Chapter Practice
PART 1
5.
In the given food chain, organisms are labelled as A
to D. Match the labelling referred in Column I
Objective Questions
with their most suitable feature in Column II.
Multiple Choice Questions
1.
Which of the following is an incorrect pair?
D
(a) River—Natural ecosystem
(b) Air—Biotic component
C
(c) Crop field—Artificial ecosystem
(d) Water—Abiotic component
B
2.
Which of the following is not a functional component of
A
an ecosystem?
(a) Communities
Column I
Column II
(b) Decomposers
A
1. Primary carnivore
(c) Sunlight
B
2. Secondary carnivore
(d) Energy flow
C
3. Autotrophs
3.
Flow of energy in an ecosystem is always
D
4. Primary consumer
(a) unidirectional
(NCERT Exemplar)
Codes
(b) bidirectional
A B C D
A B C D
(c) multidirectional
(a)
3
4
1
2
(b)
4
3
2
1
(d) no specific direction
(c)
3
1
4
2
(d)
3
2
1
4
4.
The diagram represents the flow of energy within a
6.
What will happen if deer is missing in the food
balanced ecosystem.
chain given below?
(NCERT Exemplar)
The boxes represents various trophic levels. Select the
Grass → Deer → Tiger
option which gives correct identification and main
(a) The population of tiger increases
function or characteristic
(b) The population of grass decreases
(c) Tiger will start eating grass
P
Q
R
(d) The population of tiger decreases and the population of
grass increases
S
7.
The diagram shows the flow of energy through an
ecosystem.
(a) P-Producers : They are heterotrophic in nature
(b) Q-Primary consumers : They eat only plants and their products
3
4
(c) R-Herbivores : They are secondary consumers
Primary
Secondary
(d) S-Decomposers : They act as tertiary consumers in a food chain
Sun
Producers
1
consumers
2
consumers
The smallest amount of energy transferred between
11.
Identify the option that indicates the same trophic
organisms and the largest amount of energy lost to
level of different organisms in the given food web.
the ecosystem is represented by which arrows?
Smallest energy transfer
Largest energy loss
(a)
4
3
(b)
2
1
(c)
2
3
(d)
1
4
8.
Which of the following represents the labelled parts
X and Y correctly?
Phytoplankton
Zooplankton
Y
X
X
Y
(a) Primary consumer
Producer
(a) Goat, Snake, Owl
(b) Rabbit, Fox, Peacock
(b) Secondary consumer Decomposer
(c) Frog, Fish, Bird
(d) Tiger, Fox, Eagle
(c) Primary consumer
Secondary consumer
12.
What happens in biological magnification?
(a) There is a progressive increase in the level of harmful
(d) Carnivore
Herbivore
substances through trophic levels
(b) There is a progressive increase in the body weight
9.
Carefully study the given pyramid of energy flow in
through trophic levels
an ecosystem. Select the option which gives correct
(c) There is a progressive increase in number of organisms
identification and their examples.
through trophic levels
(d) There is a progressive increase in biological activities
through trophic levels
T4
T
13.
Which of the following chemicals cause the thinning
3
of layer P?
T
2
Sunlight
T1
(a) T1—Herbivores—Deer
(b) T2—Producers—Fungi
Layer P
(c) T3—Omnivores—Bear
(d) T4—Decomposers—Grass
10.
Which of the following pyramid given below
Earth
correctly represents the food chain?
(a) Sulphur dioxide
(b) Nitrogen dioxide
(c) Chlorofluorocarbon
(d) Carbon dioxide
Plants
Plants
14.
Which of the following is the correct reaction
(a)
Caterpillars
(b)
Toads
involved in formation of ozone layer?
Toads
Caterpillars
UV
(a) O
2
⎯ ⎯→
O+ O;O+ O
2
⎯→
O
3
Snakes
Snakes
(b) O + O
⎯→
O2;O + O
2
⎯→
O
3
Infrared
(c) O
2
⎯⎯⎯⎯ →
O +O;O + O + O
⎯→
O3
(d) O
2
+
O
⎯→
O
3
;O
3
⎯→
2
O +O
Snakes
Snakes
15.
