How Nature Works in Harmony Class 8 Worksheet with Answers Science Chapter 12 - #NCSOLVE 📚

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Class 8 Science Chapter 12 How Nature Works in Harmony Worksheet

Class 8 How Nature Works in Harmony Worksheet

Worksheet On How Nature Works in Harmony Class 8 – How Nature Works in Harmony Worksheet Class 8

A. Objective Type Questions

Multiple Choice Questions

Question 1.
What does the presence of both living and non-living components in habitats like ponds and forests suggest?
(a) Only biotic components are essential for a habitat
(b) Abiotic components help organisms grow, but are not part of the habitat
(c) A habitat must have both biotic and abiotic components to support life
(d) Organisms depend only on other living beings for their survival
Answer:
(c) A habitat must have both biotic and abiotic components to support life

Question 2.
Researchers observed that plants growing near Pond A produced more seeds than those near Pond B. What could be the most likely reason for this difference?

(a) Fish eat plant seeds, helping plants grow faster
(b) Fish may support other organisms that help in pollination or seed dispersal
(c) Fish directly pollinate flowers near the pond
(d) Plants grow better without fish due to less disturbance in the water
Answer:
(b) Fish may support other organisms that help in pollination or seed dispersal

Question 3.
Which of the following correctly matches the level of organisation in mature?
(a) Community → Population → Individual → Ecosystem
(b) Individual → Community → Population → Ecosystem
(c) Ecosystem → Community → Population → Individual
(d) Individual → Population → Community → Ecosystem
Answer:
(d) Individual → Population → Community → Ecosystem

Question 4.
In a forest ecosystem, if the population of herbivores like deer and hare decreases sharply due to disease, what is the most likely immediate impact on the food chain?
(a) The population of carnivores like leopards will increase due to more hunting activity
(b) Producers like plants will decrease due to less grazing
(c) The population of omnivores will shift entirely to plant-based food
(d) Carnivores may face food shortage and their population might decline over time
Answer:
(d) Carnivores may face food shortage and their population might decline over time

Question 5.
The diagram shows different trophic levels in an ecosystem, which of the following correctly represent the third trophic level in the below diagram.

Trophic levels in an ecosystem
(a) Herbivores
(b) Carnivores
(c) Top carnivores
(d) Producers
Answer:
(b) Carnivores

Question 6.
In the food chain involving millet, mouse, and eagle, a pyramid is formed when organisms are arranged based on their number. Why is millet placed at the base and eagle at the top?
(a) Millet is the tallest among all the organisms listed
(b) The number of millets is the highest and that of eagles the lowest
(c) Eagles are more powerful, so they are kept at the top
(d) Mice eat both millet and eagle eggs, so they are placed in the middle
Answer:
(b) The number of millets is the highest and that of eagles the lowest

Question 7.
Read the following statements related to ecosystems and their components:
I. Decomposers help in recycling nutrients back into the soil.
II. Migratory birds can act as pollinators and seed dispersers.
III. Pollution in water bodies increases the amount of oxygen available for aguatic life.
IV. Beetles and flies feeding on animal droppings are examples of decomposers. How many of the above statements are correct?
(a) All four
(b) Three
(c) Only one
(d) Two
Answer:
(b) Three

Question 8.
Which of the following correctly matches the organism with its role in the ecosystem?
(a) Grass – Consumer
(b) Mouse – Producer
(c) Beetle – Decomposer
(d) Eagle – Herbivore
Answer:
(c) Beetle – Decomposer

Question 9.
Identify the correct scientific name of the animal shown in the image.

(a) Bufo melanostictus
(b) Rana temporaria
(c) Hoplobatrachus tigerinus
(d) Hyla arborea
Answer:
(c) Hoplobatrachus tigerinus

Question 10.
If many plants in a pond die, which of these is most likely to happen next?
(a) Fish get more food and increase in number
(b) There is less oxygen, so fish start dying
(c) Insects go away because fish eat them
(d) The pond becomes cleaner and healthier
Answer:
(b) There is less oxygen, so fish start dying

Question 11.
Which of the following is an example of commensalism in an ecosystem?
(a) Ticks feeding on a dog
(b) Honeybees collecting nectar from flowers
(c) Orchids growing on trees
(d) Deer being hunted by tigers
Answer:
(c) Orchids growing on trees

Question 12.
Why are the Sundarbans considered important for both biodiversity and human well-being?

(a) They are used mainly for farming and urban development
(b) They are home to mangrove trees that support endangered species.
(c) They are man-made forests that help increase industrial output
(d) They provide timber for large-scale commercial use
Answer:
(b) They are home to mangrove trees that support endangered species.

