1.There are many different species of annelid worm. Some are
very small, only a few millimetres in length. Others, such as
lugworms, are much larger. The drawing shows a lugworm and part of
one of its gills.
(a)Smaller species of annelid do not have gills. Explain why
these small worms do not need gills to obtain sufficient
oxygen.
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(2)
(b)In many of the lugworm gills, the blood flows in the opposite
direction to the current of water passing over them. Explain the
advantage of this arrangement.
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(2)
(c)Explain two ways, other than that described in part (b), in
which the structure of a lugworm gill is adapted for efficient gas
exchange.
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(d)Explain why water is always lost from the gas exchange
surfaces of terrestrial organisms.
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(2)
The table shows the ratio of the amount of water lost to the
amount of oxygen gained for two terrestrial animals, an annelid
worm and an insect.
OrganismRatio
Annelid worm2.61
Insect0.11
(e)Both the annelid and the insect take up oxygen at a rate of
2.5 cm3 g1 minute1 Calculate the rate at which water would be lost
in meeting these requirements in:
(i)the annelid;
Answer.......................mg g1 minute1(ii)the insect.
Answer........................mg g1 minute1(2)
(f)Give two explanations as to why the rate of water loss during
gas exchange is very low in most insects.
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(4)
(g)Annelids like the lugworm have blood which contains
haemoglobin. The graph shows the oxygen dissociation curves for
lugworm haemoglobin and for human haemoglobin.
(i)During exercise, the rate of respiration of muscle cells
increases. Explain what causes human haemoglobin to unload more
oxygen to these cells.
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(4)
(ii)The lugworm lives in a burrow in the sand on the seashore.
When the tide is out, water bringing a fresh supply of oxygen no
longer flows through the burrow. Suggest how the lugworms
haemoglobin allows it to survive in these conditions.
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(2)
(Total 20 marks)
2.(a)Plants and insects which live in desert conditions have
adaptations which reduce water loss. The diagrams show sections
through an insect spiracle and a plant stoma.
Describe and explain two similarities in the way in which the
structures shown in these diagrams limit water loss from these
organisms.
(4)
(b)The graph shows the rate of water loss from a desert-living
insect. Over the periods of time marked X the concentration of
carbon dioxide in the air was increased from approximately 0.03% to
5%.
Suggest an explanation for the change in rate of water loss when
the carbon dioxide concentration was increased.
(3)
(Total 7 marks)
3.Answers should be written in continuous prose. Credit will be
given for biological accuracy, the organisation and presentation of
information and the way in which an answer is expressed.
Ficks law states that the rate of diffusion of a substance
across a membrane is directly proportional to the surface area of
the membrane and to the difference in concentration on either side.
It is inversely proportional to the thickness of the membrane.
Ficks law can be written in simple mathematical terms as:
Rate of diffusion (a)(i)Describe how a large difference in
oxygen concentration is maintained between a fish gill and the
surrounding water.
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(4)
(ii)Describe the adaptations of a mammalian lung which ensure a
short diffusion pathway for respiratory gases.
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(3)
(b)Explain the link between the size of an organism and the way
in which its cells are supplied with oxygen.
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(6)
(Total 13 marks)
4.(a)Explain how water enters a plant root from the soil and
travels through to the endodermis.
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(5)
(b)From the root, water is transported upwards through the stem.
Explain how evaporation from the leaves can cause the water to move
upwards.
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(4)
S(c)In daylight, most of the water evaporates from the leaves
but some is used by the plant.Describe the ways in which this water
could be used by the plant.
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(6)
(Total 15 marks)
5.The table shows the results of an investigation into how the
distribution of the roots of three species of grass varied with
depth. The figures are given as percentages of the total root dry
mass of the species concerned.
Species of grass
Soil depth/mPanicummaximumThemedratriandraEragrostissuperba
0 0.464.966.573.6
0.4 0.814.225.915.5
0.8 1.212.15.67.4
1.2 1.64.71.42.6
1.6 2.02.60.60.8
2.0 2.41.200.1
2.4 2.80.300
Total dry mass/g per plant1145827
(a)All three of these species grow in hot, dry conditions. Which
species would you expect to grow best if the ground was lightly
sprinkled with water at regular intervals? Give an explanation for
your answer.
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(2)
(b)Panicum maximum is able to survive better than the other two
species during lengthy periods of hot, dry weather. Use the data in
the table to suggest an explanation.
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(2)
(c)Describe two ways in which the leaves of plants may be
adapted for reducing water loss in hot, dry conditions.
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(2)
(Total 6 marks)
cranford community college2
