Unit 5

Photolysis

• light energy is absorbed by chlorophyll and splits water into oxygen, H+ and e-

• H+ accepted by NADP to form reduced NADPH to be used in light dependent

• oxygen used for respiration or diffuses out

Photoionisation of chrorophyll (stg 1 of LDR)

• light energy absorbed by chlorophyll

• energy results in electrons becoming excited, raising energy level causing them to leave the chlorphyll

• some energy released used to make atp and reduced NAD

Chemiosmosis (stage 2 of LDR)

• electrons accepted by electron transport chain and are transported along a series of proteins in thylakoid membrane

• as they do so they release energy

• energy used to pump protons into THYKALOID FROM STROMA by active transport

• high concentration of protons in THYKALOID LUMEN so there is an electrochemical gradient

• the H+ travel back into the stroma through the only channel protein they can bind to - ATP synthase

• on the stroma side of the membrane, the protons combine with NADP to reduce it

Where does the calvin cycle occur?

Chloroplast stroma

Calvin cycle steps

• carbon dioxide reacts with ribulose bisphosphate catalysed by rubisco to form 6C molecule

• 6C molecule splits into two molecules of GP

• the GP is REDUCED to form triose phosphate requires energy from ATP

• accepts electrons from NADP

• Some triose phosphate is used to produce useful organic substances like glucose

• the rest of the TP is used to regenerate RuBP using energy from ATP

Role of ATP for light independent

• provides energy to reduce GP into TP

• provides energy to regenerate RuBP

Limiting factors of photosynthesis- why does each factor limit

• Carbon dioxide is a reactant for the light independent stage of photosynthesis calvin cycle

• light is needed in photolysis and photoionisation

Glycolysis location

Occurs in cytoplasm

Glycolysis steps

• ATP hydrolysis of 2 atp phosphorylates glucose to make it more reactive, unstable so splits into 2

• 2 Triose phosphate formed

• triose phosphate is oxidised to produce pyruvate (3 carbon) this forms 2 molecules of NADH as the electrons are donated to NAD

What are the products of glycolysis

• net gain of 2 atp

• 2 pyruvate

• 2 reduced NAD

Link reaction location and step

Matrix

• pyruvate is oxidised to acetate, loosing hydrogen which is accepted by NAD to become reduced nad

• Acetate combines with coenzyme A to produce acetylcoenzyme A

How is NADH and pyruvate transported into the mitochondria from the cytoplasm?

Active transport

What are the products of the link reaction?

• 2 acetylcoenzyme A molecules

• 2 co2 released

• 2 reduced nad produced

Krebs cycle location

Matrix

Krebs cycle steps

• AcoA combines with 4C molecule. CoA is released. Produces 6C molecule

  Series of redox reactions to reform the 4C molecule which produces:

• 3 reduced NAD

• 1 reduced FAD

• releases 2 CO2

• 1 ATP produced by substrate level phosphorylation

Be careful if question is asking for per CYCLE which is this^ or if its per GLUCOSE MOLECULE meaning the cycle two times as two molecules of acetylcoenzyme A are produced

Oxidative phosphorylation steps

• in the matrix the reduced co enzymes release protons and electrons

• the electrons from this are transported along the electron transport chain, releasing energy

• Energy used to actively transport protons into inter membrane space. creates electrochemical gradient, protons move by facilitated diffusion through ATP synthase. adp + pi

• OXYGEN is final acceptor of electrons and also accept the hydrogen ions once they pass through, forming water

What is final acceptor of electrons in oxidative phosphorylation?

oxygen, it also picks up hydrogen to form water

How does anaerobic respiration regenerate NAD from pyruvate?

• Pyruvate is reduced to form lactate, and NADH is reoxidised to NAD, donating the electrons to pyruvate

• this is important as it allows NAD to be used again in glycolysis so it can continue so that some atp is made

What is the downside of anaerobic respiration

-lactate forms lactic acid which can cause muscle fatigue and can denature enzymes/proteins

so cant respire anaerobically for long as the acid will denature the enzymes needed in glycolysis

What are products of anaerobic respiration in microbes?

-ethanol and carbon dioxide

how are other substances used for respiration

• ester bionds hydrolysised releasing glycerol and fatty acids

• 3 carbon glycerol enters glycolysis and is converted into pyruvate

• fatty acid molecules are broken down into 2 carbon units, each forms a molecule of AcoA

• AcoA then enters the krebs cycle

Protiens

• hydrolysed into amino acids in digestion, amino grouo is then removed by damination

• Carboxyl group is then processed for example into pyruvate, this varies between amino acids as some can be used as molecules for the krebs cycle

• energy levels for proteins are around the same as carbs

how is energy lost between trophic levels

• respiration

• excretion

GPP and NPP definitions

Gross Primary Production= total chemical energy store in plant biomass

Net primary productivity= chemical energy store in plant after respiratory loss

NPP= GPP- R

Net production of consumers equation

N= I - (F+R)

I= energy in ingested food

f= energy lost in faeces and urine

r= respiratory loss

Which molecules contain nitrogen

Proteins, ATP, nucleic acids

Nitrogen cycle key processes

1) ammonification

nitrification

nitrogen fixation

denitrification

Ammonification (step 1 of nitrogen cycle)

• nitrogen fixing bacteria convert atmospheric nitrogen into ammonium

• these live in root nodules or there is free living nitrifying bacteria in the soil

Nitrification (step 2 nitrogen cycle)

• nitrifying bacteria oxidise ammonium into nitrites (NO-2) and then further oxidise it into nitrates (NO-3)

Role of decomposers in nitrogen cycle

• break down waste produced by animals and organic matter, MUST name the biological molcules- UREA for waste or PROTEINS, DNA for organic matter.

• this is known as saprobionic nutrition

• converts it into ammonium

What is the effect of lack of oxygen on bateria in nitrogen cycle

• anaerobic denitrifying bacteria convert nitrates back into nitrogen gas by denitrification

Where in the phosphorous cycle is phosphate found?

• as phosphate ion

• in mineral form in sedimentary rocks

What are the role of mycorrhizae in phosphate and N cycle

• the fungi increase surface area for water and mineral absorbtion

• acts like a sponge for water/minerals around roots

• makes plants more drought resistant and can take up more ions

What type of relationship do fungi and plants have for in mycorrizae

Mutualistic.

the plant provides the fungi with carbohydrates

Describe the phosphate cycle

Compare natural fertilisers and

Natural

• cheaper, often free as it is animal manure

• however doesnt necesserily contain exact minerals needed by that plant

Artificial

• Created to contain exact proportions that the plant needs

• however inorganic substances are more water soluble- an advantage to the plant absorbing it, but leads to leaching with rainfall

• this causes eutrophication if the nitrates enter the ponds or rivers

Explain eutrophicaton

• nitrates leached from farming stimulates the growth of algae in pond

• created blanket on surface blocking light

• plants blow can not photosynthesise and die

• bacteria feed and respire on dead plant matter

• increase in bacteria using up oxygen in water

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