Question 13.
Why are modern farming practices from the Green Revolution now considered unsustainable?
(a) They reduce the need for fertilisers and increase soil fertility
(b) They encourage the use of organic manure and crop diversity
(c) They cause soil degradation and harm the environment due to overuse of chemicals
(d) They involve fewer machines and make farming more labour-intensive
Answer:
(c) They cause soil degradation and harm the environment due to overuse of chemicals

Assertion-Reason Questions
Given below are two statements. One is labelled as Assertion and other is labelled as Reason. Choose the correct answer from the options given below.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.

Question 1.
Assertion: Abiotic components do not depend on biotic components for any function in an ecosystem.
Reason: Biotic components, like plants, help retain soil moisture and reduce erosion.
Answer:
(d) Assertion is false, but Reason is true.

The Assertion can be corrected as
Abiotic components do depend on biotic components for certain functions. For example, plants help in maintaining soil structure and moisture.

Question 2.
Assertion: Trees are heterotrophs because they take nutrients from the soil.
Reason: Autotrophs are organisms that produce their own food through photosynthesis,
Answer:
(d) Assertion is false, but Reason is true.

The Assertion can be corrected as
Trees are autotrophs, not heterotrophs, because they make their own food through photosynthesis.

Question 3.
Assertion: Decomposers are important for the recycling of nutrients in the environment.
Reason: They break down dead organisms and animal waste into simpler substances that enrich the soil.
Answer:
(a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Question 4.
Assertion: Migratory birds are harmful to agricultural ecosystems.
Reason: Migratory birds feed on insect pests and help in maintaining the ecological balance.
Answer:
(d) Assertion is false, but Reason is true.

The Assertion can be corrected as
Migratory birds are beneficial to agricultural ecosystems. They control pests and act as pollinators or seed dispersers, helping maintain ecological balance.

Question 5.
Assertion: Mutualism is a type of interaction where one organism benefits and the other is harmed.
Reason: Honey bee and flowering plants show mutualistic interaction.
Answer:
(d) Assertion is false, but Reason is true.

The Assertion can be corrected as
Mutualism is a symbiotic relationship in which both organisms benefit from the interaction.

Fill in the Blanks

Question 1.
Fill in the blanks by choosing the appropriate word from the box given below:

Pollination, commensalism, sundarbans, benefits, biotic, abiotic, decomposers, pollen, nutrients, UNESCO

(a) _______ is the process in which is transferred from the stamens to the carpels of the same or different flowers.
Answer:
Pollination, pollen

(b) An ecosystem is formed when ________ components interact with _______ components like air, water, and sunlight.
Answer:
biotic, abiotic

(c) Organisms that break down waste and recycle ________ into the environment are called ________ .
Answer:
nutrients, decomposers

(d) The relationship between orchids and trees is called ________ , where one ________ and the other neither benefitted nor harmed.
Answer:
commensalism, benefits

(e) The ________ were declared a world heritage site by ________ in 1987 due to their rich biodiversity and ecological importance.
Answer:
Sundarbans, UNESCO

Question 2.
Fill in the blanks by unjumbling the words given in the bracket:
(a) The mutual interaction between living and non-living things forms an _______. (osecemyts)
Answer:
ecosystem

(b) The eagle is a _______ (yrtiater) consumer in the food chain.
Answer:
tertiary

(c) The process in which dead plants and animals are broken down is called _______ (otepomoidcsni)
Answer:
decomposition

(d) The relationship where both organisms benefit is called _______. (uultimsam)
Answer:
mutualism

(e) The period when machines, fertilisers, and pesticides were widely used to increase food production in India is called the _______ (rnege uoervtloin).
Answer:
Green Revolution

True/False

Question 1.
Choose the option which shows the correct sequence of True (T) and False (F) for the statements given below:
(i) An ecosystem includes only the living components of an environment.
(ii) Decomposers help recycle nutrients into the soil.
(iii) A food chain represents a linear feeding relationship.
(iv) Mutualism benefits both organisms involved.
(v) The Green Revolution used sustainable farming methods.
(vi) Artificial ecosystems like fish ponds do not require any human care,
(a) F T T T F F
(b) T T F T T F
(c) F F T F F T
(d) T T T T F T
Answer:
(a) F T T T F F
Statements (i), (v) and (vi) can be corrected as
(i) An ecosystem includes living and non-living components of an environment.
(v) The green revolutions did not. use sustainable farming methods, because they caused long-term harm to the environment and natural resources.
(vi) Artificial ecosystems like fish ponds require regular human care and management to maintain balance.

Question 2.
Write Yes or No for each of the following statements.
(a) If decomposers are removed from an ecosystem, nutrients from dead organisms would not return to the soil.
Answer:
Yes

(b) Migratory birds play no role in controlling pest populations.
Answer:
No
It can be corrected as migratory birds play an important role in pest populations as they feed on a variety of insects, larvae and small pests.

