Topic 12 Lecture

Question 1

Ecosystems

Answer 1

communities of organism interacting with each other with their physical environment under the influence of environmental factors

Question 2

Ecosystem energetics (3)

Answer 2

The study of how energy is fixed by autotrophs and made available to heterotrophs

autotrophs-primary producers (plants/algae)

Heterotrophs- eat plants/animals

Question 3

energy is measured as ……aka……(2)

Answer 3

The dry weight of organic matter in an organism or ecosystem

aka how much stuff there is in an area of space is a representation of how much energy there is

Question 4

First trophic level: Primary Producers (2)

Answer 4

• bottom of food pyramid
• Autotrophic organisms that fix inorganic nutrients (CNPO) into organic molecules.

Question 5

Primary production (First trophic level) (2)

Answer 5

Fixing energy from the sun into organic molecules available to be eaten by other organisms

happens in individual organisms

Question 6

Primary productivity (4)

Answer 6

The rate at which energy is fixed

the rate at which energy is converted to organic substances by photosynthetic producers (photoautotrophs), which obtain energy and nutrients by harnessing sunlight, and chemosynthetic producers (chemoautotrophs), which obtain chemical energy through oxidation

sum total of all the organisms in the ecosystem fixing the carbon that determines primary productivity

quality of the ecosystem

Question 7

Gross Primary production

Answer 7

Total amount energy fixed into organic molecules in an ecosystem

Question 8

Net primary production (3)

Answer 8

what the producers make minus what the producer uses for itself -(Ermr+Eactivity)

aka: The amount of energy for growth (Eproduction)

Measured as biomass

Question 9

Biomass

Answer 9

what’s created after you account for the loss the organism has had to survive (Ermr, Eactivity)

Question 10

What drives the variation we see across the different ecosystems? (2)

Answer 10

driven by precipitation and temp

Question 11

Factors affecting primary productivity:light explain

Answer 11

at low light, low pp

increase in primary productivity as light increases

adding more light won’t help you as enzymes are all saturated

Light is bad as it is radiation and excess of it ca cause damages

Question 12

Factors affecting primary productivity: Temperature (2)

Answer 12

Enzymatic rates are temp dependent. Metabolic rates, including photosynthesis, are generally faster at higher temperatures, so if everything else is perfect, productivity will increase with increasing temperatures up to a maximum

as you increase temp net pp increase

Question 13

Factors affecting primary pp: precipitation

Answer 13

too much precipitation can cause low PP bc of cloudy, less sun, flooding etc.

Question 14

Factors affecting PP Nitrogen (3)

Answer 14

Nitrogen is soluble, it tends to wash away with rainfall so it is more limiting in regions that get a lot of Tain especially on land.

Nitrogen is less limiting in aquatic ecosystems.

Adding N to deserts doesn’t change PP that much as it already has it since not washed away. Adding N in grassland causes big change

Question 15

Factors affecting productivity: phosphorous (2)

Answer 15

Insoluble , doesn’t tend to wash away

doesn’t enter aquatic ecosystem as easily. More limiting in aquatic ecosystems

Question 16

second trophic level

Answer 16

Primary consumers (herbivores)

Question 17

Secondary production occurs in ___ and …(2)

Answer 17

primary consumers or secondary consumers

organisms consume the organic molecules (biomass) of primary consumers to support its energy budget and this excess biomass it produces is called secondary production

any biomss produced outside of primary production

Question 18

Difference between primary and secondary prooduction:

Answer 18

Primary production is the production driven by photosynthesis. Secondary production is all the creation of biomass created by the subsequent levels in the trophic levels.

Question 19

Detritivores (2)

Answer 19

organisms that consume the dead organic matter of primary producers, primary consumers etc.

break down primary and secondary production and recycle nutrients

Question 20

Energy___ but nutrients _____

+explain it (4)

Answer 20

flows

cycle

Nutrients consumed by plants and animals are returned to the environment after death and decomposition and the cycle continues.

Energy flows through an ecosystem from producers to consumers. Energy flows from one trophic level to the next.