Ecosystems

All the living organisms in an ecosystem, namely, plants, animals and microorganisms form its biotic components. Depending on how they obtain their food, living organisms can be divided into three groups, namely, producers, consumers and decomposers.

Producers — Green plants make their own food in the presence of sunlight using water, minerals and carbon dioxide. Thus, green plants are called producers or autotrophs.

Consumers — Living organisms that cannot make their own food but consume either plants or other animals, are called consumers or heterotrophs. They are either herbivores, carnivores or omnivores.

Decomposers — The microorganisms that feed on the dead bodies of organisms and decaying organic matter are called Decomposers.

There is unidirectional flow of energy in an ecosystem from the sun to producers to consumers and finally to decomposers. As per scientists, only 10 percent of the energy stored by producers is passed on to primary consumers. Similarly, a secondary consumer that eats primary consumer absorbs only 10 percent of its energy. Thus, the amount of energy that is transferred decreases at each level and the flow of energy is always in one direction only.

The light affect plants in a number of ways. The green plants make food in the presence of light, light influences the closing and opening of stomata, germination of seeds and so on. The intensity of light affects the rate of photosynthesis. The amount of sunlight in a particular area has a direct influence on the types of plants.

Green plants convert solar energy into chemical energy present in food. Some energy gets stored in plants while the rest is used up by them. When the plants are eaten by herbivores, the energy stored in them is transferred to herbivores. Herbivores use some of the energy for their activities and store a part of it in their body. This stored energy is further transferred to carnivores when they eat herbivores. Thus, as one organism eats the other, energy passes on from producers to herbivores and then to carnivores. The given diagram shows the flow of energy in a food chain:

The animals depend upon the plants in many ways like for food, shelter and and most importantly for oxygen. Dependence of animals on plants can be explained as follows:

1. Animals (herbivores) depend upon plants for food.
2. Animals such as birds, squirrels and monkeys depend upon plants for their shelter. Birds also use plant materials to make their nests. Insects like ants, bee and beetles etc. also live on trees.
3. Animals also use Oxygen given out by plants for respiration.

The different types of terrestrial ecosystems are deserts, grasslands and forests.

The organisms found in the forest ecosystem are:

1. Producers like herbs, shrubs, trees and climbers etc. A wide variety of grasses, ferns, creepers, berries etc. are found in a forest.
2. The consumers in a forest ecosystem include:
   1. Herbivores such as deer, nilgai, elephants, leaf hoppers, bugs, beetles and so on.
   2. Carnivores such as tigers, lions and foxes. There are also a large number of predatory birds like eagle and kite. Omnivores like bear, crow, etc. are also present.
3. Decomposers like bacteria and fungi are also found in the forest ecosystem.

Biotic component of forest ecosystem — The biotic components of a forest includes :

1. Producers like herbs, shrubs and trees. A wide variety of grasses, ferns, creepers, berries etc. are found in a forest. The trees in a forest are home to thousand of birds and animals.
2. Consumers like herbivores(deer,nilgai, elephants, leaf hoppers and bugs), Carnivores(tiger, lion, eagle kite) and Omnivores (bear, crow) are found in forest ecosystem.
3. Decomposers like bacteria and fungi are also found in the forest ecosystem. They derive their nutrition from dead and decaying organisms.

Abiotic component of forest ecosystem — The abiotic components of a forest ecosystem include air rich in oxygen, water in several water bodies, organic and inorganic compounds in trees and soil as well as in the dead remains of plants and animals. Climatic factors such as sunlight, temperature, rainfall and humidity play a great role in determining the flora and fauna in a forest ecosystem.

The main components of an ecosystem are Biotic (living) and abiotic (non-living).

Two examples of omnivores are

1. Human beings
2. Crow

A food chain operating in a grassland ecosystem is :

Corn → Rat → Snake → Eagle

Carnivores are secondary consumers.

The herbivores that feed on the green plants (producers) are first level consumers.

An interaction in which one organism (predator) captures and eats another organism (prey) is known as predation.

Two examples of man-made ecosystem are:

1. Parks
2. Crop-Fields

Green plants are called producers or autotrophs.

Human beings and cockroaches are Omnivores.

Decomposers are also called nature's scavengers.

Ecosystem — All the living organisms in a given area that interact with each other, as well as with biotic components and abiotic components of the environment constitute an ecosystem.

Food chain — A series of organisms linked by the process of eating and being eaten which shows linear flow of energy through different trophic levels is called Food chain.

Food web — A network of various interconnected food chains which show complex feeding relationships is called food web.

Trophic level — The various steps representing organisms in a food chain at which transfer of food and energy takes place are called trophic levels.

Symbiosis — Symbiosis is a close, long-term relationship between two organisms in which both the interacting organisms benefit.

Parasitism — Parasitism is a relationship where an organism called the parasite lives in or on other organism called the host and derives food from its host. In such interaction, the parasite benefits and the host is harmed.

The term ecology was first used by a German scientist named Ernst Haeckel.

Plants, animals and microorganisms constitute the biotic components of an environment.

Temperature, light, air and water are the abiotic components of the environment.

Green plants which make their own food are called producers or autotrophs.

Living organisms that cannot make their own food are called consumers or heterotrophs.

Scavengers are carnivores that feed on dead animals.

Omnivores eat both plants and animals.

An interaction in which one organism captures and eats another organism is called predation.

Cow

Reason — Cow is herbivores but all others are carnivores.

vulture

Reason — Vulture is scavenger while others are herbivores.

Cow

Reason — Cow is herbivore but others are omnivores.

cow

Reason — Cow is a herbivore while others are not.

Following three food chains can be made:

1. grass → deer → lion

2. grass → grasshopper → frog → snake → vulture

3. grass → rat → snake → vulture

The correct sequence of the food chain is numbered in the below figure:

Most of the consumers have more than one source of food. For example, frogs eat caterpillars besides grasshopper, snakes eat rabbits as well as lizards, mice and rats. Thus, a plant or an animal may belong to several food chains.

Any food chain starts with producers because only producers can trap energy from the sun and convert it into chemical energy present in food. Producers i.e., green plants make their own food in the presence of sunlight using water, minerals and carbon dioxide. Consumers cannot make their own food and they depend directly or indirectly on producers for energy.

Scavengers and decomposers are important for the environment because they help to clean the environment by breaking down the complex organic compounds present in the remains of dead plants and animals into simpler substances. They are useful in releasing the nutrients from dead, decaying organisms back into the environment. These nutrients are reused by plants. Thus, they help in recycling of nutrients.

Decomposers are known as nature's scavengers because they help to clean the environment by decomposing the dead remains of the plants and animals.

ecology

Reason — The study of the interaction between living organisms and their environment is called ecology.

green plants

Reason — Only green plants can trap energy from the sun and make their own food in the presence of sunlight using water, minerals and carbon dioxide. Thus, green plants are called producers or autotrophs.

decomposers

Reason — Decomposers are the nature's scavengers as they break down the complex organic compounds present in the remains of dead plants and animals into simpler substances.

food chain

Reason — A series of organisms that are linked to each other through a process of eating and being eaten form a food chain.

first trophic level

Reason — All food chains start with plants as only green plants can trap energy from the sun and convert it into chemical energy present in food. Hence, they constitute first trophic level of any food chain.

food and oxygen

Reason — Animals depend on plants and trees for food, oxygen and shelter.

nocturnal animal

Reason — Animals that are active at night are called nocturnal animals.

pond

Reason — Pond is an aquatic ecosystem.