Question 1:
Which of
the following groups contain only biodegradable items?
(a) Grass,
flowers and leather
(b) Grass,
wood and plastic
(c) Fruit-peels,
cake and lime-juice
(d) Cake,
wood and grass
(c)Fruit-peels,
cake, and lime-juice
(d)Cake,
wood, and grass
Question 2:
Which of
the following constitute a food-chain?
(a) Grass,
wheat and mango
(b) Grass,
goat and human
(c) Goat,
cow and elephant
(d) Grass,
fish and goat
(b) Grass,
goat, and human
Question 3:
Which of
the following are environment-friendly practices?
(a) Carrying
cloth-bags to put purchases in while shopping
(b) Switching
off unnecessary lights and fans
(c) Walking to school instead of getting your mother to drop you on
her scooter
(d) All of
the above
(d) All
of the above
Question 4:
What will happen if we kill all the organisms in one trophic level?
Various
trophic levels are connected through the food chains. If all the
organisms of any one trophic level are killed, then it will disrupt
the entire food chain.
For
example, in a food chain, if all the plants are killed, then all the
deer will die due to lack of food. If all the deer are dead, then
soon the tigers will also die. Due to the death of these animals, the
decomposer’s population will rise in that area.
This
is just an example of one food chain. However, in nature, food chains
are not isolated. They are interconnected in the form of food web.
Therefore, killing all the plants of an area will not only affect the
deer, it will also affect other herbivores such as goat, cattle,
sheep, etc.
Question 5:
Will the
impact of removing all the organisms in a trophic level be different
for different trophic levels? Can the organisms of any trophic level
be removed without causing any damage to the ecosystem?
Organisms
of all trophic levels are equally important and are an integral part
of the ecosystem. If all the producers are removed, then it will
affect all the herbivores as it is their primary food source. Death
of herbivores will soon affect the primary carnivores and so on.
Now let us
suppose that all the deer (herbivores) are killed in a region. This
can lead to an increase in the number of producers. At the same time,
there will be an increase in the number of other herbivores such as
rabbits, goat, sheep, etc. due to less competition. This will also
lead to the increase in population of only consumers of these
increased herbivores. Thus, the balance in the ecosystem gets
disturbed if any of its component organisms are removed.
Question 6:
What is
biological magnification? Will the levels of this magnification be
different at different levels of the ecosystem?
Biomagnification
is the increase in the concentration of pollutants or harmful
chemicals within each step of the food chain. The levels of
biomagnification will be different at different trophic levels. For
example, in a pond of water, DDT was sprayed and the producers were
found to have 0.04 ppm concentration of DDT. Since many types of
planktons are eaten by some fishes and clams, their body accumulates
0.23 ppm of DDT. Sea gull that feeds on clams accumulates more DDT as
one sea gull eats many clams. Hawk, the top carnivore, has the
highest concentration of DDT.
Biomagnification
Question 7:
What are
the problems caused by the non-biodegradable wastes that we generate?
Non-biodegradable
substances affect the environment in the following ways:
(i) Since the non-biodegradable substances cannot be broken down,
they get accumulated and thus contaminate the soil and the water
resources.
(ii) These substances, when accidentally eaten by some stray animal,
can harm them and can even cause their death.
(iii) These substances occupy more space in the
landfills and require special disposal
techniques.
(iv) These materials can accumulate in the
environment and can also enter the food
chain.
Question 8:
If all the
waste we generate is biodegradable, will this have no impact on the
environment?
Generation
of only biodegradable waste will have a positive impact on the
environment. There will not be any pollution caused by the
non-biodegradable wastes. The problem associated with waste
management and disposal will also not occur. The population of
decomposers will increase to breakdown the extra biodegradable waste
generated.
Question 9:
Why is
damage to the ozone layer a cause for concern? What steps are being
taken to limit this damage?
Ozone
depletion occurs widely in the stratosphere. However, it is more
prominent over the Antarctic region and is known as the ozone hole.
Diagram representing ozone hole
Consequences
of ozone depletion:
- It causes skin darkening, skin cancer, ageing, and corneal cataracts in human beings.
- It can result in the death of many phytoplanktons that leads to increased global warming.
To limit the damage to
the ozone layer, the release of CFCs into the atmosphere must be
reduced. CFCs used as refrigerants and in fire extinguishers should
be replaced with environmentally-safe alternatives. Also, the release
of CFCs through industrial activities should be controlled.