2007
STATE A PRECISE ROLE FOR :
CARBON DIOXIDE: In the dark stage CO2 is converted to glucose using ATP and NADPH
WATER: is split into H+ and OH-
ANSWER THE FOLLOWING QUESTIONS IN RELATIONS TO AN ACTIVITY YOU HAVE CARRIED OUT TO INVESTIGATE THE INFLUENCE OF LIGHT INTENSITY OR CO2 CONCENTRATION ON THE RATE OF PHOTOSYNTHESIS.
NAME THE PLANT YOU USED: Elodea
HOW DID YOU VARY LIGHT INTENSITY: using a lamp and by varying the distance of the lamp from the elodea.
STATE A FACTOR THAT YOU KEPT CONSTANT: Temperature
HOW DID YOU ENSURE THE FACTOR YOU MENTIONED REMAINED CONSTANT: Using a water bath
HOW DID YOU MEASURE THE RATE OF PHOTOSYNTHESIS: By counting the amount of bubbles per minute
SKETCH A GRAPH OF THE RATE OF PHOTOSYNTHESIS VARIED WITH THE FACTOR:
__________________________________________________________________________________________________________________
2008
NAME THE OPENINGS IN THE LEAF WHICH ALLOW FOR THE ENTRY OF CO2 FOR PHOTOSYNTHESIS.
- Stomata
STATE A FACTOR WHICH INFLUENCES THE DIAMETER OF THESE OPENINGS
- CO2
DURING PHOTOSYNTHESIS O2 IS PRODUCED.
- FROM WHAT SUBSTANCE IS O2 PRODUCED: Water
- IN WHAT STAGE IS O2 PRODUCED:Light
- GIVE TWO POSSIBLE FATES OF O2 FOLLOWING ITS PRODUCTION:: Respiration and Excretion
GIVE AN ACCOUNT OF THE ROLE OF EACH OF THE FOLLOWING IN PHOTOSYNTHESIS
- ATP: Traps and transfers energy in light to a dark stage
- NADPH: Traps and transfers H+ and used in dark stage
__________________________________________________________________________________________________________________
2009
EXPLAIN HOW YOU MEASURED THE RATE OF PHOTOSYNTHESIS:By counting the bubbles of O2 per minute.
EXPLAIN HOW YOU VARIED THE LIGHT INTENSITY: using a lamp and by varying the distance of the lamp from the elodea.
SATE HOW YOU KEPT ANOTHER FACTOR CONSTANT: Temperature and using a water bath.
EXPLAIN THE TREND IN YOUR GRAPH:
As light intensity increases, the rate of photosynthesis also increases until it becomes light-saturated, then the rate of photosynthesis levels off.
__________________________________________________________________________________________________________________
2010
AN AQUATIC PLANT SUCH AS PONDWEED RATHER THAN TERRESTRIAL PLANT WHEN INVESTIGATING THE RATE OF PHOTOSYNTHESIS.
Because it releases oxygen and it can be seen underwater as bubbles and therefore can be counted to measure the rate.
WHERE IN A PLANT CELL DOES PHOTOSYNTHESIS TAKE PLACE
- In the chloroplast
GIVE AN ALTERNATIVE NAME OF THE FIRST STAGE OF PHOTOSYNTHESIS:
- The Light stage
DURING THE FIRST STAGE OF PHOTOSYNTHESIS ENERGISED ELECTRONS ENTER TWO PATHWAYS.
- WHERE DO THE ENERGISED ELECTRONS COME FROM: From the chlorophyll ( as light hits the chlorophyll an energised electron is released.
- BRIEFLY DESCRIBE THE MAIN EVENTS OF EACH OF THESE PATHWAYS:
Pathway 1 {cyclic photophosphorylation} : Light hits the chlorophyll and an energised electron is released. This electron is passed through a series of carriers and the energy from it is used to convert ADP + P TO ATP. This electron goes back to the chlorophyll having lost its extra energy. Product ATP is made for the dark stage.
Pathway 2:
- Light hits chlorophyll and an energised electron is released.
- This electron is picked up by NADP+ and becomes NADP-.
- NADP- bonds to H+ ions from the splitting of water and becomes NADPH. The splitting of water {photolysis} releases an energised electron to a series of carriers and energy from it is used to convert ADP + P to ATP.
- The electron goes to the chlorophyll. During splitting of water H+ and OH- is released.
- Products ATP, NADPH is made for the dark stage and Oxygen is made which can be used in the respiration or can be released from the leaf as a waste product.
IN THE SECOND STAGE OF PHOTOSYNTHESIS COMPOUNDS OF THE GENERAL FORMULA Cx(H2O)y are formed WHAT IS THE NAME GIVEN TO THIS GROUP OF COMPOUNDS.
- carbohydrates
FROM WHICH SIMPLE COMPOUND DOES THE PLANT OBTAIN THE H USED TO MAKE COMPOUNDS OF THE GENERAL FORMULA Cx(H20)y?
