An amoeba, Amoeba proteus, is a relatively large nonphotosynthetic, single-celled organism - VCE - SSCE Biology - Question 20 - 2005 - Paper 1
Question 20
An amoeba, Amoeba proteus, is a relatively large nonphotosynthetic, single-celled organism. Pond water can be used to grow cultures of amoebae. At a constant tempera... show full transcript
Worked Solution & Example Answer:An amoeba, Amoeba proteus, is a relatively large nonphotosynthetic, single-celled organism - VCE - SSCE Biology - Question 20 - 2005 - Paper 1
Step 1
A. bubble carbon dioxide into the pond water
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Answer
The addition of carbon dioxide could potentially lead to increased respiration rates, which may not significantly hinder the reproduction time. Thus, this modification may result in an effect of more than 50 hours.
Step 2
B. double the density of amoebae in the pond water
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Answer
Doubling the density of amoebae can lead to competition for resources, which could decrease the reproduction rate. Therefore, the effect is likely to be less than 50 hours.
Step 3
C. decrease temperature of the pond water from 18°C to 10°C
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Lowering the temperature can slow down biochemical processes, including reproduction. Hence, this change would predictably lead to a longer reproduction time of less than 50 hours.
Step 4
D. increase the intensity of light falling on the pond water
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Answer
An increase in light intensity may enhance photosynthetic activity in green organisms but is not applicable to Amoeba proteus, which is nonphotosynthetic. This modification may lead to stress or adverse effects, predicting an increase in reproduction time of more than 50 hours.