(c) Growing a variety of crops in the same field over different seasons helps maintain soil health.
Answer:
Yes

(d) Cutting down mangrove trees can increase the risk of damage during storms and floods.
Answer:
Yes

(e) Fish ponds, though human-made, can still support biodiversity if maintained properly.
Answer:
Yes

Match the Following

Question 1.
Match the terms in Column I with their correct descriptions in Column II.

Column I	Column II
(a) Sundarbans	(i) Breaks down waste and recycles nutrients back into the soil
(b) Abiotic factor	(ii) Relationship in which one organism benefits and the other is harmed
(c) Producer	(iii) Declared a world heritage Site by UNESCO due to its rich biodiversity
(d) Parasitism	(iv) An organism that prepares its own food through photosynthesis
(e) Decomposer	(v) Non-living component of an ecosystem such as water or air

Answer:

Column I	Column II
(a) Sundarbans	(iii) Declared a world heritage Site by UNESCO due to its rich biodiversity
(b) Abiotic factor	(v) Non-living component of an ecosystem such as water or air
(c) Producer	(iv) An organism that prepares its own food through photosynthesis
(d) Parasitism	(ii) Relationship in which one organism benefits and the other is harmed
(e) Decomposer	(i) Breaks down waste and recycles nutrients back into the soil

Question 2.
Match the ecological interaction given in Column I with description given in Column II.

Answer:
(a) – (iii), (b) – (i), (c) – (ii)

B. Subjective Type Questions

Define the Following Terms

1. Ecosystem
_________________________

2. Trophic level
_________________________

3. Food web
_________________________

4. Saprotrophs
_________________________

5. Parasitism
_________________________

6. Green revolution
_________________________

7. Monoculture
_________________________

Give Reasons for the Following

1. Food web is considered more stable than food chain.
_________________________

2. An ecosystem without decomposers does not exist in nature.
_________________________

Very Short Answer Type Questions

Question 1.
Mention a function of wild life corridors.
_________________________
_________________________

Question 2.
Name one abiotic and one biotic component of an ecosystem.
_________________________
_________________________

Question 3.
Mention the significance of the process shown in the image below.

_________________________
_________________________

Question 4.
A student notices the organism given in the diagram below, growing on decaying wood. What role do these organism play in that ecosystem and why is it important?

_________________________
_________________________

Question 5.
Why are saprotrophs essential for nutrient recycling in nature?
_________________________
_________________________

Question 6.
Migratory birds travel long distances across countries and continents and often visit farmlands and wetlands during certain seasons. Why are these migratory birds considered important for agriculture in such regions, and how do they contribute to maintaining ecological balance?
_________________________
_________________________

Question 7.
Why have the Sundarbans been declared a world heritage site by UNESCO?
_________________________
_________________________

Question 8.
What is the full form of UNESCO?
_________________________
_________________________

Question 9.
Ancient Indian texts focuses on maintaining soil fertility and encourages the use of natural methods for cultivation instead of chemicals. Name this ‘ancient Indian text that promotes soil health and supports the principles of organic farming.
_________________________
_________________________

Question 10.
How do natural predators, such as the one shown in the image, contribute to sustainable farming practices?

_________________________
_________________________

Short Answer Type Questions

Question 1.
How does the process shown in the image given below occur in flowering plants, and why is it important for their life cycle?

_________________________
_________________________

Question 2.
Why is the interaction between biotic and abiotic components essential in an ecosystem?
_________________________
_________________________

Question 3.
In a forest ecosystem, if the population of grasshoppers suddenly decline§.due to disease. Explain how such a change could affect the organisms that depend directly or indirectly on grasshoppers for food.

_________________________
_________________________

Question 4.
Complete the following flowchart based on ecosystem and its components.

(i) _______
(ii) _______
(iii) _______
(iv) _______
(v) _______

Question 5.
How did the large-scale export of frog legs in the 1980s affect agricultural ecosystems in India? Explain the consequences of this human intervention.
_________________________
_________________________

Question 6.
Why are the Sundarbans considered important, and what threats do they.currently face?
_________________________
_________________________

Long Answer Type Questions

Question 1.
Describe the importance of food webs in maintaining balance in ecosystems. How is a food web more stable than a single food chain? Use an example to explain.
_________________________
_________________________

Question 2.
Explain in detail the differences between mutualism, parasitism, and commensalism based on the nature of interaction between the two organisms involved. Describe how each of these relationships functions in nature, and support your explanation with one suitable example for each type.
_________________________
_________________________

Question 3.
What were the key features and outcomes of the Green Revolution in India? Why are these practices now considered unsustainable?
_________________________
_________________________

Case-Based Questions

Read the paragraph and answer the following questions.

