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Flashcards in Humans and the Environment Deck (24):

What commonly pollutes water?

Sewage, fertilisers from farms or toxic chemicals from industry.


What commonly pollutes air?

Smoke and poisonous gases from industry or vehicle fumes.


What commonly pollutes land?

Pesticides/herbicides from farming or industrial waste such as heavy metals.


Why is more waste being produced?

The population has grown and the standard of living increases.


How is acid rain formed and what are its effects?

Acid rain is formed when sulphur and nitrous oxides dissolve in the water vapour in the air and fall as rain; its effects are the damage of trees and the increased acidity of the soil.


What are the reasons for deforestation?

To use the timber for building work; to use the land cleared for agriculture; to use the space to grow crops for ethanol-based biofuels; to grow rice crops or keep cattle for food.


Why does deforestation release carbon dioxide?

The combustion of the trees releases carbon dioxide; the respiration of microorganisms decaying the trees releases carbon dioxide; the removal of trees reduces the rate at which they can remove carbon dioxide from the atmosphere through photosynthesis.


What is biodiversity and why do we need it?

Biodiversity is the wide range of organisms, plants and animals, that live in a habitat; it is important because species that have not yet been discovered or studied could be a source of medicine or food for the future.


Where is carbon dioxide sequestered?

Peat bogs, forests, oceans and rivers where it dissolves.


What is the greenhouse effect?

The buildup of greenhouse gases in the atmosphere which form a thicker layer around the earth; energy from the sun is trapped in this this thick gaseous layer and is reradiated back to earth, causing the temperature to rise.


What are the effects of global warming?

Increased unpredictability to the earth's climate; a rise in sea levels as the ice caps melt, leading to increased flooding; reduced biodiversity as the climate changes; changes in migration patterns to species; changes in distribution of certain species.


How are ethanol-based biofuels produced?

Glucose from maize ferments anaerobically with yeast to produce ethanol and carbon dioxide; the ethanol is extracted by distillation.


What are the advantages / disadvantages of using ethanol as a fuel?

It is an efficient fuel; it doesn't produce toxic gases when burnt; it is a carbon neutral process and isn't very polluting; it requires large amounts of crops to be grown to produce ethanol; there are ethical issues when there is world hunger but crops are grown to produce fuel for developed countries.


What is biogas?

A biofuel that is a flammable mixture of gases, formed when bacteria decompose plant material in anaerobic conditions.


What is the main gas present in biogas?



What is put into a biogas generator?

Dung from humans and animals, farm waste, garden rubbish.


What comes out of a biogas generator?

Methane for cooking or heating; slurry, which can be used as a fertiliser.


What temperature will the production of biogas work best at?

Around 30°C.


How can food production be made more efficient?

By reducing the number of stages in the food chain to prevent loss of energy and biomass; by restricting the movement of animals and keeping them in a warm temperature to prevent waste of energy.


How can overfishing be prevented?

Enforcement of fishing quotas so there is a limit as to how many and what type of fish can be caught; controlling the size of nets so that smaller fish can escape to breed; restricting fishing during breeding season so the species can reproduce.


What is mycoprotein?

A protein made from the fungus Fusarium; grown in fermenters; suitable for vegetarians and a suitable substitute for meat.


What are the features of mycoprotein fermenters?

They have an air supply to provide oxygen for the respiration of the fungi; they have stirrers to keep the microorganisms in suspension and to maintain an even temperature; they have a water-cooled jacket to remove any excess energy; they have sensors which constantly monitor the pH and temperature.


What are the effects of building dams for reservoirs?

Habitats for humans, plants and animals are lost; river ecosystems are destroyed as they dry up; flood plains disappear along with the fertile soil they provide.


What is eutrophication?

The process by which oxygen levels in a stream or pond fall so low that the aquatic animals die and the water becomes "dead".