photosynthesis Flashcards
what do plants need for phoyosynthesis?
-chlorophyll absorbs the liht energy
-(raw material) carbon dioxide diffuses into the leaves from the air
-(raw material) water is absorbed by the roots from the soil
word equation for photosynthesis?
carbon dioxide+water= glucose +oxygen
is photosynthesis an endothermic reaction?
yes, energy is absorbed into the plant
how do you know what is needed for photosynthesis?
if you take away all of the factors then the plant won’t photophynthesize
how do you destarch a plant?
leaving it in a dark room for 48hrs and the plant will use up the starch it has stored in its leaves as food
how do you test leaf for starch?
- Dip the leaf into boiling water
(to kill and stop any reactons) - Turn of bunsen burner
- Put the leaf intothe test tube of Ethanol and stand it in the beaker of hot water for 10 mins
(to remove chlorophyll) - Wash the leaf in hot water
(soften the leaf) - Spread the leaf onto a white tile and cover with iodine solution
(to stain any starch present)
how do you prepare a destarched leaf to test if it has starch?
Cover part of the destarched leaf wit tin foil which will prevent any light getting at it (no photosynthesis- no starch present- no colour change in covered parts)
what happens to a variegated leaf?
It has white parts aswell as green. The white parts contain chlorophyll and therefore won’t photosynthesis (if tested for starch- no colour change)
is carbon dioxide needed for photosynthesis?
Plants require carbon dioxide as it produces glucose and stors it in the form of starch.
factors affecting the rate of photosynthesis
-light intensity
-carbon dioxide concentration
-tempeure
factors that have to be considered to get a good crop yield
- Light- more light availablethe faster rate of photosynthesis, artificial light must contain red and blue colours
- Caron dioxide- it is pumped into greenhouses. If an oil/gas burner is used it will also increase the tempetureaswell as C20
- Tempeture- 10 degrees could double rate of photosynthesis. Tempeture above 40degrees the enzymes in the plants can becoe denatured
- Fertilisers- ensure its not raining when fertilisier is spread and to record each concentration of fertiliser for each crop yeild
-structure of a leaf-
wax cuticle
Waterproof layer that cuts down the water lost by evapouration
-structure of a leaf-
spongy layer
More rounded cels withlots of air spaces between them. Gas exchange occurs here
-structure of a leaf-
lower epidermis
No thick cuticle. Has lots of tine holes called stomata, allows gases to diffuse in and out
-structure of a leaf-
upper epidermis
single layer of cells with no chloroplasts, light goes right through
-structure of a leaf-
palisade layer
the palisade cell contains lots of chloroplasts, most photosynthesis happens here
-structure of a leaf-
vien
contains tubes called xylem that bring water and salts to the leaf and tubes called phloem and take away dissolved food away
how has the leaf been adapted to photosynthesis efficiently
-light absorbtion
-gas exchange
-how the leaf has been adapted-
light absorption
1)
-Leaves are thin which means a short distance from top to bottom toallow all cells to receive light
-Large surface area
-how the leaf has been adapted-
light absorption
2)
-Waxy cuticle is transparent and thing to allow light through but prevents water loss by evapouration, upper epidermis is also transparent (no chloroplasts present)
- Palisade layer are packed tightlty together on the upper surface area of the leaf (lot of chloroplats)
-how the leaf has been adapted-
gas exchange
- Air spaces- in the spongy mesophyll layer allows carbon dioxide to enter and oxygen to leave
-how the leaf has been adapted-
gas exchange
- Stomata pores- allows carbon dioxide to enter and oxygen to leave. Each stomata is surruonded by two gaurd cells that regualate the opening and closing of the stomata
-adaptions-
epidermis is thin and transparent
to allow more light to reach pallisade cells
-adaptions-
thin cuticle made of wax
waterproof to reduce water loss and transparent to allow light through
-adaptions-
palisade layer at top of leaf
tightly packed, lots of chloroplasts ot absorb more light
-adaptions-
spongy mesophyll layer
have little chloroplasts and alarge surface area for gas exchange
-adaptions-
palisade cells contain lots of chloroplasts
to absorb all available light
-adaptions-
intercellur spaces
air spaces allow carbon dioxide to diffuse through theleaf and inrease the surface area
-adaptions-
gaurd cellsand stomata
allow gasses to diffuse in and out of the leaf
what do plants do with the glucose made in photosynthesis
starch- energy storage
cellulose- cell walls
amino acids- proteins for health
lipids- energy store
glucose (respiration)- realse energy
respiration:
glucose+oxygen=carbon dioxide+water
-take in oxygen and give out carbon dioxide
-takes place all the time
photosynthesis:
carbon dioxide+water=
glucose+oxygen
-take in carbon dioxide and give out oxygen
-only happens when there is light
products of photosynthesis
glucose and oxygen
products of respiration
carbon dioxide and water
bicarbonate indicator
(hydrogen carbonate indicator)
give an indicationof changes in the conentration of carbon dioxide present in the solution
-bicarbonate indicator-
more carbon dioxide
YELLOW
-night
-if there is an increase in carbon dioxide concentration the plant must be respiring more than photosynthesising
-bicarbonate indicator-
normal
RED
-dawn/dusk
-no colour change in carbon dioxide concentration then photosynthesis and respiration must be equal
-bicarbonate indicator-
less carbon dioxide
PURPLE
-day
-decrease in carbon dioxide concentration then the plant must be photosynthesising more than respiring