Question 1.
On a remote island, a new bird species was introduced to control the population of a certain insect. Initially, the bird fed only on these insects, and their numbers declined rapidly. However, over time, the population of native bird species also began to decrease. This unexpected impact raised concerns among scientists studying the island’s food web.
I. What type of relationship exists between the introduced bird and the insect species?
(a) Mutualism
(b) Commensalism
(c) Predation
(d) Parasitism
Answer:
(c) Predation

II. What could be the most likely reason for the decline in native bird species?
(a) They migrated due to climate change
(b) They lost their food source due to increased competition
(c) They were hunted by the new bird species
(d) They adapted to feed on other organisms
Answer:
(b) They lost their food source due to increased competition

III. What does this case best highlight about ecosystems?
(a) Only biotic components interact
(b) Introduction of new species always benefits biodiversity
(c) All interactions in an ecosystem are beneficial
(d) Changes in one population can affect the entire food web
Answer:
(d) Changes in one population can affect the entire food web

Question 2.
In a small village, people noticed a sudden drop in the fish population in their local pond. Weeks later, the villagers observed that the number of birds that often visited the pond also decreased. Some locals recalled that the water had recently become dirty due to nearby construction and dumping of waste. Concerned, they called environmental experts to investigate.

I. What does this incident suggest about the relationship among differeptliving organisms in an ecosystem? –
(a) Organisms function independently
(b) One species’ change does not affect others
(c) Living organisms are closely linked to each other
(d) Pollution does not disturb ecosystem balance
Answer:
(c) Living organisms are closely linked to each other

II. What role do the fish most likely play in this pond ecosystem?
(a) Decomposers
(b) Producers
(c) Consumers
(d) Predators
Answer:
(c) Consumers

Question 3.
Ravi, a farmer in a village near the foothills, noticed several beekeepers setting up wooden boxes beside his mustard and sunflower fields. Curious, he learned that the beekeepers had been doing this for years during the flowering season. As the flowers bloomed, the area buzzed with honeybees visiting the crops throughout the day. Ravi also observed that the yield from his farm had increased over the past few years.
(i) What is the ecological relationship between honeybees and flowering plants? Explain its significance.
_________________________
_________________________

(ii) Name two other ecological interactions found in nature and mention their significance.
_________________________
_________________________

Question 4.
Ravi lives near an agricultural farm and often helps his uncle in maintaining the crops. The farm uses irrigation, fertilizers, and grows only selected high-yield crops. While the farm produces a good amount of food, Ravi notices that very few birds and insects visit the area compared to a nearby natural forest patch.
(i) What type of ecosystem is described in Ravi’s farm, and how is it different from a natural ecosystem?
_________________________
_________________________

(ii) Why do human-made ecosystems generally support less biodiversity than natural ecosystems?
_________________________
_________________________

Skill Based Activities

Question 1.
Classify the following into Biotic and Abiotic components:

Sunlight, Earthworm, Air, Cow, Soil, Plant, Water, Bacteria, Temperature, Fungi, Rock, Insects, Humidity, Lizard, Rainfall

Biotic and Abiotic

Biotic	Abiotic

Answer:
Biotic : Earthworm, Cow, Plant, Bacteria, Fungi, Insects, Lizard
Abiotic : Sunlight, Air, Soil, Water, Temperature, Rock, Flumidity, Rainfall

Question 2.
Identify the following words with the help of hints given.
(a) The process of transferring pollen from the anther to the stigma.
_ o _ _ i _ a _ i o _
Answer:
Pollination

(b) The first trophic level in a food chain.
_ _o_u_e_s
Answer:
Producers

(c) Type of farming that avoids synthetic chemicals.
o_ _ a _ i _ _ a_ _i_ _
Answer:
Organic farming

(d) Relationship where one organism benefits and the other is harmed.
_a_a_i_i_ _
Answer:
Parasitism

(e) A relationship where one organism benefits while the other remains unaffected.
_o_ _e_ _a_i_ _
Answer:
Commensalism

Question 3.
Circle the odd one out, and explain why it does not belong to the specified category.
(a) Light, Air, Water, Lion
(b) Carpels, Sepals, Pollen grains, Chlorophyll
(c) Beetles, Flies, Fungi, Plants
Answer:
(a) Lion
(b) Chlorophyll
(c) Plants

Question 4.
Given below is a square of letters in which are hidden different words related to life processes in plants. Find out the words with the help of the clues given below.
1. Main source of energy for ecosystems.
2. Living parts of an ecosystem.
3. An organisation declared the sunderbans a world heritage site.
4. Organic matter in soil that improves fertility.
5. Reproductive part of a plant.
6. A type of farming that avoids chemicals.

Answer:
1. Sunlight
2. Biotic
3. UNESCO
4. Humus
5. Flower
6. Organic

The post How Nature Works in Harmony Class 8 Worksheet with Answers Science Chapter 12 appeared first on Learn CBSE.

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