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The Living World – Class 11 Biology notes, important questions and MCQs

NCERT Class 11 Biology, chapter 1. Notes, key terms, important questions with answers and MCQs.

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Chapter overview

Living organisms grow, reproduce, metabolise and respond to their surroundings. Taxonomy names and classifies them using a hierarchy of categories.

Characteristics and naming

  • Defining features: metabolism, cellular organisation and consciousness (response to stimuli); growth and reproduction are not unique to life.
  • Binomial nomenclature (Linnaeus): genus + species, e.g. Mangifera indica; genus starts with a capital letter, both italicised.
  • ICBN and ICZN codes govern plant and animal names.

Taxonomic hierarchy and aids

  • Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.
  • Species is the basic unit of classification.
  • Taxonomic aids: herbarium, botanical garden, museum, zoo, keys, monographs.

Key terms

Taxonomy
science of identifying, naming and classifying organisms
Herbarium
collection of dried, pressed plant specimens on sheets
Taxon
a unit of classification at any level, such as a species, genus or family

Important questions with answers

Why are living organisms classified?2 marks

To make the study of millions of organisms easier, to understand their relationships and evolution, and to identify and name them in a standard way.

What are the main taxonomic aids? Give the use of a herbarium and a key.3 marks

Herbaria, botanical gardens, museums, zoological parks, keys, flora, manuals and monographs. A herbarium stores dried, pressed plants with labels for quick reference. A key uses pairs of contrasting characters (couplets) to identify an unknown organism step by step.

Explain the taxonomic hierarchy with the example of a housefly or wheat, and state why growth and reproduction are not defining features of life.5 marks

Taxonomic categories in order: kingdom → phylum/division → class → order → family → genus → species. Wheat: Plantae → Angiospermae → Monocotyledonae → Poales → Poaceae → Triticum → aestivum. Housefly: Animalia → Arthropoda → Insecta → Diptera → Muscidae → Musca → domestica. Growth is also seen in non-living things (crystals, mountains grow by accumulation), and many living organisms do not reproduce (mules, sterile worker bees, infertile couples). So metabolism, cellular organisation and response to stimuli (consciousness) are the defining features.

Quick revision

  • Species is the basic unit.
  • Linnaeus gave binomial nomenclature.
  • Metabolism is a defining feature of life.

Exam tips

  • Remember the order: Kingdom, Phylum, Class, Order, Family, Genus, Species.
  • Write scientific names correctly: genus capitalised, species in lower case, both italic (underline when handwritten), author's name abbreviated at the end (e.g. Mangifera indica Linn.).

Practice MCQs

  1. Binomial nomenclature was introduced by

    1. Darwin
    2. Linnaeus
    3. Whittaker
    4. Mendel
    Show answer

    Answer: (b) Linnaeus. Carolus Linnaeus.

  2. The basic unit of classification is

    1. genus
    2. family
    3. species
    4. order
    Show answer

    Answer: (c) species. Species.

  3. In Mangifera indica, "indica" is the

    1. genus
    2. order
    3. family
    4. specific epithet
    Show answer

    Answer: (d) specific epithet. Species name.

  4. A collection of dried, pressed plants is a

    1. herbarium
    2. museum
    3. zoo
    4. botanical garden
    Show answer

    Answer: (a) herbarium. Herbarium.

  5. Which is the correct scientific name of humans

    1. homo sapiens
    2. Homo sapiens
    3. Homo Sapiens
    4. HOMO SAPIENS
    Show answer

    Answer: (b) Homo sapiens. Genus capital, species small.

  6. Correct ascending order is

    1. order → family → species → genus
    2. genus → species → order → family
    3. family → order → genus → species
    4. species → genus → family → order
    Show answer

    Answer: (d) species → genus → family → order. Lowest to highest.

  7. Which is a defining property of living organisms

    1. growth
    2. metabolism
    3. reproduction
    4. increase in mass
    Show answer

    Answer: (b) metabolism. Non-living things can grow.

  8. Mango, potato and wheat belong to different

    1. kingdoms
    2. divisions
    3. genera
    4. classes only by chance
    Show answer

    Answer: (c) genera. Mangifera, Solanum, Triticum.

All chapters of Class 11 Biology

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.