B2: Photosynthesis Flashcards
What is the equation for photosynthesis?
6CO₂ + 6H₂O = C₆H₁₂O₆ + 6O₂
Why is glucose stored as starch?
Glucose is stored as starch as it is a more compact molecule. Furthermore starch is insoluble meaning it will not effect osmosis and prevents water loss.
What are other uses of glucose?(4)
- reacts with nitrates to make proteins
- used for respiration
- makes cellulose
- stored as starch
Are plants able to respire at night?
Plants ARE able to respire at night as long as starch or glucose is present. This is because respiration does not require light, unlike photosynthesis.
What are the limiting factors of photosynthesis?(3)
- concentration of CO₂ light intensity
- volume of water
What is the function of the waxy cuticle?
It protects the plant
What is the function of the guard cells?
They open and close, so gases can enter the cell through diffusion
What is the function of the palisade cells?
Large surface area for light absorption
What is the function of the spongy mesophyll?
Allows gases to pass through
What is the function of the epidermis?
Allows light to pass through
What is the function of the veins?
They carry water
What is the function of the chlorophyll?
It gives the plant its green colour
The phloem(4)
- has companion cells which store all the organelles, meaning it controls the cell functions
- has end walls with pores in them to allow sugars and amino acids to pass through
- has a source cell for substances to made
- substances go upwards and downwards
Xylem(3):
- has thick walls that are made of dead cells to withstand high water pressure
- water only travels in one direction
- has NO end cells so water can pass through easily
Define translocation
The movement of sugars and amino acids through the phloem
Define transpiration
The movement of water in a plant
Define diffusion
The movement of particles from a high to low concentration
Define osmosis
The movement of water particles through a partially Permeable membrane
Define active transport
The movement of particles against the concentration gradient
Define hydroponics
When plants are grown under water as there is a prefect balance in mineral ions
Greenhouses
+ protects plant +clear, allows light to pass through +lights at night + controlled CO₂
- expensive - ruins the look of the countryside - use a lot of energy
Why might some farmers prefer to use poly tunnels?
Polytunnels are cheaper as they are made of plastic. Some polytunnels can even control the concentration of CO₂ and light intensity
What is the adaption of a root hair cell?
They have a large surface area to absorb more water
Describe the transport of water through a plant from the roots to the atmosphere(3):
- Water goes from the root hair cell to the xylem through osmosis
- It moves up the xylem by transpiration
- It is then carried by the veins to the leaves where it evaporates into the atmosphere
