Energy Flow and Productivity Flashcards
Not all the light energy entering the leaves of the oak tree is used in photosynthesis. Give a reason for this. (1 mark)
Light is wrong colour/frequency/wavelength/does not strike chlorophyll.
Give 2 ways in which energy is lost between trophic level A (oak tree) and B(aphid) (2 marks) 4 points
- Energy is lost in respiration
- Small amount of energy is lost as heat.
- Part of oak tree not digested
- Lost in excretion/lost to decomposers/leaf fell
Explain the difference between the shapes of the 2 pyramids at the trophic levels D and E. (2 marks)
1 is a pyrmaid shaped and the other is wider at E than D
- Each bird has several parasites.
2. But total mass/energy of mites is less than that of one bird.
Suggest an explanation for the % of energy lost in faeces for the herbivore being larger than that for the carnivore. (2 marks) 3 points
- Cellulose present in faeces
- Cellulose being indigestible
- Indigestible material contains energy.
Explain why small mammals have a higher rate of respiration than large animals. (2 marks) 3 points
- Smaller animals have a larger SA:VOL ratio
- So lose more heat
- so have a higher rate of respiration to maintain body temp
Units for measurement of energy flow in the pyramid of energy. (1 mark)
kJ m^-2 y^-1
All of the energy in protoctists (producers) is eventually transferred to the environment. Explain how (3 marks) 5 points
- BY protocists
- AND BY their consumers
- AND BY their decomposers
4, transfer to environment as heat/thermal energy - Combustion of fossilised remains
The ratio of amount of energy lost in repiration to the maount of energy consumed in food is higher for mammals than for insects. Suggest a reason why. (2 marks)
- Mammals more active/higher metabolic rate
- Respiration provides heat
- To maintain body temp for endotherms/ warm-blooded
A higher proportion of energy consumed in food is absorbed from the gut in secondary consumers than primary consumers. (1 mark)
- Diet of primary consumers contains more cellulose/more indigestible material
OR - Diet of secondary consumers protein rich/more digestible materials
OR - Primary consumers lose more energy in faeces.
Explain the difference between GROSS PRODUCTION and NET PRODUCTION.
- GROSS PRODUCTION =TOTAL Energy taken in/total energy before respiratory loss.
- NET PRODUCTION = GROSS PRODUCTION - RESPIRATION LOSS
Many food chains don’t contain more than 4 trophic levels. Explain why, (4 marks)
- Energy losses
- By respiration/heat/movement
- As detritus/excreta/indigestible parts
- Too little remaining to sustain higher levels described.
Suggest 2 reasons why 95% of the light hitting the surface of a leaf isn’t used by chloroplasts. (2 marks)
- Reflection of light
- Due to incorrect wavelength/frequency/colour
- Doesnt hit chloroplast
4.
What does Jm ^-2 year -1 mean?
Joules per metre squared per year
Define Net Primary Productivity.
- Rate fo production of biomass
- Losses in respiration.
- In producers/plants
Suggest why an increase in temperature may cause an increase in NPP. (2 marks)
- Rate of metabolic/photosynthetic reactions increase
- As there is an increase in KE of enzyme molecules.
- which results in an increase of reaction rate because of more enzyme substrate interaction.
