Our Environment

Class 10 Science Chapter 13
Our Environment
Important Questions

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Here are some critical Chapter 13 Our Environment Problems for Class 10 Science. These inquiries are intended to aid students in studying for and performing well on the CBSE Class 10 Science Examination 2023–24. Students can clear up their concerns and be ready for the exams by practising different types of questions. By answering these questions, you'll increase your confidence while also sharpening your problem-solving abilities


In Chapter 13, "Our Environment," of Class 10 Science, students embark on a journey to understand the delicate balance of ecosystems. This chapter delves into the components that constitute an ecosystem, shedding light on the intricate interplay of living and non-living entities. Moreover, it scrutinizes various human activities that impact the environment, fostering awareness about our role in safeguarding the delicate ecological equilibrium for a sustainable future.

cbse class 10 Science Our Environment important questions and answers

Chapter 13 Our Environment Important Questions and Answers

Q1. If a grasshopper is eaten by a frog, then the energy transfer will be from:


(a) Producer to decomposer
(b) Producer to decomposer
(c) Primary consumer to secondary consumer
(d) Secondary consumer to primary consumer

Ans. (c)

Grasshoppers depend upon grass for their food, they cannot make their own food. Hence they are primary consumers as they depend upon producers.Now if the grasshoppers are eaten by frogs they become the secondary producers.

Q2. The decomposers in an ecosystem


(a) The decomposers in an ecosystem
(b) Convert organic material to inorganic forms
(c) Convert inorganic materials into organic compounds
(d) Do not break down organic compounds

Ans. (b)

The decomposers in an ecosystem convert organic matter present in dead remains into inorganic elements. These elements are then released into the environment to enter into biogeochemical cycles.

Q3. Why do vegetarian habits help us in getting more energy? In terms of energy, who is at an advantageous position (vegetarian or a nonvegetarian) and Why?

Vegetarians obtain food directly from plants, while non-vegetarians get food from animals which feed on plants. As a result animals which are herbivores get 10% of energy from plants, suppose 100 J according to the 10% rule. When non-vegetarians feed upon these animals they get only 10 J which is 10% of 100 J. But vegetarians which feed directly on plants get 100 J hence vegetarians are at an advantageous position and get more energy than non-vegetarians.

Q4. Answer the following questions:
(a) What is the energy pyramid? Why is it broader at base and narrower at the apex region?
(b) When plants are eaten by primary consumers a great deal of energy is lost as heat to the environment and some amount goes into carrying out various life processes. State the average percentage of energy lost in this manner.

(a) An energy pyramid is a graphical representation of the flow of energy from the producers through the various consumers. It shows the amount of energy available and the loss of useful energy at each step of the food chain in an ecosystem. As the energy gets transferred from lower trophic level to the higher one, there is a loss of large amounts of energy due to metabolism and heat. As a result very little energy (i.e., 10%) gets transferred to the next level. So the trophic level at the base has maximum energy and that at the top has the least amount of energy. Hence the energy pyramid is broader at the base and narrower at the top.
(b) The average percentage of energy lost when plants are eaten by primary consumers is 90%.

Q5. (a) Write the percentage of (i) solar energy captured by the autotrophs and (ii) energy transferred from autotrophs to the next level in a food chain.
(b) What are trophic levels? Why do different food chains in an ecosystem not have more than four to five trophic levels ? Give a reason.

(a) (i) Plants capture only about 1% of the solar energy that falls on them and use it for photosynthesis.
(ii) On average, only about 10 percent of energy stored as biomass in a trophic level is passed from one level to the next. This is known as “10 percent rule” and it limits the number of trophic levels an ecosystem can support.
(b) The various steps in a food chain or ecological pyramid, at which the transfer of food (or energy) takes place from one organism to another organism is known as trophic levels. Based on the source of their nutrition or food, organisms occupy a specific place in the food chain. Organisms in food webs are grouped into categories called trophic levels, these levels are divided into producers (first trophic level), consumers, and decomposers (last trophic level). There is only 10% flow of energy from one trophic level to the next higher level. The loss of energy at each step is so great that very little usable remains after four or five trophic levels. Hence only 4 to 5 trophic levels are present in each food chain.

cbse class 10 Science Our Environment important questions and answerscbse class 10 Science Our Environment important questions and answers

CBSE Class 10 Science Chapter wise Important Questions

Chapter No. Chapter Name
Chapter 1 Chemical Reactions and Equations
Chapter 2 Acid, Bases and Salts
Chapter 3 Metals and Non-Metals
Chapter 4 Carbon and its Compounds
Chapter 5 Life Processes
Chapter 6 Control and Coordination
Chapter 7 How do Organisms Reproduce
Chapter 8 Heredity
Chapter 9 Light : Reflection and Refraction
Chapter 10 The Human Eye and the Colourful world
Chapter 11 Electricity
Chapter 12 Magnetic Effects of Electric Current
Chapter 13 Our Environment


Oswal.io offers a thorough set of questions for learning the topic in a better way if you're looking to further practise and improve your grasp of the concepts covered in the chapter.

Frequently Asked Questions

Q1 : Why is the maximum concentration of pesticides found in human beings?

Ans: The pesticides are not biodegradable, they get accumulated progressively at each trophic level. As human beings occupy the topmost level in the food chain, their concentration becomes maximum in our bodies.

Q2: Give one method which could be applied to reduce our intake of pesticides through food to some extent.

Ans:  By using biological methods for controlling insects in fields and by washing fruits and vegetables before eating could help to reduce our intake of pesticides through food to some extent.

Q3 : Our environment is made up of various ecosystems. What is an ecosystem?

Ans: An ecosystem is defined as a structural and functional unit of the biosphere. It comprises living organisms and their nonliving environment that interact by means of food chains and biogeo-chemical cycles resulting in energy-flow, biotic diversity and material cycling to form stable self-supporting systems.

Q4 : Why is a lake considered to be a natural ecosystem?

Ans: Lake is an ecosystem where living organisms grow, reproduce and interact among each other as well as with abiotic components and carry out other activities in nature by themselves without any human interference, therefore it is referred to as a natural ecosystem.

Q5 : List two biotic components of a biosphere.

Ans: Two biotic components of a biosphere are:
(i) Producers – Include organisms which can produce their food using simple inorganic compounds, e.g., all green plants, blue green algae (cyanobacteria).
(ii) Consumers – Include organisms which are unable to synthesise their food, therefore, utilise materials and energy stored by the producers or eat other organisms, e.g., all the animals.

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