Energy & Matter Exchange in the Biosphere

Question 1

Albedo

Answer 1

• the amount of energy reflected or absorbed by clouds, water, and land.
  light = high albedo | dark = low albedo

Question 2

open vs closed system

Answer 2

• Energy = OPEN
• Matter exchange = CLOSED

Question 3

PRODUCERS (Autotrophs)

Answer 3

• “self-feeders”
• use light energy to make sugars
• Photosynthetic producers: use the Sun’s energy make food
  *Chemosynthetic producers: make own food from chemical energy stored in molecules

Question 4

CONSUMERS (heterotrophs):

Answer 4

• “other feeders”
• obtain energy by consuming other heterotrophs or autotrophs

Question 5

Consumer levels

Answer 5

1. PRIMARY CONSUMERS are herbivores which eat producers.
2. SECONDARY CONSUMERS are carnivores that eat herbivores.
3. TERTIARY CONSUMERS are carnivores that eat carnivores

Question 6

Trophic levels

Answer 6

feeding levels in an ecosystem through which energy and matter are transferred
➢ Largest amount found within the 1st trophic level
* Usually no more than 5 levels

Question 7

1) Pyramids of Numbers

Answer 7

➢ # of producers often greatly outnumbers the # of consumers
➢ Each bar of the pyramid: # of organisms in each trophic level

Question 8

2) Pyramids of Biomass

Answer 8

➢ Represent the dry mass of living organisms per unit area (in g/m2 )
➢ energy is transferred from one trophic level to another, takes into account the actual size of organisms in an ecosystem rather than just the number.

Question 9

3) Pyramids of Energy

Answer 9

➢ Shows the total amount of energy that is transferred through each trophic level (in J or kJ), are always upright

Question 10

Sources that increase carbon

Answer 10

• Hydrocarbon combustion (CO2 to atmosphere)
• Deforestation (removing carbon sink – trees – slash and burn - )
• Human caused forest fires
• Agriculture
• Acidification of oceans (CO2 in H2O à carbonic acid – impact on marine ecosystems)

Question 11

Where is the Carbon?

Answer 11

Abiotic environment:
* CO2 in the atmosphere,
* Majority is dissolved in the world’s oceans
Biotic environment:
* Primary source is the atmosphere (CO2 )
* Captured through photosynthesis – aka carbon fixation
* Some returned to atmosphere via cellular respiration
* Reverse reaction of photosynthesis.
* Chemical energy from the breakdown of glucose is released and is used by the cell to make ATP (energy for organism)

Question 12

Processes involved in the carbon cycle

Answer 12

1. photosynthesis/chemosynthesis aka carbon fixation
2. cellular respiration
3. death/decay of organisms
4. fossilization
5. burning fossil fuels
6. formation of carbonate compounds
7. sedimentation
8. volcanic heating of carbonate rocks (limestone)

Question 13

Phosphorus cycles in two ways

Answer 13

1. Long term – involving rocks and the earth’s crust
2. Short cycle – involving living organisms

Question 14

Processes Involved in the Phosphorus
Cycle

Answer 14

• Geological uplift
• Erosion/weathering (wind/rain)
• Decomposition
• Ingestion
• Absorption
• Leaching
• Sedimentation
• Run-off

Question 15

Human Impacts

Answer 15

Detergents (used to contain phosphates)
- Agriculture (fertilizers)
- Golf courses
- Excess nutrients in rivers and lakes - eutrophication

Question 16

nitrogen fixation

Answer 16

Bacteria convert nitrogen gas into ammonium (NH 3), ammonium is then converted
into nitrites (NO2) and nitrates (NO3), which can then be used by plants.
➢ Animals can only obtain nitrogen by eating plants.

Question 17

denitrification

Answer 17

➢ Excess nitrates in the soil are converted back into atmospheric nitrogen by a
a different set of bacteria.

Question 18

Nitrification

Answer 18

lightning converts N2 > NO3 -

Question 19

Nitrogen-fixing bacteria

Answer 19

-convert nitrogen into ammonium for the plants, and the plants provide the bacteria with sugars produced through photosynthesis

Question 20

Lightning as a cause in the nitrogen cycle

Answer 20

causes a reaction to occur between the nitrogen (N 2) gas in the air and the oxygen in the air.
* Result is formation of NO3 – ions which combine with water and enter the soil.
* Plants then absorb this NO3 – by their roots.

Question 21

Nitrogen Fixing Bacteria as a cause in the nitrogen cycle

Answer 21

– bacteria fix nitrogen gas from the air, producing ammonia [NH 3(g)] (becomes ammonium ions dissolved in soil water) and nitrifying bacteria convert NH 4+ into NO 3-.
* These bacteria can be found in the soil and more often root nodules (on legumes)
* Provides the plant with more than enough nitrogen and the excess is released into the soil

Question 22

Denitrifying bacteria

Answer 22

• anaerobic bacteria (O 2 intolerant) that live in soil
• reduce nitrates (NO 3 - ) and nitrites (NO 2 - ) to nitrogen gas (N 2 ) and nitrous oxide – which returns to atmosphere
  *Note: denitrification increases in rate, if the soil is acidic or waterlogged.

Question 23

Human Impacts on the nitrogen cycle

Answer 23

• Agriculture (fertilizers) à run off
• Excess nutrients in rivers and lakes – eutrophication
• Burning of fossil fuels à The chief culprit is fossil fuel combustion, which releases nitric oxides into the air that combine with other elements to form smog and acid rain

Question 24

SULFUR CYCLE

Answer 24

1) Through volcanic activity, geologic uplift, or the mining & burning of fossil fuels, sulfur is then released into the air in the form of sulfur dioxide (SO2 )
2) Sulfates do not stay in the air for very long; they are returned to the earth through acid precipitation (caused primarily by the burning of fossil fuels)
3) Bacteria in the soil then allow the sulfates to be used by plants. These sulfur compounds return to the soil once the plants die and decompose
4) Some of the sulfur returned to the ground is also re-deposited in rocks, and the cycle continues

Question 25

SULFUR smell

Answer 25

caused by decomposers who are hard at work producing hydrogen sulfide gas can be dangerous in high concentrations