The direction of energy flow in an ecosystem is:
uni-directional but in any direction
multi-directional
uni-directional but from lower trophic level towards the higher trophic level
bi-directional
(3)
Energy flows in a unidirectional manner in an ecosystem from the lower trophic level towards the higher trophic level.
Cutting of forests for growing crops would:
reduce the stability of the ecosystem
enhance the stability of the ecosystem
not affect the stability of the ecosystem
first increase and then decrease the stability of the ecosystem
(1)
Cutting a large number of trees would affect all the other organisms dependent on those plants. Many organisms would even die. Some would migrate to other places. All such events would disturb the ecological balance and thus would decrease the stability of the ecosystem.
Which activity would gradually reduce the occurrence of pests, thereby reducing damage to the crops year by year without affecting the environment?
Use of nitrogen based fertilizer
Crop rotation
Use of DDT
Use of manure
(2)
Crop rotation can gradually reduce the occurrence of pests, thereby reducing damage to crops year by year without affecting the environment.
Fish diet can play significant role in biological magnification of pesticides like DDT because:
harmful chemicals get washed into water bodies and enter the aquatic food chains.
fishes can also produce these chemicals in their bodies.
fishes increase in number rapidly.
fishes have special enzymes in their body to digest these pesticides.
(1)
Biological magnification occurs when the harmful chemicals used in the crop fields get washed into water bodies and enter the food chains.
Biological magnification is defined as:
the accumulation of harmful chemicals at each trophic level of the food chain.
the accumulation of organic matter at the first trophic level of the food chain.
the reduction of energy at each trophic level of the food chain.
an increase in the population of a species at each trophic level of the food chain.
(1)
The accumulation of harmful chemicals at each trophic level is called biological magnification.
Which agricultural activities are affecting the environment?
Overuse of fertilisers and pesticides
Using groundwater for irrigation
Extensive cropping in the same area of land
All of the above
(4)
Different agricultural activities are affecting the environment. Fertilisers and pesticides are non-biodegradable. They cause soil and water pollution. Soil loses fertility due to extensive cropping and water table is lowering due to the overuse of groundwater for irrigation.
Pesticide can disturb the balance within the ecosystem by:
indiscriminately killing pests and the predators of these pests
biomagnification
eutrophication
bioaccumulation
(1)
Pesticides can disturb the balance within the ecosystem by indiscriminately killing pests and the predators of these pests.
Which of the following are environment friendly practices?
Carrying cloth bags to put purchases in while shopping
Switching off unnecessary lights and fans.
Walking to school instead of getting your mother to drop you on her scooter.
All of the above
(4)
Being eco-friendly refers to a way of life that is better for the environment. It involves taking little measures towards ensuring that the Earth’s environment is properly maintained for current and future generations. Carrying cloth bags to put purchases in while shopping, switching off unnecessary lights and fans, walking to school instead of getting your mother to drop you on her scooter are all examples of environment friendly practices.
Several factories were pouring their wastes in rivers A and B. Water samples were collected from these two rivers. It was observed that sample collected from river A was acidic while that of river B was basic. The factories located near A and B are:
Soaps and detergents factories near A and alcohol distillery near B.
Soaps and detergents factories near B and alcohol distillery near A.
Lead storage battery manufacturing factories near A and soaps and detergents factories near B.
Lead storage battery manufacturing factories near B and soaps and detergents factories near A.
(3)
The lead storage batteries use sulphuric acid which is acidic in nature while soaps and detergents are basic in nature.
Excessive exposure of humans to UV rays results in:
(i) damage to immune system
(ii) damage to lungs
(iii) skin cancer
(iv) peptic ulcers
(i), (ii)
(ii), (iv)
(i), (iii)
(iii), (iv)
(3)
UV rays are extremely hazardous to humans, animals, and even plants. It can cause skin cancer, cataracts in the eyes, and immune system damage by reducing the body’s response to infections.
