Ecology: Geochemical Cycles Concept 2

What is one biotic factor that affects the size of a population in an ecosystem?

• Local geography

• Number of predators present

• Average yearly temperature

• Average yearly precipitation

Organisms, such as plants or phytoplankton that carry out photosynthesis would cause a decrease of which gas in the atmosphere?

• Carbon dioxide

• Oxygen

• Ozone

• Water

In the carbon cycle, decomposers return carbon to the soil. Which of the following is NOT something decomposers can break down?

• The bodies of dead plants and animals

• Waste products like urine or feces

• Carbon dioxide found in the air

• Scraps of discarded food

Humans increase carbon dioxide in the atmosphere, and contribute to the carbon cycle by....

• Planting trees to improve photosynthesis

• Combustion from driving cars

• Using more solar power electricity

• Conserving energy with alternative energies

Nitrogen in the air must be "fixed" before it can be used by plants. Atmospheric nitrogen is "fixed" by...

• Bacteria and insects

• Bacteria

• Plants

• Bacteria and fungi

When deforestation occurs in an area, what immediate effect does this have on the water cycle?

• Less is returned to the air by transpiration and mudslides can occur easier

• More photosynthesis occurs, and CO₂ begins decreasing

• There is less runoff water, but more transpiration

• More water is returned to the atmosphere by transpiration

The main result of photosynthesis is....

• Global warming caused by CO₂ being removed

• Decreased atmospheric nitrogen

• CO_{2 is removed and captured by plants}

• Absorbing nitrogen for the plant to use

Bacteria are involved in many steps of the geochemical cycles. Which of the following steps is bacteria NOT involved?

• Transpiration

• Nitrification

• Decomposition

• Nitrogen fixation

Which of the following is common to the carbon cycle, the nitrogen cycle, and the water cycle?

• The substances are rearranged into different types of molecules as they move through their cycles

• The substances must pass through organisms in order to complete their cycles

• The largest reserves of these substances are always in organisms

• These substances are required by all living things and are involved in many processes that occur in all living things

Water can be returned to the atmosphere through the leaves of plants by....

• Condensation

• Precipitation

• Evaporation

• Transpiration