Week 10 Friday

Question 1

what is the first law of thermodynamics?

Answer 1

energy cannot be created nor destroyed, but transformed.

Question 2

what is the second law?

Answer 2

heat energy will move from a warmer system to a cooler one

Question 3

what is the 10% rule?

Answer 3

the idea that energy is passed thru an ecosystem from one trophic level to the next, only 10% of the energy is passed on

Question 4

why do food webs generally only have 3-5 levels?

Answer 4

higher levels would not be productive enough

Question 5

what are the groups of organisms in trophic levels

Answer 5

primary producers, primary consumers, secondary consumers, e.t.c

Question 6

influences of bottom up control

Answer 6

influences of physical and chemical factors

Question 7

influences of top down control

Answer 7

influences of consumers

Question 8

what determines whether a community is controlled from the top or the bottom?

Answer 8

the relative importance of predation and primary production

Question 9

when is compensation more likely to happpen, and what does it do?

Answer 9

when many species are present at each trophic level and it blocks cascading effects

Question 10

what is a green world (trophic level wise)

Answer 10

3 or 5 levels

Question 11

what is a brown/blue world (trophic level wise)

Answer 11

2 or 4 levels

Question 12

why are trophic dynamics still debated

Answer 12

• both top-down and bottom-up forces can play roles - but the forces they exert are not always equal or easy to see
• organism with a wide diet breadth and omnivores complicate understanding the extent of relationships and their interconnectedness
• a trophic cascade is blocked by the effects of compensation and within-level competition
• complex and diverse communities could limit the impact of trophic cascades
• even simple systems are not so simple