Lecture 24

Question 1

Nutrients

Answer 1

A substance required for the growth and maintenance of an organism that must be obtained from the environment

• Water, Oxygen, Nitrogen, Sulfur, Calcium, etc.
• These substances move through air, water, soil, rock and living organisms in ecosystems in cycles

Question 2

Macronutrients

Answer 2

Needed in large quantities

• Major components of cells
• N,C,H,O,P,S

Question 3

Micronutrients

Answer 3

Needed in small amounts but still essential

• Vitamins and coenzymes needed to catalyze reactions
• Na, Cu, Mn, Zn, Cl, Fe

Question 4

Why are nutrients essential?

Answer 4

Building blocks of biological molecules

proteins, carbohydrates, fats, nucleic acids

Question 5

Stores

Answer 5

Where nutrients are found in an ecosystem

Question 6

Fluxes

Answer 6

Processes that move nutrients from one store to another; change the nutrient from one form to another
-precipitation, absorption, combustion, decomposition, dust, evaporation, respiration

Question 7

Nitrogen

Answer 7

Crucial component of proteins, many vitamins and nucleic acids (DNA, RNA)
-N2 makes up 78% of the atmosphere

Question 8

Nitrogen Fixation

Answer 8

N2—>NH4+

-Gaseous nitrogen (N2) is converted into ammonium ions (NH4+) that can be used by plants

Question 9

Community Ecology Connection

Answer 9

Mutualism between nitrogen-fixing bacteria and some plants (particularly from the legume family)

Question 10

Nitrification

Answer 10

NH4+–>NO3-
-Ammonia not taken up by plants may undergo nitrification; NH4+ is converted first to nitrite ions (NO2-) which are toxic to plants, and then to nitrate (NO3-) which can be taken up by roots of plants

Question 11

Denitrification

Answer 11

NO3—->N2 and N2O
-Nitrite and nitrate ions are converted to nitrogen gas (N2) and nitrous oxide gas (N2O). These gases are released to the atmosphere to begin the nitrogen cycle again

Question 12

What do arrow widths tell us?

Answer 12

Much less nitrogen leaves or enters the system than is required internally through assimilation and decomposition

Question 13

Do humans fix nitrogen

Answer 13

Yes, a lot

• Industrial produced fertilizers
• Planting of crops that harbor nitrogen-fixing bacteria
• burning of fossil fuels

Question 14

Good and bad of more available nitrogen

Answer 14

Good:
-Increase in productivity of agricultural crops has helped us feed an expanding human population
Bad:
-Nitrogen pollution and human health (contamination of drinking water)
-Pollutant in aquatic habitats
-change in species composition of some communities
-increase in amount of nitrogen gases produced

Question 15

Eutrophication

Answer 15

The conversion of a body of water to a highly productive ecosystem with rapid decomposition and low oxygen levels

Question 16

Nitric Oxide and Nitrous Oxide

Answer 16

NO=Smog
N2O=Greenhouse Gas
Both contribute to acid rain