energy transfer Flashcards
Define Biomass
• Mass of carbon (organic compounds)
• Dry mass of tissue per given area
Suggest what you should do to ensure all water is removed from a tissue / sample.
• Regularly weigh and Heat (less than 100 °C)
• Until mass is constant
Gross Primary Productivity
• Chemical energy store in plant biomass, in a given area or volume. (Rate of photosynthesis)
Net Primary Production
• Chemical energy store in plant biomass after respiratory losses to the environment have been taken into account. NPP= GPP -R
• NPP is available for new plant growth and reproduction OR available for other trophic levels in the ecosystem, such as herbivores and saprobionts.
• kJ ha–1 year–1 OR kJ km–2 year–1 OR kJ km–3 year–1
The percentage of the light energy trapped by the producers is very low. Give two reasons why.
• Reflected / absorbed by water vapour;
• Reflected from producers / wrong wavelength;
• Transmitted / passes between chloroplasts/ between plants / too few chloroplasts;
The biomass of primary consumers is less than the biomass of producers. Explain why.
• Loss of energy/heat / use of energy / less energy to be passed on;
• In respiration;
• In excreta / excretion / urine / carbon dioxide;
• Inedible parts / indigestible parts / egesta / egestion / to decomposers;
Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer.
• Some light energy fails to strike/is reflected/not of appropriate wavelength;
• Efficiency of photosynthesis in plants is low/approximately
• 2% efficient;
• Respiratory loss / excretion / faeces / not eaten;
• Loss as heat;
• Efficiency of transfer to consumers greater than transfer to producers/approximately 10%;
• Efficiency lower in older animals/herbivores/ primary consumers/warm blooded animals;
• Carnivores use more of their food than herbivores;
Explain how the intensive rearing of domestic livestock increases net productivity
• Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue/production;
• Fed on concentrate /controlled diet /controlled conditions/so higher proportion of (digested) food absorbed/lower proportion lost in faeces / valid reason for addition;
• Movement restricted so less respiratory loss / less energy used;
• Kept inside/heating/shelter / confined so less heat loss / no predators;
• Genetically selected for high productivity;
Describe the need for plants to both photosynthesise AND respire
• In the dark no ATP production in photosynthesis;
• Some tissues unable to photosynthesise/produce ATP;
• ATP cannot be moved from cell to cell/stored;
• Plant uses more ATP than produced in photosynthesis;
• ATP for active transport;
• ATP for synthesis (of named substance);
The concentrations of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours. Use your knowledge of photosynthesis to describe these changes and explain why they occur.
• High concentration of carbon dioxide linked with night/darkness;
• No photosynthesis in dark/night / light required for photosynthesis/light-dependent reaction;
• (In dark) plants (and other organisms) respire;
• In light net uptake of carbon dioxide by plants/plants use more carbon dioxide than they produce/ rate of photosynthesis greater than rate of respiration;
• Decrease in carbon dioxide concentration with height;
• At ground level fewer leaves/less photosynthesising tissue/more animals/less light;
Which cardo regulatory centre is linked to the sinoatrial node by the sympathetic nervous system? (1)
Acceleratory centre
Name 2 saprobionts (2)
- Bacteria
- Fungi
How can you calculate net primary production? (1)
NPP = GPP - R
How can you calculate the net production of consumers? (1)
N= I - (F + R)
