13. energy and ecosystems Flashcards
describe the role of producers
photosynthetic organisms that manufacture substances using light energy, water, co2 and mineral ions
Describe the role of consumers
Obtain energy by consuming other organisms
primary consumers being first in food chain, secondary next then tertiary.
describe the role of sacrobionts
decomposers like fungi and bacteria break down complex materials in dead organisms into simpler ones, which can be absorbed by plants
what is biomass?
dry mass (mass of carbon) in a specific area at a given time
how is chemical energy store estimated?
calorimetry;
dry sample is burnt in pure oxygen in a sealed chamber surrounded by a water bath. heat from combustion increases temperature of water. This can be used to calculate energy released from the mass in kj/kg-1
what % of light energy is used by producers?
1-3%
what is the sequence that most nutrient cycles follow?
- Nutrient is taken up by producers as simple (inorganic) molecules.
- producer incorporates the nutrient into complex, organic molecules
- producer is eaten, nutrient is passed onto consumers
- passed along food chain
- when consumers die, saprobionts release nutrient in simple form
What are the four main stages of the nitrogen cycle?
ammonification, nitrification, nitrogen fixing and denitrification
What are the two stages of nitrification?
ammonium oxidised into nitrite ions, nitrite ions oxidised into nitrate ions
what conditions do denitrifying bacteria need
anaerobic process, lack of oxygen
give the equation for net primary production
NPP = GPP - R
R = respiratory losses to environment
define gross primary production
the chemical energy store biomass, in a given area
define net primary production
chemical energy store of biomass after respiratory losses have been accounted for
equation for net production of consumers
chemical store ingested - loss by waste + loss from respiration
describe the process of ammonification
production of ammonia from organic nitrogen-containing
Draw the nitrogen cycle
Use photos online or notes to mark
What is released during nitrification?
- oxidation releases energy, used by some bacteria.
Why do framers plough soil?
To maintain air spaces for nitrifying bacteria to respirate
Draw the phosphorus cycle.
Use photos online or notes to mark.
Describe Saprobiontic nutrition. (4)
- HYDROLYSE dead organisms
- enzymes are secreted ONTO organsim, digestion occurs externally
- Products are absorbed into cells, some remains in environment
- ions are secreted as waste
What organic compounds can be broken down into mineral ions?
Nucleic acids, amino acids, ATP
What is the role of mycorrhizae in the nitrogen cycle?
fungi that associates with plant roots, increases their surface area for absorption of H2O and mineral ions.
The relationship between mycorrhizae and plants can be described as…
mutualistic. Fungi receives glucose from roots, roots have an increase surface area.
Contrast what natural and artificial fertilisers are made up of.
Natural - organic matter, organisms remains, waste, manure, sewage, food.
Artificial - inorganic matter, powder/palettes maintaining pure chemicals, eg ammonium nitrate.
