Photosynthesis Flashcards
What is photosynthesis?
It is a chemical reaction that is of the form
6CO2 + 6H2O –> C6H12O6 + 6O2
The plant uses the light energy from the sun that is tapped by the chlorophyll (a green pigment) to complete this reaction and create glucose. This can then be burnt for respiration. The plant stores it as starch.
Where does Photosynthesis occur?
It occurs in the chloroplasts in a cell.
What is Glucose used for?
It used as an energy source. It can also be reacted to make other sugars that are easy to store. It makes cellulose in cell walls and it is used for growth.
What is the Cuticle?
The cuticle is the top layer of the leaf. It is waxy and transparent. It prevents the leaf from losing moisture through evaporation.
What is the upper epidermis?
It is the top layer of the leaf. It protects the layers below and it is transparent so that it allows light through.
What is the Palisade layer?
It is an extremely densely packed layer full of Palisade cells that have lots of chloroplasts. This layer absorbs all of the light that comes through, and it is adapted to get the most light possible.
What is the Spongy mesophyll?
It is below the palisade layer. It has less chloroplasts, as there isn’t as much light. There are lots of air pockets which allow the gases to flow in and get to each cell before diffusing.
What is the Lower epidermis?
It is the skin and protective layer on the bottom of the leaf. It has lots of small holes called Stomata that allow gas exchange. There are guard cells around the Stomata that control when it opens and closes in order to minimise water loss.
What are the two veins?
There is the xylem which transports water and minerals from the roots and there is phloem which transports glucose around the plant.
How are gases transported?
Through diffusion.
How can one test a leaf for starch?
You can drop iodine onto the leaf. If the iodine turns bluish black then it has starch in it.
How can you remove chlorophyll from a leaf?
Firstly place it in boiling water to kill the leaf, then place it in boiling ethanol.
How do you remove CO2 from a sealed jar?
Soda lime absorbs Carbon Dioxide.
What factors affect the rate of photosynthesis?
Temperature, light level, CO2 level and water level.
What determines whether the stomata are open?
Open stomata cause water loss, so when the leaf has enough water, then the guard cells are turgid and open the stomata. However, when they become plasmolyzed, the stomata close. They are also light sensitive, so when it is night time and there is no photosynthesis, they close.
