Studied by 12 people
CO2 (has one carbon) reacts with RuBP (five carbons)- forms two molecules of GP (a 3 carbon compound, so 6 in total)
GP is reduced to TP- using energy from ATP and accepting a H from reduced NADP- reduction reaction as GP gains a hydrogen
2 molecules of TP- one of carbon atoms is removed from cycle each time- 6 times- to be converted into useful organic substances
To allow cycle to continue- have to regenerate RuBP with energy from ATP
Growing plants under artificial lighting- maximum light intensity
Heating green house to increase temp
Burning fuel- release more co2
Aerobic respiration- glycolosis (stage 1)- where?
The cytoplasm
Glycolysis process:
-Glucose (6 carbons) is phosphorylated to glucose phosphate- by hydrolysing 2 ATP to release phosphate
-Glucose phosphate is a high energy molecule- splits into 2 TPs (3 carbons)
-Both Tp molecules are oxidised as the co-enzyme NAD picks up a hydrogen from the TP- converted into NADH- TP molecules oxidised producing pyruvate (3 carbon)
-Oxidation of TP into pyruvate releases 2 molecules of ATP
What happens to the pyruvate at the end of glycolysis?
Transported into mitochondrial matrix for the next step
Aerobic respiration-the link reaction (stage 2)- where ?
Occurs in the mitochondrial matrix
The link reaction process:
-The pyruvate (3 carbons) made in glycolysis is oxidised- makes acetate (2 carbons)
-The hydrogen from pyruvate is picked up by enzyme NAD to make NADH
-1 stage where carbon dioxide is formed
-Acetate combines with co-enzyme A to produce- acetylcoenzyme A (2 carbon)- to enter next stage, Krebs cycle
3 products of link reaction:
-2 Acetyl CoA
-2 Co2 released
-2 reduced NAD
Aerobic respiration- the krebs cycle (stage 3)- where?
-Takes place in the mitochondrial matrix
Aerobic respiration- the krebs cycle process
-Acetyl CoA (2 carbons) produced in the link reaction reacts with a 4 carbon compound- producing 6 carbon compound
-Co enzyme A -released and re used in link reaction
-Lose 2 carbon dioxide- this stage produces ATP
-In a series of redox reaction the reduced co-enzymes FADH and NADH
Products produced per one krebs cycle?
-3 reduced NAD
-1 reduced FAD
-1 ATP
-2 Co2
(multiply by 2 for one gllucose molecule as there is 2 pyruvate in one)
Aerobic respiration- oxidative phosphorylation- where?
-Cristae- mitochondria inner membrane
What does OP stage involve?
-The most ATP is made
-The electron transfer chain
-Movement of protons across inner mitochondrial membranes
-Catalysed by ATP synthase
OP process:
-Reduced co-enzymes NAD and FAD in mitochondrial matrix split hydrogen atoms into H+ ions and electrons
-Electrons are passed along electron transport chain releasing energy which is used to transport H+ ions to the intermembrane space
-This creates an electrochemical gradient- build up of protons in intermembrane space
-H+ ions move down their conc gradient through ATP synthase by facilliated diffusion- this catalyses the phosphorlyation of ADP to make ATP
-The oxygen in matrix picks up electrons at end of chain and protons- creating water- it is called the terminal acceptor
Where does anaerobic respiration occur?
-In the cytoplasm and the absence of oxygen
Anaerobic respiration in animals
-The pyruvate produced in glycolysis is reduced (gains hydrogen from NADH) to form lactate
-This oxidises NAD so that it can be re used in glycolysis ensuring more ATP is continued to be produced
Anaerobic respiration in plants and microbes
-Same as anaerobic but ethanol and Co2 is prodcued instead of lactate.
Why are plants known as the producers in a food web?
-They produce their own carbohydrates using co2 in atmosphere and or water
What is biomass?
The mass of living material of the organism
It is what is left over after the loss of energy between trophic levels in a food web due to excretion and respiration
How is the amount of 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 calorimetry
What is productivity?
