The Biosphere

1

• The Biosphere
• General Objectives

2
Sub-topic (a) Investigating an Ecosystem

• Describe the main parts of an ecosystem
• An ecosystem is a natural biological unit made up
  of living and non-living parts.
• Non-living factors (abiotic)
• Living factors (biotic)
• Describe techniques used to sample organisms
• Pitfall traps
• Pooter
• Tree beating

3

• Identify two abiotic factors
• pH
• moisture
• temperature
• Light Intensity
• Describe methods of measuring abiotic factors
• Light Intensity light meter
• Moisture moisture meter
• Temperature thermometer
• pH pH meter

4

• Describe the effect of an abiotic factor on the
  distribution of organisms
• Light
• Increased numbers of daisies in a unshaded area
  compared to a shaded area. The availability of
  light is effecting their distribution.

5
Sub-topic (b) How it works

• Define the words habitat, population, community
  and ecosystem
• Habitat place where an organism lives
• Population group of organisms of one species in
  an ecosystem
• Community all the plants, animals and
  micro-organisms that live together in an
  ecosystem
• Ecosystem natural biological unit made up of
  living and non-living parts

6

• Describe what is meant by a producer and a
  consumer
• Producer
• Green plant that uses light energy to make its
  own food.
• Consumer
• Organism that depends on another living thing as
  a food source.
• Give an example of a food chain and a food web.
• Remember they always start with a producer (green
  plant). Ensure the direction of the arrows is
  understood.

7

• Explain the meaning of the arrows in a food web
• The arrows represent the direction of energy
  flow.
• Describe two ways in which energy is lost from a
  food web
• Heat production
• Movement
• Chemical Reactions
• Waste production

8

• State the effect of birth rate and death rate on
  a population
• If the birth rate is greater than the death rate
  then the population will increase.
• If the death rate is greater then the birth rate
  then the population will decrease.
• If the birth rate and death rate are equal the
  the population will remain steady.
• List three factors which can limit growth in a
  population
• Limited supply of food and water
• Lack of space
• Disease

9

• State how competition comes about and describe
  its effects
• Competition can occur when a resource is in
  limited supply. In an natural ecosystem
  competition can occur when two or more members of
  a community need a particular resource.
• Whenever competition occurs some of the
  competitors grow more slowly than others. These
  weaker individuals lose out in the struggle for
  existence and often die before reaching
  reproductive age.

10

• Explain why nutrient cycles are important.
• Nutrients are chemical substances such as
  nitrogen, oxygen, mineral salts and carbon
  dioxide.
• Nutrient cycling is important because the the
  supply of many chemicals is limited. If the
  chemicals remain locked up in dead bodies and
  wastes, supplies would soon run out.

11

• Sub-topic (c) Control and Mangement
• State that pollution affects air,fresh water, sea
  water and land.
• Name the main sources of pollution.
• Industry and coal fired-power stations.
• Car exhausts
• Homes and farms
• Agriculture
• Oil tankers
• Nuclear power stations

12

• Give an example of one way to control pollution
• Controlling acid rain
• Scrubbing the fumes produced before releasing
  them.
• Fuel burners can be redesigned to operate at
  lower temperatures and produce less of the
  poisonous gas.
• Add lime to water to bring pH in water back to a
  level that fish can tolerate.
• Describe the importance of organic waste to
  micro-organisms.
• Bacteria and fungi use organic waste as a food
  source.

13

• Describe the effects of micro-organisms on
  available oxygen
• As micro-organisms breakdown organic waste they
  use up the available oxygen. Therefore, in
  highly polluted areas oxygen concentrations will
  be low.
• Name two examples of poor management of natural
  resources and suggest improvements
• Use of vast quantities of grain to feed
  livestock.
• This could be improved by encouraging people to
  eat less meat. Feed less grain to animals and
  more to starving people.

14

• Overgrazing of grassland
• This could be improved by providing economic
  support to plant shelter beds for trees and
  resilient grass cover.
• Describe how the effect of poor management of
  natural resources can produce problems.
• Over use of pesticides can lead to them entering
  the food chain.
• Malnutrition.
• Overgrazed plants die which can lead to increased
  desert land.