Energy And Ecosystems Flashcards
What do you call organisms that photosynthesise
Producer, autotroph
What are consumers and heterotrophs
Organisms that obtain energy by feeding on other organisms
What are the diagrammatic representations showing feeding relationships between organisms and direction of energy flow
Food chain, food web
What is the trophic level
The stage in the food chain where an organism feeds
What are the organisms that break down dead material, releasing minerals
Decomposer and saprobiont
What are animals that eat plants
Herbivore, primary consumers
What are animals that eat animals
Carnivore, secondary consumer, tertiary consumer
What is an animal that eats plants and animals
Omnivore
Define biomass
The mass of carbon or dry mass of tissue in a given area at a given time
What are the units for measuring biomass
g m -2 or g m -3 (in water)
What are two ways to measure biomass
- Burn food mounted on a needle under a tube with water and thermometer (measure temp change) 2. Use a calorimeter (put dried sample in chamber, wires set it alight, there is stirrer and 02 supply to water and temp change is measured)
What are the problems with measuring biomass
The sample has to be dead as fresh mass contains water which isn’t organic and doesn’t represent stored chemical energy, water is also variable
Definition of gross primary production
The total quantity of energy stored as plant biomass in a given area or volume in a given time
Net primary production definition
The chemical energy store left after taking respiration into account
How to work out NPP
NPP=GPP- R (photosynthesis take respiration)
What are the common features of all nutrient cycles
Inorganic nutrients are taken up by producers, producers convert nutrients into bio mols, organic bio mols pass through food chains to consumers, org mols in consumers waste and dead organisms are consumed and broken down by saprobionts that release nutrients back into environment in inorganic form
What is nitrogen used in biological molecules
Amino acids, DNA, ATP, RNA, NAD, proteins
What is phosphate used for in bio mols
Phospholipids, ATP, DNA, RNA, NADP
Explain the features of the phosphorus cycle
Inorganic phosphate ions in soil and water are absorbed by active transport by producers. The organic biomass is then passed to consumers by feeding. Biomass from consumers in death and waste is consumed by saprobionts and decomposed back into inorganic phosphate. Also rock cycle where deposition of saprobionts into rocks occurs then erosion into phosphate ions
Describe the features of the nitrogen cycle
Some organisms covert atmospheric nitrogen into ammonia (to produce proteins for growth)during nitrogen fixation for producers. Biomass passed to primary consumers through feeding and also passed to secondary consumers through feeding. Death and waste (PROTEINS/AA broken down) from producers and consumers are consumed by saprobionts which release ammonium ions into soil and water in ammonification. Ammonium oxidised to nitrite ions by nitrifying bacteria (nitrification). Further oxidation by same bacteria forms nitrate ions which are absorbed by ROOTS IN producers or converted to atmospheric N by denitrification
What is mycorrhizae
Associations between fungi and plant roots where fungi act as extensions of plant root system ( increasing SA) mycorrhizae hold water and minerals around root and enhance mineral ion uptake in return for sugars
How do fertilisers increase productivity
Plants require minerals for growth, Nitrogen used for amino acids & protein synthesis, the bases in nucleotides (ATP,DNA,RNA) ATP. phosphate used for phospholipids and nucleotides. Early growth increases the leaf area so plants can photosynthesise more efficiently Leading to greater productivity.
The difference between natural and artificial fertilisers
Natural: organic, made of decaying plants and animals and animal wastes artificial: inorganic, mined from rocks, chemically synthesised
Why are fertilisers needed in agricultural ecosystems
They increase the growth rate of crops, minerals can be a limiting factor of growth. Increase yield means increased profit and more efficient food production. When crops harvested, minerals are removed from ecosystem, leaving soil depleted
What are the main environmental effects of nitrogen containing fertilisers
N rich soils favour growth of grasses and many plant species are out competed so biodiversity is reduced. Leaching and run off pollutes water and causes eutrophication
What is leaching
Nitrates in fertilisers very soluble and are easily removed by the soil and run into rivers and lakes
What is the process of eutrophication
- Leaching increases nitrate concs so it’s no longer a limiting factor for growth of plants and algae 2. Algae grows rapidly at surface and upper layer of water becomes densely populated W plants (algal bloom) 3. Dense surface layer absorbs all light and stops light penetrating to lower depths. 4. Light becomes limiting factor for algae at lower depths and many die 5. Increase in dead plants stimulates growth of saprobiontic bacteria as their food supply no longer limiting factor 6. As they consume dead algae they respire and consume 02 7. Conc of 02 in water falls and ammonia and nitrates are released 8 anaerobic orgs flourish without competition and further decompose dead materials releasing more ammonia and nitrates and hydrogen sulphide, making water putrid / plants unable to photosynthesise so no 02 for fish
What is a process other than ammonification and nitrogen fixation carried out by microorganisms which adds ammonium ions to soil
Protein and amino acids are broken down into ammonia/ammonium ions by saprobionts
How could you determine the dry mass of a sample of plant material
Heat at 100c/evaporate water, then weight and heat until no further mass change
What are ways crop rotation can lead to high crop yields
Grow crops with nitrogen fixing bacteria (legumes) such as clover. Different crops use different minerals/ions from the soil, different crops also have different pathogens and diseases
Why is farming cattle for humans to eat less efficient than farming crops because of energy transfer?
Energy is lost between/at tropic levels. Energy is also lost via respiration, excretion, faeces