- Water
NAME THE SIMPLE COMPOUND WHICH SUPPLIES THE NECESSARY ENERGY FOR THE 2ND STAGE REACTIONS.
- ATP
__________________________________________________________________________________________________________________
2011
WHY IS IT NECESSARY TO KEEP (TEMPERATURE) CONSTANT ?
- Because it might interfere with the results. So there is only one variable.
__________________________________________________________________________________________________________________
2012
WHAT IS THE MAIN SOURCE OF CO2 USED BY PLANTS IN THE DARK STAGE OF PHOTOSYNTHESIS.
- Respiration / Atmosphere
STATE ONE ROLE OF NADP: Traps and transfers H+ and electrons for reducing (converting) CO2 to glucose.
STATE ONE ROLE OF ATP: traps and transfers energy for bonding H+ to CO2 to make glucose.
__________________________________________________________________________________________________________________
2013
PHOTOSYNTHESIS : FIRST STAGE { PATHWAY 1 & PATHWAY 2 } --------> SECOND STAGE
GIVE THE NAME OF THE FIRST STAGE: the light stage
IN THE FIRST STAGE, PATHWAYS 1 AND 2 RELATE TO THE PASSAGE OF ENERGISED ELECTRONS.
- EXPLAIN WHAT HAPPENS TO THESE ELECTRONS IN PATHWAY 1.Light hits the chlorophyll and an energised electron is released.
This electron is passed through a series of carriers and the energy from it is used to convert ADP + P TO ATP.
This electron goes back to the chlorophyll having lost its extra energy.
Product ATP is made for the dark stage.
- DESCRIBE THE EVENTS OF PATHWAY 2.
Light hits chlorophyll and an energised electron are released.
This electron is picked up by NADP+ and becomes NADP-.
NADP- bonds to H+ ions from the splitting of water and becomes NADPH.
The splitting of water {photolysis} releases an energised electron to a series of carriers and energy from it is used to convert ADP + P to ATP. The electron goes to the chlorophyll.
During splitting of water H+ and OH- is released.
Products ATP, NADPH is made for the dark stage and Oxygen is made which can be used in the respiration or can be released from the leaf as a waste product.
GIVE THE NAME OF THE SECOND STAGE: The dark stage
EXPLAIN WHY? Because Light is not needed for the dark stage. It just needs the products of the light stage ATP and NADPH and the CO2 the plants breathes in.
GIVE ONE REASON THE SECOND STAGE CANNOT HAPPEN WITHOUT THE FIRST.
Because the products of the first stage are needed to convert CO2 into glucose.
OUTLINE THE MAJOR EVENTS OF THE SECOND STAGE.
- Carbon dioxide is converted to glucose using ATP from the light stage. ATP provides energy
- NADPH is needed for hydrogens and electrons.
- The ADP and P and the NADPH + made during this stage is reused in the light stage again.
__________________________________________________________________________________________________________________
2015
WHAT IS THE ENERGY SOURCE FOR THE DARK STAGE
- ATP
GIVE THE DETAILS OF THE DARK STAGE.
- Carbon dioxide is converted to glucose using ATP from the light stage. ATP provides energy
- NADPH is needed for hydrogens and electrons.
- The ADP and P and the NADPH + made during this stage is reused in the light stage again.
GIVE TWO USES OF THE MAIN PRODUCT OF THE DARK STAGE.
- Glucose is used in respiration
- Glucose can be converted to starch
SUGGEST ONE ADVANTAGE OF USING GENETICALLY MODIFIED CROPS
- Can enhance the rate of photosynthesis
__________________________________________________________________________________________________________________
2016
WHAT IS THE FATE OF CARBON IN CARBON DIOXIDE USED IN THE DARK STAGE
- Makes carbohydrates
GIVE ON REASON WHY A SUITABLE TEMPERATURE IS NECESSARY FOR THE DARK STAGE TO OCCUR
- Controlled by enzymes
__________________________________________________________________________________________________________________
2017
GIVE TWO WAYS BY WHICH PHOTOSYNTHESIS COULD BE ACCELERATED IN HORTICULTURE
- By increasing the temperature (glasshouse).
- By increasing CO2 levels.
EXPLAIN HOW ONE OF THE METHODS COULD ACCELERATE PHOTOSYNTHESIS
- Increasing temperature (up to a point) increases enzyme-controlled reactions; therefore, the rate of photosynthesis would increase.
WHAT HAPPENS TO BOTH ADP AND NADP+ AT THE END OF THE DARK STAGE
- They are reused again in the light stage
__________________________________________________________________________________________________________________
2018
STATE 2 OTHER WAYS IN WHICH THE LEAF IS ADAPTED FOR PHOTOSYNTHESIS.
- The leaf is very thin - this allows light to penetrate easily
- The air space allows for quick evaporation
DRAW A LABELLED DIAGRAM OF A TRANSVERSE SECTION THROUGH A LEAF