13.0 Energy and ecosystems Flashcards
What is biomass?
The total mass of livibng material in a specific
area at a given time.
How is biomass measured?
The sample is dried (in an oven at a low
temperature), then weighed at regular intervals
until he mass is constant (so you know all the
water has been removed). The sample is then
placed in a calorimeter.
How do you use a calorimeter?
The dry biomass is burned in a calorimeter and
the energy given off is used to heat water. The
increase in temperature tells you the energy in
the sample.
What is Gross primary production?
The total amount of energy converted by plants,
in a given area, at a given time.
What is Net primary production?
Gross primary production minus respiratory
losses (NPP = GPP - R)
What is net production in consumers?
Chemical energy ingested minus energy lost
through faeces, urine and respiration (N = I -
(F+R)
What is the efficiency of energy transfer?
Net production at a trophic level divided by the
net production in the previous trophic level
How can farmers increase the net primary production of their crops?
Removing pests i.e. by insecticides, herbicides,
or biological control.
How can farmers increase the net production in their livestock?
restrict movement, keep the environment
warm, control feeding and exclude predators.
What is nitrogen used for in organisms?
Amino acids, ATP, DNA, enzymes
What is nitrogen fixation?
When nitrogen in the atmosphere is converted
into ammonium ions by nitrogen fixing bacteria,
these can be mutualistinc nitrogen-fixing
bacteria or free-living
What is nitrification?
The conversion of ammonium ions into first
nutrite ions and then nitrate ions bynitrifying
bacteria. This is an oxidation reaction and takes
place in aerobic conditions.
What is ammonification?
when organic material containing ammonia
molecules is broken down by saprobionts into
ammonium ions
What is denitrification?
the conversion of nitrate ions to nitrogen gas by
denitrifying bacteria. Happens in anaerobic
conditions like water logged fields
Why do farmers want to discourage denitrifying bacteria?
They remove nitrates from the soil so less is
available for crops.
what are phosphates used to make?
phospholipids, ATP, DNA
Describe the phosphorus cycle
Phosphorus normally found in sedimentary
rocks at phosphate ions. When the rock erodes
the phosphate ions end up in the soil. Plants can
then absorb the phosphate ions. Consumers
eating plants will take up phosphate through
phospholipids, DNA and ATP. Saprobionts break
down dead organisms releasing phosphate ions
back into the soil.
What are mycorrhizae?
Mutualistic fungi that live on the roots of plants.
They help with the uptake of phosphate and
nitrogen ions. In return the plant provides them
with carbohydrates.
What are the benefits of ploughing?
Increases air space, supports aerobic respiration
of nitrogen fixing bacteria and nitryfying
bacteria
What are the differences between artificial and natural fertilisers?
Artificial - are inorganic (easier to store and apply
in precise amount, are soluble)
Natural - organic matter, slowly released as it needs to be decomposed first.
What is leaching?
When water soluable compounds (i.e. nitrates and phosphates) are washed away
What happens in eutrophication?
1) Algae blooms block light
2) No photosynthesis, so plants die.
3) Saprobiotic decomposition occurs.
4) Microorganisms respire aerobically (use up oxygen)
5) Less oxygen for fish to respire, therefore they die
6) Increase in anaerobic microorganisms; release hydrogen sulphide/ nitrates/ toxic waste
7) Water becomes putrid
