Patterns in Life Diversity and Classification — Class 9 Science NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 9 Science chapter "Patterns in Life Diversity and Classification" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 9 Science chapter "Patterns in Life Diversity and Classification" — 8 important questions with detailed an…
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NCERT Solutions for Class 9 Science — Patterns in Life Diversity and Classification. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
Patterns in Life Diversity and Classification — All 8 Questions Solved
Q1. What is classification? Why is it necessary to classify living organisms?
Classification = Organizing living organisms into groups based on their similarities and differences.
Necessity of classification:
(1) Identify organisms easily
(2) Understand relationships between organisms
(3) Understand evolution of organisms
(4) Study diversity of life
(5) Predict properties of unknown organisms
(6) Make study of biology systematic and organized
Biological classification groups organisms based on:
• Morphological features (body structure)
• Anatomical features (internal structure)
• Physiological features (functions)
• Genetic/molecular features (DNA similarity)
Q2. Explain the hierarchical classification system. Give the hierarchy levels.
Hierarchical classification = Grouping of organisms from broadest to most specific category.
Hierarchy levels (Kingdom → Species):
(1) Kingdom: Largest, most general group (e.g., Animalia, Plantae)
(2) Phylum: Major subdivisions within kingdom (e.g., Chordata, Arthropoda)
(3) Class: Subdivisions of phylum (e.g., Mammalia, Insecta)
(4) Order: Subdivisions of class (e.g., Primates, Coleoptera)
(5) Family: Subdivisions of order (e.g., Hominidae, Carabidae)
(6) Genus: Group of similar species (e.g., Homo, Carabus)
(7) Species: Organisms that can interbreed and produce fertile offspring
Mnemory: Kingdom, Phylum, Class, Order, Family, Genus, Species (KPCOFGS)
Example: Humans: Animalia → Chordata → Mammalia → Primates → Hominidae → Homo → sapiens
Q3. Describe the five kingdom classification system.
Five Kingdom Classification (Whittaker, 1969):
(1) Monera: Prokaryotes (bacteria, cyanobacteria)
• Single-celled, no nucleus
• Cell wall present
• Example: E. coli
(2) Protista: Single-celled eukaryotes
• Nucleus present
• Live in moist/aquatic environment
• Example: Amoeba, Euglena, Paramecium
(3) Fungi: Multi-cellular eukaryotes
• Cell wall of chitin (not cellulose)
• Absorb nutrients (heterotrophic)
• Example: Mushroom, Yeast, Bread mould
(4) Plantae: Multi-cellular eukaryotes, autotrophic
• Cell wall of cellulose
• Contain chlorophyll
• Example: Moss, Fern, Flowering plants
(5) Animalia: Multi-cellular eukaryotes, heterotrophic
• No cell wall
• Obtain nutrients by ingestion
• Example: Sponge, Worm, Fish, Bird, Mammal
Q4. Explain the main groups of plant kingdom with examples.
Major groups of plant kingdom (based on vascular tissue and reproduction):
(1) Algae: Primitive plants; mostly aquatic
• Examples: Green algae (Chlamydomonas), Brown algae (Kelp), Red algae
• Reproduce by spores or vegetative propagation
(2) Bryophytes: Non-vascular plants; depend on moisture
• Examples: Moss, Liverwort
• Require water for sexual reproduction
(3) Pteridophytes: Vascular plants without seeds
• Examples: Fern
• Reproduce by spores
(4) Gymnosperms: Seed-bearing plants; seeds exposed
• Examples: Pine, Cedar, Deodar
• Cones contain seeds
(5) Angiosperms: Flowering plants; seeds in fruits
• Examples: Rose, Mango, Wheat, Sunflower
• Most advanced; most diverse
Q5. Explain the main groups of animal kingdom with examples.
Major groups of animal kingdom (based on presence of backbone):
(1) Porifera: Sponges
• Most primitive; no true tissues
• Sessile (fixed to surface)
• Example: Bath sponge
(2) Cnidaria (Coelenterates): Radially symmetrical
• Two body layers
• Have tentacles with stinging cells
• Example: Hydra, Jellyfish, Coral
(3) Platyhelminthes: Flatworms
• Bilaterally symmetrical
• Flattened body
• Example: Planaria, Tapeworm
(4) Arthropoda: Jointed legs; exoskeleton
• Most diverse; largest phylum
• Example: Insect, Spider, Crustacean
(5) Mollusca: Soft body
• Example: Snail, Octopus, Squid
(6) Annelida: Segmented worms
• Example: Earthworm, Leech
(7) Chordata: Backbone (vertebrates)
• Fish, Amphibian, Reptile, Bird, Mammal
Q6. Classify human being according to the five kingdom system.
Human classification in five kingdom system:
Kingdom: Animalia (multi-cellular, heterotrophic, eukaryotic)
Phylum: Chordata (has backbone/spinal cord)
Class: Mammalia (warm-blooded, hair, mammary glands for lactation)
Order: Primates (opposable thumbs, forward-facing eyes, large brain)
Family: Hominidae (apes and humans)
Genus: Homo (upright posture, large brain)
Species: sapiens (wise human)
Full notation: Homo sapiens
Key characteristics: Bipedal, large brain (1400 cm³), complex language, tool making
Q7. What are the basis of classification? Explain morphological classification.
Basis of classification (Criteria used to classify organisms):
(1) Morphological: Body structure and appearance
(2) Anatomical: Internal structure of organs and tissues
(3) Physiological: Body functions and metabolism
(4) Genetic/Molecular: DNA and protein sequences
Morphological classification = Based on external features and body structure:
• Body shape and size
• Symmetry (radial, bilateral, asymmetrical)
• Presence/absence of body parts (legs, wings, tentacles)
• Texture and color of skin/outer covering
Examples:
• Sponge: Porous, irregular shape
• Hydra: Cylindrical with tentacles
• Earthworm: Segmented, elongated
Advantage: Easiest and quickest method
Disadvantage: Similar external features may not reflect true relationships (convergent evolution)
Q8. Distinguish between vertebrates and invertebrates. Give examples of each.
Vertebrates = Animals with backbone/vertebral column (internal skeleton)
Characteristics: (1) Backbone protects spinal cord
(2) Internal skeleton of bone/cartilage
(3) Generally larger animals
Examples:
• Fish: Shark, Salmon
• Amphibia: Frog, Salamander
• Reptilia: Snake, Lizard
• Aves (Birds): Sparrow, Eagle
• Mammalia: Human, Dog, Whale
Invertebrates = Animals without backbone (no vertebral column)
Characteristics: (1) No internal backbone
(2) Body supported by external skeleton/hydrostatic pressure
(3) Make up 99% of all animal species
Examples:
• Cnidaria: Hydra, Jellyfish
• Arthropoda: Insect, Spider, Crab
• Mollusca: Snail, Squid
• Annelida: Earthworm
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.