Photosynthesis

11/05/10

-light-dependent reaction/photolysis light plays an important role in electrolysis (using electric current to split a molecule - in this case, water molecules)

three primary colours of light - RBG plants absorb red and blue light, reflecting only green

-different colour pigments in plants e.g. carotene, xanthophyll different plants absorb different colours of light


 * label cross section of a leaf/chloroplast

-chloroplasts have double-membranes and interconnected stacks -contain DNA -could have been single celled blue-green algae

-phloem contain plant sap and are closer to the bark than the xylem is. -aphids just need to have a sharp mouth to pierce the bark and due to the pressure, the sap will gush out -ants will eat the aphids' excretion (the excess sap), contained with sugar

cells of the palisade layer are very compact at the upper part of the leaf to maximise photosynthesis the longer axis of the palisade mesophyll is arranged perpendicular to the upper epidermis every palisade mesophyll cell contains chloroplasts structure -> function

stomata are used to take in air the plant takes in carbon dioxide water will evaporate out through the stomata putting stomata on the underside of the leaf ensures that not too much water gets evaporated

water - stable polar molecule sunlight removes electron

-light independent reaction/carbon fixation calvin cycle takes place in stroma, chemical reaction

13/05/10 ATP -> ADP -> AMP


 * Structure || Function ||
 * spongy mesophyll are irregular cells with large intercellular space || so that air can enter easily ||
 * lower epidermis has more stoma with guard cells than upper epidermis || to cut down water loss through transpiration ||
 * stoma regulated by guard cells || to allow gaseous exchange ||
 * leaf is thin and flat, with large surface area || large surface area to volume ratio for absorption of sunlight/so that air from lower epidermis can also transport up ||
 * has main stalk/vein || exposes large surface area to maximum amount of sunlight, so that leaf does not flop ||
 * presence of xylem || so that water can be transported ||
 * presence of phloem || so that photosynthesised nutrients can be drawn away, thus not increasing the osmotic concentration too much ||
 * cells of the palisade layer are very compact and longer axis of the palisade mesophyll cells are arranged perpendicular to the upper epidermis, every cell contains chloroplasts || to maximise the exposure of chloroplasts to sunlight so that more photosynthesis can take place ||

after obtaining glucose, plants convert them to starch for storage to ensure that he glucose does not increase the osmotic concentration too much starch is better as storage substance: -inert -insoluble

the process of putting a plant in a dark room is called de-starching

leaf experiment -boil water in hot water to kill enzymes and stop reaction -put in ethanol to dissolve the fats in the plasma membranes of the plant so as to decolourise it

temperature affects the rate of reaction of photosynthesis due to enzymes which require a specific temperature