General Science Notes Chapter 1 Class 7 Maharashtra Board

Notes For All Chapters – General Science Class 7

The Living World : Adaptations and Classification

1. Introduction to Adaptation

• Adaptation is the ability of living organisms to adjust to their environment for survival.
• Organisms develop adaptations over a long period to survive in different habitats.
• Adaptations can be structural (physical changes), behavioral (changes in habits), or physiological (internal changes in the body).

2. Adaptation in Aquatic Plants (Water Plants)

Features of Aquatic Plants:

1. Floating Plants:
   • These plants float on water because their leaves have air spaces.
   • Example: Lotus, Water Hyacinth
2. Fixed Plants:
   • These plants are rooted in the soil underwater, but their leaves float on the surface.
   • Example: Lotus, Water Lily
3. Underwater Plants:
   • These plants grow completely underwater and absorb dissolved oxygen from water.
   • Example: Hydrilla, Vallisneria

Adaptations in Aquatic Plants:

• Leaves have a waxy coating to prevent waterlogging.
• Stems are soft and flexible to move with water currents.
• Roots are short and fibrous as they do not need to absorb much water.

3. Adaptation in Aquatic Animals (Water Animals)

Features of Aquatic Animals:

1. Fish:
   • Have gills to breathe underwater.
   • Streamlined body helps them swim smoothly.
   • Fins and tail help in movement and balance.
2. Frogs:
   • Have webbed feet for swimming.
   • Can live both on land and in water.
3. Ducks and Swans:
   • Have waterproof feathers to keep dry.
   • Webbed feet help in swimming.
4. Whales and Dolphins:
   • Use lungs to breathe air.
   • Have blubber (thick fat layer) to keep warm in cold water.

4. Adaptation in Desert Plants

Features of Desert Plants:

1. Cactus:
   • Has thick, fleshy stem to store water.
   • Leaves are modified into spines to reduce water loss.
2. Acacia Tree:
   • Has deep roots to absorb water from underground.
   • Leaves are small to prevent excessive evaporation.

5. Adaptation in Desert Animals

Features of Desert Animals:

1. Camel (Ship of the Desert):

• Hump stores fat, which provides energy.
• Long eyelashes protect eyes from sand.
• Padded feet help in walking on sand.

2. Snakes and Lizards:

• Live in burrows during the day to escape heat.
• Have scaly skin to prevent water loss.

6. Adaptation in Cold Regions (Polar Regions)

Features of Cold-Climate Animals:

1. Polar Bear:
   • Has thick fur and a layer of fat (blubber) to stay warm.
   • White fur helps in camouflage in snowy surroundings.
2. Penguin:
   • Has a thick fat layer to keep warm.
   • Webbed feet help in swimming.
   • Lives in groups (flocks) to share body heat.

7. Adaptation in Grassland Animals

• Grasslands have plenty of food and open spaces.
• Animals need adaptations to escape from predators.

Examples of Grassland Animals:

1. Deer and Antelope:
   • Have long and strong legs to run fast.
   • Have sharp hearing to detect danger.
2. Lions:
   • Have sharp claws and strong teeth to catch prey.
   • Their golden fur helps them blend with dry grass.

8. Adaptation in Insects

• Insects are found in large numbers and have different adaptations.

Examples:

1. Butterflies and Bees:
   • Have long mouthparts (proboscis) to suck nectar.
   • Help in pollination.
2. Cockroach and Ants:
   • Can live in different climates and hide in small places.

9. Protection Mechanisms in Animals

1. Camouflage:
   • Some animals blend with their surroundings to hide from predators.
   • Example: Chameleon, Tiger, Stick Insect
2. Mimicry:
   • Some animals copy the look of harmful creatures to avoid being eaten.
   • Example: Certain butterflies mimic poisonous ones.
3. Body Covering:
   • Animals have special body coverings for protection.
   • Example: Tortoises have hard shells, Hedgehogs have spines.

10. Importance of Adaptation

• Helps organisms survive in extreme conditions.
• Prevents extinction of species.
• Helps maintain balance in nature.