Topic 5B - Energy transfer and Nutrient cycles. Flashcards
(25 cards)
In an ecosystem and in a food web, plants are producers as…
They are able to produce their own carbohydrates using carbon dioxide in the atmosphere or water.
Between each trophic level, most of energy is lost due to…
What does the remainder of the energy form?
Respiration and excretion.
Biomass.
How can biomass be measured.
In terms of mass of carbon or dry mass of tissue.
What determines how productive an ecosystem is?
Abiotic and biotic factors.
What is gross primary production?
The chemical energy store in plant biomass, in a given area or volume. It is the total energy resulting from photosynthesis.
What is net primary production?
The chemical enegry store in plant biomass taking into account the energy that will be lost due to respiration.
It is the energy left over that is avaliable to the plant to create new biomass and therefore avaliable to the next trophic level in a food web.
What is the formula to the net production of consumers?
N = I - F + R.
I = the chemical energy store in ingested food.
F = chemical energy lost to the environment in faeces and urine.
R = Respiratory losses.
Rates of productivity are recorded using the units…
kJ ha-1 year-1.
Why is rate of productivity recorded per unit area?
To standardize the results to enable environments to be compared.
What are fertilisers?
Fertilisers are added to soil to replace nitrate and phosphate ions lost when plants are harvested and removed from nutrient cycles.
Two types of fertiliser.
Natural - manure.
Artificial - Inorganic chemicals.
Advantage of using natural fertilisers.
Cheaper, can be free if the farmer owns animals.
Disadvantage of fertilisers.
Exact minerals cannot be controlled.
Advantage of artificial fertilisers.
Chemicals contain exact proportions of minerals.
Disadvantage of artificial fertilisers.
Inorganic substances are more water soluble and therefore they dissolve in the surrounding soil, therefore larger amounts are washed away.
What is leaching?
When water soluble compounds are washed away often into rivers or ponds.
What is eutrophication?
When nitrates leached from fertilised fields stimulate growth of algae in pond. The excessive growth of alae creates a blanket on the surface of the water which blocks out light. The plants below cannot photosynthesis and die.
Eutrophication results in…
A n increase in bacteria, which feed and respire on dead plant matter which are then all respiring and using up oxygen within water.
What is phosphorus used for in organisms?
DNA/ RNA.
ATP.
Phospholipid bilayer.
What is mycorrhizae?
Fungal associations between plant roots and beneficial fungi.
Why are mycorrhizae beneficial for plant growth?
The fungi increase the surface area for water and mineral absorption. The mycorrhizae acts like a sponge so holds water and minerals around the roots. This makes plants more drought resistant and able to take up more inorganic ions.
What is mycorrhizae’s role in the nutrient cycles?
Improving the uptake of relatively scarce ions such as phosphate ions.
Why can plants and animals not obtain nitrogen through gas exchange?
Nitrogen contains a triple bond.
Which biological molecules contain nitrogen?
Protein, ATP, nucleic acids.
