Question

Icefish and Antarctic fish remain active in extremely cold water due to?
(a) Development of a thick layer of subcutaneous fat
(b) Development of extra solute in body fluids
(c) Development of ice-nucleating protein in extracellular spaces
(d) Both (2) and (3)

Answer 1

Hint: Plants and animals have modifications in their body to survive the environment in which they are living. Fishes that live in ice-cold water are able to do so because of a special compound in them. Also, ice acts as an insulator and does not allow the cold outside to freeze the water, thus allowing aquatic animals to thrive.

Complete Answer:
Icefish and Antarctic fish are able to remain active in extremely cold water because they have extra solutes present in them such as glycerol and antifreeze proteins that do not allow these fishes to freeze. This antifreeze protein is an ice- nucleating protein found in extracellular spaces (interstitial spaces) of the fishes. Glycerol is also an anti- freezing agent and thus helps fishes to not freeze by lowering the freezing temperature of their body fluids.

Additional information: Let us look at the functioning of this antifreeze protein found in such fishes.
- The antifreeze was first extracted from the body of the Antarctic toothfish and mixed with water.
- A special method was used to record the movement of water molecules.
- It was observed that the antifreeze made the water molecules move in a very ordered way.
- This caused the water molecules to not interact with each other and thus not make any covalent bonds.
- In this way, the antifreeze prevented the formation of ice by preventing the formation of covalent bonds.
So, the correct option is ‘Both (2) and (3) ’.

Note:
- Organisms that can tolerate a wide range of salinities in water are known as euryhaline and those that cannot are known as stenohaline.
- Usually, very small organisms are not found in cold polar regions as their surface to volume ratio is very high and thus they lose heat at a much faster rate.
- A thick layer of subcutaneous fat known as blubber is seen in seals.