Chapter 22 PCB 3044

Which of the following is not an example of weathering (i.e., the release of elements form rock minerals)?

Decomposition of rocks by carbon dioxide forming a weak acid

Rock breakdown during repeated freeze-thaw cycles

All of the above are examples of weathering

Abrasion by wind and water

All of the above are examples of weathering

_____ is a natural anaerobic process that removes nitrogen (in the form of nitrate, NO3-) from the environment, converting it to ____.

Nitrification; ammonium

Mineralization; plant biomass

Denitrification; plant biomass

Denitrification; dinitrogen gas

Denitrification; dinitrogen gas

Which of the following is not part of the decomposition process

photodegradation

fragmentation

fixation

mineralization

fixation

Treatment wetlands, such as the Orlando Wetlands Park, are utilized because of their ability to remove excess __ from wastewater.

Nitrogen and phosphorus

Carbon

Oxygen

Pesticides and herbicides

Nitrogen and phosphorus

Which of the following does not impact decomposition rates?

presence of secondary compounds

None of these (i.e. all impact decomposition rates)

complexity of organic molecules

redfield ratio

None of these (i.e. all impact decomposition rates)

The original source of all nutrients is _____. Because these sources are slow to make nutrients available to organisms, there is a high degree of ______ in most ecosystems.

microorganisms; decomposition

minerals in rocks and gases in the atmosphere; leaching

rivers and streams; internal recycling

minerals in rocks and gases in the atmosphere; internal recycling

minerals in rocks and gases in the atmosphere; internal recycling

Which figure best illustrates the relationship between temperature and primary productivity and temperature and rates of decomposition?

Figure A

Figure B

Figure D

Figure C

Figure D

Excess nitrogen can become a pollutant in aquatic systems, contributing to eutrophication and harmful algae blooms. Denitrification is a natural process that occurs at very high rates in __ and converts nitrate to harmless _.

estuaries; NH4+

forests; NH4+

wetlands; N2

the atmosphere; N2

wetlands; N2

Soils composed of high amounts of __ typically hold the least amount of water and nutrients.

silt

organic matter

clay

sand

sand

Element (symbol) Bacteria (in general) Plant (corn, Zea mays) Animal (human, Homo sapiens)

Oxygen (O) 20 44.43 14.62

Carbon (C) 50 43.57 55.99

Hydrogen (H) 8 6.24 7.46

Nitrogen (N) 10 1.46 9.33

Silicon (Si) 1.17 0.005

Potassium (K) 1–4.5 0.92 1.09

Calcium (Ca) 0.01–1.1 0.23 4.67

Phosphorus (P) 2.0–3.0 0.20 3.11

Magnesium (Mg) 0.1–0.5 0.18 0.16

Sulfur (S) 0.2–1.0 0.17 0.78

Chlorine (Cl) 0.14 0.47

Iron (Fe) 0.02–0.2 0.08 0.012

Manganese (Mn) 0.001–0.01 0.04 –

Sodium (Na) 1.3 – 0.47

Zinc (Zn) – 0.01

Rubidium (Rb) – 0.005

According to the table, which of the following statements about the elemental composition of organisms is true?

Animals contain less calcium than plants.

Bacteria have an equal amount of carbon and nitrogen.

Plants contain more phosphorus than bacteria or animals.

Animals, plants, and bacteria all contain iron.

Animals, plants, and bacteria all contain iron.