Ecosystem MCQs Quiz | Class 10

This quiz covers ‘Ecosystem MCQs Quiz’ for Class X Science (Code 086), specifically from Unit V: Natural Resources. Topics include Definition, components, and interactions. Answer all 10 multiple-choice questions, then submit to see your score and download a detailed answer PDF.

Understanding Ecosystems: A Comprehensive Guide

An ecosystem represents a fundamental unit in nature, where living organisms interact with each other and with their surrounding physical environment. These interactions are crucial for the flow of energy and the cycling of nutrients, sustaining life on Earth.

Definition of an Ecosystem

An ecosystem is a community of living organisms (biotic components) interacting with the non-living components (abiotic components) of their environment. This includes all plants, animals, and microorganisms in an area, together with the physical environment like soil, water, and atmosphere. Ecosystems can vary greatly in size, from a small pond to a vast forest or ocean.

Components of an Ecosystem

Ecosystems are comprised of two main types of components that are interdependent:

1. Biotic Components (Living Organisms)

  • Producers (Autotrophs): Organisms, primarily green plants and some bacteria, that produce their own food using sunlight (photosynthesis) or chemical energy (chemosynthesis). They form the base of the food chain.
  • Consumers (Heterotrophs): Organisms that obtain energy by feeding on other organisms.
    • Primary Consumers (Herbivores): Eat producers (e.g., deer, rabbits).
    • Secondary Consumers (Carnivores/Omnivores): Eat primary consumers (e.g., foxes, small birds).
    • Tertiary Consumers (Top Carnivores): Eat secondary consumers (e.g., lions, eagles).
  • Decomposers (Detritivores): Organisms like bacteria and fungi that break down dead organic matter (dead plants and animals) into simpler substances, returning nutrients to the soil and atmosphere. They are vital for nutrient recycling.

2. Abiotic Components (Non-Living Factors)

These are the physical and chemical factors that influence living organisms in an ecosystem. They include:

  • Sunlight: Primary energy source for most ecosystems.
  • Temperature: Affects metabolic rates and survival of organisms.
  • Water: Essential for all life processes.
  • Soil: Provides nutrients, anchorage for plants, and habitat for many organisms.
  • Air: Supplies gases like oxygen, carbon dioxide, and nitrogen.
  • Minerals: Nutrients like nitrogen, phosphorus, and potassium required for growth.

Table: Biotic vs. Abiotic Components

Feature Biotic Components Abiotic Components
Definition Living organisms Non-living physical and chemical factors
Examples Plants, animals, bacteria, fungi Sunlight, water, soil, air, temperature, minerals
Role Interact with each other (food chains), produce/consume/decompose organic matter Determine the type of life an ecosystem can support, provide raw materials

Interactions within an Ecosystem

Organisms in an ecosystem are constantly interacting, leading to energy flow and nutrient cycling.

Food Chains

A food chain illustrates the linear feeding relationships between organisms, showing how energy is transferred from one trophic level to the next. For example: Grass → Deer → Tiger.

Food Webs

Food webs are more complex and realistic representations of feeding relationships, consisting of multiple interconnected food chains. They show that most organisms consume, and are consumed by, more than one type of organism.

Energy Flow

Energy flows unidirectionally from the sun to producers, then to consumers, and finally to decomposers. Only about 10% of the energy is transferred from one trophic level to the next, with the rest lost as heat. This is known as the 10% Law of Energy Transfer.

Nutrient Cycling

Unlike energy, nutrients (like carbon, nitrogen, water) are recycled within an ecosystem. Decomposers play a crucial role in breaking down dead organic matter and returning these essential nutrients to the environment for reuse by producers.

Quick Revision Points

  • An ecosystem is where living and non-living things interact.
  • Biotic components are living (producers, consumers, decomposers).
  • Abiotic components are non-living (light, water, temperature, soil, air).
  • Food chains show who eats whom.
  • Food webs are interconnected food chains.
  • Energy flows one-way, decreasing at each level (10% law).
  • Nutrients are recycled by decomposers.

Practice Questions

  1. Explain the role of decomposers in maintaining the balance of an ecosystem.
  2. Differentiate between a food chain and a food web with suitable examples.
  3. Why is the flow of energy in an ecosystem considered unidirectional, and what is the 10% law?
  4. Give examples of both natural and artificial ecosystems.
  5. How do abiotic factors like temperature and water influence the biotic components of an ecosystem?