1.2 Photosynthesis Flashcards
What type of reaction is photosynthesis
Endothermic
What 2 reactants are needed for photosynthesis
Carbon dioxide and water
What are the 2 products of photosynthesis
Glucose and oxygen
learn the word and symbol equation for photosynthesis
Carbon dioxide + water ——> glucose + oxygen
(chlorophyll and light go above and below arrow)
Formula of glucose
C6H12O6
What are the layers of the leaf from top to bottom
Waxy cuticle
Upper epidermis
Palisade (mesophyll) layer
Spongy (mesophyll) layer
Lower epidermis - with stomata and guard cells
Where is the main site of photosynthesis in leaf
Palisade layer
How is the palisade layer adapted for photosynthesis
Cells contain many chloroplasts
Cells sit upright so can pack more in
Near upper surface
How does carbon dioxide reach the palisade layer
Enters in through the stomata - passes along the air spaces in the spongy layer and enters cell in palisade layer
How does water reach the palisade layer
Water enters through roots
travels up Xylem vessels in stem and enters leaf in veins
How to test leaf for starch
Destarch plant in dark cupboard for 48hrs
expose to light
remove leaf and boil in water
then boil in ethanol
wash leaf
spread out and add iodine
if starch present turns blue black
If a leaf is partially covered in card which part of the leaf will have starch
The part of leaf that is exposed will have starch - turn blue black
the part covered in card will stay yellow brown showing light needed for photosynthesis
Another experiment may be to count bubbles of oxygen produced. You can then work out rate of photosynthesis.
What other measurement would you need to take to work out rate
Time - need to know rate which is number of bubbles/time
In the experiment measuring rate of photosynthesis by counting bubbles- why is a transparent glass shield put between lamp and experiment
So light passes through but the temperature does not change (from heat of lamp)
How can you change light intensity in an experiment
Move the lamp further away from plant
What is meant by limiting factor
A factor that will prevent photosynthesis happening at its highest rate
What are the 3 main limiting factors of photosynthesis
Carbon dioxide
Light intensity
Temperature
On the graph showing light intensity against rate of photosynthesis - the graph initially increases and then levels out. What is the initial limiting factor?
The light intensity
- as the light intensity increased initially the rate also increases so this shows that light was slowing down photosynthesis at this stage
On the graph showing light intensity against rate of photosynthesis - the graph initially increases and then levels out. What is the limiting factor when the graph levels out
No longer light as even though light intensity still incresing the rate is staying the same.
Other factors such as temperature or carbon dioxide now limitin
What happens to the rate of photosynthesis if the temperature increases too much
The rate of photosynthesis decreases because enzymes for the reaction are now destroyed (denatured)
What is the name of the indicator that shows changes to carbon dioxide levels
Hydrogen Carbonate indicator
If rate of photosynthesis is greater than rate of respiration what colour does the hydrogen carbonate turn and why
Goes from Red to Purple
Carbon dioxide levels are going down (as used in photosynthesis) at a greater rate than Carbon dioxide being made in respiration
If the rate of photosynthesis is the same as rate of respiraiton what is this known as
What time of the day is this most likely to occur
Compensation point
happens at sunrise and sunset
What colour will hydrogen carbonate turn at the compensation point
It will remain red - levels of carbon dioxide balanced as rate at which carbon dioxide produced in respiration = rate at which carbon dioxide is used in photosynthesis
