Characteristics of Living Organisms

Birds, fish and animals move on their own because they are living organisms. They move to find food, protect themselves and respond to their surroundings. This movement happens from inside their own body — they use their muscles, wings, fins or legs to move.

Shed leaves and vehicles like tractors and bullock carts cannot move on their own. Leaves fall because of wind or gravity. Vehicles move only when someone drives them or an outside force is applied.

So the important difference is: Living organisms move by themselves using their own energy, while non-living things move only when an outside force acts on them.

Yes, germs (microorganisms) do reproduce, even though they are too small to see with the naked eye.

We can decide this because reproduction is one of the main characteristics of all living organisms. Germs are living organisms, so they must reproduce. We know this is true because:

• When a person falls ill, the number of germs in the body increases rapidly. This shows that germs are multiplying.
• If food is left out for a few days, it gets spoiled because bacteria and fungi grow and multiply on it.

So even though we cannot see germs, they definitely reproduce and grow in number very quickly.

Animals like rats, cats and dogs show awareness of their surroundings through their behaviour. This is called response to stimuli.

Here are some examples:

• 🐕 A dog wags its tail when its owner comes home. It also barks loudly when it senses danger or sees a stranger.
• 🐈 A cat quickly jumps away when it hears a loud sound. It also moves silently when hunting a mouse, showing it is aware of its surroundings.
• 🐀 A rat runs and hides immediately when it sees a human or senses danger. It comes out only when it feels safe.

All these behaviours show that animals can sense their surroundings and react to them. This ability to sense and respond is called stimulus and response, and it is one of the important characteristics of living organisms.

Different animals move in different ways. Here is a list:

Type of Movement	Animals
🚶 Walking	Dog, cat, elephant, horse, human beings
🏃 Running	Cheetah, deer, rabbit, rat
🐦 Flying	Eagle, sparrow, butterfly, crow, parrot
🐟 Swimming	Fish, dolphin, whale, crocodile, frog
🐍 Crawling / Slithering	Snake, lizard, earthworm, caterpillar
🐸 Jumping / Hopping	Frog, rabbit, grasshopper, kangaroo
🐒 Swinging / Climbing	Monkey, squirrel

Movement helps animals find food, escape from enemies and find shelter.

Yes, plants also respond to stimuli. Here are some observations that show this:

• 🌻 Sunflower turns its face towards the sunlight throughout the day. This shows it responds to light.
• 🌿 The roots of plants always grow downwards towards water in the soil. This shows response to moisture.
• 🌱 The branches and stem of a plant always grow upwards towards sunlight.
• 🍃 The leaves of the touch-me-not plant (Mimosa) fold up immediately when touched. This is a very clear response to touch.
• 🌙 Some plants close their leaves at night and open them during the day, showing response to light and darkness.
• 🌸 Lotus flowers open at sunrise and close at sunset, responding to sunlight.
• 🌡️ Plants also respond to changes in weather, temperature and injury.

All these examples show that plants are aware of their surroundings and respond to stimuli, even though they cannot move from place to place.

Turtles come to the surface of the water repeatedly to breathe air. Even though they live in water, turtles have lungs to breathe. They cannot take oxygen directly from the water like fish do. So they must come up to the surface to take in fresh air. This is called respiration.

Fish, on the other hand, have gills which allow them to take in oxygen directly from the water. So fish do not need to come to the surface to breathe.

This shows that both turtles and fish need oxygen to survive, but they get it in different ways because of the differences in their body structure.

The correct sequence of the life cycle of a frog is:

When there is a drought and no food or water is available, animals face many serious problems:

• Without food and water, animals become very weak and lose energy.
• Animals may migrate (travel) to other places in search of food and water.
• Their growth stops because food provides the energy needed to grow.
• Animals that do not find food and water may fall ill or die.
• The process of reproduction slows down because animals need good nutrition to reproduce.
• Animals fight with each other over limited food resources, causing conflict in nature.

This shows that food and water are absolutely necessary for the survival, growth and reproduction of all living organisms.

Yes, a tiger cub both grows and develops.

Growth means an increase in the size, height and weight of a living organism. As the tiger cub eats food, its body gets bigger and heavier. This is growth.

Development means progress in the organism’s body, intelligence, skills and ability to work. As the tiger cub grows:

• It learns to hunt on its own, which it could not do when it was a baby.
• It becomes faster and stronger, and can run and jump better.
• It develops the skills and intelligence of an adult tiger.
• Its teeth, claws and muscles develop and become powerful.

So a tiger cub does not just grow bigger — it also develops new abilities and skills. This is why we say that growth and development go together in all living organisms.