energy exchanges in and between organisms Flashcards
glycolysis is…
first stage in both aerobic and anaerobic respiration, occurs in the cytoplasm
net products of glycolysis are…
2 x ATP
2 x NADH
glycolysis: glucose splits into…
glucose phosphate, then hexose biophosphate, then into 2 triosephosphate molecules, then 2 pyruvate molecules
link reaction occurs in the…
mitochondria matrix
link reaction: pyruvate turns into…
acetate, then acetyl coenzyme A
link reaction: net products
2 x CO2
2 x NADH
link reaction: what is added to acetate to make it acetyl coenzyme A
coenzyme A
Krebs cycle basics…
occurs in mitochondrial matrix
pyruvate enters matrix by active transport
link reaction converts pyruvate to acetyl coenzyme A
Anaerobic respiration…
NADH is re-oxidised so it can re-enter glycolysis
Krebs cycle: acetyl coenzyme is converted into…
6C compound, 5C compound, 4C compound, then back into coenzyme A to be used at start if the reaction again
Krebs cycle: net products…
6 x NADH
2 x ATP
2 x FADH
4 x CO2
lipids and amino acids that can be used instead of glucose process…
lipids hydrolysed to glycerol + fatty acids
glycerol phosphorylated into triose phosphate + enters Krebs cycle
amino acid hydrolysed + amino acid group removed
carbon compound left Krebs cycle
oxidative phosphorylation process…
electrons and protons (H+) are reduced from reduced coenzymes
NADH–> e- + H+ + NAD
FADH –> e- + H+ + FAD
electrons flow along e.t.c in series of redox reactions
electrons release energy, which is used to join ADP + Pi –> ATP
oxygen is the final electron acceptor, combines with electrons and protons to form water
oxidative phosphorylation makes most ATP in aerobic respiration.
what is an ecosystem…
form of biological community containing all living + non-living factors
flow of energy through ecosystems
some organisms obtain energy from the sun or consuming organisms
energy used to synthesise organic compounds
most sugars synthesised by plants respiratory substrates, rest used to from biological molecules (forms biomass of the plants)
how is biomass measured….
in terms of mass of carbon or dry mass of tissue per given area
chemical energy store in dry biomass can be measured using colorimetry
food chains…
go in order of producer, primary consumer, secondary consumer, tertiary consumer
energy loss occurs due to respiration, excretion of faeces and urine etc.
measuring energy loss (GPP)…
gross primary production (GPP)= chemical energy store in plant biomass, in a given area or volume
measuring energy loss (NPP)…
chemical energy store in plant biomass after respiratory loses to environment
NPP= GPP- R
used mainly for plant growth reproduction, is available for other trophic level
net production is…
N= I - (F+R)
I= chemical energy store in ingested food
F= chemical energy lost to environment in faeces and urine
R= respiratory loses to environment
measuring the rate of primary + secondary production…
primary/ secondary productivity
measured in biomass in a given area in a given time
nutrient cycles…
nutrients are recycled within natural ecosystems
microorganisms play a vital role in recycling chemical elements such as phosphorus and nitrogen
saprobionts= organism that digests their ‘food’ externally and then absorb the products
mycorrhizae is…
fungal ‘associations’ between plant roots + fungi
provide a large surface area for uptake of water + inorganic ions
acts like a ‘sponge’ so can absorb and hold water and minerals easily
relationships between pants + fungi are mutualistic, as the plant provides the fungi with carbohydrates
nitrogen cycle (nitrogen fixation)…
nitrogen fixing bacteria convert atmospheric nitrogen to ammonium ions
N2 –> NH4+
either free living in the soil or have a mutualistic relationship with leguminous plants
nitrogen cycle (ammonification)…
organic nitrogen from decomposition of proteins, DNA, urea etc are converted to ammonium ions which are released into the soil
carried out by saprobionts (bacteria + fungi can digest waste extracellularly)
nitrogen cycle (nitrification)…
ammonium ions in the soil are oxidised to nitrites, then nitrates by nitrifying bacteria
NH4+ –> NO2- –> NO3-
nitrogen cycle (denitrification)…
converts nitrogen in compounds back to nitrogen gas
not useful as nitrogen gas cannot be absorbed by plants
anaerobic denitrifying bacteria
phosphorus cycle is…
essential to form DNA, ATP, RNA and phospholipid bilayers
phosphorus cycle steps…
- environment conditions (erosion, weathering) cause the release of phosphate ions by rocks into soil and bodies in water
- plants assimilate (taken in) these phosphate ions
- animals eat the plants and use the ions to synthesise organic materials
- animals die + decompose, returning phosphate ion to the soil
- bacteria in the soil break down phosphate into inorganic form (mineralisation)
- inorganic forms of phosphorus can end up in waterways again + be assimilated in plants
fertilisers…
replace the nitrates and phosphates lost by harvesting plants and removing livestock
fertilisers (natural)…
natural fertilisers= manure, seaweed, peat, guano etc
advantages= cheaper and free if it comes from your own livestock
disadvantages= exact minerals and proportions can’t be controlled
fertilisers (artificial)…
contain exact amount of minerals
more water soluble- more ions dissolve in the water surrounding the soil, so higher absorption of inorganic ions
can lead to leaching and eutrophication
leaching…
water-soluble compounds are washed away into bodies of water (rivers and ponds)
if nitrogen fertilisers leach, eutrophication can occur
eutrophication steps…
- leached nitrates in bodies of water cause algae growth in the surface of water
- excessive algae growth blocks light, so plants below the surface can’t photosynthesise, can die
- aerobic Bactria feed on dead plants matter and respire, using up the oxygen in the water
- fish and other aquatic organisms die due to lack of oxygen
light dependent reaction is…
uses light energy and water to form ATP and NADPH
occurs in thylakoid membrane of chloroplasts
light dependent reaction basic steps…
- photoionisation of chloroplast + photolysis of water
- chemiosmosis- ATP production
- NADPH production
light dependent reaction (photoionisation of chlorophyll/ photophosphorylation) steps…
- photosynthesis pigments (chlorophyll) absorbs light energy
- excites an electron, leaves the chlorophyll in PSII (photo ionisation)
- electron moves along the electron transport chain, releases energy, used to join ADP + Pi –> ATP
- NADP is reduced to NADPH
- photolysis of water make protons (H+), electrons (e-) and oxygen
light independent reaction (Calvin cycle) steps…
CO2 –>2 x GP –> 2 x TP –> RuBP
limiting factors of photosynthesis are…
temp= affects rate of reaction
CO2= affects rate of light-independent reaction
light intensity= affects rate of light-dependent reaction
agricultural practices to overcome limiting factors of photosynthesis are…
growing plants in LED lights to maximise light intensity, whilst maintaining temp
use a greenhouse
burn fuels to produce more CO2
