energy and ecosystems pass paper questions Flashcards
A trophic level is:
A step in a food chain / food web; [1 mark]
Based on the feeding behaviour of an organism; [1 mark]
Examples including producers, consumers; [1 mark]
Advantages of heated sheds:
and disadvantages
Advantages of artificial feed and disadvantages.
Less respiratory loss of energy as heat; [1 mark]
Less movement of animals so more energy can be transferred to biomass; [1 mark]
Less risk of livestock loss to predators; [1 mark]
Disadvantages of heated sheds:
Expensive to build/heat; [1 mark]
Lack of movement leads to lack of muscle condition and inferior meat quality; [1 mark]
Evaluation of artificial feed:
Advantages of artificial feed:
Regular input of the correct nutrients; [1 mark]
Feed can promote muscle growth; [1 mark]
Disadvantages of artificial feed:
Expensive (versus grazing); [1 mark]
Livestock cannot be left unattended e.g. when grazing in fields; [1 mark]
Creates hazardous effluent which has to be treated; [1 mark]
Only 1% of light energy is made available to other organisms because…
Energy is reflected back into space by clouds and atmospheric dust; [1 mark]
Energy is absorbed by the atmosphere; [1 mark]
Only certain wavelengths (of light) are absorbed during photosynthesis; [1 mark]
Light may fall away from a plant so can’t be absorbed; [1 mark]
Other factors such as low temperature may limit the rate of photosynthesis; [1 mark]
The differences in the amounts of crop harvested from both fields at nitrate levels of 0 to 40 kg ha-1 are…
Cattle dung in field X the previous year will return nutrients to the soil / act as a natural fertiliser; [1 mark]
(Slight) benefit at 40 kg ha-1 due to artificial and natural fertiliser being present; [1 mark]
More proteins / amino acids being produced allows increased crop growth; [1 mark]
Ideal fertiliser rate for Field X :
0-15 kg ha-1; [1 mark]
High enough fertiliser use to improve crop yield from 11 to approximately 16 kg m-2; [1 mark]
Reduction of cost to the farmer; [1 mark]
Excess usage of nitrate could cause environmental problems (leaching/eutrophication); [1 mark]
An experimental method for calculating biomass is as follows:
Remove plants from a defined area e.g. 4 separate quadrats of 0.25 m2 each; [1 mark]
Remove all matter from above and below ground; [1 mark]
Remove extraneous soil and other non-plant matter; [1 mark]
Dry in a cool oven (80℃) /a desiccator until constant dry masses are obtained; [1 mark]
Measure the area of the field in m2; [1 mark]
Multiply the dry mass per m2 by the area of the field; [1 mark]
Three molecules that a plant uses nitrate to synthesise are:
Amino acids/protein/polypeptide chains; [1 mark]
Forms of nucleic acid DNA / RNA; [1 mark]
Nucleotides (adenine, guanine, thymine, cytosine, uracil); [1 mark]
ATP or ADP; [1 mark]
NAD or NADP; [1 mark]
Cyclic Amp / cAMP; [1 mark]
Chlorophyll; [1 mark]
Reasons for barley biomass loss:
Only the grain contains the sugars and nutrients for animal feed; [1 mark]
The grain husks are indigestible so pass through the animals as dietary fibre; [1 mark]
Malt is partly germinated barley grain, incurring respiratory loss of energy; [1 mark]
Pure oxygen is used instead of air in the calorimeter because…
Pure oxygen increases the chance of complete combustion of the biomass; [1 mark]
So the maximum amount of energy can be transferred to the water; [1 mark]
To give an accurate representation of the energy content of the biomass; [1 mark]
The energy content of a tree’s biomass, measured in a calorimeter, can only be an estimate because…
Different organs have different energy contents; [1 mark]
Difficult to quantify the energy content of a large organism from a small calorimeter sample; [1 mark]
Not all the biomass will combust fully in the calorimeter; [1 mark]
Not all the energy given out as heat will be transferred to the water; [1 mark]
how to calculate net production
NP = IF - (EG+RL);
Flooded rice fields produce more methane than dry rice fields because…
Dry fields allow aerobic soil conditions / more oxygen to penetrate the soil OR flooded fields promote anaerobic conditions / less oxygen; [1 mark]
Flooded fields have more active anaerobic microorganisms / respiration OR unflooded fields have more active aerobic microorganisms / respiration; [1 mark]
