Plant structures and Functions Flashcards
what does chlorophyll do?
absorbs light
equation for photosynthesis
carbon dioxide + water - glucose + oxygen
what kind of reaction is photosynthesis?
endothermic reaction
what effects the rate of photosynthesis?
light intensity
concentration of CO2
temperature
what is a limiting factor?
something that stops the reaction happening any faster
Light intensity relationship
the rate of reaction is directly proportional to light intensity up to a certain point
why does the light graph plateau?
Because temperature or volume of CO2 needs to be increased as is the limiting factor
relationship between distance of lamp and light intensity
they are inversely proportional so when the distance increases the light intensity decreases
Temperature for photosynthesis
enzymes needed for photosynthesis work slower at low temps
if it gets too hot the enzymes denature at around 45 degrees
Root hair cell function
takes in minerals and water through active transport and osmosis
Root hair cell structure
covered in millions of micro hairs
large surface area to absorb
What are phloem tubes?
made up of columns of elongated living cells with small pores in the end walls to allow stuff to flow through
what do phloem tubes do?
transport food substances for immediate use or storage
what is translocations?
transport of food using energy from respiration in both directions
what are xylem tubes?
made up of dead cells joined end to end with no end walls between them and a hole down the middle.
what strengthens xylem tubes?
lignin
what do xylem tubes do?
carry water and mineral ions from roots to stem and leaves
what is a transpiration stream?
movement of water from roots through xylem and out of the leaves
what causes transpiration?
evaporation and diffusion of water from a plants surface
what is transpiration?
loss of water from the plant
what does transpiration cause?
a slight shortage of water in the lead
How to deal with the shortage of water
more water is drawn up from plant through xylem vessels and causes a constant transpiration stream
what are stomata?
tiny pores on the surface of a plant
what do stomata cells do?
allow gas exchange through diffusion in and out of the leaf.
What escapes through the stomata?
water vapour
why does the water escape?
because there’s more water inside the plant than outside so it diffuses out the leaves
what happens when guard cells are turgid?
the stomata is open
what happens when guard cells are flaccid?
the stomata is closed
what do guard cells do?
change shape to control the size of the pore
Light intensity affect on transpiration
the brighter the light the greater the transpiration rate
Temperature affect on transpiration
the warmer it is the faster the transpiration happens
why does this happen due to temperature?
particles have more energy to evaporate and diffuse out
air flow affect on transpiration
the better the air flow the greater the transpiration rate
what happens if the air flow is poor around the leaf?
water vapour just surrounds the leaf and doesn’t move away because there is a high concentration inside as well as outside so diffusion doesn’t happen as quick
what happens if there is good air flow around the leaf?
water vapour is swept away maintaining a low concentration of water in the air outside the leaf and diffusion happens quickly
how to estimate transpiration rate?
use a potometer which measures water uptake
start stopwatch and record distance moves by bubble per unit time
what is the problem with a potometer?
is assumes that water uptake by the plant is directly related to water loss from the leaves
