Biosphere

Investigating an Ecosystem

• Ecosystem this is a natural biological unit that is made up of living and non living parts. All ecosystems are made up more than one habitat.
• Habitat is the place where an organism lives.
• Community this is made up of all the animals, plants and micro organisms living there.
• Population is a group of organisms of the one type e.g. foxes or oak trees.
• Biotic factors are factors that relate to living things e.g. food availability, number of predators or incidence of disease.
• Abiotic factors are factors that are non living e.g. light intensity, temperature or soil pH
• Sampling of organisms in an ecosystem allows an investigator to find out the numbers of species present in an ecosystem.

Sampling techniques used are: 

1. Quadrats
2. Pitfall traps
3. Water net

 

When sampling the technique is carried out more than once to validate the results and establish an average.
Measuring abiotic factors:

1. Light meter
2. Moisture meter

Care has to be taken when using these meters to ensure valid results and reduce any possible sources of error.

How it works

• Producers are always green plants as they are the only living thing that can produce their own food through the process of Photosynthesis. This is when they use the light energy from the sun and change it into chemical energy in the form of the food starch.

• All animals and non green plants (fungi) are called consumers because they have to eat either plants or other animals to obtain the energy required for living.

• Herbivores only eat plant material.

• Omnivores eat both plant and animal material.

• Carnivores eat animal material.

• An animal that hunts another for its food is called a predator.

• An animal that is hunted is called the prey.

• A food chain demonstrates the relationship between predators and prey. The arrows in a food chain represent the FLOW OF ENERGY.

• A food web contains many interlinked food chains.

Energy is lost as it moves through a food chain. It is lost in a number of different ways:

1. Movement
2. Maintaining body temperature
3. Waste production

• A pyramid of numbers illustrates the number of species present at each trophic level.
• A pyramid of biomass illustrates the weight (mass) of species at each trophic level.
• Disease, natural disasters and the introduction of man has the ability to disturb a food chain.
• The birth and death rate help control numbers of a population naturally.
• Factors that can limit population growth are:

1. Shortage of food and/or water.
2. Lack of space.
3. Predators.
4. Toxic wastes.
5. Disease.

• Competition occurs in nature particularly when a resource is in short supply.
• Green plants compete for: - light, water, soil nutrients and root space.
• Animals compete for: - water, food, shelter, nesting sites and mates
• During competition normally the fittest (strongest) will survive.
• Nutrient Cycles involve the recycling of nutrients using special bacteria and fungi called decomposer

Control and Management

• Environmental Pollution is the contamination of our surroundings by substances that can harm living things and at times result in death.
• Pollution can be divided into 4 different types.
  
  1. Type of pollution: Air
  Main source of pollution: Car exhausts
  Example of pollution: Fumes containing Carbon Monoxide
  Possible methods: Fitting filters and catalytic convertors to car exhausts
  
  
  2. Type of pollution: Land
  Main source of pollution: Homes
  Example of pollution: Domestic Rubbish
  Possible methods: Recycling, burying, or burning
  
  
  3. Type of pollution: Fresh water
  Main source of pollution: Agriculture
  Example of pollution: Excess fertilisers and pesticides
  Possible methods: Use of minimum concentrations, especially near water
  
  
  4. Type of pollution: Sea
  Main source of pollution: Nuclear Power Stations
  Example of pollution: Radioactive Waste
  Possible methods: Sealing waste in lead containers and dumping them on the sea bed. Or find alternative methods of disposal.

• If a river is heavily polluted there will be a high number of bacteria present. As a result the oxygen concentration will be very low since bacteria use oxygen to live and produce carbon dioxide.
• Indicator species are used to highlight the environmental conditions of certain areas.
• Lichens are small algal-type plants that grow on the bark of trees. If pollution is very low these plants are bright green in colour and are moist to the touch. As the air becomes more polluted they darken in colour and become powdery to the touch.