Lecture 5 -- The Biological Environment: Food Webs, Energy & Carbon Cycle

Question 1

What does trophic structure mean?

Answer 1

• Levels within a food chain that transfer energy from one another
• how nutrition (matter) and energy flows through different levels

Question 2

Build a general food chain. Whats the difference between a primary and secondary consumer?

Answer 2

Producers
 Primary Consumer-mainly herbivors
 Secondary consumer- mainly carnivors
 Tertiary consumer
 Quarternary consumer

Question 3

How much of the suns energy is captured by photosynthesis? About how much energy is passed from one level of a food chain to the next? What happens to the part that is not passed on?

Answer 3

1% of sun’s energy is captured in photosynthesis
10% of energy captured by one level is passed on to the next
Other 90% is used in metabolism, released as heat and entering into the det

Question 4

What are the two major energy sources for consumers in food webs?

Answer 4

The sun and plants

Question 5

Which species has an indirect trophic level effect on kelp, urchins or sea otters?

Answer 5

Sea otters, because they eat the urchins that wipe out kelp forest. Their particpation in maintaining kelp forests is indirect.
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Question 6

How do coyotes enhance some bird populations in sagebrush shrub habitats?

Answer 6

Coyotes control the number of bobcats, the main predator in shrub habitats

Question 7

Which ecosystem has higher average net primary production per square meter, oceans, tropical rainforests, or estuaries? What ecosystem produces the most global net primary production? Which ecosystem is likely to support the greatest biomass of tertiary consumers: temperate forest, temperate grassland, swamps or oceans?

Answer 7

• Estuaries have the highest average net primary production, then tropical rainforests, then the open ocean
• The ocean produces the most global NPP per year though, and probably (not represented in charts, so not totally sure) has the most biomass

Question 8

In oceans, where is the greatest NPP per square meter found?
On land?

Answer 8

-Not on land, but along the coast

Question 9

Where reservoir has the greatest amount of carbon stored: fossil carbon, plant biomass, or the deep ocean?

Answer 9

The deep ocean has the most carbon stored

Question 10

Which has a greater store of carbon, the soil or the atmosphere?

Answer 10

The soil

Question 11

How have humans altered the carbon cycle? (humans are shifting carbon from the _____ reservoir to the _____ reservoir.)

Answer 11

Humans are shifting carbon from the stable, deep-earth carbon resevoir into the atmosphere, where it affects the earth’s energy balance

Question 12

Why is photosynthesis important to the carbon cycle? What are the products of photosynthesis? Of respiration?

Answer 12

Each day, more than 100,000,000 tons of CO2 are fixed into organic molecules by phytoplankton photosynthesis
-Marine phytoplankton produce 50% of the planet’s NPP and oxygen

Question 13

T/F: coal consumption is declining.

Answer 13

FALSE

Question 14

How many metric tons of carbon per year do humans shift from fossil fuels into the atmosphere?

Answer 14

About 9 billion metric tons