Burning of waste products at high temperature to
(c)
(d)
Toads
Toads
form ash, reduces waste considerably. This method
Caterpillars
Plants
of waste disposal is called
Plants
Caterpillars
(a) composting
(b) sewage treatment
(c) recycling
(d) incineration
(i)
The correct order of animals in food chain
Assertion-Reasoning MCQs
operating in a river is
Direction (Q. Nos. 16-20) Each of these questions
(a) W → X → Y → Z
(b) Y → W→ X → Z
contains two statements, Assertion (A) and Reason (R).
(c) Z → X → W → Y
(d) X → W → Z → Y
Each of these questions also has four alternative choices, any
(ii)
If concentration of DDT in W is estimated to
oneof which is thecorrect answer.You have to select oneof
be 0.4 ppm, then amount of DDT in Y and Z
the codes (a), (b), (c) and (d) given below.
would respectively be
(a) Both A and R are true and R is the correct explanation of A
(a) 0.02 ppm and 2 ppm
(b) Both A and R are true, but R is not the correct explanation
(b) 2 ppm and 0.02 ppm
of A
(c) 0.3 ppm and 0.5 ppm
(c) A is true, but R is false
(d) 0.04 ppm and 0.02 ppm
(d) A is false, but R is true
(iii).
Due to biomagnification, which of the following
16.
Assertion Biotic components of an ecosystem include all
substances accumulate and go on concentrating
the living organisms present in that ecosystem.
at each trophic level?
Reason Biotic components also include wind, gases,
(a) Biodegradable substances
light, etc.
(b) Non-biodegradable substances
(c) Biotic components
17.
Assertion Food chains generally consist of more than
(d) Abiotic components
four trophic levels.
(iv)
The decomposers are not included in the food
Reason There is loss of energy at each trophic level
chain. The correct reason for the same is
and very little usable energy remains after four trophic
because decomposers :
levels.
(a) act at every trophic level of the food chain
(b) do not breakdown organic compounds
18.
Assertion Producers are present at the first trophic level.
(c) convert organic material to inorganic forms
Reason Consumers or heterotrophs fix energy and make
(d) release enzymes outside their body to convert
it available for autotrophs.
organic material to inorganic forms
19.
Assertion Certain pesticides and other chemicals used to
(v)
Which amongst the following are hazardous for
protect our crops from diseases and pests are
the environment?
non-biodegradable.
I. Pesticides
II. Fertilisers
Reason They do not get accumulated at various trophic
III. Heavy metals
IV. Manures
levels.
Codes
20.
Assertion Ozone layer shields the surface of Earth from
(a) I, II and IV
(b) I and II
UV radiations.
(c) I, II and III
(d) Only IV
Reason The UV radiations are highly damaging to
22.
Read the following and answer the questions
organisms.
from (i) to (v) given below
Sheenu took three different types of solid wastes
Case Based MCQs
R, S and T. She buried them under the soil in a
pit, as she wanted to study their rate of
21. Read the following and answer the questions from (i) to
decomposition. Her findings are shown in the
(v) given below
given graph.
A group of scientists analysed samples of four different
animals from a river for possible accumulation of DDT in
their body due to biomagnification. The result obtained
S
is shown in the given graph.
Amount
of solid in pit
Z
(grams)
T
R
Amount
X
Number of days
of DDT
(in ppm)
W
(i) Which of the following waste does not
Y
decompose at all?
(a) R
(b) S
O
Animals
(c) T
(d) Both (a) and (c)
(ii) Choose the correct statements regarding
6.
Based on their feeding habits, differentiate between
non-biodegradable wastes.
parasites and decomposers.
I. Easily decomposed by fungi.
7.
What are trophic levels? Give an example of a
II. Enter into food chain and get magnified.
food chain and state the different trophic levels in it.
III. Biological in origin.
(NCERT)
IV. Cause soil pollution.
8.
Number of trophic levels is limited to 3-4 in a food
Codes
chain. Give reason.
(a) I and II
(b) II and IV
(c) I and IV
(d) II and III
9.
