Look around you and you will see a variety of living things and non-living things. Trees, birds, dogs, and insects are living things. Rocks, water, soil, and cars are non-living things. But have you ever wondered what makes something living? What characteristics do all living organisms share? And how do they survive in the places where they live?
This chapter answers these questions. We learn about the characteristics of living organisms, the habitats they live in, and the adaptations that help them survive. A habitat is the natural home of a living organism, and it includes the living and non-living things present in that place. Deserts, forests, grasslands, oceans, and mountains are all examples of habitats.
Living organisms and their surroundings are closely connected. Each organism is adapted to its habitat. A camel can survive in the hot desert, a polar bear in the cold polar region, and a fish in water. In this chapter, we study these fascinating connections between organisms and their environment.
A habitat is the natural home or environment of a living organism. The habitat of an organism includes all the living and non-living things in its surroundings. For example, the habitat of a deer includes the forest, the trees, the grass, the water, and the other animals living there.
A habitat provides everything an organism needs to survive: food, water, shelter, and space. Different organisms live in different habitats because they need different conditions. A cactus lives in the desert, a lotus lives in water, and a polar bear lives in the icy polar regions.
Habitats can be broadly divided into two types: - Terrestrial habitats: These are land-based habitats like forests, grasslands, deserts, and mountains. - Aquatic habitats: These are water-based habitats like oceans, seas, rivers, lakes, and ponds.
A habitat has two main components: living components (biotic) and non-living components (abiotic).
Living (biotic) components include all the living organisms in the habitat, such as plants, animals, birds, insects, and micro-organisms. These organisms depend on each other for food and shelter.
Non-living (abiotic) components include all the non-living things in the habitat, such as soil, water, air, sunlight, temperature, and rocks. These non-living things affect the living organisms in the habitat.
Both components are essential for the survival of organisms. For example, plants need sunlight, water, and soil (non-living) to make food, and animals need plants (living) for food and shelter. The habitat is a complete system of living and non-living parts working together.
All living organisms share some common characteristics. These are: - Need food: Living organisms need food for energy and growth. Plants make their own food, while animals get food from plants and other animals. - Respiration: Living organisms respire, which means they take in oxygen and release carbon dioxide to get energy from food. - Excretion: Living organisms remove waste products from their bodies. - Response to stimuli: Living organisms respond to changes in their surroundings. For example, we close our eyes when bright light shines on us, and plants bend towards light. - Reproduction: Living organisms reproduce to produce more of their kind. - Growth: Living organisms grow. Growth is a permanent increase in size. - Movement: Living organisms can move. Animals move from place to place, and plants move their parts.
These characteristics together define life. Non-living things do not show these characteristics.
Living organisms respond to changes in their surroundings. Any change in the surroundings that causes an organism to react is called a stimulus. The reaction of the organism is called the response.
Examples of responses to stimuli: - We blink when a bright light shines in our eyes. - We move our hand away quickly when we touch a hot object. - Plants grow towards sunlight. - The leaves of a touch-me-not plant (mimosa) close when touched. - Earthworms move away from bright light.
Responding to stimuli helps organisms survive. For example, moving away from danger or towards food increases the chances of survival.
All living organisms perform certain life processes that keep them alive. These include: - Nutrition: Taking in food and using it for energy and growth. - Respiration: Breaking down food to release energy, usually using oxygen. - Excretion: Removing waste products from the body. - Growth: Increase in size by cell division and cell enlargement. - Reproduction: Producing new individuals of the same kind.
These processes are common to all living organisms, whether plants or animals. The sum of all these processes is called life.
Adaptation is the process by which organisms develop special features that help them survive in their habitat. These features can be structural (body parts) or behavioural (actions). The habitat of an organism shapes its adaptations.
Adaptation is not a quick change; it develops over many generations. It is a natural result of living in a particular environment.
Aquatic habitats are of two types: freshwater (rivers, ponds, lakes) and marine (oceans, seas). Organisms living in water have special adaptations.
Aquatic animals: - Fish have gills to breathe oxygen dissolved in water. - Fish have streamlined bodies and fins for swimming. - Frogs have webbed feet for swimming. - Whales and dolphins have lungs and come to the surface to breathe.
Aquatic plants: - Plants floating on water, like water hyacinth and lotus, have light, spongy parts that keep them afloat. - Plants under water, like Hydrilla, have soft, thin leaves. - Roots of aquatic plants are smaller because they can absorb water all around them.
Aquatic plants and animals are specially built to survive in water. Their adaptations show how closely organisms are connected to their surroundings.
Mountain animals: Animals like the mountain goat and yak have thick fur to keep them warm in the cold mountains. They have strong hooves that help them climb steep, rocky slopes. Their bodies are adapted to the low oxygen and cold temperature of high mountains.
Desert plants: - Cacti have no leaves; their stems are green and fleshy and store water. The leaves are reduced to spines, which reduce water loss. - The roots of desert plants spread wide and go deep to absorb water. - Desert plants may have thick, waxy coatings to prevent water loss.
Adaptations in desert plants and animals all focus on surviving with very little water and very high temperatures.
Living organisms and their surroundings are always interacting. The non-living environment (abiotic) affects the living organisms (biotic), and the living organisms also affect the environment.
Understanding this relationship is very important for protecting nature. When humans damage a habitat, the organisms living there are affected. This is why we must protect habitats and conserve biodiversity.
| Habitat | Living Organism | Adaptation |
|---|---|---|
| Desert | Camel | Long eyelashes, padded feet, hump storing fat |
| Polar region | Polar bear | Thick fur, fat layer, white colour |
| Water | Fish | Gills, fins, streamlined body |
| Mountains | Mountain goat | Thick fur, strong hooves |
| Forest | Lion | Strong teeth and claws, sharp eyesight |
| Characteristic | Example |
|---|---|
| Need food | Plants make food; animals eat food |
| Respiration | Taking in oxygen and releasing carbon dioxide |
| Excretion | Removing waste products |
| Response to stimuli | Plant bending towards light |
| Reproduction | Laying eggs, giving birth |
| Growth | A seed growing into a plant |
In this chapter, we explored the deep connection between living organisms and their surroundings. We learned that a habitat is the natural home of an organism and includes both living and non-living components. We studied the common characteristics of all living organisms, from the need for food and respiration to responding to stimuli and reproduction. Most importantly, we discovered how organisms adapt to their habitats. The camel is built for the desert, the polar bear for the icy polar regions, and the fish for water. These adaptations show the wonderful design of nature and remind us why we must protect habitats. When we protect habitats, we protect the countless living organisms that depend on them.