Class 6 Science Notes Chapter 9 (Chapter 9) – Examplar Problem Book

Detailed Notes with MCQs of Chapter 9, 'The Living Organisms — Characteristics and Habitats' from your Science Exemplar book. This is a fundamental chapter, and understanding it well is crucial, not just for your regular studies but also for various competitive government exams where basic science concepts are often tested.

Chapter 9: The Living Organisms — Characteristics and Habitats - Detailed Notes

1. What are Living Organisms?
Organisms that exhibit certain characteristics like growth, respiration, response to stimuli, reproduction, excretion, movement, and require food are called living organisms. Examples: Plants, animals, microorganisms.

2. Habitat:

• Definition: The natural environment or surroundings where an organism lives, finds food, water, shelter, and reproduces is called its habitat.
• Components of a Habitat:
  • Biotic Components: All the living things in a habitat. Examples: Plants, animals, microorganisms.
  • Abiotic Components: All the non-living things in a habitat. Examples: Rocks, soil, air, water, sunlight, temperature, humidity.
  • Key Point: Biotic and abiotic components are interdependent. Living organisms depend on abiotic factors for survival.

3. Types of Habitats:

• A. Terrestrial Habitats: Habitats found on land.

  • Deserts:
    • Characteristics: Very hot days, cold nights, very little rainfall, sandy soil.
    • Adaptations (Examples):
      • Camel: Long legs (keep body away from hot sand), stores fat in hump (energy reserve), excretes concentrated urine and dry dung (conserve water), can close nostrils (prevent sand entry), wide feet (walk on sand).
      • Cactus (Plant): Leaves reduced to spines (reduce water loss via transpiration), thick waxy stem (stores water, performs photosynthesis), deep roots (absorb groundwater).
      • Rats & Snakes: Live in burrows deep in the sand during the day to escape heat.
  • Mountain Regions:
    • Characteristics: Very cold, often snowy, strong winds, varying sunlight depending on altitude.
    • Adaptations (Examples):
      • Mountain Goat/Yak: Thick fur (protection from cold), strong hooves (climbing rocky slopes).
      • Snow Leopard: Thick fur, wide paws (walk on snow).
      • Trees (e.g., Pines, Firs): Cone-shaped with sloping branches (snow slides off easily), needle-like leaves (reduce water loss, withstand cold).
  • Grasslands:
    • Characteristics: Dominated by grasses, moderate rainfall.
    • Adaptations (Examples):
      • Lion (Predator): Light brown colour (camouflage in dry grass), strong claws (retractable), eyes in front (judge distance).
      • Deer (Prey): Strong teeth (chewing hard plant stems), long ears (hear predators), eyes on the side (wide view), fast runner.

• B. Aquatic Habitats: Habitats found in water.

  • Oceans:
    • Characteristics: Salty water, vast, varying pressure and light with depth.
    • Adaptations (Examples):
      • Fish: Streamlined body (easy movement in water), gills (breathe dissolved oxygen), fins (balance, direction), scales (protection).
      • Dolphins & Whales: Mammals, breathe air through blowholes located on top of their heads, come to the surface to breathe. (Note: They don't have gills).
      • Octopus/Squid: Streamlined body, don't always stay near the seabed, change body shape.
  • Ponds and Lakes:
    • Characteristics: Freshwater habitats.
    • Adaptations (Examples):
      • Aquatic Plants:
        • Floating: Lotus, Water Hyacinth (large leaves, spongy stems).
        • Submerged: Hydrilla, Vallisneria (narrow ribbon-like leaves, flexible stems, absorb nutrients directly from water).
        • Fixed: Water Lily (roots fixed, leaves float).
      • Frogs: Can live both on land (breathe through lungs) and in water (breathe through moist skin), webbed hind feet (swim), strong back legs (leaping).

4. Adaptation:

• Definition: The presence of specific features or certain habits which enable an organism (plant or animal) to live successfully in its particular habitat is called adaptation.
• Acclimatisation: Small changes that take place in the body of a single organism over short periods to overcome small problems due to changes in its surroundings (e.g., adjusting to high altitude). This is different from adaptation, which occurs over thousands of years and involves genetic changes.

