Topic 5A - Photosynthesis And Respiration Flashcards
What are the 2 types of respiration
Aerobic and anaerobic respiration
Where do the light-dependant and light-independant reactions occur in plants
Light-dependant - in thylakoid of chloroplast
Light-independant - in the stroma of chloroplasts
Explain the role of light in photoionisation
Chlorophyll molecules absorb energy from photons of light
This ‘excites’ 2 electrons, causing them to be released from the chlorophyll.
Name the 2 main stages involved in ATP production in the light dependant reaction.
- Electron transfer chain
- Chemiosmosis
What happens in the ETC
Electrons released from chlorophyll move down a series of carrier proteins embedded in the thylakoid membrane and undergo a series of redox reactions which releases energy
How is a proton concentration gradient established during chemiosmosis
Some energy released from the ETC is coupled to the active transport of H+ ions from the stroma into the thylakoid space
How does chemiosmosis produce ATP in the light dependant stage
H+ ions move down the concentration gradient from thylakoid membrane into the stroma via the channel protein ATP synthase.
ATP synthase catalyses ADP + Pi -> ATP.
Explain the role of light in photolysis
Light splits water
What happens to the products of the photolysis of water
H+ ions (move out of thylakoid space via ATP synthase) are used to reduce the coenzyme NADP
e- - replace lost electrons (from chlorophyll)
02 - used for respiration or diffuses out of leaf as waste gas.
Where do H+ ions and electrons used to reduce NADP come from
H+ ions - photolysis of water
Electrons - NADP acts as final electron acceptor of the ETC
Name the 3 main stages of the Calvin cycle
- Carbon fixation
- Reduction
- Regeneration
What happens during carbon fixation
Reaction between CO2 and RuBP catalysed by rubisco
Forms unstable 6c intermediate that breaks down into 2 GP.
What happens during reduction
2 x GP reduced to 2 x TP
Requires 2 x reduced NADP and 2 x ATP
Forms 2 x NADP and 2 x ADP
What happens during regeneration
After 1C leaves the cycle, the 5C compound RuBP forms
RuBP is regenerated from RuP using 1 ATP
Forms 1 x ADP
STATE THE NUMBER OF CARBON ATOMS IN RuBP, GP AND TP.
RuBP - 5
GP - 3
TP - 3
Name 4 environmental factors that can limit the rate of photosynthesis
Light intensity
CO2 concentration
Temperature
Mineral/magnesium levels
State common agricultural practices used to overcome the effect of limiting factors in photosynthesis
- artificial light
- artificial heating
- addition of CO2 to greenhouse atmosphere
Why do farmers try to overcome the effect of limiting factors
Increase yield
Lower cost
Reduce time for crops to grow
State the purpose and principle of paper chromotography
Molecules in mixture are seperated based on their relative attraction to the mobile phase vs the stationary phase
Outline a method for extracting photosynthetic pigments
Use a pestle and mortar to grind a leaf with an extraction solvent
Name the 4 main stages in aerobic respiration
Glycolysis
Link reaction
Kerbs cycle
Oxidative phosphorylation
Where does each stage in aerobic respiration occur
1 - cytoplasm
2 - mitochondrial matrix
3 - mitochondrial matrix
4 - membrane of cristae
What are the stages of glycolysis
Glucose is phosphorylated to glucose phosphate by 2 x ATP
Glucose phosphate splits into 2 x TP
2 x TP is oxidised to 2 x pyruvate
Net gain of 2 x NADH, 2 x ATP, and 2 pyruvate
How does pyruvate enter the mitochondria
Via active transport
What happens during the link reaction
Oxidation of pyruvate to acetate
Decarboxylation and reduction occurs to form acetate
Acetate combines with coenzyme a to form acetyl CoA
What happens in the kerbs cycle
Series of redox reaction produces:
ATP by substrate level phosphorylation
Reduced coenzymes
CO2 from decarboxylation
What is the ETC
Series of carrier proteins embedded in the membrane of the cristae of the mitochondria
Produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration
What happens in the ETC
Electrons released from NADH & FADH undergo redox reactions
The energy released is coupled to maintain proton gradient or released as heat
Oxygen acts as the final electron acceptor
How is a proton concentration gradient established during chemiosmosis in aerobic respiration
Some energy released from the ETC is coupled to the active transport of H+ ions from the mitochondrial matrix into the intermembrane space
How does chemiosmosis produce ATP during aerobic respiration
H+ ions move down their concentration gradient from the intermembrane space into the mitochondrial matrix via ATP synthase
ATP synthase catalyses ADP + Pi = ATP
State the role of oxygen in aerobic respiration
Final electron acceptor
Name 2 molecules that can be used as an alternative respiratory substitute
Amino acids from proteins
Glycerol and fatty acids from lipids
What stages produce ATP through substrate level phosphorylation
Glycolysis
Kerbs cycle
What happens during anaerobic respiration in animals
Only glycolysis continues
Reduced NAD + pyruvate
=
Oxidised NAD + lactate
Pyruvate acts as hydrogen acceptor
What happens to the lactate produced in anaerobic respiration
Transported to liver via blood stream where it is oxidised to pyruvate
Can enter link reaction in liver cells or be converted to glycogen
What are the similarities between aerobic and anaerobic respiration
Both involve glycolysis
Both require NAD
Both produce ATP
