Environmental Change (Ecology)

Which organism in the food web shown to the right would

contain the highest concentration of chemical pollutants?

• Producers

• Primary consumers

• Secondary consumers

• Tertiary consumers

The accumulation of heavy metals or other pollutants causes

a decline in the population of predatory birds because –

• heavy metals make it difficult for the birds to hunt

• pesticides diminish the amount of available food

• the pollutants interfere with bird reproduction

• birds cannot tolerate any amount of pollution

Chemical pesticides tend to be used in terrestrial ecosystems, but they are commonly found in the tissues of aquatic organisms. Because of this, birds and other animals with a diet high in fish commonly suffer the effects of biological magnification. How do these pesticides end up in these aquatic ecosystems?

• Pesticides evaporate and are delivered to water sources by rainfall

• Land animals containing pollutants die and decompose in waterways

• Pesticides are carried to water sources by freshwater runoff.

• Human fishing practices add pesticides to water sources.

The rapid growth of algae, called an algal bloom, can lead to the formation of dead zones that cannot sustain aquatic life. This is mainly because the algal bloom lowers the amount of –

• chemical pollutants

• soluble salts

• dissolved oxygen

• freshwater runoff

The eutrophication of a water supply can lead to a phytoplankton bloom. The excess nutrients allow these microscopic organisms to reproduce at a faster rate than normal. What is one ecological problem that can occur as a result of these blooms?

• The reduction of fish populations as oxygen levels in the water decline

• Fertilizers become less effective causing an increase in their use by farmers

• The phytoplankton become poisonous to the animals that typically consume it

• The fish become poisonous to the animals that typically consume it

Eutrophication is caused by

• excess nutrients building up in the water.

• industrial point-source pollution.

• unlined landfills and septic tanks.

• wastewater from homes mixing with drinking water.

Why should farmers be concerned about unused nitrate fertilizer contaminating surface water and groundwater supplies?

• Unused nitrates reduce algae growth.

• Unused nitrates increase oxygen in the water.

• Excessive amounts of nutrients cause overpopulation of fish.

• Excessive amounts of nutrients speed up the eutrophication process.

What is deforestation?

• Clearing Earth's forests on a massive scale
• Eating too much vegetables
• Going to a forest and pulling weeds
• Clearing the five trees in my backyard

What does deforestation effect?

• Plants and animals
• Our biosphere
• Humans
• All of the above

Why does cutting down trees increase global warming?

• trees soak up carbon dioxide
• trees provide shade which counteracts global warming
• trees absorbs the sun's energy without radiating back into the atmosphere
• trees drain greenhouse gases like methane from soil