General Science Notes Chapter 2 Class 7 Maharashtra Board

Notes For All Chapters – General Science Class 7

Plants : Structure and Function

1. What is Adaptation?

• Adaptation is a special feature that helps plants and animals survive in their surroundings.
• It helps organisms get food, water, air, and protection from extreme conditions.
• Organisms that cannot adapt struggle to survive and may become extinct.
• Different environments need different types of adaptations.

2. Types of Habitats

A habitat is a place where an organism lives and gets food, water, and shelter.The main types of habitats are:

1. Desert Habitat (Hot and dry places)
2. Polar Habitat (Very cold and covered with snow)
3. Aquatic Habitat (Lakes, rivers, and oceans)
4. Grassland Habitat (Plains covered with grass)
5. Forest Habitat (Dense trees and plants)

3. Adaptation in Plants

Plants show adaptations based on where they live.

(A) Desert Plants (Xerophytes)

• Example: Cactus, Acacia
• Thick, fleshy stems to store water.
• Small or thorny leaves to reduce water loss.
• Deep roots to absorb water from underground.

(B) Aquatic Plants (Hydrophytes)

• Example: Lotus, Water Hyacinth
• Broad and waxy leaves to float on water.
• Light and spongy stems to stay afloat.
• Short roots as water is always available.

(C) Grassland Plants

• Example: Grasses, Wheat, Rice
• Soft and flexible stems to bend with wind.
• Fibrous roots to hold soil tightly.

(D) Climbers and Creepers

• Example: Money Plant, Pumpkin
• Weak stems need support to grow upwards.
• Use tendrils or grow along the ground.

(E) Special Plants with Adaptations

1. Venus Flytrap – Traps insects for nutrients.
2. Cuscuta (Dodder Plant) – A parasite that takes food from other plants.
3. Mimosa (Touch-Me-Not) – Closes its leaves when touched.

4. Adaptation in Animals

Animals adapt based on where they live and how they get food.

(A) Desert Animals

• Example: Camel, Lizard
• Camels store fat in their humps for energy.
• Have long legs and padded feet to walk on sand.
• Do not sweat much to save water.

(B) Polar Animals

• Example: Penguin, Polar Bear
• Thick fur and a fat layer for warmth.
• White skin to blend with snow.
• Penguins live in groups to keep warm.

(C) Grassland Animals

• Example: Deer, Lion
• Deer have long legs to run fast and escape predators.
• Lions have sharp teeth and claws to hunt.

(D) Aquatic Animals

• Example: Fish, Dolphin, Duck
• Fish have gills to breathe in water.
• Dolphins have streamlined bodies for fast swimming.
• Ducks have webbed feet to swim easily.

(E) Birds and Their Adaptations

• Eagles and hawks have sharp claws for catching prey.
• Woodpeckers have strong beaks to drill into trees.
• Ducks have waterproof feathers to stay dry.

5. Special Adaptations in Some Animals

1. Chameleons – Change color to blend with surroundings.
2. Owls – Have big eyes to see in the dark.
3. Frogs – Have webbed feet for swimming.
4. Bats – Use echolocation to find food at night.

6. Importance of Adaptation

• Survival: Helps organisms live in extreme environments.
• Protection: Saves them from predators and harsh weather.
• Reproduction: Ensures the continuation of species.
• Food Availability: Helps them get food in their surroundings.

7. Adaptation and Classification of Organisms

• Organisms are classified based on their adaptations and body structures.
• Vertebrates: Animals with a backbone (e.g., fish, birds, mammals).
• Invertebrates: Animals without a backbone (e.g., insects, worms).

8. Interdependence of Organisms and Their Surroundings

• Plants and animals depend on each other for survival.
• Plants provide food and oxygen to animals.
• Animals help in pollination and seed dispersal.
• Decomposers (like fungi and bacteria) break down dead plants and animals.

9. What If Adaptations Did Not Exist?

• Without adaptation, plants and animals cannot survive in their habitats.
• Polar bears would freeze without fur.
• Cactus would dry up without water-storing stems.
• Camels would struggle to walk in deserts.