Chapter 2: Biological Classification

Biology • Class 11

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Chapter Analysis

Intermediate12 pages • English

Quick Summary

The chapter 'Biological Classification' in Class 11 Biology discusses the evolution of classification systems from Aristotle's early attempts to the more scientific five kingdom system proposed by Whittaker. It covers the kingdoms Monera, Protista, Fungi, Plantae, and Animalia, detailing characteristics such as cell structure, body organization, and modes of nutrition. The chapter also introduces viruses, viroids, prions, and lichens, explaining their unique features and roles in the biological world.

Key Topics

  • Five Kingdom Classification
  • Characteristics of Monera
  • Features of Protista
  • Diversity in Fungi
  • Viruses and their nature
  • Concept of lichens
  • Alternation of Generations
  • Economic importance of bacteria and fungi

Learning Objectives

  • Understand the historical development of classification systems.
  • Identify the different kingdoms and their defining features.
  • Explain the role of fungi in ecosystems and industry.
  • Describe the life cycles of various organisms including plants and fungi.
  • Analyze the characteristics and roles of viruses, viroids, and prions.
  • Distinguish between prokaryotic and eukaryotic life forms.

Questions in Chapter

Discuss how classification systems have undergone several changes over a period of time?

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State two economically important uses of: (a) heterotrophic bacteria (b) archaebacteria

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What is the nature of cell-walls in diatoms?

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Find out what do the terms ‘algal bloom’ and ‘red-tides’ signify.

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How are viroids different from viruses?

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Describe briefly the four major groups of Protozoa.

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Plants are autotrophic. Can you think of some plants that are partially heterotrophic?

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What do the terms phycobiont and mycobiont signify?

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Give a comparative account of the classes of Kingdom Fungi under the following: (i) mode of nutrition (ii) mode of reproduction

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What are the characteristic features of Euglenoids?

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Give a brief account of viruses with respect to their structure and nature of genetic material. Also name four common viral diseases.

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Organise a discussion in your class on the topic – Are viruses living or non-living?

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Additional Practice Questions

Explain the concept of alternation of generations in the plant kingdom.

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Answer: Alternation of generations refers to the life cycle of plants that alternates between a haploid gametophytic phase and a diploid sporophytic phase. This cycle results in a sequence of phases that contribute to genetic diversity and adaptation.

Why are viruses considered as both living and non-living?

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Answer: Viruses are considered living because they replicate within host cells by hijacking the cell's machinery. However, they are also seen as non-living since they are inert outside host cells and lack cellular structure, metabolism, and the ability to reproduce independently.

Discuss the economic significance of fungi.

easy

Answer: Fungi play a crucial role in decomposing organic matter, cycling nutrients, and forming symbiotic relationships with plants. They are also used in producing food products like bread and cheese, and in biotechnology for antibiotics and enzymes.

What is the role of cyanobacteria in the nitrogen cycle?

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Answer: Cyanobacteria contribute to the nitrogen cycle by fixing atmospheric nitrogen into forms usable by plants, enriching the soil and promoting plant growth. This process is critical for maintaining soil fertility.

Differentiate between prokaryotic and eukaryotic cells.

easy

Answer: Prokaryotic cells lack a defined nucleus and membrane-bound organelles, presenting a simpler structure. Eukaryotic cells have a true nucleus enclosed by a membrane, multiple organelles, and more complex organization.

NCERT Exemplar

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Practice with NCERT Exemplar problems and solutions for this chapter. Exemplar problems are designed to help you master the concepts with advanced-level questions.

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