Living organisms and their surroundings Notes


  • The characteristics of living organisms of surviving in their local environment are called adaptation.
  • The non-living things such as air, water and soil are essential for the living things to stay alive. Moreover, the living things are also dependent on themselves for their food.
  • The influence of non-living and living things present nearby a particular living thing is called its environment.
  • In an environment, the interaction between the living components with each other, and with the non-living components is called ecosystem.
  • A branch of biology in which the relationship between a living organism and its environment is studied called ecology.
  • There are two major components of an ecosystem: biotic and abiotic components.
  • The existence of all living organisms in a particular environment is called biotic components. While the existence of all non-living organisms in an environment is called abiotic components
  • The region or place where an organism lives is termed as its habitat. Habitat provides an organism everything it needs to survive like food, shelter, proper weather condition.


Biotic and Biotic Interaction

  • The biotic components are depended on each other for their living. For example, herbivores(plant-eating) animals depend on the plants for their food, and these herbivores animals are eaten by the carnivores(flesh-eating) animals. Meanwhile, the omnivores animals eat both animals and plants. Moreover, the dead decaying matter of the animals add nutrients to the soil that later, carried by the roots of the plants for growing.
  • The abiotic components are the major source of running processes for the biotic components. For example, all plants and animals need air, water and soil to survive.


The regions that exist in the environment where the living organisms live and grow naturally are called habitats. The habitat provides proper food, shelter, temperature ad suited climatic conditions. For example, the reptiles live in the forest where they found all the suitable things they need.

Types of Habitats

Living organisms live in different types of habitats such as terrestrial, aquatic, aerial and arboreal.
Terrestrial habitat:
The organisms found in the land part of the environment is called terrestrial habitat. Several species of plants and animals exist on the land. The terrestrial habitat consists of forests, deserts, mountains and grasslands. For example, rattle snakes are found in the desert, whereas tigers are found in the forest(Figure 2).

Figure 2: Terrestrial habitats.
Aquatic habitat
The water bodies of the earth where several species of plants and animals live. The aquatic habitat are of two types:-
i. Marine aquatic habitat: The water bodies that contain coastal zones, intertidal zones, sandy shores and rocky shores. There are varieties of flora and fauna found in the marine habitat such as the sharks, whales, tentacles and hydra(Figure 3).

Figure 3: Marine Aquatic Habitat.
ii. Freshwater habitat: The water bodies that contain ponds, rivers, streams, springs, bogs and wetlands. Some living organisms found in the freshwater habitat are turtles, snakes, mollusks and alligators(Figure 4).

Figure 4: Freshwater habitat 
Amphibians: Some animals that live on both land and water are called amphibians. Some of the examples are frogs, turtles and crocodiles.
Aerial habitat
The organisms that fly in the sky such as birds. Such habitat is known as aerial habitat(Figure 5).

Figure 5: Aerial habitat.
Arboreal habitat:
The animals that live on trees like monkeys, squirrels and several insects(Figure 6).

Figure 6: Arboreal habitat.


The organisms are made to live and survive in a particular habitat. Take an example of fish, which can’t survive on land. All living organisms are made up of specific features that allow them to survive in a particular environment. These adaptive features of the organisms are known as adaptation.

Adaptations for Terrestrial Habitats

A desert is an arid land made up of sandy soil. Due to sandy soil, the temperature of the desert area is over 50°C in the daytime and drop down to 0°C at night. The adaptation of animals and plants in the desert is difficult due to the shortage of water.
The adaptive features of plants exist in the desert are:-
i. They have a well-developed tap root system to collect the underground water.
ii. Some plants have modified leaves that help them to reduce the water loss through the stomata.
iii. The desert plants are also known as succulent plants.
iv. They also have modified stem that helps them perform photosynthesis and store a lot of water.
v. They have a waxy coating to prevent water loss.
Some examples of the desert plants are cactus, acacia and aloevera(Figure 7).

Figure 7: Desert plants.
Some desert animals like snakes and rats spend the daytime in the burrow to protect themselves from the heat. One of the most important desert animal which is also known as “A Ship of Desert”, a camel, has adaptive features such as(Figure 8):-
i. The eyelashes of a camel are long and thick that help to prevent it from the sand.
ii. The feet of a camel are padded, which help to walk on the sand.
iii. The capacity of drinking water of a camel is high as it drinks 120 litres of water at a time.
iv. The hump of a camel stores fats to give energy to the camel. It reduces its size when the stored food is exhausted and regains its original size when the camel eats the food again.
v. The thick skin of the camel helps to prevent it from the heat.
vi. For the conversation of the water, a camel does not sweat and releases a minimal amount of concentrated urine.

