Chapter 17- Photosynthesis Flashcards
How grana is adapted to its function?
- contains chlorophyll pigments
- contains e- carriers
- large SA for light absorption
Why theoretical rate of photosynthesis not achieved at high light intensity?
- another factor becomes limiting factor
- temp becomes limiting as light independent reaction involves enzymes
How till structure of a leaf adapted to living in shade differ from a leaf adapted to living in sunlight?
- larger SA
- Larger chloroplasts
How heterotrophic organisms are dependent on plants?
- plants produce glucose + O2 during photosynthesis
- these used in respiration by animals
- animals eat plants to obtain organic materials
Primary pigment?
Chlorophyll a
Accessory pigment?
- chlorophyll b
- xanthophylls
- carotenoids
Adv of having range of accessory pigments?
Can absorb different wavelengths of light
Compound synthesis as a result of an electrical + pH gradient across thylakoid membrane?
ATP
Enzyme that catalysts fixation of CO2?
Rubisco
Ribulose bisphosphate carboxylase
1st stable product of carbon fixation?
GP
Glycerate 3 phosphate
Compound regenerated so more CO2 can be fixed?
RuBP
Polysaccharides that can be synthesised from end products of light independent stage?
- amylose
- cellulose
Products of light dependent that is used in light independent?
ATP
NADPH
Autotroph?
-can make organic molecules from inorganic molecules
Heterotroph?
Feeds on + digests organic molecules that have been made by another organism
How light is harvested in chloroplast membrane?
- primary + accessory pigments form a photosystem
- light energy absorbed by pigment molecules
- e- excited as move to higher energy level
- energy passed to chlorophyll a in reaction centre
- range of pigments allow range of wavelengths to be absorbed
What would happen if movement of e- between e- carriers at PSII was blocked?
- prevents non cyclic phosphorylation
- no ATP + NADPH available for Calvin cycle
What would happen if movement of e- between e- carriers at PSI was blocked?
- prevents cyclic + non cyclic phosphorylation
- no ATP + NADPH available for Calvin cycle
Why herbicide can emit light + heat?
-energy given off from excited e-
Why measuring CO2 uptake may or may not give better indication of photosynthesis than measuring O2 production?
- CO2 only used in one stage
- O2 only produced in one stage
- O2 produced may be used for respiration
Products of light dependent stage?
ATP
NADPH
O2
Graph. What happens at point that plant starts photosynthesising?
- is at compensation point
- rate of photosynthesis = rate of respiration
Graph. What happens at point that rate of photosynthesis starts increasing?
Rate of photosynthesis greater than rate of respiration
Function of DNA and ribosomes in chloroplasts?
- DNA to provide coding for protein
- ribosome for protein synthesis
- protein can be used for e- carrier
How to supply plant with CO2?
- dry ice
- sodium hydrogen carbonate
Why not all O2 produced collected in capillary tube?
- dissolves in water
- used in respiration
- may escape collection apparatus
Assumptions made when carrying out practical forms measure rate of photosynthesis by measuring gas produced?
- all O2 produced by plant collected
- all gas collected is O2
Why nitrogen present in gas given off by plant?
Was present in air spaces in the leaf
Why presence of these pigments is an advantage to seaweeds that live in deeper water?
- in dealer water there is lower light intensity
- these pigments can absorb what little light there is
Fate of TP?
- regenerates RuBP so cycle can continue for further carbon fixation
- formation of glucose
- formation of amino acids, nucleic acids, lipids
Effect on photosynthesis of an increase in oxygen conc?
- O2 competes with CO2 for active site of Rubisco in Calvin cycle
- oxygen will be used + less CO2 fixed
How temp can be controlled to increase rate of photosynthesis?
- photosynthesis controlled by enzymes so increasing temp will increase rate
- heater
How CO2 can be controlled to increase rate of photosynthesis?
- burning paraffin
- increases CO2 fixation