May 17

Which factors can have the greatest effect on the health of a river system?

• type of soil and salinity

• nitrate levels and turbidity

• human consumption and pH

• natural disasters and tidal change

Which best determines the health of a lake used as a source of freshwater?

• its depth and width

• its temperature and pH

• its location and depth

• its temperature and depth

If a body of water has high turbidity levels, what can most likely be concluded?

• It has a low pH

• It is unsafe to drink

• It is too hot to drink

• It contains lots of chemicals

Which will occur if humans continue to overload water systems with excess nutrients?

• chemosynthesis

• eutrophication

• nitrification

• photosynthesis

Which does an increase in eutrophication indicate to scientists studying a body of water?

• an increase in fertilizer runoff

• a decrease in pollutants from farm runoff

• an increase in the health of the body of water

• an increase in oxygen levels in the body of water

Which aspect of fertilizer pollution would have the greatest negative impact on an aquatic ecosystem?

• Nitrates poison the water that fish breathe through their gills.

• Microorganisms in the water absorb all the oxygen, suffocating animals.

• Aquatic animals increase, adding producers to the food chain and feeding fish.

• Algal blooms deplete the oxygen and block the sunlight from penetrating a body of water.

Which groundwater contaminant contained in fertilizers and pesticides comes from farms?

• bacteria

• mercury

• nitrates

• sodium

Why does fertilizer pollution stimulate the growth of algae in a pond?

• Algae are producers and use the fertilizer’s nutrients to rapidly multiply.

• Algae are producers and use the fertilizer’s nutrients during decomposition.

• Algae are parasites and absorb energy from the fertilizers in order to grow.

• Algae are herbivores that feed off of the plants, which grow due to the excess fertilizers.

Which would most affect the health of fish in a local pond?

• The daily release of hot water into the pond from a local factory.

• A storm temporarily stirring up water and sediments in the pond.

• The occasional erosion of sediments into the pond from a nearby field.

• A slight increase in the number of people who fish in the pond for food.

Which is most likely to happen when river water temperature rises above 35°C?

• The water will become polluted.

• The dissolved oxygen levels will increase.

• There will be negative health effects on wildlife.

• There will be decreased evaporation from the river.