in what direction are substances transported during translocation?
upand down
where does transpiration happen?
xylem
in what direction are substances transported during transpiration?
up
what substance is transported by translocation?
sugars/sucrose
what substances are transported by transpiration?
water and dissolved minerals
what are inbetween adjacent phloem cells in a column?
pores
what is the purpose of pores in a phloem column?
they enable the movement of cell sap (a liquid mixture of water and sugar)
in translocation, what happens once the sugars that were made in the leaves, make it to whatever cells they're going to?
they are either directly usedforenergy or storedtobeusedforenergy later
what is the movement of water through a plant driven by?
the evaporation of water from the leaves
what is the structure of the phloem in translocation?
phloem cells joined together end to end to form a phloem tube
what is the structure of the xylem in transpiration?
a long column of xylemcells but they're dead cells with no ends between them so they form 1 long, hollow tube
what material strengthens the xylem tube?
lignin
what is the role of the xylem tube in transpiration?
to transport water and mineral ions from the roots, up the stem, to the leaves, where the water can be used in photosynthesis
what are the 4 factors that affect the rate of transpiration?
temperature, humidity, light intensity, air flow
in transpiration, why is there a steady stream of water flowing up the plant?
water is continually evaporating, because the stomata need to be open to letin the carbon dioxide
how does light intensity affect the rate of transpiration? (in terms of CO2)
the brighter the light intensity, the more photosynthesis that can take place meaning that more stomata will have to be open to let in the carbon dioxide required for photosynthesis.
how does light intensity affect the rate of transpiration? (in terms of water)
the brighter the light intensity, the more water that can evaporate, meaning a higher transpiration rate
how does light intensity affect the rate of respiration? (in terms of the night)
stomata are closed at night as there is no light, meaning there is very little transpiration
how does temperature affect the rate of transpiration?
the warmer the temperature, the higher the transpiration rate. The water particles will have more energy and so are more likely to diffuse out of the stomata
how does air flow affect the rate of transpiration?
when air flow is high (windy) then the water molecules that leave the leaf are quickly blown away so the concentration gradient between the inside and outside are going to be kept high, increasing the rate
how does humidity affect the rate of transpiration?
more humid air will decrease the rate as the large amount of water in the air will decrease the concentration gradient meaning less water is going to diffuse out and so we have less evaporation overall
what is transpiration caused by?
the evaporation and diffusion of water from a plant'ssurface
what does the loss of water in a plant create?
a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through xylem vessels to replace it
what does the translocation process require?
energyfromrespiration
what do root hair cells take in?
water and mineral ions
what is the purpose of the hairs on a root hair cell?
gives the plant a large surface area for absorbing water and mineral ions from the soil
what is the equation for photosynthesis?
carbon dioxide + water = glucose + oxygen
what is the balanced symbol equation for photosynthesis?
6CO2 + 6H2O = C6H12O6 + 6O2
where does photosynthesis happen?
inside chloroplasts, they contain chlorophyll which absorbs light
what transfers energy to the chloroplasts?
Sunlight
what type of reaction is photosynthesis?
endothermic (energy is taken in during the reaction)
what factors affect the rate of photosynthesis?
light intensity, the concentration of CO2, temperature
what is the purpose of stomata?
allows CO2 to diffuse directly in and out of a leaf. They also allow water vapour to escape during transpiration
what are stomata surrounded by?
guard cells, which change shape to control the size of the pore
when are the stomata open/closed?
when the guard cells are turgid (swollen with water) the stomata are open, when the guard cells are flaccid (low on water and limp) the stomata are closed
what piece of apparatus is used to estimate transpiration rate?
potometer
how do you use a potometer to estimate transpiration rate?
set up the apparatus and record the startingposition of the air bubble. Start a stopwatch and record the distancemoved by the bubble per unit time. Calculating the speed of air bubble movement gives an estimate or transpiration rate
what is the purpose of the palisade layer of a leaf?
it has a lots of chloroplasts, meaning that they're near the top of the leaf where they can get the most light
what is the purpose of the upper epidermis?
it's transparent so that light can pass through it to the palisade layer