What will happen if we kill all the organisms in one
trophic level?
(iii) Which of the following solid waste comes under the
category of R?
10.
State 10% law. Explain with an example how energy
(a) Cow dung
(b) Leather shoes
flows through different trophic levels.
(c) Plastic bottles
(d) Electronic waste
11.
Indicate the flow of energy in an ecosystem. Why it
(iv) Which of the following is the safe method of
is unidirectional?
(NCERT Exemplar)
disposal of the non-biodegradable waste?
12.
What do you mean by biological magnification?
(a) By recycling
(b) By burning
13.
What is biological magnification? Will the levels of
(c) By disposing them in water bodies
this magnification be different at different levels of the
(d) By mixing with biodegradable waste
ecosystem?
(NCERT Exemplar)
(v) Incineration is another method of waste disposal
14.
Write the major cause of ozone depletion. What steps
which is used for
should be taken to limit the damage to ozone layer?
(a) kitchen waste
15.
Explain how ozone being a deadly poison can still
(b) electronic waste
perform an essential function for our environment.
(c) biomedical waste
(CBSE 2020)
(d) plastic waste
16.
Give reason why a food chain cannot have more than
four trophic levels?
(CBSE 2020)
PART 2
17.
(i) Explain the role of UV radiation in producing ozone
layer.
Subjective Questions
(ii) Mention the reaction involved.
(iii) Why is excessive use of CFCs a cause of concern?
Short Answer Type Questions
18.
How is ozone formed in the upper atmosphere? State
1. Define an ecosystem. Draw a block diagram to show
its importance. What is responsible for its depletion?
the flow of energy in an ecosystem.
(CBSE 2019)
Write one harmful effect of ozone depletion.
(CBSE 2019)
2.
(i) What do you understand by the term ecosystem?
(ii) Autotrophs are at the first level of food chain. Give
19.
Give some methods that could be applied to reduce
reason.
accumulation of pesticides in our body.
(iii) In a food chain of frogs, grass, insects and snakes,
20.
How can you help in reducing the problem of waste
assign trophic level to frogs. To which category of
disposal? Give any two methods.
consumers do they belong to?
(CBSE 2020)
21.
If all the waste we generate is biodegradable, will this
3. What is the role of decomposers in the ecosystem?
have no impact on the environment?
(NCERT)
22.
Give any two ways in which non-biodegradable
4. Natural water bodies are not regularly cleaned
substances would affect the environment.
whereas an aquarium needs regular cleaning. Why?
(CBSE 2019)
23.
Why should biodegradable and non-biodegradable
5. How does study of food chain in an area or habitat
wastes be discarded in two separate dustbins?
help us? Give an example of four steps of food chain
24.
‘Effective segregation of wastes at the point of
operating in a large lake.
generation is very important’. Justify this statement.
25. Sheenu went to a picnic where she saw a pond. Her
35. What is ozone and how does it affect any
teacher gives her an assignment to draw the pond
ecosystem?
(NCERT Exemplar)
ecosystem and show its different components. Help her
36.
(i) What is ‘environmental pollution’?
to complete the assignment.
(ii) Distinguish between biodegradable and
26. Name the wastes which are generated in your house
non-biodegradable pollutants.
daily. What measures would you take for their disposal?
(iii) Choose the non-biodegradable pollutants
(NCERT Exemplar)
from the list given below
27. A modern insecticide has been introduced with
Paper, DDT, Radioactive waste, Plastic,
certain new properties like, accumulation in the bodies
Insecticides.
of predators, broken down by soil bacteria, easily
37. Suggest any five activities in daily life, which are
washed into lakes and rivers and taken up by plant roots.
eco-friendly.
(NCERT Exemplar)
Among all these properties, which one will help in
reducing or keeping the level of environment pollution
38. What are the reasons for the shift from plastic to
to lowest?
kulhads and then finally to paper cups?(CBSE 2020)
28. Mona eats curd and yogurt and follows vegetarian diet.
Case Based Questions
For this food intake, what should be the trophic level
occupied by her in a food chain ?
