CSHS 11 ATAR Biology Carbon and Nitrogen cycles

What is the most common way that nitrogen fixation occurs?

• lightening

• nitrogen fixing bacteria

• fossil fuel combustion

• forest fires

Atmospheric nitrogen (N2 gas) is easily taken up and used by plants and animals.

• true

• false

Which of the following is a component of acid rain?

• ammonium

• denitrifying bacteria

• nitrogen oxides

• organic nitrogen

Organic nitrogen is converted back to inorganic nitrogen like ammonium through the process of

• nitrogen fixation

• nitrification

• decay

• none of these choices

Eutrophication in coastal waters can cause an increase in

• respiratory diseases in fish

• agricultural productivity

• harmful algal blooms

• denitrification

Ammonium (NH4) stays in soil, while nitrate (NO3) is easily leached out. Why do they behave so differently?

• NO3 is broken down by bacteria, so it is easily carried away

• NH4has a positive charge and sticks to soil particles.

• NH4 is unavailable to organisms, so it remains unchanged in the soil.

• NO3 is only produced when water is flowing through soil.

Which process releases dinitrogen gas (N2) back into the atmosphere?

• denitrification

• nitrogen fixation

• decay

• nitrification

Once bacteria have fixed nitrogen, it can be taken up by plants and animals, where it is used in the production of

• nitrogen oxides

• carbohydrates

• proteins

• energy

Synthetic fertilizers add _____________ to the soil.

• organic nitrogen

• fixed nitrogen (ammonium)

• nitrogen oxides

• Rhizobium bacteria

Legumes host nitrogen fixing bacteria, and thus are good crops to plant to replenish the soil.

• true

• false