ecological pyramids

Question 1

ecological pyramids

Answer 1

contain quantitative information that includes:

number, mass or amount of energy stored by organisms at each trophic level

Question 2

pyramids of numbers

Answer 2

• bars are drawn that are proportional to the number of organisms present at a certain trophic level
• usually moving from lower to higher trophic levels the number decreases

Question 3

drawbacks of using pyramids of numbers to describe a food chain

Answer 3

• number of organisms may be so large it would be impossible to represent them all accurately
  e. g. an oak tree can have millions of greenfly living off of it
• no account is taken of size
  e. g. one giant treated as on tiny aphid

Question 4

pyramids of biomass

Answer 4

a quantitative description of a food chain that includes measuring the biomass of organisms present

Question 5

how to make measurement of biomass more reliable

Answer 5

measurement of dry mass

Question 6

ethical implications with measuring dry mass

Answer 6

animals must be killed in order to perform the measurement

Question 7

why is dry mass used

Answer 7

fresh mass is easy to measure but there is a presence of varying amounts of water mass

Question 8

disadvantages of using biomass

Answer 8

because animals have to be killed to measure dry mass, only a small number of organisms are chosen and killed and become representatives, but because they are in small amounts it makes it an inaccurate measurement for the whole population

Question 9

unit of biomass when an area is being sampled

Answer 9

g m^-2

gram per square meter

Question 10

unit of biomass when a volume is being sampled

Answer 10

g m^-3

grams per cubic meter

Question 11

what do pyramids of numbers and pyramids of biomass have in common

Answer 11

• only show the organisms present in a particular time - seasonal differences are not apparent

Question 12

why is it a drawback that pyramids of numbers and pyramids of biomass do not include number of organisms in all seasons

Answer 12

during different seasons, organisms’ quantity of consumption will differ as well as their numbers

Question 13

pyramids of energy

Answer 13

a quantitative description of the energy flow through a food chain that includes measuring the energy stored in organisms

Question 14

drawback of using pyramids of energy

Answer 14

collecting data for pyramids of energy be difficult and complex

Question 15

how is data for pyramids of energy collected

Answer 15

data collected in a given area for a set period of time

Question 16

why is pyramids of energy more reliable than the pyramids of biomass

Answer 16

• organisms of the same dry mass may store different amounts of energy
  e. g. an animal with more fat content will contain more energy than an animal with more carbohydrate content

Question 17

unit of energy flow

Answer 17

kJ m^-2 year^-1
kilojules per square meter per year
(unit may vary sometimes)