unit 4 Flashcards
Explain how the growth of the forest results in a decrease in the carbon content of the atmosphere.
- More carbon dioxide is taken up by photosynthesis
- More carbon is fixed into compounds in the plant
- More photosynthesis than respiration
Give a reason to explain why the rate of recycling of carbon would be greater in summer than in winter.
Higher temperatures which increase the enzyme action
Explain how carbon-containing compounds present in the pine leaves that fall from the trees are absorbed and used for growth by fungi that live in the soil.
- Extracellular digestion
- Enzymes are secreted
- Broken down into smaller compounds (amino acids)
- These soluble compounds are absorbed
- Micro-organisms respire which provides energy for growth
Describe how micro-organisms make carbon in starch available to plants.
- Extracellular digestion by enzymes that are secreted break down starch into smaller compounds.
- These smaller compounds are absorbed by the sacrobiont.
- These respire which releases carbon dioxide into the atmosphere which the plants are then able to fix by photosynthesis.
Describe how you would decide the number of quadrats to use in order to collect representative data.
- Calculate running mean/description of running mean
- When enough quadrats, this shows little change/levels out.
- Enough to carry out a statistical test
- A large number to make sure results are reliable
- Need to make sure work can be carried out in the time available
Explain how a decrease in temperature would affect the rate of carbon dioxide production.
- Respiration is controlled by enzymes
- Rate decreases with lower temperature as less kinetic energy so fewer collisions and fewer E-S complexes formed
Why was rate of carbon dioxide production higher when the apple slices were in the nitrogen than when they were in the air?
- In nitrogen they were respiring anaerobically which produces less ATP
- More anaerobic respiration/ more glucose/substrate must be respired to produce same amount of ATP
Therefore more carbon dioxide is produced.
Explain why it is important to check repeatability of measurements?
- Increases the reliability of the measurements
- If measurements are repeatable, differences less likely to be due to measurement or personal error therefore anomalies are less likely
Describe how light energy regenerates ATP in the light-dependent reaction of photosynthesis.
1 Light (energy) excites/raises energy level of electrons in
chlorophyll
2 Electrons pass down electron transfer chain.
3 Electrons reduce carriers/passage involves redox
reactions
4 Electron transfer chain / role of chain associated with
chloroplast membranes / in thylakoids / grana
5 Energy released / carriers at decreasing energy levels
6 ATP generated from ADP and phosphate/Pi /
phosphorylation of ATP
Describe and explain why the efficiency of energy transfer is different at different stages in the transfer?
1 Some light energy fails to strike/is reflected/not of
appropriate wavelength
2 Efficiency of photosynthesis in plants is low/approximately 2% efficientto producers/approximately 10%
3 Respiratory loss / excretion / faeces / not eaten
4 Loss as heat
5 Efficiency of transfer to consumers greater than transfer
6 Efficiency lower in older animals/herbivores/ primary
consumers/warm blooded animals/homoiotherms
7 Carnivores use more of their food than herbivores
Explain how intensive rearing of domestic livestock increases net productivity.
1 Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue/production;
2 Fed on concentrate /controlled diet /controlled
conditions/so higher proportion of (digested) food
absorbed/lower proportion lost in faeces
3 Movement restricted so less respiratory loss / less energy used
4 Kept inside/heating/shelter / confined so less heat loss / nopredators
5 Genetically selected for high productivity
