Biogeochemical Cycles Quiz Review

Organisms that make their own food:

• Producers

• Consumers

Organisms that acquire their nutrients by eating other organisms.

• Producers

• Consumers

Which of the following is NOT a source of nitrates and phosphates into a river?

• Fertilizers

• Animal waste

• Wastewater

• Burning fossil fuels

What is the very next thing that happens after fertilisers enter a river in eutrophication?

• Fish die due to a lack of oxygen

• Plants below the surface die due to a lack of sunlight

• The number of aerobic bacteria increases

• Fast growth of plants

In eutrophication, what directly causes the death of fish?

• The plants use up oxygen in respiration

• The fish are poisoned by high CO₂ levels

• Bacteria use up oxygen in respiration

• The fish use up oxygen in respiration

In eutrophication, what does 'algal bloom' refer to?

• The rapid increase in the number of bacteria

• The rapid increase in the number of plants

• The rapid decrease in the number of fish

• The rapid increase in the amount of nitrates in the river

Eutrophication is defined as a change that occurs to an aquatic ecosystem. This change is mainly due to what?

• Newly introduced fish

• Depletion of the ozone layer

• Increased nutrient concentration

• Increase in atmospheric carbon dioxide.

The green plants on the surface of the lake turned out the be algae! There is a sudden increase in the rate of growth of the algae. What would happen next?

• The algae continue to grow due to excess nutrients, and some of the algae die

• The algae would stop growing

• The algae are not affected by the fertilisers

The size of dead zones will ________ with more nitrogen run-off.

• Increase

• Stay the same

• Decrease

In a dead zone, _________ levels are really low such that living organisms are not able survive.

• nitrogen

• oxygen

• fertilizer

• carbon dioxide