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Photosynthesis How plants make their food, Photosynthesis is Anabolic,…
Photosynthesis
How plants make their food
Energy Conversion
Light to chemical energy
Plants are
autotrophs
, (producers) as they make their own food
Location of Photosynthesis in the cell: Chloroplast
Temperature
Suitable temperature is needed for photosynthesis to occur, as it is controlled by enzymes and temperature affects enzymes
4 Requirements for photosynthesis
Carbon Dioxide
CO2 diffuses into the leaf from the air or CO2 made from respiration is used
Water
Enters root by osmosis from soil + travels up through the xylem to the leaf
Chlorophyll
Stored in chloroplast in the palisade layer. Plants reflects green light
Light
Absorbed though the green pigments from the sun
Products made during Photosynthesis
Glucose
Monosaccharides. If in excess can be stored as starch in vacuoles, used in respiration or converted to protein
O2
O2 diffuses out through the stomata into the air or it can be used by the plant in aerobic respiration
Photosynthesis word equation
Carbon Dioxide + Water --------> Glucose + oxygen
Chemical Equation for Photosynthesis
6CO2 + 6H2O --------> C6H12O6 + 6O2
Internal structure of a leaf, (T.S of a Leaf)
Epidermal layers are for protection
Chloroplasts are the cell organelles in the palisade layer that trap light for photosynthesis, so photosynthesis occurs here
In the vein xylem tissue which carries water to the palisade layer for photosynthesis and phloem carries away food that's mae to other parts of the plant
Air spaces in the spongy mesophyll allow gases to move through the leaf easily for photosynthesis
How is the leaf adapted for Photosynthesis
Leaves a large flat surface area to capture as much possible light
Thin to allow rapid diffusion of grass
Cuticle and epidermis are transparent to allow light through
Palisade layer which is at the top of the leaf is packed with chloroplast to trap light (Photolysis)
Stomatas for gaseous exchange
Air spaces in the spongy mesophyll for rapid gaseous exchange of gases
Veins in the leaf have xylem and phloem to carry water and food to and from leaf
Co2 and Opening/Closing of Stomata
Day-Time Stoma Open
When there is sunlight, Co2 levels start to decrease in the guard cells as it is used up in photosynthesis, in palisade layer
Water from nearby cells starts moving into the guard cells by osmosis forming the turgid kidney shape which opens up
Night-Time Stoma Closed
At night, no light so photosynthesis stops but respiration continues, Co2 is made and accumulates in the guard cells
Water moves out of the guard cells and the guard cells lose their turgid kidney shape causing the stoma to close
Human Intervention in Photosynthesis
Artificial Light
In greenhouses to extend the photosynthesis time
Extra Co2
Into greenhouses by burning fossil fuels to speed up photosynthesis
Rate of Photosynthesis varies when a plant is subjected to Varying Levels of Light Intensity
Photosynthesis is Anabolic
Lenticels, holes in bark or stems allowing for gaseous exchange
Opening/Closing of stomata depends on the Co2 Levels