Maintenance of soil fertility without addition of nutrition is due to
Floods
Crop residue
Favourable temperature
Microbial activity
Agents which make free atmospheric nitrogen available to plants are
Lightning
Free living nitrogen fixing bacteria
Symbiotic nitrogen fixing bacteria
All the above
Process of evapo-transpiration and precipitation is called
Carbon cycle
Nitrogen cycle
Hydrological cycle
Component of biosphere related with soil is
Lithosphere
Hydrosphere
Atmosphere
None of the above
A logical sequence of carbon cycle is
Producer-Consumer-Decomposer
Decomposer-Producer-Decomposer
Consumer-Producer-Consumer
Producer-Decomposer-Consumer
Green-house gases are
Absorbers of long-wave radiations from earth
Transparent to both solar radiations and long-wave radiations from earth
Absorbers of solar radiations for warming the atmosphere of earth
Transparent to emissions from earth for passage into outer space
Biosphere consists of
Amount of carbon fixed annually through photosynthesis is
4.6 Χ 1010 kg
7 Χ 1013 kg
7 Χ 1020 kg
4.6 Χ 1021 kg
The reason for green house effect is
Higher CO2 concentration causing global warming
Absorption of infra-red rays by gases and dust particles
Both A and B
Refraction of CO2
In one year, one hectare of forest shall
Consume 10 tonnes of CO2 and evolve 10 tonnes of O2
Consume 20 tonnes of CO2 and evolve 10 tonnes of O2
Consume 30 tonnes of CO2 and evolve 30 tonnes of O2
The combustion of fossil fuels and deforestation have caused the atmospheric concentration of carbon dioxide to increase by about 35% since the beginning of the age of industrialization. Hence consumption of carbon dioxide will increase every year.