39. Read the following and answer the questions
from (i) to (v) given below
Long Answer Type Questions
Food web is the interconnection of different food
chains, which correlate at various trohpic levels
29.
What are decomposers? What will be the consequence of
operating in an ecosystem.
their absence in an ecosystem?
(NCERT Exemplar)
30.
(i) What are consumers? What will be the consequence of
Foxes
the absence of primary consumers in an ecosystem?
Snake
Mice
Rabbits
(ii) What will be the direction of energy transfer in each
of the following cases?
Seeds
Young trees
Grass
(a) Grasshopper eaten by a frog
Food web
(b) Deer feeds on grass
(c) Deer eaten by a lion
(i) How many food chains are present in the given
food web?
31.
(i) Will the impact of removing all the organisms in
a trophic level be different for different trophic
(ii) Name the primary consumer in the given food
levels?
web.
(ii) Can the organisms of any trophic level be removed
(iii) How much percentage of energy is less at each
without causing any damage to the ecosystem?
trophic level?
(NCERT Exemplar)
(iv) If all the foxes are killed due to a disease, what
32.
(i) ‘Energy flow in a food chain is unidirectional’. Justify
will be your observations about food web?
this statement.
(v) Name the organism in which accumulation
(ii) Explain how the pesticides enter a food chain and
of toxic non-biodegradable substances is the
subsequently get into our body.
(CBSE 2014)
lowest.
33.
(i) How do food chains get shortened? How does the
40. Read the following and answer the questions from
shortening of food chain affect the biosphere?
(i) to (v) given below
(ii) How will you justify that vegetarian food habits give
Food chains are very important for the survival of
us more calories?
most species. When only one element is removed
from the food chain it can result in extinction of a
34.
Explain some harmful effects of agricultural practices on
species in some cases.
the environment.
(NCERT Exemplar)
The foundation of the food chain consists of
Analyse the populations and their effects on each other.
primary producers.Primary producers or
autotrophs can use either solar energy or chemical
energy to create complex organic compounds,
whereas species at higher trophic levels cannot
and so must consume producers or other life that
itself consumes producers.
Because the Sun's light is necessary for
photosynthesis, most life could not exist if the Sun
disappeared.
Even so, it has recently been discovered that
there are some forms of life, chemotrophs that
appear to gain all their metabolic energy from
chemosynthesis driven by hydrothermal vents,
thus showing that some life may not require solar
energy to thrive.
Food webs
Food web
(i) How many trophic levels are there in the longest food
Secondary
chain?
carnivores
(ii) What is the role of rabbit in the given food web?
(iii) Give the significance of food web.
(iv) Why do all food chain start with plants?
Primary
(v) What leads an organism to increase in number?
carnivores
42.
Read the following and answer the questions from (i) to
(v) given below
Herbivores
To study the ozone layer depletion, Mrs. Sharma, a
science teacher draw the given flow chart on the
blackboard. She asked students to fill the bubbles
Producers
labelled as 1-5 in the flow chart.
Grass
Ozone depleting
(i)
If 10,000 J solar energy falls on green plants in a
substances
terrestrial ecosystem, what percentage of solar
1
energy will be converted into food energy?
(ii)
Why decomposers are not included in the food
chain?
Formation of ozone
Effects of ozone
depletion
(iii)
How primary consumers are different from
2
Ozone Layer
5
primary carnivores?
(iv)
State one reason that limits the number of trophic
levels in a food chain.
(v)
In the given food web, name the organism in
Where is it found?
What is ozone?
which highest accumulation of toxic substance is
3
4
found.
41. Read the following and answer the questions from
(i) What are ozone depleting substance?
(i) to (v) given below
(ii) How is ozone formed?
Each organism is generally eaten by two or more
(iii) Ravi want to drawn a ozone layer in a diagram
other kinds of organisms. They in turn are eaten by
showing different layers of atmosphere, where he
several other organisms.
should label it?
Study the figure which shows the similar
(iv) What is the difference between good ozone and bad
relationship between various organisms of
ozone?
ecosystem through a food web.
(v) What could be the effect of ozone depletion?