Chapter 46 - Ecosystem Ecology

Question 1

Ecosystem Ecology

Answer 1

Ecosystem consists of organisms in a community and their physical environment, mutually influencing each other over time.

Question 2

Carbon Cycle

Answer 2

The chemistry of life is, to a first approximation, the chemistry of carbon.

• Most carbon stored in sediments/sedimentary rock, then deep ocean water reservoirs
• Marine photosynthesis and respiration balance in terms of carbon

Question 3

The Bends

Answer 3

Nitrogen doesn’t react with much

If you go too deep diving, nitrogen reacts in your blood makes you
“drunk” as it makes bubbles in your tissues and blood + bursts alveoli in as you swim to surface

Question 4

Nitrogen cycle

Answer 4

Nitrogen is introduced through dead plants and animals and feces (becomes NH3) = ammonification

Is used by plants through roots OR converted to N2 through nitrification / annamox

Nitrogen fixation turns N2 from air into NH3 to be used by plants through roots too

Question 5

Phosphorous

Answer 5

Found in mountains / rocks

Weathering = released and used by plants = animals eat plants = they die + poop out the phos = back into plants OR runoff into ocean

In ocean cycled / upwelled / becomes sediments that eventually become mountains again

Question 6

Human Impact on CO2 Levels

Answer 6

Industrial Revolution led to a significant increase in CO2 levels.

Approximately half of human-generated CO2 enters the atmosphere, the rest accumulates in oceans!!!, vegetation, and soils.

Question 7

Seasonal cycle of CO2 levels

Answer 7

Increase and decrease with higher rates of photosynthesis in the summer and the lower rates in the winter (except in regions near the equator)

Increase in CO2 leads to warming. Conversely, high temperatures can decrease CO2 levels as plants thrive in heat, leading to increased photosynthesis.

So… no plants + CO2 increase = warming

Question 8

C-transfers and Trophic Levels

Answer 8

Local c transfers go up from primary carbon producers (ex. grass) at the first trophic level

Only 10% of biomass from each trophic level is passed up.

Explanation: Some biomass used for metabolism; temperature tends to follow CO2 levels.

Both energy and carbon are transferred

Question 9

How do we know humans are the cause of CO2 increases

Answer 9

Atmospheric carbon lacking the isotope C13 is increasing - which comes from burning fossil fuels

Fossil fuels = no C13, C12

Ratio of C12 to C13 increasing

Question 10

Timeline of oxygen

Answer 10

A time line shows:
- something releases O2 about 2
billion years ago
- then more about 600 million years
ago
- biotic actions changed conditions
→ coincided/predicated animal
evolution

Question 11

The Keeling Curve

Answer 11

Keeling curve records changing CO2 levels in the atmosphere over time

CO2 cycles up and down over the year (max in April, min in September)

Observation: Keeling’s work showed a 25% increase in atmospheric CO2 levels over the past 50 years - steady increase

Question 12

Autotrophs

Answer 12

Photosynthetic organisms (“self feeders”) - aka primary producers

Consumed by primary consumers