The Biosphere

General Objectives

Sub-topic (a) Investigating an Ecosystem

Describe the main parts of an ecosystemAn 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 organismsPitfall trapsPooterTree beating

Identify two abiotic factorspHmoisture temperatureLight IntensityDescribe methods of measuring abiotic factorsLight Intensity: light meterMoisture: moisture meterTemperature: thermometerpH: pH meter

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.

Sub-topic (b) How it works

Define the words; habitat, population, community and ecosystem

Habitat: place where an organism livesPopulation: group of organisms of one species

in an ecosystemCommunity: all the plants, animals and micro-

organisms that live together in an ecosystemEcosystem: natural biological unit made up of

living and non-living parts

Describe what is meant by a producer and a consumer

ProducerGreen plant that uses light energy to make its

own food.ConsumerOrganism 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.

Explain the meaning of the arrows in a food webThe arrows represent the direction of ‘energy

flow’.Describe two ways in which energy is lost from

a food webHeat productionMovementChemical ReactionsWaste production

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 waterLack of spaceDisease

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.

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.

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 exhaustsHomes and farmsAgricultureOil tankersNuclear power stations

Give an example of one way to control pollutionControlling acid rainScrubbing 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.

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.

Overgrazing of grasslandThis 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.