Natural Science-Biology: ecology and eco-columns
Year 9
Name______________________________________________
Marks:
40
Instructions:
1. Answer all the questions.
QUESTION 1: MULTIPLE CHOICE. Place one letter of your choice
in the box provided.
1.1 Survival of an organism in any ecosystem depends on
a) biotic factors only
b) physical factors only
c) both biotic and abiotic factors
d) none of the above
1.2 Decomposers are
a) microscopic organisms which cause dead animals to decay
b) are only secondary consumers
c) animals which eat the flesh and organs of dead organisms
d) organisms that produce their own organic food
1.3 Study the food chain below
algae→ snail → fish → human
Which of the following is most unlikely to happen if humans over-fish
and damage the fish population?
a) an increase in algae and snail populations
b) a decrease in fish as food for humans
c) an increase in snail populations
d) a decrease in algae populations
1.4 The correct sequence of the group of ecological terms from the
simplest to the most complex is
a) Population, organism, ecosystem, community
b) Population, community, organism, ecosystem
c) Organism, ecosystem, population, community
d) Organism, population, community, ecosystem
1
1.5 Small unicellular organisms with a nucleus are classified in the
kingdom
a) Fungi
b) Prokaryotes
c) Protista
d) Animals
(5x2=10)
QUESTION 2
2.1 Some year 9 ISCT boys conducted an investigation on the effects
of the presence of plants on soil erosion. The diagram below shows the
apparatus used.
Tray A contained soil only
Tray B contained the same type of soil, but with grass growing in it
Water from a spray was allowed to fall into each tray. Any water
running off was collected and examined for soil washed from the tray.
2.1.1 Identify two variables which must be kept constant in both sets
of apparatus during the experiment
(2)
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2.1.2 Identify the variable which was altered in this investigation (1)
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2
2.1 3 Write an interpretation for the results of this experiment. Hint:
look at the level of the water collected in the beakers in the
diagram.
(4)
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2.2 Study the incomplete equation of a biological process below
Sun light
Carbon dioxide and water → glucose and b
a
2.2.1 Give the missing labels for a and b
a: ______________________
(2)
b:_______________________
2.2.2 What is the name of this biological process as shown in the
equation?
(1)
________________________________________________________
2.2.3 Give two factors which could limit the rate at which this
biological process takes place
(2)
________________________________________________________
________________________________________________________
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QUESTION 3
3
Scientists from the University of Cape Town found that the Virginia Creeper plant
grows faster and larger with more carbon dioxide available in the atmosphere.
They are currently testing the effect of carbon dioxide on the mass of the Virginia
Creeper leaf. The results from a similar experiment are presented below.
Table showing the effect of carbon dioxide on the increase in mass of
Virginia creeper leaves
3.1
Concentration of carbon dioxide (%)
Mass Virginia creeper leaf (g)
0
50
2
53
4
59
5
61
8
64
10
65
15
66
Name the independent variable in this investigation.
(1)
________________________________________________________
3.2
Name the dependent variable.
(1)
________________________________________________________
3.3 Write a conclusion for this experiment
(2)
________________________________________________________
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4
3.4 Draw a graph to illustrate the results in the table of concentration
of carbon dioxide and the mass of the Virginia creeper leaf.
(10)
Mark scheme for graph:
All correct = 2
One mistake = 1
More than one mistake = 0
Axes correctly identified and labelled with units
An appropriate scale used
An appropriately descriptive title used for the graph
Graph plotted accurately
Points joined accurately and in pencil. Axes and labels in pen.
5
10
Total
3.5 Refer to the diagram below to answer the questions.
3.5.1 What is the name given to the diagram above?
(1)
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3.5 2 What type of consumer can fill position X?
(1)
________________________________________________________
3.5.3 What effect would it have on the snail population if the worms
were removed from the diagram above? Give a reason for your
answer.
(2)
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TOTAL
40
6