4.2 Energy flows

Question 1

What is teh initial source of energy in the majority of ecosystems?

Answer 1

Sunlight - light E is absorbed and converted into chemical E via photosythesis

Other ecossytems rly on chemoautotrophs whihc produce E from oxidation fo inorganic substances

Question 2

What is a trophic level? What trophic levels exist?

Answer 2

TROPHIC LEVEL: the position of an organism in the food chain

Question 3

Give an examples of a terrestrial and marine food chains

Answer 3

TERRESTRIAL: flower -> grasshopper -> mousee -> snake -> eagle

MARINE: phytoplankton -> shrimps -> cod -> seal -> killer whale

Question 4

How many percent of energy are transerred to the next trophic level? Why only that?

Answer 4

10%

• E used for metabolism, growth, homeostasis, movement
• chemical by-product heat is lost
• lost in excretion
• not all tissues are consumed: ex bones, fur (decomposers can use)

Question 5

Why do higher trophic levels need more food?

Answer 5

• because the E and biomass are lost through trophic levels - least amount consumed by highest trophic level (number of trophic levels is limited)
• larger organisms

Explains why lower trophic levels produce more offspring and higher less - environment is in balanced due to consumption

Question 6

How to draw a pyramid of energy?

Answer 6

Graphical representation of E passed to each trophic level in a food chain

UNITS: kJ m^–2 year^–1

Each level 90% smaller (10% E passed)

When a pyramid is drawn - must fit into all of the given area

Question 7

What is a food web?

Answer 7

FOOD WEB: diagram which represents how several food chains are related