The rate at which something is produced-depends on the abiotic and biotic factors- quantified using GPP and NPP
What is gross primary production?
-The chemical energy store in plant biomass, in a given area or volume. So the total energy entering the food chain from photosynthesis
What is net primary production?
-The chemical energy store in plant biomass taking into account the energy that will be lost due to respiration
-GPP - R
-Its the energy left over that is available to the plant to create new biomass and therefore available to the next trophic level in a food web
What ecosystem would have high prodcutivity levels?
Rainforest
How to calculate the net production of consumers in e.g animals
N = I - F + R
I- chemical energy store in ingested in food
F- the chemical energy lost to the environment in faeces and urine
R- respiratory losses
How is the rate of primary and secondary production measured
-Measured as biomass in a given area in a given time e.g KJ ha-1 year-1
Why is the unit per unit area used
-To standardize the results to enable environments to be compared- it takes into account that different environments will vary in size
Per year used why?
-Takes into account the impact seasons will have on rain, light and heat-provides an annual average to allow fair comparisons between environemtn
How to calculate the effieciency of energy transfers?
energy available after transfer'/energy available before the transfer x 100
The nitrogen cycle: nitrogen fixation- step 1
-Nitrogen fixing bacteria convert atmospheric nitrogen to ammonium ions
-There either free-living in the soil or have a symbiotic relationship with leguminous plants e.g beans as they live in their root nodules
Step 2 - ammonification
-Organic nitrogen from decomposition of proteins, urea etc are converted to ammonium ions which are released into the soil
-This is carried out by saprobionts- these digest waste extracellularly
Step 3 - nitrification
-ammonium ions producd by ammonification and nf in soil are oxidised to nitrites then nitrates- carried out by nitrifying bacteria- TWO stage oxidation reaction
Step 4 -Denitrification
-Converts nitrogen in compounds back to nitrogen gas-loosing nitrogen
-Not useful as nitrogen gas cannot be absorbed by plants
-Carried about by anaerobic dentrigying bacteria-often why farmers aerate their soil
What is the phosphorus cycle used for?
Essential to form DNA, ATP and pbs
The phosphorus cycle:
-Plants absorb the phosphate ions from oceans etc by active transport
-Animals eat the plants- use ions to synthesise organic materials
-Animals excretion containing phosphate ions enter oceans etc again
-Excretion and decompisition- excretion meaning that the phosphate ions from waste and remains- guano in their excretion and is rich in phosphorus
-Guano, bones etc will erode- releasing phosphate ions back
-Some guano may go through deposition- forms phosphate ions in rocks
-Rocks will erode and returns PI back- also addition of fertillers mean it will run off into oceans
-Sedimentation- build of sediment to create rocks, contains phosphate ions.
What is the use of fertilisers?
to replace the nitrates and phosphates ions lost when plants are harvested and removed from nutrient cycles as crops
What are natural fertillers?
-dead and decaying remains of plants and animals as well as animal wastes e.g manure
What are artificial fertilisers?
Inorganic chemicals which are synthesised?
Pros of natural fertillisers?
-They are cheap/free if farmer owns animals
Cons of natural fertillisers?
-The exact minerals and proportions cannot be controlled
Pros of artificial fertillisers?
-They are chemicals created to contain exact proportions of minerals
Cons of artifical fertilllers?
-Soluble in water- more likely to leach into rivers-has negative impact on environment
-Could also be seen as advantage- minerals are easily absorbed
What is leaching?
When water soluble compounds are washed away into rivers or ponds
Impact of leaching?
Eutrophication
Describe eutrophication
-Nitrates leached from soil stimulate algae growth in pond- algae bloom
-This blanket of algae on surface of water blocks sunlight
-As a result plants below cannot photosynthesise and plants will die
-bacteria in water feed and respire on the dead plant matter
-This results in increased bacteria- respiring now and using up the oxygen within the water
-eventually plants and animals in water will die due to lack of dissolved oxygen in water
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