1. Multiple choice questions.
(i) Which one of the following is included in biosphere?
(a) only plants
(b) all living
and non-living organisms
(c) only animals
(d) all living organisms
(ii) Tropical grasslands are also known as :
(a)
the prairies
(b) the savannas
(c) the steppes
(d) none of the above
(iii) Oxygen combines with iron found in the rocks to form :
(a)
iron carbonate
(b) iron nitrites
(c) iron oxides
(d) iron sulphate
(iv) During photosynthesis, carbon dioxide combines with
water in the presence of sunlight to form : (a) proteins
(b) amino acids
(c) carbohydrates
(d) vitamins
2. Answer the following questions in about 30 words.
(i) What do you understand by the term ‘ecology’?
Ans. The term ecology is derived from the Greek word ‘oikos’
meaning ‘house’, combined with the word ‘logy’ meaning the ‘science of’ or ‘the
study of’. Ecology is the study of the earth as a ‘household’, of plants, human
beings, animals and micro-organisms.
(ii) What is an ecological system? Identify the major types
of ecosystems in the world.
Ans. The interactions of a particular group of organisms with
abiotic factors within a particular habitat resulting in clearly defined energy
flows and material cycles on land, water and air, are called ecological
systems.
The two major types of ecosystem are - terrestrial and
aquatic
(iii) What is a food-chain? Give one example of a grazing
food-chain identifying the various levels.
Ans. This sequence of eating and being eaten and the
resultant transfer of energy from one level to another is known as the
food-chain. For e.g. – Plants (producers) get eaten by rabbits, deer, cow
etc...(herbivores animals), similarly herbivores animals get eaten by fox,
lion, tiger, eagle etc...(carnivores animals).
(iv) What do you understand by the term ‘food web’? Give
examples.
Ans. A food web is a natural interconnection of food chains.
In other words, a network of food chains mixed together to form food web.
(v) What is a biome?
Ans. A biome is a plant and animal community that covers a
large geographical area. This geographical area is usually determined by
climate.
3. Answer the following questions in about 150 words.
(i) What are bio-geochemical cycles? Explain how nitrogen is
fixed in the atmosphere.
Ans. Bio-geochemical cycles are chemical exchange between
living organisms that is where the term “bio” come from, and the “geographic”
element of the earth such as - rocks, soil, air, and water. In simple terms, it
is a cycle that shows the movement of chemical elements between the biotic
(living organism) and the abiotic (non-living organism) components of the
environment.
Nitrogen is a major constituent of the atmosphere comprising
about 79% of the atmospheric gases. Nitrogen is considered as an unreactive
gas. Nitrogen gas is formed when two nitrogen atoms bond together. Nitrogen
molecules have a triple covalent bond and it requires a huge amount of energy
to break triple bonds. Hence, this massive energy can be obtained by lightning
and cosmic radiation.
(ii) What is an ecological balance? Discuss the important
measures needed to prevent ecological imbalances.
Ans. Ecological balance is a state where there is equality
between organisms and their environment in terms of coexistence.
Ecological imbalance occurs due to the introduction of new
species, natural hazards or human causes.
Measures to prevent ecological imbalance:-
1. Manage Natural Resources Carefully
2. Controlling Population - reducing human consumption of
natural resources
3. Protecting the Water
4. Recycling
5. Planting more trees
6. Improving farming techniques to avoid land degradation
7. Shifting from Fossil Fuels to Sustainable Energy