Energy Flow and Nutrient Cycles Flashcards
What is nitrogen fixation?
When nitrogen gas in the atmosphere is turned into ammonia by bacteria in root nodules of leguminous plants, natural occurrences like lightning or artificial processes like the Haber process.
What is saprobiontic nutrition?
Feeding on dead organic matter.
What is ammonification?
When nitrogen compounds from dead organisms and animal waste are turned into ammonium compounds by decomposes. Saprophytes break down proteins which are then turned into ammonium compounds.
What is nitrification?
When ammonium compounds in the soil are changed into nitrogen compounds that can be used by plants. Nitrifying bacteria turn ammonium compounds into nitrites and then nitrites to nitrates.
What is denitrification?
When nitrates in the soil are converted to nitrogen gas by denitrifying bacteria - they use nitrates in the soil to carry out respiration and produce nitrogen gas.
How do you calculate net productivity?
Net productivity = gross productivity - respiratory loss
Reeds have hollow air-filled tissue in their stems which supply oxygen to their roots. How does this enable roots to take up nitrogen-containing substances?
Uptake by roots involves active transport which requires ATP.
What are the advantages of biological pesticides?
- Specific (to one pest);
- Only needs one application/ reproduces;
- Keeps/maintains low population;
- Pests do not develop resistance;
- Does not leave chemical in environment/on crop / no bioaccumulation;
- Can be used in organic farming;
What is a large animals surface area to volume ratio like? What does this mean?
They have a small SA/ V ratio so it is harder for them to lose heat as it has further to diffuse out of their body.
Describe how microorganisms make carbon in starch available to plants.
Extracellular digestion / releases enzymes,
Starch to monosaccharides /glucose/sugars/smaller molecules,
Respire product of digestion,
Produce carbon dioxide from respiration.
What does nitrogenase turn nitrogen gas into?
Ammonia
What percentage of energy available to plants is converted to organic matter? Why?
Only 1 - 3% of the energy available to plants is converted into organic matter
This is because:
• Over 90% of the suns energy is reflected back into space by the atmosphere
• Not all wavelengths of light can be absorbed by plants in photosynthesis
• Light may not actually fall of the chlorophyll molecule
• Limiting factors may slow down photosynthesis
What percentage of energy is passed onto primary and secondary consumers? What is the reason for low amount of energy absorbed?
10% is passed to primary consumers. 20% to secondary consumers.
The low amount of energy absorbed at each stage is due to:
• Some of the organism not being eaten
• Some parts can be eaten but not digested
• Some of the energy is lost in excretion
• Some of the energy is lost via respiration that is used to maintain a high body temperature. This is especially the case in mammals
How does clearing forests and burning vegetation affect CO2 concentration?
CO2 concentration increases. Clearing means less vegetation so no photosynthesis. So less CO2 is removed. Also burning and combustion produces CO2.
How do bacteria make nitrogen in dead leaves available to growing plants?
Saprophytes digest/ break down proteins by releasing certain enzymes. Ammonia is produced in this process. This is converted to nitrite. Nitrifying bacteria then turn this into nitrogen that can be used by plants.
