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CBSE Class 10 Science Question 7 of 9

Our Environment — Question 1

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Question 1

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

Answer

The various steps or levels in a food chain at which the transfer of energy takes place are called trophic levels.

An Example of food chain is:

Grass → grasshopper → frog → snake

  • The autotroph or the producer — In the above given food chain grass is the producer. It is at the first trophic level. It fixes up the solar energy and makes it available for heterotrophs or the consumers.

  • The herbivores or the primary consumers — They are the second trophic level. In the above given food chain grasshopper is the primary consumer as it feeds on grass.

  • Secondary Consumers — They are third trophic level. Small carnivores like frog in the given food chain is the secondary consumer.

  • Tertiary consumer — They are the fourth trophic level. Larger carnivores like snake in the given food chain constitute the fourth trophic level.

Different organisms may be on different trophic levels depending upon their position in different food chains.

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Science | Chapter 13: Our EnvironmentWeb Content

Chapter 13: Our Environment — Quick Revision Guide

Introduction

Our environment is a complex web of living and non-living components. This chapter covers ecosystems, food chains, energy flow, ozone layer depletion, and waste management.

Key Points at a Glance

  1. Ecosystem: biotic (producers, consumers, decomposers) + abiotic (temperature, water, soil, light)
  2. Food chain: linear energy transfer; Grass → Grasshopper → Frog → Snake → Hawk
  3. Trophic levels: T1 (producers), T2 (primary consumers), T3, T4; usually 4–5 levels max
  4. 10% law (Lindeman): only 10% energy transfers to next level; rest lost as heat in life processes
  5. Food web: interconnected chains; more stable; if one species declines, alternatives exist
  6. Biological magnification: non-biodegradable chemicals (DDT) concentrate at higher trophic levels
  7. Ozone (O3) in stratosphere absorbs UV; CFCs deplete ozone; Montreal Protocol (1987) limits CFCs
  8. Biodegradable waste: broken down by microorganisms; composting, vermicomposting, biogas
  9. Non-biodegradable waste: persists; plastic, glass, DDT; reduce, reuse, recycle
  10. Problems: biomagnification, plastic pollution, e-waste toxicity, air pollution from burning waste

Real-World Connections

Banning single-use plastic reduces pollution; composting reduces landfill load; ozone layer is slowly recovering; understanding food chains helps conservation; DDT ban protected bird populations.

Quick Self-Test (5 Questions)

  1. What is the most important concept you learned from this chapter?
  2. Can you write three key equations/formulae from this chapter from memory?
  3. Draw a labelled diagram relevant to this chapter without looking at your notes.
  4. Explain one real-world application of a concept from this chapter.
  5. What is one common mistake students make in this chapter, and how can you avoid it?

Further Study

  • NCERT Textbook Chapter 13
  • NCERT Exemplar Problems
  • Bright Tutorials Detailed Notes: ch13-our-environment.html
  • Bright Tutorials Practice Questions: ch13-our-environment.html
  • Previous Year CBSE Board Papers

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