Photosynthesis Flashcards
Suggest two reasons why 95% of the light hitting the surface of a leaf is not used by the chloroplasts.
- It is reflected.
- Idea of not hitting the chloroplast /chlorophyll
- Idea of light being in excess e.g. at max. photosynthesis so more light can be used
Explain what is meant by the unit J m–2 year–1.
Energy per square meter per year.
The metabolic process that best describes
the process that accounts for most of the difference between GPP and NPP in plants.
Respiration
With reference to the structures in a chloroplast, explain how the energy from light is made available in ATP molecules for the synthesis of organic materials.
- Thylakoids (membranes)
- in granum / grana
- (light energy) raises energy level of electrons in chlorophyll and the electrons get excited.
- Electrons released from chlorophyll (photosystem)
- A photo system is an electron {carrier / eq} ;
- A series of redox / oxidation & reduction reactions occur.
- Energy level of electrons falls
- Synthesise ATP from ADP +P (inorganic phosphate)
- Reaction is called photophosphorylation
- idea of electrons from photolysis used
to replace those lost
When light is absorbed by chlorophyll, it excites
Electrons
Oxygen is produced when water molecules are split in the process of
Photolysis
The products of the light-dependent reactions that are used in the
light-independent reactions are reduced NADP and
ATP
Describe the structures in a chloroplast that are involved in the light-dependent reactions of photosynthesis.
- Thylakoids
- Made of membranes
- Arranged as stacks
- Contain pigment chlorophyll
- Arranged as photosystems
The stage in which RuBP combines with
carbon dioxide.
B The light-independent reactions of the Calvin cycle
The enzyme that catalyses carbon fixation.
Rubisco
The site of carbon fixation
Stroma of a chloroplast
Suggest why the development of corn cobs, suitable for producing cereal products, depends on the rate of carbon fixation in maize plants.
- Carbon fixation produces {GP / eq}
- (product) is converted to {starch / sugar /
- Faster C-fixation means faster
{sugar / starch / eq} production / - Rate of {growth / development} depends on rate of carbon fixation ;
- Increased GPP
Explain how oxygen is produced during the light-dependent reactions of photosynthesis
Process is called photolysis where light energy breaks bonds of water.
Describe the structures in a chloroplast that are involved in this reaction.
- Granum
- Is a stack of thylakoids membranes.
- Thylakoids contain electron carriers / chlorophyll / photosystems.
- Membranes contain ATPase
channel - Electron carriers / ATPase are
associated with thylakoid membranes}
Suggest how GALP may be used to synthesise cellulose.
- GALP is a 3C
- Forms glucose/hexose/6C
- Enzymes involved in the synthesis of glucose
/ cellulose - Cellulose consists of B glucose
- Joined by 1-4 glycosidic bonds.
- Cellulose is a polysaccaride
- Unbranched molecule.
The region of the chloroplast that would be
involved in the fixation of carbon dioxide.
Stroma
Suggest why it would be advisable to illuminate the cells at a high light intensity during this investigation.
- light is needed for light-dependent reaction ;
- light (intensity) will not be a limiting factor /
- idea that {the effect of carbon dioxide
concentration can be seen / carbon dioxide
(concentration) is (only) limiting factor / - {ATP / NADPH / eq} produced during lightdependent
reactions ; - {ATP / NADPH / light-dependent products /
required for {light-independent
reactions / Calvin cycle / carbon dioxide
fixation
The molecule produced by photophosphorylation.
ATP
State where carbon fixation takes place in a chloroplast.
Stroma
Name the enzyme involved in carbon fixation.
Rubisco
What molecule reacts with Carbon Dioxide during carbon fixation?
RuBP
What molecules are produced as a result of carbon fixation.
x 2 GP
Suggest how molecule GP, the product of carbon fixation, can be used to synthesise starch.
- Conversion of GP to GALP
- using ATP and reduced NADP
- GALP to glucose /hexose
- (which is) α glucose ;
- reference to formation of glycosidic bonds ;
- these bonds are 1-4 and 1-6 (glycosidic bonds)
- by condensation ;
- ref to amylose and amylopectin ;
- credit details of amylose e.g. straight chain, 1-
4 bonds ;
10.credit details of amylopectin eg branched, 1-4
and 1-6 bonds
Suggest how GALP can be used to synthesise cellulose of a plant cell wall.
- GALP is converted into glucose.
- B glucose.
- Glycosidic bonds are formed.
- 1-4 glycosidic bonds via condensation.
- Straight chain
- Cellulose is a polysaccaride.
Describe how oxygen is produced
- Oxygen is made from water.
- Photolysis is used to split the water molecule.
- Oxygen atom, H+ and electrons are produced.
- 2 water molecules are needed to form one molecule of oxygen.
- Occurs within a chloroplast.
Describe the structure of chloroplasts in relation to their roles in photosynthesis.
- Thylakoid (membranes) are site of {light-dependent
reaction / photophosphorylation - idea that (thylakoid) membranes provide a space for
accumulation of H+ ; - stroma is site of {light-independent reaction / Calvin
cycle / carcon fixation} ;
Describe the role of RUBISCO in the production of GALP in the light-independent reaction.
- Rubisco is an enzyme/catalyst
- In the Calvin Cycle
- Involved in Carbon Fixation bonding CO2 to RUBP
- To form GP
- GP is converted to GALP
- Using ATP and reduced NADP
Describe how the membranes inside the chloroplast are involved in photosynthesis.
- Site of light-dependent reactions.
- Includes chlorophyll and photosystems.
- Thyklaoid space provides accumulation of H+
- Photophosphorylation
