure of a cell membrane.
b)
Outline the roles of (i) respiration and (ii) carrier proteins in the maintenance of the resting
potential in a neurone.
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1112-Level O Biology Basic Questions
10- a)
With reference to enzyme function, explain why it is important for mammals to
control the temperature and pH of their body fluids.
b)
Explain how a large increase in blood glucose concentration could affect the water
potential of body fluids, and discuss the effects that this could have on body cells.
11- a)
b)
Describe how genetic engineering has been used to manufacture insulin on a large scale.
Explain why some diabetics may need to inject insulin, and discuss the advantages to them of
using insulin produced by genetic engineering.
12- a)
b)
Describe how ions such as Na+ and Ca2+ can pass across cell membranes.
Compare the mechanisms by which insulin is released from ß cells with that by which transmitter
substance is released from a presynaptic neurone.
Part B
Structure and function of kidneys
1-
2-
Describe the following processes with reference to the kidney:
a-
homeostasis
b-
ultrafiltration
c-
excretion
d-
osmoregulation
Write a list of the most suitable word(s) to fill the gaps in the following account.
The kidneys are supplied with blood by the ----------------- artery, which splits into arterioles supplying
the knot of capillaries known as the --------------- inside the Bowman’s capsule of each --------------. The
blood pressure is high because the diameter of the ------------------ arteriole is entering the capillary knot
is -------------- than the arteriole which leaves the capillary knot. This causes the process known as ------------ to occur.
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1112-Level O Biology Basic Questions
3-
4-
a-
Name the parts labelled A,B,C, and D on the diagram of the kidney and associated parts.
b-
Name the parts labelled E, F, G, H and I on the diagram of a kidney tubule.
c-
In which region of the kidney would you expect to find E?
a-
Name the ways in which water is lost by mammals.
b-
Name the nitrogenous excretory product of:
c-
d-
i)
mammals
ii)
terrestrial insects
iii)
fish
Explain the term:
i)
isotonic
ii)
hypotonic
Name the site of uptake of much water by osmosis in fresh water fish.
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1112-Level O Biology Basic Questions
5-
Explain why eating extra protein may have a greater effect on the urea content of the urine of an adult
than in a child.
Part C
1-
The graph below shows how the rates of filtration and reabsorption of glucose in human nephrons vary
with concentration of glucose in the blood plasma.
a-
i)
From the graph determine the maximum rate of glucose reabsorption.
ii)
Comment on the relationship between filtration rate and reabsorption rate as shown by these
two curves.
b-
If the concentration of glucose in the blood plasma exceeds 20 mmol.dm-3 glucose
appears in the urine. Suggest an explanation for this observation.
2-
The graph shows the rate of glucose reabsorption in, and excretion from, a mammalian kidney in
relation to the glucose concentration in the plasma.
a-
Draw a line on the graph to show the rate of filtration of glucose in the renal capsule.
b-
In which part of the nephron is glucose reabsorbed?
c-
Explain the shape of the glucose reabsorption curve.
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1112-Level O Biology Basic Questions
3-
a-
Name the kidney region where the proximal convoluted tubule is found.
The graph shows the glucose concentration at various points from the beginning of the proximal
convoluted tubule.
b-
Assume that the fluid moves along at a speed of 0.5 mm.s-1.
Showing your working:
i)
Calculate the average rate of change in mMdm-3 for region A (0 to 1mm).
ii)
Calculate, as a percentage of the concentration at 0 mm, the fall in the glucose
concentration between 0 and 0.25 mm.
iii)
Over region B (1.25 to 5 mm) the values corresponding to those you have
calculated are 0.53 mM dm-3 s-1 and 10.67%.
Compare these values with your calculated values and suggest the main factor
influencing the uptake of glucose.
c-
Where else in the body would glucose concentration be very similar to that at point
0 mm.
d-
i)
Suggest a medical condition which would result in higher values at point 0 mm.
ii)
Explain the simplest way in which a doctor could detect this condition.
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1112-Level O Biology Basic Questions
4-
The graph below shows the concentration of the solutes in the fluid in the different regions of a nephron
from a human kidney. Curve A shows the concentration in the presence of the hormone ADH. Curve B
shows the concentrations when no ADH is present.
a-
Although solutes such as glucose are reabsorbed in the first convoluted tubule the concentration
of these solutes does not change as the fluid flows along this part. Explain why.
b-
What causes the concentration of the solutes to increase, then decrease as the fluid
flows through the loop of Henle?
c5-
Explain the difference in concentration of the fluid in the collecting duct in curves A and B.
