Environment and Environmental Problems Part-1

Environment means everything which surrounds us.

  • It is a structural and functional unit of the biosphere.
  • The term ecosystem was coined by AG Tansley in 1935.
  • It constitutes both living and non-living things, i.e. physical, chemical and biotic factors.
  • Environment affects the life and development of an organism in its natural habitat & vice a versa.
  • Substances that can be decomposed by the action of micro-organism like bacteria are called bio-degradable. E.g. cattle dung, cotton, jute, paper, fruit and vegetable peels, leaves etc.
  • Substances which cannot be decomposed by the action of microorganisms are called non-biodegradable.E.g. plastics, polythene bags, synthetic fibers, metals, radioactive wastes.

Ecosystem Components

  • There are two components of an ecosystem: (i) biotic component and (ii) abiotic component.

Biotic Component

  • Living organisms of the environment like plants, animals, microbes and fungi.
  • It includes three types of organisms-Producers, Consumers and Decomposers.
  • Producer- All green plants, blue green algae can produce their food (Sugar & starch) from inorganic substance using light energy (Photosynthesis).
  • Consumers: Include organisms which depend on the producers either directly or indirectly for their sustenance. Consumers depend on others for food.It can be classified into herbivores, carnivores, parasite and Omnivores.
  • Decomposers: Fungi & Bacteria which break down (decompose) the dead plant, animal’s complex compounds into the simpler one. Thus decomposers help in the replenishment

Abiotic Components

  • They are the non-living chemical and physical components of the environment like the soil, air, water, temperature, etc.

Food Chain

  • It is the sequence of living organisms in which one organism consumes another organism for energy. It has only one direction, or it is unidirectional (single directional).
  • In a food chain, each stage where energy is transferred is referred to as a trophic level.
  • 1% of the sun's energy is captured by green plants.
  • In a food chain, energy moves in a single direction.

Trophic levels

  • In a food chain, each stage where energy is transferred is referred to as a trophic level.
  • There are generally 3 to 4 trophic levels.
  • It is always straight.
  • Organism can occupy different trophic levels in different food chain.
  • The different trophic levels are –
    • Producers (T1)
    • Primary consumers (herbivores-T2)
    • Secondary consumers (primary carnivores -T2)
    • Tertiary consumers(Secondary carnivores -T3)
    • Quaternary consumers (Tertiary carnivores T4)
    • Decomposers
  • There is a unidirectional flow of energy from producers to consumers.

Energy Flow

  • Transfer of energy from one trophic level to another depicting its direction and amount.
  • Represented by the pyramid of energy.
  • There is a gradual decrease in the amount of energy transfer from one trophic level to the next trophic level in a food chain.
  • So only 10% of energy is transferred to next trophic level while 90% of energy is used by present trophic level in its life processes.

Ecological Pyramids

  • It is a graphical representation to show biomass or bio productivity.
  • There are different ecological pyramids such as pyramid of biomass, pyramid of number and pyramid of energy
  • Start with producers.
  • Pyramid of numbers: gives the number of organisms presents at each trophic level. It can be upright or inverted.
  •  Pyramid of biomass: gives the biomass of each trophic level and could be upright or inverted. In aquatic ecosystem pyramid of biomass is inverted.
  •  Pyramid of energy: is always upright as it shows the flow of energy from one trophic level to the next trophic level.