Q.
State the role of the atmosphere in climate control?
Ans: Atmosphere
prevents sudden increase in temperature during the day light hours. It slows
down the escape of heat into outer space during the night.
Q. How
is acid rain caused ?
Ans: The fossil fuels
like coal and petroleum/contain small amounts of nitrogen and sulphur/When the
fossil fuels are burnt,/nitrogen and sulphur are burnt/and produces different
oxides of nitrogen and sulphur/When these oxides dissolve in rain it gives rise
to acid rain.
Q. What
are the different ways in which water gets polluted ? How does it affect the
life forms ?
Ans: (a) The addition
of undesirable substances like fertilizers and pesticides, mercury salts in
water/can cause cholera produced by the bacteria.
(b) The removable of
desired substances like oxygen from the water/adversely affect the aquatic
organisms.
(c) A sudden change
in temperature in water bodies/would be dangerous and effect their breeding.
The eggs and larvae are affected by the change in temperature.
Q. What
are the biogeochemical cycles ? Name the gas that is incorporated into life
forms through photosynthesis.
Ans: The transfer of energy
and matter between the biotic components of the biosphere is called
biogeochemical cycle.
The
gas that is incorporated into life forms through photosynthesis is
carbondioxide
Q. What
is the function of humus in soil?
Ans: Humus cause the soil to
become more porous and allows water and air to penetrate deep underground
Q. List the
causes that affect the life forms that are found in water bodies in various
ways. Name the element present in coal other than carbon that releases harmful
gases during combustion of coal.
Ans:(i) Excess of
fertilizers and pesticides used in the farms are washed into water bodies.
(ii)
Dumping of sewage from dwelling places into water bodies
(iii) Release of hot
water contaminated water from industries.
(iv) Release of water from dams
affect the temperature of river.
(b) Sulphur and nitrogen
Q. Explain how
the nitrogen molecules are converted into nitrates and nitrites by
(i)
Biological Process (ii) Physical process.
Ans: Biological process :
Nitrogen fixing bacteria found in the root nodules of the legumes convert
nitrogen molecules to nitrates and nitrites.
Physical process : During
lightning, the high temperature and pressure created in the air convert
nitrogen into oxides of nitrogen. These oxides dissolve in water to give nitric
and nitrous acids. These acids when falls to land form nitrates and nitrites.
Q. What is the
main cause of increase in CO2 in atmosphere ? Explain the harmful effect of
increase in CO2 content in atmosphere
Ans: Industrial revolution
is the main cause of increase in carbon dioxide in the atmosphere.
Increase in carbon dioxide gives rise to green
house effect. This increases global warming. This causes imbalance in nature,
affects monsoons and rainfall.
Q. What is
ozone hole ? Where is it found ? What is its effect ?
Ans: (a) In the upper
regions of the atmosphere there is a layer of ozone , which gets deflected due
to chlofluro carbons and created a hole that is called ozone hole.
(b) it is
found above antartica/over north pole
(c) UV radiation will reach the earth and
cause disease – cancer, reduce immunity, reduce crop yield.
Q. (a) A motor
car with its glass totally closed is parked directly under the sun. The inside
temperature of the car rises very high. Explain why ?
(b) Why lichens do not
occur in Delhi whereas they commonly grow in Manali or Darjeeling ?
(c) How are
root modules useful for the plants ?
Ans: (a) Glass trap sunlight
that heats up the interior. Since glass is an insulator heat waves do not
escape. Thus, Interior of the car becomes very hot similar to glass house
effect.
(b) Lichens are sensitive to
sulphur dioxide which occur in sufficient quantity in Delhi. Delhi is semi arid
– atmosphere and moisture is very low. In Manali and Darjeeling atmosphere is
Humid. Sulphur dioxide pollution comparatively low.
(c) Root nodules contain
Nitrogen fixing bacteria. Nitrogen from atmosphere is converted into organic
compounds in soil.
Q. Why is step
farming common in hills ?
Ans This is because step farming
prevents soil erosion from the fast flowing water
Q. Which cycle is
known as the perfect cycle in biosphere? Why?
Ans. Nitrogen cycle is known as the perfect cycle in biosphere as it
maintains the over all amount of nitrogen constant in atmosphere, water and
soil.
Natural
Resources class 9 CBSE NCERT Solved Questions with solutions
|
|
CCE Test Paper Biology Chapter Natural Resources
ix Biology-1
|
|
CCE Test Paper Biology Chapter Natural Resources
ix Biology-2
|
|
CBSE Class 9th natural resources Solved
Board Questions
|
Download File
|