Our Environment - 3 - Class 10

Environment refers to those surroundings that surrounds living beings from all sides and affect their lives in toto. It consists of atmosphere, hydrosphere, lithosphere and biosphere. It's chief components are soil, water, air, organisms and solar energy.

The ozone layeror ozone shield is a region of earth's stratosphere that absorbs most of the sun's ultraviolet radiation. It contains high concentration of ozone in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. As the Ozonosphere only contains high levels of ozone gas, therefore all the other things such as the dust particles, water vapour and CO₂ are absent from it.

When ultraviolet light waves (UV) strike CFC* (CFCl3) molecules in the upper atmosphere, a carbon-chlorine bond breaks, producing a chlorine (Cl) atom. The chlorine atom then reacts with an ozone (O3) molecule breaking it apart and so destroying the ozone. This forms an ordinary oxygen molecule(O2) and a chlorine monoxide (ClO) molecule. Then a free oxygen** atom breaks up the chlorine monoxide. The chlorine is free to repeat the process of destroying more ozone molecules. A single CFC molecule can destroy 100,000 ozone molecules.

Ozone is a molecule made up of three oxygen atoms, often referenced as O3. Ozone is formed when heat and sunlight cause chemical reactions between oxides of nitrogen and volatile organic compounds, which are also known as hydrocarbons.

Pedology is the study of soils in their natural environment. It is one of two main branches of soil science, the other being edaphology.

The term ecology was coined in 1866 by the German biologist, Ernst Haeckel. 

The study of the interrelationships between living organisms and the living and non-living components and processes in an environment

An ecosystem includes all of the living things (plants, animals, and organisms) in a given area that interact with each other, as well as the non-living environments (weather, earth, sun, soil, climate, atmosphere) that surround the living things.

Food chain, in ecology, the sequence of transfers of matter and energy in the form of food from organism to organism. 

It is Series of palnts/animals which are interelated in the form of organism being eaten as food by the other.

An organism found at the top of the PYRAMID OF NUMBERS that preys on other organisms but which is not itself preyed on.

Lion is a Top Carnivore. 

All food chains start with energy from the sun. This energy is captured by plants. Thus the living part of a food chain always starts with plant life and ends with an animal. Plants are called producers because they are able to use light energy from the sun to produce food (sugar) from carbon dioxide and water. 

Gross primary productivity is the total organic matter synthesized by the producers in the process of photosynthesis. Hence, total energy fixed by a gram plant in an ecosystem will be called as gross production.

Grazing food chain is a food chain in which the energy in the lowest trophic level is derived from photosynthesis. Hence, it directly depends on solar radiation. Plants are the producers which capture solar energy to synthesize food. 

The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers, such as plants and algae, use energy from sunlight to make food energy by combining carbon dioxide and water to form organic matter.

A food web (or food cycle) is the natural interconnection of food chains and a graphical representation (usually an image) of what-eats-what in an ecological community. Another name for food web is consumer-resource system.

The producers occupy the basic trophic level in the food chain.

The flow of energy in the ecosystem is said to be unidirectional because the energy lost as heat from the living organisms of a food chain cannot be reused by plants in photosynthesis. During the transfer of energy through successive trophic levels in an ecosystem, there is a loss of energy all along the path.

The Tropical forests have the greatest biodiversity on the planet, and, within the tropics, the areas richest in species are the rainforest

The correct food chain is:

Phytoplankton → Zooplankton → Fish

i.e. Producers → Primary consumer → Secondary consumer

The term ecosystem was first used in 1935 in a publication by British ecologist Arthur Tansley.

Food chain is the flow of energy in a sequential process of one organism eating the other and itself being eaten by another in turn. Thus, it is a series of organisms taking part at various biotic levels from the producer and ends in consumer.
Example- Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer
Examples of food chains:
(i) Food chain in forest or grassland ecosystems:- 
Grass → Grasshopper → Frog  → Snake →  Eagle
(Producer) → (Herbivore)  →  (Carnivore) → (Carnivore) → (Top Carnivore) 

Phytoplankton form the basis of life in the ocean. Some of this food passes directly along the food chain when zooplankton eat the phytoplankton and in turn are consumed by larger animals such as fish, whales, squid, shellfish and birds.

The correct answer is D as Food chains start with primary producers and end with decomposers. Food chains start at trophic level 1 with primary producers such as plants, move to herbivores at level 2, predators at level 3 and finish with carnivores or apex predators at level 4 or 5. Decomposers mark the end of a food chain. Decomposers recycle nutrients, so they can be reused by primary producers.

Energy enters a food chain through producers. Producers are able to make their own food and do not rely on the ecosystem for nourishment. Producers are self-feeders, i.e., they prepare their own food.

 They are also known as autotrophs. Only 10% of the total energy generated by the producer, is passed to the next trophic level

They are stable because of their chemical composition. they are saline. other features like temperature, light, dissolved oxygen etc also make it a stable ecosystem.