Xeric environment is characterized by
Precipitation
Low atmospheric humidity
Extremes of temperature
High rate of vapourization
The rate at which light energy is converted into chemical energy of organic molecules is the ecosystem's:
Net primary productivity
Gross secondary productivity
Net secondary productivity
Gross primary productivity
Sewage drained into water bodies kill fishes because:
Excessive carbon dioxide is added to water.
It gives off a bad smell.
It removes the food eaten fish.
It increases competition with fishes for dissolved oxygen.
In a biotic community,the primary consumers are
Carnivores
Omnivores
Detritivores
Herbivores
Green -house effects is warming due to
Infra-red rays reaching earth
Moisture layer in atmosphere
Increase in temperature due to increase in carbon dioxide concentration of atmosphere
Ozone layer of atmosphere
Which one of the following organism is used as indicator of water quality ?
Beggiatoa
Chlorella
Azospirillum
Escherichia
Niche of a species in an ecosystem refers to its:
Function at its place of occurrence
Place of its occurrence
Competitive ability
Centre of origin
Phosphate pollution is mainly caused by:
Phosphate rock only.
Agricultural fertilizers only.
Sewage and phosphate rocks.
Sewage and agricultural fertilizers.
Soil water available to roots is
Surface water
Hygroscopic water
Gravitational water
Capillary water
When huge amount of sewage is dumped into a river, its BOD will:
Increase
Decrease
Sharpily decrease
Remain unchanged
