Functioning Ecosystems

Question 1

Trophic Structure

Answer 1

The hierarchy of feeding relationships which determines the pathway for energy flow and nutrient cycling

Question 2

Producers

Answer 2

Autotrophic (self-feeding) organisms that form complex organic compounds (that contain carbon and hydrogen atoms) from simple inorganic molecules including carbon dioxide or sulphur dioxide, are the primary energy source for all other organisms in the ecosystem

Question 3

Consumers

Answer 3

Heterotrophs (feed on other living organisms), they cannot produce their own food but must consume already formed organic molecules

Question 4

Herbivores

Answer 4

First order consumers, eat producers

Question 5

Carnivores

Answer 5

Second and higher order consumers, eat living animals

Question 6

Omnivores

Answer 6

Have a plant and animal diet so are a first order consumer and higher order consumer

Question 7

Detrivores

Answer 7

Special group of consumers that eat decomposing organic matter such as rotting leaves or decaying animal remains

Question 8

Decomposers

Answer 8

Release enzymes onto dead animal and plant remains to absorb digested matter, in doing so, many complex organic chemicals are broken down into simple inorganic molecules that are recycled back into the environment for further use by producers

Question 9

Food Chain Energy Flow

Answer 9

Energy is lost as heat from each trophic level via respiration

Question 10

Energy in Ecosystems

Answer 10

Energy, unlike matter, cannot be recycled, ecosystems must receive a constant input of energy from an outside source, mostly the sun, energy is ultimately lost as heat to the atmosphere

Question 11

Primary Production

Answer 11

The energy entering ecosystems is fixed by producers in photosynthesis

Question 12

Gross Primary Production (GPP)

Answer 12

The total energy fixed by a plant through photosynthesis

Question 13

Net Primary Production (NPP)

Answer 13

the GPP minus the energy required by the plant for respiration. It represents the amount of stored chemical energy that will be available to consumers in an ecosystem. The biomass per unit area per unit of time eg. g/m^2/y

Question 14

Productivity

Answer 14

Defined as the rate of production

Question 15

Secondary Production

Answer 15

The amount of biomass at higher trophic levels (the consumer production), represents the amount of chemical energy in consumer’s food that is converted to their own biomass

Question 16

Ecological Efficiency

Answer 16

The percentage of energy transferred from one trophic level to the next, varies between 5% and 20%, an average figure of 10% is used

Question 17

Ten Percent Law

Answer 17

The total energy content of a trophic level in an ecosystem is one-tenth that of the preceding level

Question 18

Pyramids of Numbers

Answer 18

The size of each tier is proportional to the number of individuals present at each trophic level

Question 19

Pyramids of Biomass

Answer 19

Each tier represents the total dry weight of organisms at each trophic level

Question 20

Pyramids of Energy

Answer 20

The size of each tier is proportional to the production of each trophic level. The energy content at each trophic level is generally comparable to the biomass because similar amounts of dry biomass tend to have the same energy content