biology - chapter 5: energy transfers in and between organisms

measuring amount of biomass in organism

mass of carbon/dry mass of tissue per given area

producers

• plants

• produce own carbohydrates using CO2 in atmosphere or water (autotrophs)

energy in each trophic level

between trophic level energy is lost through excretion and respiration

gross primary production

GPP is the chemical energy store in plant biomass, in given area. the total energy from photosynthesis

net primary production

NPP is the chemical energy store in plant biomass taking account the energy that will be lost due to respiration. NPP is the energy avaable to the plant to create new biomass and availble to new trophic level in food web.

NPP formula

GPP - R

formula for net production of consumer

N = I - F + R

I= the chemical energy store in ingested food

F = the chemical energy lost to the environment in faeces and urine

R = respiration loss

rates of productivity

units kJ ha^-1 yr^-1

kj unit for energy, recorded as per unit area to standardise the results to enable environments to be compared . per year to take into account the impact seasons, annual average allows fair comparison

what is phosphorus used for in organisms

• DNA

• RNA

• RUBP

• GP

• TP

• ATP

• Phospholipid bilayer

state phosphorus is in the environment

as a phosphate ion, in mineral form in sedimentary rocks

mycorrhizae

fungal associations between the plant rot and benefical fungus

why are mycorrhizae are beneficial for plant growth?

1. the fungal increases the surface area for water and mineral ion absorption

2. the mycrohizzae acts like a sponge so holds water and mineral around the roots

3. this makes plants more drought resistant and able to take up more inorganic ions

   • mutualistic relationship —> improving the uptake of relatively scare ions such as phosphate

the importance of the nitrogen cycle

• the air is 78% nitrogen, plants and animal cannot absorp through gas exchange

• nitrogen gas contains a triple bond

  • microrganisms are needed to convert nitrogen into nitrogen containg substances that plants and animals can absorb

which biological molecules contain nitrogen?

• protein

• ATP

• nucleic acids

the nitrogen cycle

the key processes are:

1. saprobiotic nutrituition and microbes

2. ammonification

3. nitrification

4. nitrogen fixation

5. denitrication

fertilisers

added to soil to replace the nitrates and phosphate ions lost when plants are harvested and removed from nutrient cycle as crops

• can be natural (manure), artificial (inorganic chemicals)

pros and cons of natural fertilisers

pros:

• cheap and free

cons:

• the exact minerals and proportions cannot be controlled

pros and cons in artificial fertilisers

pros:

• chemical created to contain exact proportions of minerals

cons:

• inorganic substances are more water soluble, and therefore more of these ions dissolve in the water surroundings the soil.

• it is an advantage to the plant for absorbing the nitrates and phosphates, the downside is that their high solubility means that larger quantities are washed away with rainfall and therefore have a greater impact on the environment

leaching

when water soluble compounds are washed away often into rivers or ponds. if nitrogen fertilisers leach into waterwayds it causes eutrophication.

eutrophication

when nitrates leached from fertilised fields stimulate growth of algae in ponds

• the excessive growth of algae creates a blanket on the surface of the water which blocks out light preventing photosynthesis

  • bacteria within the water feed and respire on the dead plant matter, increasing amount of bacteria using up all the O2 in water

  • fish and other aquatic organisms die due to the lack of dissolved oxygen in the water