Biology 2 - Photosynthesis Flashcards
What does photosynthesis do?
Produces food for plants
In what part of the plant does photosynthesis mostly take place?
Leaves
What’s the word equation for photosynthesis?
Carbon dioxide+water->glucose+oxygen
Where is chlorophyll found and what does it do?
Found in chloroplasts
Absorbs the light energy
What is light energy used for in photosynthesis?
To concert carbon dioxide and water into glucose
Oxygen is given off as a by product during photosynthesis. How can you use this to measure the rate of photosynthesis?
Water plants- put in a beaker of water and count the number of bubbles produced per minute
Or measure the volume collected per minute
Plant used is elodea aka pond weed
How can you measure the effect of light intensity
Measure oxygen produced with lamp at different distances
What electronic equipment can be used to get precise measures of the rate of photosynthesis? (2)
Oxygen/CO2 sensors and data loggers
Oxygen produced, carbon dioxide used up
Name the environmental factors affecting the rate of photosynthesis
Temperature
Light intensity
Carbon dioxide concentration
(Limiting factor controls rate)
If starch is present on a leaf what colour will it turn when covered in iodine?
Dark blue/black
What does the presence of starch on a leaf indicate? Why?
That photosynthesis has happened because glucose can’t be stored so is either used up or stored as starch
Why does the plant have to be kept in the dark prior to the photosynthesis starch experiment
It will use up its starch supply so any starch present will have been made by photosynthesis afterwards
Stages of testing plant for starch?
- Boil leaf (breaks down cell membrane- iodine enters more easily)
- Put the leaf in ethanol and place in hot water (removes green colour by dissolving chlorophyll)
- Remove leaf and wash it (softens it)
- Cover it in iodine (should go blue/black if contains starch)
How do you prove chlorophyll is needed for photosynthesis?
Variegated leaf - test for starch - only green bits have it
How do you show light is needed for photosynthesis?
Deprive part of leaf of light using stencil - test for starch - only bits exposed to light have it
How do you prove CO2 is needed for photosynthesis?
2 jars with plants - one with soda lime (absorbs it), one win marble chips (releases it) - test for starch - only works with CO2
If you remove water from a plant what will happen?
It will die
What are the uses of glucose in photosynthesis?
Releases energy
Changed to starch and stored
Make cellulose/protein which make up body of plants
