Chapter 9

Science chapter 09

Organisms and surroundings

Living and Non-living Things

  • The study of living organisms is called biology.

Habitat and Adaptation

Habitat

  • The place where an organism lives is called its habitat.
  • Deserts, mountains, forests, grasslands, soil, ponds, lakes and rivers are some examples of habitats.
  • The habitat provides food, water, air, light, shelter and a place for breeding to plants and animals living in it.

 

Types of Habitat

Habitats of Some Common Plants and Animals

Components of a Habitat

Adaptation

  • The presence of specific body features which enable a plant or an animal to survive in a particular habitat is called adaptation.
  • Adaptation is of two kinds – structural adaptation and behavioral adaptation.
  • Structural adaptation refers to changes in the shape and size of the body of an animal. Examples: Ducks have webbed feet which enable them to wade through water easily.
  • Behavioral adaptation refers to changes shown by an animal with respect to its behavior. Examples: Penguins move in large groups to protect themselves from redactors.

Adaptations in Animals

Some Terrestrial Habitats

Deserts

  • A waterless area of land covered with sand and with little or no vegetation is called a desert.
  • It receives very low rainfall. The annual rainfall is less than 250 mm per year.
  • The maximum temperature in deserts ranges between 43.5°C and 49°C. The minimum temperature ranges between 0°C and 3°C.

 

Adaptations of Organisms Living in Deserts

Adaptations in Desert Animals

  • Most of the animals in the deserts remain inactive during the day and are called nocturnal.
  • They live in burrows to escape from intense heat.
  • Desert animals need to maintain an optimal body temperature.
  • So, animals such as jack rabbits have developed long ears which provide greater surface area to dissipate heat.
  • Desert animals such as desert rats and desert snakes pass out very small

amounts of urine which helps them to conserve water in their body.

Adaptations in desert plants

  • Plants growing in hot and dry regions such as deserts are called xerophytes or xerophytic plants.
  • They have a well-developed root system which spreads deep into the soil. This helps them to absorb water from the deepest soil layers possible.
  • In some plants, the surface area of the stem and leaves is reduced.
  • Some plants shed their leaves under unfavorable conditions.
  • The leaves are either absent, very small or present in the form of spines. This helps to reduce the loss of water through transpiration.
  • Stem or leaves are covered with a thick waxy layer called cuticle which prevents the loss of water.
  • The leaves of plants possess sunken stomata which are slightly deeper than the

leaf surface.

Adaptations in Cactus

  • The leaves are smaller and fewer in number.
  • When water is scarce, the leaves get transformed into fine pointed spines.
  • The stem is fleshy, thick and green so that it can store food and water.
  • The stem is covered with a cuticle to prevent the loss of water through evaporation.
  • It has long roots to absorb water from a larger area.

Mountain Regions

  • A very high hill is called a mountain.
  • Mountains can be covered with snow.
  • Mountainous habitats are usually very cold and windy.

Adaptations of Organisms Living in Mountain Regions

Adaptations in mountainous plants

  • Trees are usually cone-shaped with sloping branches
  • Leaves are small, needle-shaped to minimize the loss of water in windy conditions
  • Broad-leaved trees shed their leaves before the onset of winter to prevent the

loss of water from their leaves

Adaptations in mountainous animals

 

  • Thick skin of fur to protect them from the cold environment

Adaptations in Yak

  • Long hair on its body protects it from cold

Adaptations in Mountain goat

  • Long hair protects the goat from cold and keeps it warm
  • Strong hooves help in running up the rocky slopes of mountains for grazing

Adaptations in Snow leopard

  • Thick fur on its body protects it from cold and keeps it warm
  • Thick layer of fat beneath its skin provides insulation and protects it from cold
  • Rounded body and small ears to minimise the body surface area
  • Big feet to spread the weight on snow and to prevent it from sinking into soft snow

Forests

  • A large area of land covered mainly with trees and plants is called a forest.

Adaptations of animals living in forests

Adaptations in lion

  • Strong, fast and agile animal which can hunt and kill its prey
  • Long, strong and sharp claws on its front legs so it can catch its prey
  • Eyes are in front of its head to have an exact idea of the location of its prey
  • Its light brown colour helps it to hide in dry grasslands when it hunts its prey

Adaptations in deer

  • Eyes on the sides of its head enable vision in all directions at the same time
  • Big ears help the deer to hear the movements of predators very easily
  • High speed enables it to escape from its enemies
  • Brown colour helps it to camouflage itself in dry grasslands without being noticed by its predators
  • Strong teeth for chewing hard stems of forest plants

Adaptations of Organisms Living in Mountain Regions

Oceans

  • A very large area of sea is called an ocean.

Adaptations in animals living in oceans

  • Streamlined bodies.
  • Gills for breathing.
  • Blowholes in case of Dolphins and whales for breathing.

Ponds, Lakes and Rivers

  • Small water bodies are referred to as ponds, lakes and rivers.

Adaptations in aquatic plants

  • They have very short and small roots.
  • They have soft, hollow and light stems with large spaces filled with air. This helps them to stay afloat in water.
  • The submerged aquatic plants have narrow and thin ribbon-like leaves which can bend in the flowing water of rivers and streams and hence, do not obstruct the flow of water.
  • The thin leaves also allow minerals to pass through the plants easily.
  • The leaves are broad but flexible.

Adaptations in animals to live in water and on land

  • Frogs have webbed feet which help them to swim and survive in water.
  • They have strong hind legs for hopping and catching their prey. This helps them to survive on land
  • The process of being accustomed to a different environment over short periods of time is called acclimatization.

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