energy transfer

Question 1

describe succession 3 marker

Answer 1

pioneer species,
change in abiotic conditions conditions become less hostile more habitats or niches
increase in number of species

Question 2

why does npp show little increase productivity after 100 years

Answer 2

npp= gpp-respiratory loss

decrease in gpp increase in resp

Question 3

explain how the intensive rearing of domestic livestock increases net productivity

Answer 3

slaughtered when still growing so more energy transferred to biomass
fed on controlled diet so higher proportion of food absorbed
movment restricted so less heat loss
heating kept warm so less energy lost
genetically selected for high productivity

Question 4

describe the reasons for the low efficiency of energy transfer through ecosystems

Answer 4

some light is reflected
some light misses leaves
heat loss
energy loss via respiration
loss via faeces
excretion

Question 5

why is the efficiency of energy transfer from producers to primary consumers in this food web is higher than 10 percent

Answer 5

Single celled producers are more digestable
All of producer eaten
less heat lost

Question 6

energy from the sun may ultimately end up in dead plant matter. how

Answer 6

photosynthesis/ ldr

carbon containing substances

Question 7

in the investigation the scientists used pigs of the same breed with similar genotypes, why

Answer 7

same breed so similar alleles

controls variable

Question 8

The diagram above includes one process in which microorganisms add ammonium
ions to soil.
Describe another process carried out by microorganisms which adds ammonium
ions to soil.

not ammonification

Answer 8

Protein / amino acids broken down (to ammonium ions / ammonia);
by saprobiotic organisms

Question 9

Suggest two ways in which crop rotation may lead to high crop yields.

Answer 9

(Different crops use) different minerals / salts / nutrients / ions (from the

soil) ;
3. (Different crops have) different pests / pathogens / diseases

Question 10

Suggest what the scientists should have done during the drying process to be sure
that all of the water had been removed from the plant samples.

Answer 10

Weigh samples at intervals during drying

to make sure the mass became constant

Question 11

Describe the role of microorganisms in producing nitrates from the remains of dead animals

Answer 11

saprobiotic micoorganisms break down dead material
ammonia into nitrite and then nitrate
by nitrifying bacteria

Question 12

Leguminous crop plants have nitrogen-fixing bacteria in nodules on their roots.
On soils with a low concentration of nitrate ions, leguminous crops often grow better
than other types of crop. Explain why.

Answer 12

as they can directly form ammonia from nitrogen gas and this can be used to produce proteins or amino acids for growth.

Question 13

Applying very high concentrations of fertiliser to the soil can reduce plant growth.
Use your knowledge of water potential to explain why

Answer 13

the soils would then have a low water potential and roots or plants would have a higher one so water moves via osmosis out of the plant.

Question 14

The legume plants have nodules containing nitrogen-fixing bacteria on their roots.
Explain how nitrogen-fixing bacteria could increase the growth of the maize.

Answer 14

Nitrogen-fixing bacteria convert nitrogen (in the air) into ammonium compounds (in the soil) which are converted into nitrates / nitrification occurs;

2. Maize uses nitrates (in soil) for amino acid / protein / ATP / nucleotide
   production;