Figure 8: A ship of desert: Camel.
Polar and Mountain Regions
At higher altitudes, the temperature of these regions is very cold and windy. They are mostly covered in snow in the winter season due to the snowfall.
The adaptive features of polar and mountain plants are(Figure 9):-
i. Trees are conical in shape as the snow can slide down to the ground.
ii. They have modified needle-like leaves covered in the waxy coating, which helps them to prevent the loss of water due to transpiration.
Some examples of polar plants are pine, oak and conifers.

Figure 9: Mountain plants.
The adaptive features of mountain and polar animals are(Figure 10):-
i. They have thick hair and skin which protect them from the cold.
ii. To break the ice, they use their horns and hooves.
iii. Some specific birds, like penguins, have oily and waterproof feathers that help them to regulate their body temperature.
Some examples of polar and mountain animals are polar bear, penguin, yak, mountain leopard and goat.

Figure 10: Mountain leopard.
The bears have a special feature of protecting themselves from cold conditions by going to the den for a long sleep. This feature is called hibernation.
Grasslands are the most suitable condition for living and surviving for living organisms. They consist of several types of grass and trees.
The adaptive features of the plants of these regions are(Figure 11):-
i.They are composed of a well-developed deep root system.
ii. They have thin leaves which help them to prevent water loss.
iii. The stalks of leaves are designed flexibly, so they can survive in strong windy conditions.
Some examples are lupines, milkweed, and cone flowers.
Figure 11: Grassland plants.
The adaptive features of grassland animals are(Figure 12):-
i. The animals consist of strong molar teeth for chewing grass properly.
ii. Some animals have long legs as they run fast to protect themselves from their predators like the tiger.
iii. The intestine of grazing animals is strong, so, they can digest the grass easily.
iv. They have long and sharp ears for listening to minute sounds, and also they have a strong smelling sense.
Some common examples are deer, rabbit, mice, foxes and lions.

Figure 12: Grassland animals.
Predators are the animals that depend on their prey for food.
Tropical Rainforests
The climatic conditions of tropical rainforests are warm and raining every day. The trees are big. Therefore, the forests are dense, and the sunlight cannot reach the bottom.
The adaptive features of tropical rainforest plants are(Figure 13):-
i. The leaves of smaller plants are large for absorbing the sunlight.
ii. For prevention of water accumulation, the leaves are designed with grooves and drip tips that can allow them to fall off the excess amount of rainwater.
Some examples are mahogany, ebony, dyewoods, kapok and rubber.

Figure 13: Tropical rainforest plants.
The adaptive features of tropical rainforest animals are
i. Several species of animals are found in the tropical rainforest which causes competition of the sources.
ii. Some of the animals are found in the tropical rainforest live on trees as they have strong arms and muscles to swing from one tree to another.
iii. To save themselves from their predator, the animals are camouflaged.
Some examples are monkeys, chimpanzee, leaf insects and apes.
Aquatic Habitats
The water bodies present on the earth also have a wide range of animals and plants living in them. There are two types of aquatic habitats: freshwater and marine.
The aquatic plants are called hydrophytes. These plants can be free-floating, partly submerged or fully submerged concerning their formation of roots inside the water.
The adaptive features of free-floating and partly submerged plants are
i.They have poorly developed roots or do not have roots.
ii. The designing of leaves with cuticles which prevent them from collecting the water.
iii. The positioning of the stomata is on the upper surface of the leaves, so they can perform the gaseous exchange process easy. As the leaves are found on the upper surface, chlorophyll is also found on the upper surface of the leaves for performing the photosynthesis process easily.
iv. The stems are designed long and narrow and hollow inside, which contains air spaces for providing buoyancy to the plant.
Some examples of free-floating and partly-submerged are water lily, lotus, duckweed and Wolfia.
The adaptive features of aquatic animals are
i. They are composed of streamlined bodies for swimming deep in the water.
ii. Some organisms, such as fish, have gills that help them to breathe and also fins for moving inside the water.
iii. The birds that live in the water have webbed feet and have oil glands for preventing their feathers from the water.
iv. Amphibians have strong back legs for catching their prey on land and water. They also webbed feet for swimming.


  1. Structural organization
  2. Growth
  3. Movement
  4. Nutrition
  5. Respiration
  6. Excretion
  7. Reproduction
  8. Respond to stimuli
  9. Death

Structural organization

  • Living beings are made up of cells. Cells are the structural and functional unit of all living organisms.
  • Based on number of cells, living beings are of two types
  1. UNI CELLULAR: made up of single cell. E.g., Amoeba, Paramecium
  2. MULTICELLULAR: made up of more than one cell. E.g., Plants , animals


  • Growth is the increase in size and volume of the body. When cells present in an organism divide, their number increases which causes increase in size
Growth Development
1.  Growth refers to the increase in size and number. Development refers to an improvement in circumstances.
2. Has a quantitative measure. Has a qualitative measure.
3. Growth is for limited period. It happens throughout life.
4. It is due to cell division. It is not due to cell division


  • Movement can be external or internal.
  • Movement may or may not involve a change in position
  • Plants don’t show locomotion.
  • Locomotion –movement from one place to another in search of food, shelter, escape from enemie


  • All living organisms that is animals and plants need food for growth and development. Living things consume food to obtain energy to carry out different functions in their body. Animals depend on other organisms for food and hence called heterotrophs.
  • Plants prepare their own food with the help of sunlight, water and carbon dioxide by the process of photosynthesis, hence they are called autotrophs. Since they produce food for others, they are also called producers.