A diagram of a cell from the wall of the proximal convoluted tubule is given. In this region of the
nephron the concentration of glucose inside the tubule falls to zero.
a-
Explain how the glucose concentration is decreased.
b-
Explain how the structure of the cell is adapted to bring about this process.
c-
What other substances are removed from the nephron filtrate in the proximal tubule?
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1112-Level O Biology Basic Questions
6-
The diagram below shows the simplified structure of a kidney tubule (nephron).
a-
In the table below, columns 1 & 2 show the quantities of water, glucose and urea
passing through P and Q in a 24 hour period. Columns 3 and 4 show the quantities and
percentages reabsorbed during the same period. Complete the table by writing the
correct figures in the boxes labelled i to iv
.
b-
Describe how R is involved in adjusting the concentration of the filtrate as it passes through the
medulla of the kidney.
Nerves and reflexes.
1-
The diagram shows a mammalian neurone.
a-
What type of neurone is shown?
b-
Name the parts labelled A, B, C, and D.
c-
i)
Suggest two reasons why the fibre is surrounded by a fatty layer.
ii)
Name the fatty layer.
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1112-Level O Biology Basic Questions
d-
e-
i)
The part labelled E is branched. Suggest reasons for this.
ii)
Name the swellings at the branched ends of E.
The pressure receptor is found in the skin of the hand. Where would the other end of the neurone
be located?
2-
Read the following passage about synapses carefully and then write a list of the most suitable words to
fill the gaps.
The junction between the axon of one neurone and the --------------- of the next neurone is called a
synapse. Here the axon terminal or synaptic --------------- as it is called, contains many ------------- to
supply energy. The synaptic ------------- are bounded by membranes and contain a transmitter substance
called -----------------. This diffuses across the synaptic --------------- to bind with ------------- on the -------------- membrane.
3-
An example of a reflex action occurs when you burn your finger. This would cause you to contract the
biceps, thus pulling the finger away from the source of heat. Such a reflex action involves three
neurones.
a-
b-
i)
Name the effector in this action.
ii)
Explain the meaning of the term ‘reflex action’.
iii)
Draw a diagram to show such a spinal reflex. Label the neurones.
iv)
Give two advantages of this response being a reflex action.
v)
Give two other examples of reflex actions.
When the detective Hercule Poirot was thinking he often referred to his ‘little grey cells’.
Explain what these consisted of and where in the body they would be found.
4-
c-
What gives the white appearance to ‘white matter’?
d-
Name the two main co-ordinating systems.
Some of the early research into conduction of impulses was carried out on the giant axons of molluscs
ssuch as squid and octopus. These do not have a myelin sheath around their axons. The table below
shows the speed of conduction in the axons of cat & octopus.
a-
Describe how the rate of conduction is related to the structure of the axon in cats.
b-
Describe how the rate of conduction is related to the diameter of non-myelinated axons
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1112-Level O Biology Basic Questions
c-
Explain how a myelin sheath affects the rate of transmission of impulses along the
axon.
d-
Suggest why giant axons may have developed in squid and octopus rather than snails.
5-
Compare the structure and functions of sensory neurones and motor neurones
6-
The diagram shows some of the events which occur in a synapse after the arrival of an impulse at the
presynaptic membrane.
a-
b-
i)
Put the events 1-6 on the diagram in the correct sequence.
ii)
Name the ions labelled A & B.
iii)
By what process do transmitter molecules move across the synaptic cleft?
iv)
Name one transmitter molecule released by synaptic vesicles.
One impulse arriving at the presynaptic membrane does not produce an action potential in the
postsynaptic neurone, but several impulses arriving in close succession do.
i)
Explain the observation.
ii)
What name is given to the process described?
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1112-Level O Biology Basic Questions
7-
The graph shows the electrical events associated with a nerve impulse.
a-
What is the value of the resting potential?
b-
Which part of the graph corresponds to:
c-
i)
repolarisation of the axon membrane.
ii)
the refractory period?
Explain why there is a change in the potential difference across the axon membrane between
points B and C on the graph.
8-
The diagram below shows a synapse as seen with an electron microscope.
a-
Explain the function of each of the following:
i)
the mitochondria
ii)
the synaptic vesicles
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1112-Level O Biology Basic Questions
b-
The graphs show the effect of adding acetylcholine to skeletal muscle and heart muscle
i)
Describe the effects of acetylcholine on skeletal muscle.
ii)
State how the effects of acetylcholine on heart muscle differ from its effects on
skeletal muscle.
iii)
Suggest how these differences may be related to the functions of the two types of
muscle.
c-
i)
Suggest why it is important that acetylcholine is rapidly hydrolysed after its release.
ii)
Some organophosphate insecticides work by inhibiting the enzyme that catalyses
the hydrolysis of acetylcholine. Suggest what effects this will have in the body of
the insect.
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