5. Characteristics of Living Organisms: (Crucial for distinguishing living from non-living)

• Need Food: To get energy for life processes, growth, and repair. Plants make their own food (photosynthesis); animals depend on plants or other animals.
• Show Growth: Increase in size over time. Growth is irreversible.
• Respire: Take in oxygen and give out carbon dioxide to release energy from food. (Plants also respire day and night, though photosynthesis occurs only in daylight). Gills in fish, lungs in mammals, stomata/lenticels in plants, skin in earthworms are respiratory structures/organs.
• Respond to Stimuli: React to changes in their surroundings. Examples: Touch-me-not plant closing leaves when touched, moving towards food, moving away from danger, plants growing towards sunlight. The change in the environment is the 'stimulus'.
• Excrete: Get rid of waste products from the body. Examples: Urine, sweat, carbon dioxide (in respiration), faeces. Plants excrete wastes as secretions (gum, resin) or store them in leaves that they shed.
• Reproduce: Produce young ones of their own kind. Ensures continuity of the species. Methods vary: laying eggs (birds, reptiles), giving birth (mammals), seeds (plants), spores (fungi, ferns), budding (hydra), vegetative propagation (plants).
• Show Movement: Animals move from place to place. Plants show movement like opening/closing of flowers, growth of roots towards water, growth of stem towards light, but generally don't move from place to place (locomotion).
• Have a Definite Lifespan: Organisms are born, grow, reproduce, and eventually die.

Key Takeaway for Exams: Focus on definitions (habitat, adaptation, biotic/abiotic, stimuli, etc.), specific examples of adaptations in different habitats (especially desert and aquatic), and the fundamental characteristics that define life. Understand the difference between adaptation and acclimatisation.

Multiple Choice Questions (MCQs)

Here are 10 MCQs based on Chapter 9 to test your understanding:

1. Which of the following are abiotic components of a habitat?
   (a) Plants and animals
   (b) Soil, water, and air
   (c) Microorganisms and fungi
   (d) Predators and prey

2. The presence of specific features that enable a plant or animal to live in a particular habitat is called:
   (a) Habitat
   (b) Acclimatisation
   (c) Adaptation
   (d) Respiration

3. Camels are adapted to desert life. Which feature helps them conserve water?
   (a) Long legs
   (b) Storing fat in the hump
   (c) Excreting small amounts of concentrated urine
   (d) Having wide feet

4. Mountain goats have strong hooves primarily for:
   (a) Running fast on flat ground
   (b) Digging burrows
   (c) Walking on snow
   (d) Climbing rocky slopes

5. Fish breathe using:
   (a) Lungs
   (b) Blowholes
   (c) Gills
   (d) Skin

6. Which of the following is NOT a characteristic of all living organisms?
   (a) Respiration
   (b) Photosynthesis
   (c) Growth
   (d) Reproduction

7. Plants respond to stimuli. The growth of a plant shoot towards sunlight is an example of response to:
   (a) Touch
   (b) Gravity
   (c) Light
   (d) Water

8. Dolphins and whales come up to the water surface to breathe because they:
   (a) Have gills like fish
   (b) Breathe through lungs using blowholes
   (c) Need sunlight for energy
   (d) Absorb oxygen through their skin

9. Which type of aquatic plant typically has narrow, ribbon-like leaves and flexible stems?
   (a) Floating plants (e.g., Lotus)
   (b) Submerged plants (e.g., Hydrilla)
   (c) Desert plants (e.g., Cactus)
   (d) Mountain plants (e.g., Pine)

10. The process of getting rid of waste products by living organisms is called:
    (a) Respiration
    (b) Reproduction
    (c) Excretion
    (d) Adaptation

Answer Key for MCQs:

1. (b)
2. (c)
3. (c)
4. (d)
5. (c)
6. (b) - Photosynthesis is specific to plants and some other organisms, not all living things.
7. (c)
8. (b)
9. (b)
10. (c)

Study these notes thoroughly. Pay attention to the examples and the reasons behind specific adaptations. Good luck with your preparation!