  • Respiration is the chemical process in which food taken by an organism combines with oxygen to release energy. This energy is used by the organism to carry out its various life processes. Carbon dioxide and water are the other products of the process of respiration.


  • The energy produced during respiration is utilized by all living organisms for carrying out various life processes.
  • The physical process, by which the air containing oxygen is drawn into the lungs and air containing carbon dioxide is forced out from lungs is called breathing. Breathing involves two steps, inhalation (inspiration) and exhalation (expiration).
It is the process of inhaling and exhaling the air in and out of lungs. It is the process of breakdown of glucose to produce energy.
It takes place in the lungs. It takes place in the cells.
It is a physical voluntary process. It is a chemical involuntary process.
No energy is produced during the process. Energy is released in the form of ATP.
It is an extracellular process, as it occurs outside the cells. It is an intracellular process, as it occurs inside the cells.
No enzymes are used during the process. A large number of enzymes are used during the process.
Breathing takes places through respiratory organs like lungs and nose. Respiration takes place in cells and cell organelles such as mitochondri
  • “MITOCHONDRIA” is the part of the cell where energy is produced and is thus known as the POWERHOUSE of the cell.
  • Different living organisms have different respiratory organs For example, earthworms breathe through their skin. Fish, we have learnt, have gills for using oxygen dissolved in water. The gills absorb oxygen from the air dissolved in water
  • Plants also respire.They takes oxygen through leaves and give Carbon dioxide to air but we know that Photosynthesis requires Carbon dioxide.Then how do that this gaseous exchange happens
    GASEOUS EXCHANGE IN PLANTS : Photosynthesis occurs only during daytime since sunlight is an integral component of the same. Nevertheless, respiration, on the other hand, is a continuous process, day or night. Photosynthesis requires all plants to have a supply of carbon dioxide and means the production of oxygen. The amount of oxygen released in the process of food preparation by plants is much more than the oxygen they use
    in respiration

Respond to stimuli: Stimulus

Anything that triggers a reaction in an organism is called stimulus. The reaction of the organism is called response.
  • Response to stimuli in plants
  1. Geotropism: growth of roots towards gravity. Away from source of light
  2. Phototropism: growth of plant stem towards light
  • Response to stimuli in human
  1. External stimuli are capable of producing systemic responses throughout the body, as in the fight-or-flight response.


  • What is excretion?
Excretion is a process by which metabolic waste is eliminated from the body of an organism.
  • What is the need of excretion?
The process of excretion helps to remove the waste products from the body. If   these are allowed to accumulate, they cause poisoning in the body that slows down the other important processes in the body.
  • What are the different excretory products in the human body?
  1. Urea (excreted through urine)
  2. Carbon dioxide (given out during exhalation)
  3. Sweat (salt + water)


  1. Plants perform photosynthesis which uses carbon dioxide, water, sunlight, and chlorophyll to synthesize food. During photosynthesis, oxygen is given out as a by-product. This oxygen acts as an excretory product and is given out by a process called diffusion.
  2. Certain plants perform a process known as photorespiration where oxygen is taken in and carbon dioxide is given out as a waste product.
  3. All plants perform transpiration which is the process by which plants transport water from the roots to the aerial parts of the plant for elimination in the form of water droplets or water vapour. This process occurs because the plants take in more water than they need for their biochemical processes and the excess water is eliminated by transpiration.
  4. Another commonly produces waste material of plants is tannins. Tannin is a product of plants that are stored in the trunks of trees. They are present in the bark of the trees. (Gums and resins are used by humans for making adhesives and varnishes)
  5. Another waste product that plants produce is latex. It is actually very useful to man in the manufacture of many rubber products.


  • Reproduction means to reproduce. It is a biological process by which an organism reproduces an offspring who is biologically similar to the organism. 
  • Reproduction enables and ensures the continuity of species, generation after generation. Reproduction is important for the survival of all living organisms.
  • Reproduction in plants: Most plants produce seeds inside their fruits. These seeds when sown in soil, produce new plant of same species.
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Class 6 Maths Class 6 Science

Practice Question

Question 1 What is $\frac {1}{2} + \frac {3}{4}$ ?
A)$\frac {5}{4}$
B)$\frac {1}{4}$
D)$\frac {4}{5}$
Question 2 Pinhole camera produces an ?
A)An erect and small image
B)an Inverted and small image
C)An inverted and enlarged image
D)None of the above