January 27, 2015

Jr Inter Zoology SA Questions from Ecology and Environment

Q: Explain Vant' Hoff rule
A: i. Van't Hoff stated that "with the increase of every 10°C, the
rate of metabolic activities doubles". It was popularly called Vant'
Hoff rule.
ii. It also states that with the decrease of every 10°C, the Naction
rate is halved.
iii. The effect of temperature on rate of a reaction is expressed in
terms of temperature coefficient or Q10
iv. In the living systems the Q10 value is about 2.0

Q: Describe green house effect.
A: Under normal conditions the temperature at the surface of earth is
maintained by the energy balance of sun rays that strike the earth and
heat that is radiated back into space. However, when there is an
increase in concentration of green house gases (like CO2, methane
etc.) in the atmosphere prevents the heat from being reradiated out.

The thick layer of green house gases acts like the glass panels of a
green house, allowing the sun light to filter through but preventing
the heat from being re-radiated into outer space. This is so called
green house effect. Thus most heat is absorbed by the green house
gases and water vapour adds to the heat already present.

The net result is the heating up of the earth's atmosphere (global
warming). As a result, meeting of ice caps in polar regions resulting
in rise of sea levels, causing submersion of certain islands and
coastal areas.

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