Pests which only feed and oviposit on crop are called
major pests
minor pests
accidental pests
occasional pests
In which stage of its life cycle, the silk moth begins to produce silk fibre?
3rd instar larva
4th instar larva
5th instar larva
Pupa
Increase of BOD in water leads to
increase in the dissolved O2 concentration
decrease in the dissolved O2 concentration
maintenance of dissolved O2 concentration at the same level
no effect on dissolved O2 concentration
B.
decrease in the dissolved O2 concentration
Biochemical Oxygen Demand (BOD) is the oxygen in milligrams required-for five days in one litre of water at 20C for the micro-organisms to metabolise organic waste. Increase of BOD in water leads to decrease in the dissolved oxygen concentration.
Freon gas causing stratospheric O3 depletion is mainly released from
refrigerator
automobile
thermal power plant
steel industry