CBSE Class 6 Science Ch 9: Notes & Q&A

Chapter 9: The Living Organisms — Characteristics and Habitats

CBSE Class 6 Science Notes

Chapter Summary

• Organisms and Surroundings: All living organisms live in specific surroundings. The environment around them plays a crucial role in their survival.
• Habitat: The specific place or surroundings where an organism lives is called its habitat. A habitat provides food, water, air, shelter, and other necessities to an organism.
• Types of Habitats:
  • Terrestrial Habitats: Habitats on land. Examples include forests, grasslands, deserts, mountains, and coastal regions.
  • Aquatic Habitats: Habitats in water. Examples include oceans, ponds, lakes, and rivers.
• Adaptation: The presence of specific features or certain habits that enable an organism to live naturally in a particular place or habitat is called adaptation. Organisms adapt over thousands of years to suit their environment.
• Adaptations in Deserts:
  • Camel: Has long legs to keep its body away from the hot sand, excretes small amounts of urine, its dung is dry, and it does not sweat. These adaptations help it conserve water.
  • Desert Plants (e.g., Cactus): Have long roots that go deep into the soil for water, stems are covered with a thick waxy layer to reduce water loss, leaves are often reduced to spines to prevent water loss through transpiration, and photosynthesis is carried out by the stem.
• Adaptations in Mountain Regions:
  • Trees: Generally cone-shaped with sloping branches, and have needle-like leaves. This helps rainwater and snow slide off easily.
  • Animals (e.g., Yak, Mountain Goat): Have thick skin or fur to protect them from the cold. Mountain goats have strong hooves for running up the rocky slopes.
• Adaptations in Oceans:
  • Fish: Have streamlined bodies (tapering at both ends) to help them move easily through water. They have gills to use oxygen dissolved in water.
  • Dolphins and Whales: Do not have gills. They breathe in air through nostrils (blowholes) located on the upper part of their heads, allowing them to breathe when they swim near the surface of water.
• Adaptations in Ponds and Lakes:
  • Plants: Roots are reduced in size as their main function is to hold the plant in place. Stems are long, hollow, and light, growing up to the surface of water. Leaves and flowers float on the surface. Some submerged plants have narrow and thin ribbon-like leaves.
  • Animals (e.g., Frog): Can live in water and on land. Have strong back legs for leaping and catching prey, and webbed feet for swimming.
• Biotic and Abiotic Components:
  • Biotic Components: All living organisms in a habitat (plants, animals, microorganisms).
  • Abiotic Components: Non-living factors like rocks, soil, water, air, sunlight, and heat.
• Characteristics of Living Organisms:
  • Need Food: All living things need food to get energy for growth and other life processes.
  • Show Growth: Living organisms increase in size over time.
  • Respire: All living organisms breathe to take in oxygen and give out carbon dioxide (or vice versa in some cases). This process is called respiration.
  • Respond to Stimuli: Living organisms react to changes in their surroundings (stimuli). For example, touching a hot object or a sudden bright light.
  • Excrete: Living organisms remove waste products from their bodies.
  • Reproduce: Living organisms produce more of their own kind, either by laying eggs, giving birth to young ones, or through seeds/spores.
  • Show Movement: Most living things move from one place to another (animals) or show movement of parts (plants, e.g., bending towards light).
  • Have a Definite Lifespan: All living organisms eventually die.
• Non-Living Things: Do not possess these characteristics collectively. For example, a car moves, but it doesn't grow, reproduce, or excrete.

Questions and Answers

1. What is a habitat?

Answer: The surroundings where an organism lives is called its habitat. A habitat provides everything an organism needs to survive, such as food, water, air, shelter, and suitable conditions.

2. How are cacti adapted to survive in a desert?

Answer: Cacti are adapted to survive in a desert in the following ways:

• Their leaves are modified into spines to reduce water loss through transpiration.
• Their stems are thick, fleshy, and green, performing photosynthesis and storing water. They are also covered with a thick waxy layer to minimize water loss.
• They have deep roots that go far into the soil to absorb water.

3. Fill in the blanks:

(a) The presence of specific features, which enable a plant or an animal to live in a particular habitat, is called _____.

(b) The habitats of plants and animals that live on land are called _____ habitats.

(c) The habitats of plants and animals that live in water are called _____ habitats.

(d) Soil, water and air are the _____ factors of a habitat.

(e) Changes in our surroundings that make us respond to them, are called _____.

Answer:

(a) The presence of specific features, which enable a plant or an animal to live in a particular habitat, is called adaptation.

(b) The habitats of plants and animals that live on land are called terrestrial habitats.

(c) The habitats of plants and animals that live in water are called aquatic habitats.

(d) Soil, water and air are the abiotic factors of a habitat.

(e) Changes in our surroundings that make us respond to them, are called stimuli.

4. Which of the following are non-living?

Plough, Sewing Machine, Radio, Boat, Water Hyacinth, Earthworm

Answer: The non-living things from the given list are: Plough, Sewing Machine, Radio, Boat.

Water Hyacinth and Earthworm are living organisms.

5. List common characteristics of living things.

Answer: The common characteristics of living things are:

• They need food.
• They show growth.
• They respire (breathe).
• They respond to stimuli.
• They excrete waste products.
• They reproduce.
• They show movement.
• They have a definite lifespan and eventually die.

6. Explain why speed is important for survival in the grasslands for animals that live there. (Hint: there are two types of animals, herbivores and carnivores)

Answer: Speed is crucial for survival in grasslands for both herbivores and carnivores:

• For Herbivores (e.g., Deer): Grasslands have open spaces with less cover. Herbivores need speed to run away from predators (carnivores) when they are attacked. Long ears also help them detect predators from a distance.
• For Carnivores (e.g., Lion): Carnivores rely on speed to chase and catch their prey (herbivores). Without sufficient speed, they would not be able to hunt effectively and would starve. Their light brown color also helps them camouflage in the dry grasslands.

7. How are aquatic animals adapted to live in water?

Answer: Aquatic animals have several adaptations to live in water:

• Most have streamlined bodies that help them move easily through water.
• They have gills (like fish) for using oxygen dissolved in water for respiration.
• Many have fins and tails that help them swim and balance in water.
• Some, like frogs, have webbed feet for swimming.
• Dolphins and whales have blowholes to breathe air when they come to the surface.

8. What are the adaptations of fish to live in water?

Answer: The adaptations of fish to live in water are:

• They have a streamlined body shape, which reduces resistance and helps them move through water easily.
• They have fins and a powerful tail for swimming and maintaining direction.
• They have special organs called gills, which absorb oxygen dissolved in water, allowing them to breathe underwater.
• Their skin is often covered with scales, which provide protection and reduce friction in water.

9. Do you find a relationship between the height of a person and the place he lives in?

Answer: While there isn't a direct and universal relationship where living in a specific place directly dictates a person's height in all cases, certain environmental factors over generations can influence human characteristics, including average height within populations. For example:

• Availability of Nutritious Food: Regions with better nutrition tend to have taller populations on average.
• Climate and Lifestyle: Historically, populations in colder climates might have developed certain body types, while those in warmer climates might have others, sometimes influencing average stature.
• Genetic Factors: The genetic makeup of people living in certain regions plays a very significant role in determining average height.

Therefore, indirect relationships exist due to factors influenced by the environment and lifestyle associated with certain places, but it's not a simple cause-and-effect relationship between "place" and "individual height."