Give reason for the following  The water-potential of pure wate

Subject

Biology

Class

ICSE Class 12

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

11.

Give one significant difference between each of the following:

Open vascular system and closed vascular system.

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12.

Give one significant difference between each of the following:

Uricotelism and Ammonotelism.

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13.

Give one significant difference between each of the following:

Auxetic growth and Accretionary growth.

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14.

Give reason for the following

Most people living in hilly region suffer from goiter.

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15.

Give reason for the following

 The water-potential of pure water changes when solute is added to it.


The water potential of pure water in an open container is zero because there is no solute and the pressure in the container is zero. Adding solute lowers the water potential by consuming some of the potential energy available in the water. Solute molecules can dissolve in water because water molecules can bind to them via hydrogen bonds; a hydrophobic molecule like oil, which cannot bind to water, cannot go into solution. The energy in the hydrogen bonds between solute molecules and water is no longer available to do work in the system because it is tied up in the bond. In other words, the amount of available potential energy is reduced when solutes are added to an aqueous system.
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16.

Give reason for the following

When we turn round and round, we lose our balance.

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17.

Give reason for the following

The spores of Bacillus thringiesis are used as bioinsecticide.

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18.

Give reason for the following

Owls have better night vision than day vision.

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19.

Give scientific terms for each of the following

Adjustment of the eye in order to obtain a clear vision of objects at different distances.

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20.

Give scientific terms for each of the following

A device to measure growth in length of a plant.

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