PHOTOSYNTHESIS

Question 1

in the experiment to test for starch, what is the step to prepare for the experiment

Answer 1

you have to destarch the leaf by leaving it in the dark to stop photosynthesis. it will use up all its energy store of starch as it cannot photosynthesise

Question 2

equation for photosynthesis

Answer 2

carbon dioxide + water -> glucose + oxygen

                                     sunlight 6CO2                + 6H2O      ->           C6H12O6 + 6O2
                                     chlorophyll

Question 3

what product of photosynthesis is used to make starch

Answer 3

glucose polymerises to make starch which is more stable

Question 4

define the rate limiting factor of photosynthesis in plants

Answer 4

plants compete vigorously with each other - they need to gain access to light which is required to the power of photosynthesis. Even if the leaf gets plenty of light, it’s rate of photosynthesis may be limited by another factor. There is always some factor which provide a limit to the maximum rate of photosynthesis which is called the rate limiting factor.

FACTORS:
light intensity
carbon dioxide concentration
temperature

Question 5

in the experiment to test for starch, describe the steps that take place.

Answer 5

1) The leaf needs to be killed by dunking it in hot water (use tweezers) this stops any chemical reactions from happening inside the leaf
2) Place the leaf into a boiling tube with some ethanol which you should then heat in a water bath. - This gets rid of any chlorophyll that’s inside of the leaf… the colour of the leaf should go from green to white (this helps us see the colour change from yellow to blue black in the starch test)
3) Finally rinse the leaf in cold water and add a few drops of iodine solution - if starch is present it will turn blue black