Question:

If a fresh water protozoan is placed in marine water, then what change will be observed in its contractile vacuole?

Updated On: Jun 7, 2022
  • It will increase in size.
  • It will decrease in size
  • It will collapse and become non functional
  • It will divide to form multiple vacuoles
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The Correct Option is B

Solution and Explanation

In fresh water protozoans, the function of contractile vacuole is hydrostatic or osmoregulatory. Water in freshwater protozoan enters the organism by endosmosis and during feeding. The cytoplasm of a freshwater protozoan represents a medium denser than surrounding water and outermost plasmalemma acts as a semi-permeable membrane. Thus water continuously flows inside to dilute the cytoplasm. The vacuole periodically increases in volume (diastole) to get filled with water and contracts (systole) to discharge its water content to the surrounding environment. When freshwater protozoan is placed in marine water which is denser (hypertonic) than its cytoplasmic medium then the oragnism tends to lose water. Thus contractile vaculoes will no longer need to constantly pump out the excess water and hence will decrease in size.
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Organisms and Populations

Organisms:

An attached living system that lives in an environment is commonly known as an organism. These organisms are able to retain certain behaviors and structures. Some examples of organisms are plants, animals, bacteria, fungi, and humans. A group of these organisms leads to the formation of a population. The collection of the population forms a community that assists in the operation of ecosystems. 

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Populations:

A collection of organisms or individuals of a species that live, at a specific time, in a geographical area that is well-defined and capable of interbreeding is described as a population.

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