Which one of the following is an artificial ecosystem?
Pond
Crop field
Lake
Forest
In a food chain, the third trophic level is always occupied by
carnivores
herbivores
decomposers
producers
An ecosystem includes
all living organisms
non-living objects
both living organisms and non-living objects
sometimes living organisms and sometimes non-living objects
In the given food chain, suppose the amount of energy at fourth trophic level is 5 kJ, what will be the energy available at the producer level?
Grass → Grasshopper → Frog → Snake → Hawk
5 kJ
50 kJ
500 kJ
5000 kJ
Accumulation of non-biodegradable pesticides in the food chain in increasing amount at each higher trophic level is known as
eutrophication
pollution
biomagnification
accumulation
Depletion of ozone is mainly due to
chlorofluorocarbon compounds
carbon monoxide
methane
pesticides
Organisms which synthesise carbohydrates from inorganic compounds using radiant energy are called
decomposers
producers
herbivores
carnivores
In an ecosystem, the 10% of energy available for transfer from one trophic level to the next is in the form of
heat energy
light energy
chemical energy
mechanical energy
Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the
food web
ecological pyramid
ecosystem
food chain
Flow of energy in an ecosystem is always
unidirectional
bidirectional
multi directional
no specific direction
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) and (ii)
(ii) and (iv)
(i) and (iii)
(iii) and (iv)
In the following groups of materials, which group(s) contains only non-biodegradable items?
(i) Wood, paper, leather
(ii) Polythene, detergent, PVC
(iii) Plastic, detergent, grass
(iv) Plastic, bakelite, DDT
(iii)
(iv)
(i) and (iii)
(ii) and (iv)
Which of the following limits the number of trophic levels in a food chain?
Decrease in energy at higher trophic levels
Insufficient food supply
Polluted air
Water
Which of the statement is incorrect?
All green plants and blue green algae are producers
Green plants get their food from organic compounds
Producers prepare their own food from inorganic compounds
Plants convert solar energy into chemical energy
Which group of organisms are not constituents of a food chain?
(i) Grass, lion, rabbit, wolf
(ii) Plankton, man, fish, grasshopper
(iii) Wolf, grass, snake, tiger
(iv) Frog, snake, eagle, grass, grasshopper
(i) and (iii)
(iii) and (iv)
(ii) and (iii)
(i) and (iv)
The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about
1 %
5 %
8 %
10 %
In the given Figure 15.1 the various trophic levels are shown in a pyramid. At which trophic level is maximum energy available?
T4
T2
T1
T3
What will happen if deer is missing in the food chain given below?
Grass → Deer → Tiger
The population of tiger increases
The population of grass decreases
Tiger will start eating grass
The population of tiger decreases and the population of grass increases
The decomposers in an ecosystem
convert inorganic material, to simpler forms
convert organic material to inorganic forms
convert inorganic materials into organic compounds
do not breakdown organic compounds
If a grass hopper is eaten by a frog, then the energy transfer will be from
producer to decomposer
producer to primary consumer
primary consumer to secondary consumer
secondary consumer to primary consumer
Disposable plastic plates should not be used because
they are made of materials with light weight
they are made of toxic materials
they are made of biodegradable materials
they are made of non-biodegradable materials
Why is improper disposal of waste a curse to environment?
Wastes pollute our environment — air, soil and water — and cause harmful effects on all living organisms.
Write the common food chain of a pond ecosystem.
Phytoplanktons and aquatic plants → small aquatic animals (larvae, insects etc.) → fish → bird
What are the advantages of cloth bags over plastic bags during shopping?
(a) Capable of carrying more things
(b) Made of biodegradable material
(c) Do not pollute our environment
(d) Can be reused
Why are crop fields known as artificial ecosystems?
Crop fields are man-made and some biotic and abiotic components are manipulated by humans.
Differentiate between biodegradable and non-biodegradable substances. Cite examples.
Biodegradable substances are broken down into simpler substances by biological processes. Example: wood, paper.
Non-biodegradable substances cannot be broken down into simpler substances by biological processes. Example: plastic, DDT.
Suggest one word for each of the following statements/definitions:
(a) The physical and biological world where we live in
(b) Each level of food chain where transfer of energy takes place
(c) The physical factors like temperature, rainfall, wind and soil of an ecosystem
(d) Organisms which depend on the producers either directly or indirectly for food
(a) Environment/biosphere
(b) Trophic level
(c) Abiotic factors
(d) Consumers/heterotrophs
Explain the role of decomposers in the environment.
Decomposers break down dead and decaying organic matter and return the nutrients to the soil. They play an important role in nutrient recycling in the environment.
Select the mis-matched pair in the following and correct it:
(a) Biomagnification — Accumulation of chemicals at successive trophic levels of a food chain
(b) Ecosystem — Biotic components of environment
(c) Aquarium — A man-made ecosystem
(d) Parasites — Organisms which obtain food from other living organisms
(b) is not a matching pair.
Correct statement: Both biotic and abiotic components of environment constitute an ecosystem.
We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?
An aquarium is an artificial and incomplete ecosystem, whereas ponds and lakes are natural, self-sustaining and complete ecosystems.
Indicate the flow of energy in an ecosystem. Why is it unidirectional? Justify.
The general flow of energy in an ecosystem is:
Sun → Producer → Herbivore → Carnivore
Energy flows progressively from one trophic level to another and does not revert back. Hence, it is said to be unidirectional.
Available energy decreases at higher trophic levels, making it impossible for energy to flow in the reverse direction.
What are decomposers? What will be the consequence of their absence in an ecosystem?
Decomposers break down complex organic substances of garbage, dead animals and plants into simpler inorganic substances. These substances go into the soil and are reused by plants.
In the absence of decomposers, recycling of material in the biosphere will not take place.
Suggest any four activities in daily life which are eco-friendly.
(i) Separation of biodegradable and non-biodegradable substances
(ii) Gardening
(iii) Use of gunny bags/paper bags instead of polythene/plastic bags
(iv) Use of compost and vermicompost in place of fertilisers
(v) Harvesting rainwater
Give two differences between food chain and food web.
| Food Chain | Food Web |
|---|---|
| (a) Food chain is a series of organisms feeding on one another. | (a) Food web consists of a number of interlinked food chains. |
| (b) Members of higher trophic level feed upon a single type of organism of the lower trophic level. | (b) Members of higher trophic level can feed upon organisms of the lower trophic levels of other food chains. |
Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Household wastes include:
(a) Kitchen wastes
(b) Paper wastes like newspapers, bags, envelopes
(c) Plastic bags
(d) Vegetable/fruit peels/rinds
Measures for disposal:
(a) Segregation of biodegradable and non-biodegradable wastes
(b) Safe disposal of plastic bags
(c) Vegetable/fruit peels can be placed near trees/plants; on decomposition they enrich the soil with nutrients
(d) Give paper wastes for recycling
(e) Prepare a compost pit for kitchen wastes
Suggest suitable mechanism(s) for waste management in fertiliser industries.
(a) Control of air pollution
(b) The effluent should be treated before discharge into the surrounding environment
What are the by-products of fertiliser industries? How do they affect the environment?
The harmful by-products are gases such as SO2 and NO. They cause extensive air pollution and are responsible for acid rain.
Explain some harmful effects of agricultural practices on the environment.
(a) Excessive use of fertilisers changes the chemistry of soil and kills useful microbes.
(b) Excessive use of non-biodegradable chemical pesticides leads to biological magnification.
(c) Extensive cropping causes loss of soil fertility.
(d) Excess use of groundwater for agriculture lowers the water table.
(e) Damage to natural ecosystem/habitat.