Biosphere: (Modeling Feeding Relationships)

Question 1

History (Modeling feeding relationships):

Answer 1

•1920s, Charles Elton set out from Oxford University in England to study the organisms on a desolate island in the frigid Arctic waters off the northern coast of Norway. Together, with another ecologist, Victor Summerhayes, Elton was interested in documenting the feeding relationships in this remote place, called Bear Island.

Question 2

Food chains:

Answer 2

•model that shows the linear pathways through which food is transferred from producers to primary consumers and to higher trophic levels. (Arrows indicate energy flow).

Question 3

Food webs:

Answer 3

•a series of interlocking food chains representing the transfer of energy through various trophic levels in an ecosystem.

Question 4

Ecological pyramids:

Answer 4

•pyramids- used to represent energy flow in food chains and webs.
•3 types:
-1. Pyramid of numbers.
-2. Pyramid of biomass.
-3. Pyramid of energy.

Question 5

Pyramid of numbers:

Answer 5

•drawn by counting the numbers of organisms at each trophic level.
•each bar on the pyramid represents a different trophic level.
•the width represents the relative number of organisms at that trophic level.

Question 6

Inverted pyramid of numbers:

Answer 6

•occasionally, the pyramid is inverted.
•eg. A single tree can support thousands of consumers.

Question 7

Pyramid of biomass:

Answer 7

•measure of dry tissue at each trophic level.
•a more accurate representation of energy transfer because it considers the size of the organisms at each level.
•measured in grams per square meter
(g/m^2).

Question 8

Inverted biomass pyramid:

Answer 8

•in ocean ecosystems, the amount of producers (microscopic phytoplankton) may be much less than the biomass of organisms that feed on them.

Question 9

Pyramid of energy:

Answer 9

•measure of thermal energy released from chemical bonds at each trophic level.
•MOST accurate representation of energy.
•this pyramid is ALWAYS upright because some energy is always lost as we move up trophic levels.

Question 10

Biomagnification:

Answer 10

•biomagnification refers to the condition where a chemical concentration in an organism exceeds the concentration of its food when the major exposure to said chemical is the organisms diet.

Question 11

Biological half-life:

Answer 11

Ex) 100–> 50.

Question 12

Bioaccumulation:

Answer 12

•bioaccumulation is the gradual accumulation of substances, such as pesticides, or other chemicals, in a single organism.
•bioaccumulation occurs when an organism absorbs a substance faster than that substance is lost or eliminated by catabolism and excretion.
•therefore, the longer the biological half-life of a toxic substance, the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high.

Question 13

Detritivore:

Answer 13

An animal that feeds on dead organic material. (Especially plant detritus).