4.3 carbon cycling

Question 1

carbon cycle

Answer 1

continued availability of carbon in ecosystems depends on carbon cycling

Question 2

photosynthesis

Answer 2

• all autotrophs convert carbon dioxide (from the atmosphere or dissolved in water) or into organic compounds
• plants initially synthesize sugars (glucose) which are then converted into other organic compounds such as: complex carbs (starch, cellulose), lipids, amino acids
• plants must have a constant supply of carbon dioxide to continually photosynthesize

Question 3

How does CO2 enter into plants?

Answer 3

• CO2 diffuses from the atmosphere or water into the autotrophs
• CO2 enters through the stomata ( some aquatic plants have stomata but in many fully submerged pants diffusion happens directly through the surface tissues
• CO2 moves down the stomata; pores into the leaf

Question 4

Ocean uptake of CO2

Answer 4

• someCO2 will directly dissolve in water, but most will combine with water to become carbonic acid.
• know formula:

Question 5

cell respiration

Answer 5

• organisms carry out respiration to release energy in the form of ATP. Carbon dioxide is a waste product of cell respiration.
• in terms of carbon cycle three main categories or organisms carry out respiration:
  1. autotrophs, plants
  2. heterotrophs, animals
  3. saprotrophs and decomposer, fungi and bacteria

Question 6

fossil fuels

Answer 6

peat formation:
- partially decomposed organic matter can be compressed to form brown soil-like peat
- peat is a highly effective carbon sink, it is estimated that the world’s peat contains 550 gigatonnes or carbon
- one dried, peat burns easily and can be used as a fuel
- peat forms when organic matter is not fully decomposed because of acidic and anaerobic conditions in waterlogged soils

Question 7

fossil fuels

Answer 7

coal, oil, and gas
- partially decomposed organic matter from past geological eras was converted either into coal or into oil and gas that accumulate in porous rocks
- coal is formed when deposits of pear are buried under other sediments
the peat is compressed and heated over million years eventually becoming coal
- oil and gas formation occurred in ancient oceans
silt deposits and deposits of dead marine organisms oil and gas
the mixture of different types of oil and gas is the result of complex chemical changes (methane forms the largest part of natural gas.

Question 8

fossil fuels

Answer 8

limestone:
- some animals secrete calcium carbonate structures to protect themselves (shells of molluscs, hard corals exoskeletons)
- when the animals die the soft body parts decompose, but the calcium carbonate
- the deposits are buried and compressed and eventually form limestone rock.
limestone rock is a huge carbon sink

Question 9

fossil fuels

Answer 9

combustion:
- carbon dioxide is produced by the combustion of biomass and fossilized organic matter
- is heated, dried biomass or fossilized will burn in the presence of oxygen

Question 10

fossil fuels

Answer 10

methanogenesis:
- methanogens are archaean microorganisms that produce methane as a metabolic byproduct in anoxic (without oxygen)
they are found in a variety of anoxic environments:
- mud in the beds and shores of lakes
- wetlands (paddies, swamps, and mangroves)
- digestive tracts of animals (cows, humans, and termites)
- landfill sites (in which organic matter has been buried)

• measurements indicate that the levels of atmospheric methane are increasing
• methane released into the atmosphere can be removed by a number of mechanisms (the most important process of methane removal is oxidation by hydroxyl radicals)

Question 11

estimation of carbon flux in carbon cycle

Question 12

know to draw carbon cycle!!