Photosynthesis

Question 1

Where does LDR take place?

what makes chloroplasts adapted to their function?

Answer 1

thylakoid membranes of chloroplasts

thylakoid membrane provide large surface area for attachment of chlorophyll, electron carriers, and enzymes
proteins in grana hold chlorophyll to allow maximum absorption of light
atp synthase channels catalyse production of ATP and selectively permeable to H+
Chloroplasts contain DNA and ribosomes so can quickly manufacture proteins needed in LIR

Question 2

Steps of LDR: 3

Answer 2

Photoionization
Photolysis
ETC

Question 3

Steps of each:

Answer 3

Photoionization: light hits chlorophyll- excites electrons to higher energy level
chlorophyll molecules= ionised
electrons leave to an electron carrier/ reduced

Photolysis:
2H20== 4H+ 4e+ O2

ETC: electrons move down ETC- series of oxidation and reduction reactions

• electrons release energy- provides energy for protons to be pumped from the stroma to thylakoid space by active transport
• creates a concentration gradient for H+ to pass back through the ATP synthase enzyme which catalyses the synthesis of adp+ pi = atp
• protons taken up by NADP- reduces them to NADPH.

Question 4

LIR:

Answer 4

ribulose bisphosphate (5C)+ CO2 - catalysed by rubisco == 2xGP (3C) + (ATP+ADP=Pi)+(NADPH=NADP)= 2xTP(3C)
2xTP + (ATP=ADP+Pi)= Ribulose bisphosphate
or can be used to form useful organic substances

Question 5

adaptations of chloroplasts for LIR:

Answer 5

Fluid of stroma contains enzymes required for LIR

stroma fluids surrounds the grana and so the products of LDR can diffuse into the stroma

contains DNA and ribosomes so can manufacture proteins involved in LIR.

Question 6

correlation of: Light intensity
CO2 conc
Temperature on rate of photosynthesis

Answer 6

light intensity:
directly proportional- strait diagonal line- ldr

CO2 conc- affects LIR

temp- affects rate of reaction

Question 7

Agricultural practices that increase Photosynthesis:

Answer 7

• Grow using LED lights
• Grow in greenhouse- control temperature and sunlight
• burn fuels for CO2