CBSE Class 11 Geography Chapter 15: Life on the Earth NCERT Solutions

Reviewed by NCERT Help Editorial Team · Updated on 29 Jul 2026

NCERT Solutions PDF Class 11 PDF

This chapter, 'Life on the Earth,' delves into the fundamental concepts of ecology and the interconnectedness of life on our planet. It explores the biosphere, the components of ecological systems, and the flow of energy through food chains. The NCERT Solutions provide clear explanations for key terms like ecology and ecosystem, differentiating between terrestrial and aquatic types. It also illustrates the concept of a food chain with a practical example, detailing the producer, consumer, and predator levels. These solutions are designed to help students grasp the essential principles of life sciences within a geographical context, aiding in their preparation for exams by offering structured answers and clear definitions.

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Quick info

Board	CBSE
Class	Class 11
Subject	Geography
Session	2026
Language	English
Type	NCERT Solutions
Chapter	15. Life on the Earth

Chapter summary

Chapter 15, 'Life on the Earth,' focuses on the basic principles of ecology and biological systems. The NCERT Solutions cover the definition of the biosphere, the components of an ecological system, and the concept of a food chain. It clarifies terms like ecology and provides examples of terrestrial and aquatic ecosystems, along with a detailed explanation of a grazing food chain.

Learning outcomes

Understand the concept of the biosphere and its components.
Define and explain the term 'ecology'.
Identify and differentiate between major types of ecosystems.
Explain the structure and function of a food chain.
Recognize the process of photosynthesis and its products.
Understand the chemical reactions involved in rock weathering.

Topics covered

Paper topics

Biosphere
Ecology
Ecological System
Terrestrial Ecosystems
Aquatic Ecosystems
Food Chain
Photosynthesis
Rock Weathering
Oxidation
Producers
Consumers
Predators

Important topics

Definition of Ecology
Types of Ecosystems
Food Chain Structure
Biosphere Components
Photosynthesis Process

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Questions and Solutions

Multiple Choice Questions

(i) Which one of the following is included in biosphere?

(a) only plants

(b) all living and non-living organisms

(d) all living organisms

Solution: The biosphere refers to the sum total of all living organisms on Earth. This includes all plants, animals, and microorganisms, along with their interactions with the non-living components of the environment. Therefore, the correct option is (d).

(ii) Tropical grasslands are also known as:

(a) the prairies

(b) the savannas

(d) none of the above

Solution: Tropical grasslands, which are characterized by warm temperatures and distinct wet and dry seasons, are commonly referred to as savannas. Prairies and steppes are types of temperate grasslands found in different regions.

(iii) Oxygen combines with iron found in the rocks to form:

(a) iron carbonate

(b) iron nitrites

(d) iron sulphate

Solution: The process described is oxidation, a common form of chemical weathering. When oxygen in the atmosphere reacts with iron minerals present in rocks, it leads to the formation of iron oxides. This is a significant process in the breakdown of rocks over time.

1. During photosynthesis, carbon dioxide combines with water in the presence of sunlight to form:

1. proteins

2. amino acids

3. carbohydrates

4. vitamins

Solution: Photosynthesis is the vital process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigment. During this process, carbon dioxide from the atmosphere and water absorbed from the soil are converted into glucose (a type of carbohydrate) and oxygen. Therefore, carbohydrates are the primary organic compounds formed.

2. What do you understand by the term 'ecology'?

Solution: Ecology is the scientific study that examines the relationships and interactions between living organisms (such as plants, animals, and microorganisms) and their physical environment. It views the Earth and its inhabitants as an interconnected 'household' where all components influence each other.

3. What is an ecological system? Identify the major types of ecosystems in the world.

Solution: An ecological system, or ecosystem, is a dynamic complex formed by a community of living organisms (biotic components) interacting with each other and with their non-living physical environment (abiotic components) within a specific area. The major types of ecosystems found globally are broadly classified into two categories: terrestrial ecosystems, which are land-based (like forests, grasslands, deserts), and aquatic ecosystems, which are water-based (like oceans, lakes, rivers).

4. What is a food-chain? Give one example of a grazing food-chain identifying the various levels.

Solution: A food chain illustrates the linear sequence of organisms where nutrients and energy are transferred from one trophic level to another as one organism consumes another. It begins with producers and ends with apex predators or decomposers.

An example of a grazing food chain is:

Producers: Grass (forms the base, converting sunlight into energy through photosynthesis).

Primary Consumer (Herbivore): A grasshopper that feeds on the grass.

Secondary Consumer (Carnivore/Omnivore): A frog that eats the grasshopper.

Tertiary Consumer (Carnivore): A snake that consumes the frog.

Quaternary Consumer (Apex Predator): A hawk that preys on the snake.

Each step in this sequence represents a transfer of energy from one level to the next.

Common mistakes

Confusing the biosphere with only living organisms.
Not clearly distinguishing between different types of ecosystems.
Incomplete or inaccurate identification of trophic levels in a food chain.
Misunderstanding the reactants and products of photosynthesis.

Revision tips

Focus on understanding the definitions of key terms like ecology and ecosystem.
Memorize the components of a food chain and practice identifying them in examples.
Review the different types of ecosystems and their characteristics.
Pay attention to the chemical processes described, such as photosynthesis and oxidation.

Practice MCQs

Q1. Which of the following is included within the biosphere?

Q2. What is the alternative name for tropical grasslands?

Q3. When oxygen reacts with iron in rocks, what compound is typically formed?

Q4. During photosynthesis, what are the primary products formed when carbon dioxide and water react in the presence of sunlight?

Q5. Which term describes the study of the Earth as a 'household' for plants, humans, animals, and microorganisms?

Frequently asked questions

What is the biosphere according to NCERT Class 11 Geography?

The biosphere is understood as the sum total of all living organisms on Earth, encompassing plants, animals, and microorganisms, and their interactions.

How is 'ecology' defined in this chapter?

Ecology is defined as the study of the Earth as a 'household', focusing on the relationships between plants, human beings, animals, and microorganisms.

What are the two main types of ecosystems mentioned?

The two main types of ecosystems identified are terrestrial ecosystems (land-based) and aquatic ecosystems (water-based).

Can you explain what a food chain is?

A food chain is a linear sequence showing how energy is transferred from one organism to another, starting from producers and moving up through consumers and predators.

What is the role of sunlight in photosynthesis as per the solutions?

Sunlight is essential for photosynthesis; it provides the energy needed for carbon dioxide and water to combine and form carbohydrates.

What happens when oxygen interacts with iron in rocks?

When oxygen combines with iron found in rocks, it forms iron oxides, a process that contributes to the weathering of rocks.

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