chapter 13- energy and ecosystems Flashcards
(27 cards)
what are producers
photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and mineral ions
what are consumers
organisms that obtain their energy by feeding on other organisms rather than using the energy of sunlight directly
what are saprobionts (decomposers)
a group of organisms that break down the complex materials in dead organisms into simple ones
what is a food chain
a feeding relationship in which producers are eaten by primary consumers which are eaten by secondary consumers and then tertiary consumers
what is a food web
many food chains linked together
what is biomass
the total mass of living material in a specific area
how can the chemical energy store be measured in dry mass
- A sample of dry mass is weighed and burnt in pure oxygen within a sealed chamber called a bomb
- The bomb is surrounded by a water bath and the heat of combustion causes a small temperature rise in this water
why is most of the suns energy not converted to organic matter by photosynthesis
-reflected back into space by clouds
- not all wavelengths of light can be used and absorbed for photosynthesis
- light may not fall on a chlorophyll molecule
what is the equation for net primary production
gross primary production-respiratory losses
why is there a low percentage of energy transferred between consumers
- some of the organism is not consumed
- some parts are consumed but cannot be digested so are lost in faeces
- some energy loses occur as heat from respiration and lost to the environment (these loses are high in mammals and birds because of their high body temperature. Much energy is needed to maintain body temp when heat is also being lost to the environment)
what is the equation for net production of consumers
chemical energy store of ingested food - (energy lost in faeces + energy lost in respiration)
what is the equation for percentage efficiency
energy available after the transfer/energy available before the transfer x 100
how does keeping livestock in confined spaces minimise energy loss
- movement is restricted so less energy is needed for muscle contraction
- environment can be kept warm to reduce heat loss from the body and less energy is needed to maintain body temp
- feeding can be controlled so animals receive optimum amount and type of food for maximum growth
- predators excluded so no loss to other organisms
Ammonification
- the production of ammonia from nitrogen containing compounds
- saprobiontic microorganisms feed on faeces and dead organisms material, releasing ammonia which then forms ammonium ions in the soil
Nitrification
- nitrifying bacteria
-oxidation of ammonium ions to nitrite ions
-oxidation of nitrite ions to nitrate ions
nitrogen fixation
- free-living nitrogen fixing bacteria reduce gaseous nitrogen to ammonia which they use to manufacture amino acids. Nitrogen rich compounds are released from them when they die and decay
- mutualistic nitrogen fixing bacteria live in nodules on the roots of plants. They obtain carbohydrates from the plants and the plant acquires amino acids from the bacteria
denitrification
-when soils become waterlogged there is a decrease in aerobic NITRIFYING bacteria and an increase in anaerobic DENITRIFYING bacteria
- denitrifying bacteria convert soil nitrates into gaseous nitrogen. This reduces the availability of nitrogen containing compounds for plants
the phosphorus cycle
- Phosphorus in rocks is slowly released into the soil and into water sources in the form of phosphate ions by the process of weathering
2.Phosphate ions are taken up from the soil by plants through their roots or absorbed from water by algae - Phosphate ions are transferred to consumers during feeding
4.Phosphate ions in waste products and dead organisms are released into the soil or water during decomposition by saprobionts
5.The phosphate ions can now be taken up and used once again by producers or may be trapped in sediments that, over very long geological time periods may turn into phosphorus-containing rock once again
Importance of phosphorus
- ATP
-nucleic acids - Phospholipids
Role of mycorrhizae
- increases surface area for absorption and holds water and minerals around the roots which enables the plants to better resist drought and take up inorganic ions more readily
- mutualistic relatinship between plants and fungi. Plant benefits from improved water and inorganic ion uptake while the fungus receives organic compounds such as sugars and amino acids from the plant
why are fertilisers needed in agricultural ecosystems
- when crops are removed from the soil the mineral ions in the soil are not replenished
- mineral ions need to be replenished to allow for maximum plant growth
natural fertilisers
consist of dead and decaying plants and animals as well as animal waste
artificial fertilisers
mined from rocks and deposits and then converted into different forms to give the the appropriate balance of minerals for a certain crop
how do fertilisers increase productivity
- nitrogen is essential component of ATP and nucleotides in DNA which are both needed for plant growth
- more nitrate ions means plants will grow earlier, taller and have a greater leaf area
- this increases rate of photosynthesis and improves crop productivity
