Pat Hamer

Period 5

3/8/04

Chapter 49

People and the Bioshpere

 

I.                    Population Growth

a.       Birthrates vary from country to country, time to time etc.

                                                               i.      Most growth is occurring in Africa, South America and Asia

1.      continues to grow annually at 3%

                                                             ii.      In 1970’s birthrates decreased, rose slightly in 80’s.

                                                            iii.      At current rate population will double in less than 100 years

b.      Death rate has decreased worldwide. Why?

                                                               i.      Food is more attainable and filled with artificial nutrients.

                                                             ii.      Better health care

c.       Human effects:

                                                               i.      Demand for food too high

                                                             ii.      Not enough land to farm on or live on

                                                            iii.      Destruction of forests

                                                           iv.      Overuse of natural resources

d.      Moral questions arise

                                                               i.      Should elderly people’s lives be prolonged?

                                                             ii.      Should more cures for diseases be pursued?

II.                 Pollution

a.       Two categories of waste materials:

                                                               i.      Biodegradable – can be broken down into essential nutrients by microorganisms.

1.      sewage and scraps of food

                                                             ii.      Nonbiodegradable – cannot be broken down by natural processes or broken down very slowly.

1.      asbestos, glass, certain plastics and metals, radioactive wastes, and chemicals such as DDT, Dieldrin and PCB’s.

b.      Biological Magnification: Nonbiodegradable products increase concentration as they move through the food chain. Ex: DDT effected egg shells, killed fish

                                                               i.      Some animals at the end of a food chain may have a concentration of Nonbiodegradable compounds 10,000,000 times original concentration.

c.       Air Pollution:

                                                               i.      Temperature inversions or weather conditions can make smog a serious health hazard

                                                             ii.      Smog

                                                            iii.      acid rain

                                                           iv.      greenhouse effect

                                                             v.      ozone depletion

d.      Water Pollution:

                                                               i.      chemical and sewage contamination

                                                             ii.      thermal pollution

                                                            iii.      oil spills.

III.               Fate of the Earth

a.       Forests – What roles do they play?

                                                               i.      Deforestation leaves fertile topsoil exposed to elements. If washed away, soil cannot sustain plant-like as before.

                                                             ii.      At current rate Rain forests likely to be gone in 30 years.

                                                            iii.      Land trees provide 20% of oxygen in the world

b.      Endangered Species – An animal or plant that has become so rare that it is threatened with extinction.

                                                               i.      99.9% of all Animals who have ever lived on earth are now extinct.

                                                             ii.      Why save them?

1.      Useful products

a.       industrial compounds

2.      Medical uses

a.       antibiotics, anticancer drugs, painkillers

3.      Food sources

a.       Genetically similar plants can help maintain crop yields by providing resistance to diseases.