4. Nutrient Cycles

Question 1

“There is an important difference between energy and …. in ecosystems.” Fill in the blank.

Answer 1

inorganic nutrients

Question 2

How is energy supplied to ecosystems?

Answer 2

• in the form of light and converted to chemical energy by producers (autotrophs).
• chemical energy used in living cell and converted to heat, which cannot be recycled, but more light is received

Question 3

How is nutrients supplied to ecosystems?

Answer 3

• carbon, nitrogen, phosphorous and all other essential elements are absorbed from environment, used, and then returned to the environment
• ecosystems have a limited supply of nutrients, but these supplies do not run out because nutrients can be recycled

Question 4

Draw a diagram of the carbon cycle. (p.58)

Answer 4

-

Question 5

What do the arrows on a diagram of the carbon cycle show? What does the thickness of the arrow indicate? What do the boxes on a diagram of the carbon cycle indicate? What could also be added to a carbon cycle diagram?

Answer 5

• fluxes - transfers of carbon
• the size of the flux
• sinks - methods of carbon storage in the ecosystems
• the sink of methane in the atmosphere and also methane fluxes (methane = CO4 = contains carbon)

Question 6

How is methane gas produced naturally?

Answer 6

by a group of prokaryotes called ‘methanogenic archaeans’

Question 7

What do ‘methanogenic archaeans’ do?

Answer 7

break down organic matter in anaerobic conditions and release methane as a waste product

Question 8

Whereabouts is methane usually produced?

Answer 8

in swamps, bogs and other sites where there are anaerobic conditions,
- dead organic matter is not fully decomposed by saprotrophic bacteria and fungi (because they need oxygen)

Question 9

What happens to naturally produced methane?

Answer 9

can accumulate in the ground or diffuse into the atmosphere

Question 10

Is methane a stable substance in the atmosphere?

Answer 10

yes, relatively, although:

- it is eventually oxidized to carbon dioxide, so concentrations of methane in the atmosphere have remained low

Question 11

How is carbon dioxide produced?

Answer 11

by the combustion of carbon compounds

Question 12

Is production of carbon compounds a biological process? How so? Does production of carbon compounds occur naturally?

Answer 12

• no
• it is not carried out by living organisms
• yes, in some ecosystems where lighting can set fire to forest or grassland - biomass burns releasing carbon dioxide

Question 13

During the industrial revolution, methods were developed for extracting coal, oil and gas and for generating energy from their combustion. What is this impact of this?

Answer 13

• it releases large and increasing quantities of carbon dioxide into the atmosphere…