What is environment?

What is environment?

Environment refers to all things that surround man. These things can be air water , plants temperature , fuel , people building etc.


The environment is composed of the following

  • Water
  • Land (soil)
  • Air (wind)
  • Plants
  • Animals
  • Temperature
  • Mountains (hills)
  • Minerals
  • Sun


Environment is divided into two types:-

Biological environment  (Abiotic / non physical environment )

This is the type of environment which consists if living things eg plants and animals

Physical environment  (a biotic  environment )

This is the type of environment which consists of non – living things eg mountains , lakes , rivers , temperature , wind  (air ) vapour.


A food chain  is the way how organisms in an environment get their food. In the environment , plants make their own food and are called producers .

The organisms which depend on food made by plants (producers )  are called consumers are consumers

Consumers are divided into the following groups

Primary consumers

These are organisms which feed directly on producers eg goats , cattle , rabbits, sheep etc

Secondary consumers

These are organism which feed on primary consumers eg foxes , dogs , lions

Tertiary consumers

Tertiary consumers which feed on secondary consumers eg. leopards ,  man birds of prey etc.

NB: In a food chain , organism like fungi and bacteria help in reducing food to its component parts ( decay / rot) are called decomposers

The sun is the main source of sunlight energy in a food chain from which energy flows  to other organism in the environment

Illustration of a food chain

Producer – primary consumer – secondary consumers – Tertiary consumers – plants grasshoopers – lizard – Hawks


A food web is a more complicated interrelationship of how organism in an environment obtain their food.

A food web involves many organism in an ecosystem how they get food from many other living things

Illustration of a food web


An ecosystem is the community of livingthings (organisms) in a habitat plus the non living part in the environment .

A habitat

A habitat is a home of a living organism in the environment


Degradation is the way of lowering (spoiling ) the quality , stability and usefulness of  a resource.

Environment degradation

Is the lowering the quality , stability and usefulness of  resources in the environment

Types of environment degradation

  • Soil / land degradation
  • Degradation / deforestation
  • Wetland drainage
  • Air / atmospheric pollution
  • Water pollution
  • Wild life destruction ( degradation )

Causes of environmental degradation

There are two main causes of environmental degradation

a)  Human activities

b) Natural causes


a) Mining / quarrying

b) Construction and road work

c)  Poor waste disposal

d) Bad agricultural practices eg bush burning , over grazing etc


  • Soil  erosion / leaching
  • Silting
  • Hurricanes
  • Tornados
  • Whirl wind / whil pools
  • Earth quakes
  • Hailstones
  • Land slides
  • Floods
  • Tsunamis
  • Volcanic eruptions
  • Global warning

a) Soil / land degradation

This is the destruction / lowering the quality or usefulness of land by human activities or natural causes.


Is a process through which mineral salts or nutrients sink deeper into the soil layers where they can not be reached by plants

It is caused by too much  rain.

Soil erosion : Is the washing / blowing  away of top soil by agents of erosion.


Is the process by which fine sand , mud or other things are carried into the water body.

Causes of silting

  • Soil erosion
  • Cultivation near water sources
  • Allowing animals to drink from water bodies
  • Swamp drainage
  • Burning / destroying vegetation in the swamp

Effect of silting

  • It destroys habitat for animals that live  live in water
  • Lower water level and  so dries out water bodies
  • Destroys source of food for fish and other aquatic animals
  • Kills fish of other animals and plants in water
  • Destroys eggs of fish and other aquatic animals.


Deforestation is also called devegetaion ie cutting down large number of trees / plant with out replacing them.

Causes of deforestation

  • Population growth leading to need for land for settlement , farming and recreation
  • Industrialization (development of  industries in an area)
  • Wild fires / bush burning
  • Clearing forests for fire wood , charcoal , building poles timber etc

Effects of deforestation

  • It leads to reduction of rain fall causing  drought / desertification
  • Loss of habitat for different plants and animal species
  • Soil erosion leaving infertile soils
  • Silting of water bodies.

Wet land

A wet land is any area which has water and growing vegetation through out the year

Examples of wet lands

  • Swamps
  • Marshes
  • Bogs
  • Lakes and rivers

Importance of wet lands

  • They are habitats to many plant and animals speces
  • They control floods by sucking the water
  • They filter muddy water by trapping the impurities
  • They regulate the climate by influencing the temperature and humidity
  • They provide water
  • They provide water for domestic and industrial use.
  • They are sources of food e.g. fish
  • They provide raw materials for arland crafts e.g. clay, papyrus etc
  • They are sources of building materials


Pollution is the addition of  harmful (dangerous ) chemicals into the environment

Pollution takes place naturally or through human activities.


  • Waste gases from industries
  • Industrial waste / chemical
  • Exhaust fumes from vehicles
  • Oil spills from ships in the ocean
  • Chemical sprays
  • Non bio-degradable wastes eg polythene , glass plastics etc
  • Smoke from burning tyres , oil or bushes
  • Dust


a)  Air pollution   –     caused by smoke and fumes / poisonous gases.

b) Soil pollution – caused by agricultural  sprays, industrial waste , refuse etc

c)  Water pollution  – By silt , oil spills , refuse , human waste and industrial waste  washed into it.

d) Noise pollution – Due to too many vehicles or industries in the environment loud music etc


  • Poisoning of soil and water by chemical wastes dumped on them.
  • Death and disappearance of biodiversity (variety of plants and animals living things )
  • Out break of disease in the environment
  • Loss of soil fertility leading to poor yields
  • Formation of acidrains due to gases from industries and vehicles as they dissolve in rain.
  • Destruction of habitats for many plants and animals
  • Less production of plants such as fibers , timbers fruits and other construction materials


  • Uses of alternative energy source eg. bio gas , natural gas , solar energy , wind power , hydro electricity
  • Ensure proper disposal of domestics and industrial wastes
  • Educating people about the dangers of pollution
  • Using good method of farming