Nutrient Cycles
What is the name for rain, sleet or snow?
Precipitation
The role and position a species has in its environment, including how it uses resources and interacts with others is called what?
Niche
What type of succession occurs after a disturbance like a fire?
Secondary succession
What percentage of energy is typically transferred between trophic levels?
10%
An organism that makes its own food is called what?
Autotroph/producer/plant
What process returns carbon dioxide to the atmosphere from organisms?
Cellular Respiration
What is a species that has a disproportionately large effect on its ecosystem relative to its abundance called?
Keystone Species
What is succession?
The gradual change in species composition in an ecosystem over time
Why is only 10% of energy transferred through each trophic level?
Most is lost as heat through respiration
* also waste (faeces), and uneaten biomass.
What does a pyramid of biomass show?
The total mass of living material at each trophic level.
In the nitrogen cycle, what process converts (fixes) nitrogen gas into ammonia?
Nitrogen fixation
Two species cannot occupy the same niche indefinitely; one will outcompete the other refers to which principle?
Competitive Exclusion Principle
What is one difference between primary and secondary succession?
Primary starts from bare rock/no soil; secondary occurs where soil already exists
Primary= faster Secondary = slower
Primary = pioneer species
Calculate the efficiency of an energy transfer between eucalyptus leaves of 25 000 KJ and stick insects 2600KJ
2600/25000 x 100 = 10.4%
What process converts light energy into chemical energy in plants?
Photosynthesis
How do decomposers contribute to nutrient cycles?
They break down dead organisms and waste, releasing nutrients back into the environment
Define carrying capacity
The maximum population size an environment can sustain long-term
Describe one change in species composition during succession.
Increase in biodiversity
Shift from pioneer species to more complex organisms
A leaf fixes 20,000 kJ of energy per year. It uses 13,000 kJ per year for respiration. Calculate the gross primary productivity.
20 000- 13 000 = 7000
A food chain has producers (GPP 20,000 kJ), primary consumers (NPP 2,000 kJ), secondary consumers (200 kJ), tertiary consumers (20 kJ). Construct an energy pyramid and explain the energy loss.
Energy pyramid: 20,000 → 2,000 → 200 → 20 kJ; energy loss is mainly through respiration and heat (90% lost each level).
What is ammonification?
Ammonification is the process where microscopic organisms like bacteria or other types of decomposing organisms, break down nitrogen-containing chemicals from dead organic matter, into simple substances like ammonia.
List the four threats to ecosystem functioning we explored.
◦Overexploitation, habitat destruction, monocultures, pollution
Identify some three features of Pioneer species
R selected/reproduce rapidly/produce large number of seeds or spores, able to fix nitrogen, photosynthetic ability, able to tolerate extreme conditions
In a temperate forest, the Net Primary Productivity (NPP) is recorded as 8000kcal/m2/year. The plants in this forest lose 5500kcal/m2/year of energy through respiration to maintain their cellular functions.
Calculate the Gross Primary Productivity (GPP) of this forest.
8000- 5500 = 2500
If a pyramid of numbers is inverted at one level, what might this indicate?
A few large producers supporting many small consumers (e.g., trees supporting insects).