Photosynthesis Practicals Flashcards
What does TLC do?
- separates different pigments in plant extract
- different solubilities of the pigments in the mobile phase leads them to move at different rates ( pigments separated as they move through silica gel)
What’s the mobile phase in TLC?
- solution containing mixture of pigments
What’s the stationary phase in TLC?
- thin layer of silica gel applied to glass
How do you calculate the Rf?
Distance travelled by pigment/ distance travelled by solvent front
Give an example of an extraction solvent?
Propanone
The Hill reaction- uses isolated ___________ from spinach leaves.
The chloroplasts are added to _______ solution that is ________ to minimise pH change
- chloroplasts
- sucrose
- buffered
Why are chloroplasts added to sucrose solution that’s buffered?
- sucrose prevents osmotic effects, so keeps water potential the equal on the inside and outside of the chloroplasts
- buffer minimise pH change
Which stage of photosynthesis is the Hill reaction monitoring and what is the role of DCPIP?
- light dependent reaction monitored by the reduction of DCPIP solution
- DCPIP acts as the final electron acceptor instead of NADP, and allows photolysis to continue
- DCPIP solution is blue when oxidised and becomes colourless when reduced ( by the electrons from photolysis)
How would the following things help improve the validity of the experiment:
- use ice cold solutions
- centrifuge at different speeds
- use a water baths
- use the same light source
Ice cold solutions= prevents damage to components
Centrifuge at different speeds= obtain different fractions/ a pellet containing mainly chloroplasts
Water bath= to maintain a constant temperature
Same light source= so light intensity is the same
