Biological Classification And System Of Classification Question 257
Question: Two species of Amoeba X and Y were kept in fresh water and got adapted. Species X developed contractile vacuole. When both were transferred to sea water and got adapted, both X and Y lost their contractile vacuole. From these observation we conclude that
[AFMC 1983, AIIMS 1983]
Options:
A) Both X and Y are marine species
B) Species Y is marine and X is fresh water
C) Species X is marine and Y is fresh water
D) Both X and Y are fresh water
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Answer:
Correct Answer: C
Solution:
The contractile vacuole eliminates excess water which enters the cell by osmosis. Because of the hypotonic nature fresh water continuously transfers into amoeba by osmosis.
To avoid this, they develop contractile vacuoles. Marine amoeba is isotonic in water and they do not have contractile vacuoles.
Both X and Y species are marine species. That’s why they developed contractile vacuoles when they kept in freshwater.
But they lost their contractile vacuoles when transferred to seawater.
There is already hypertonic environment in seawater to control water loss by themselves.
BETA
