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Biology (Transpiration & Factors Affecting Transpiration Summer} …
Biology (Transpiration & Factors Affecting Transpiration Summer} :sweat_smile:
Transpiration- the evaporation of water from the surface of a plant
Full Process:
water moves into root cells via osmosis, water moves up the xylem because of the transpiration stream, each water molecule 'pulls' the one below it, loss of water through evaporation of water at the surface of the spongy mesophyll cells followed by the water vapour through the stomata when they are open.
Function
transport mineral ions
provide water to keep plant cells turgid (structure)
provide water for photosynthesis
keep leaves cool from conversion of liquid to gas (water vapour) when it leaves the plant
Factors Affecting Transpiration
wind speed
as wind speed increases the rate of transpiration increases. This is because the faster the wind speed the quicker water vapour from the surface of the leaf will move so the concentration gradient for diffusion is larger
temperature
as temperature increases the rate of transpiration increases. This is because at higher temperatures the water molecules have more kinetic energy allowing for faster diffusion
humidity
as humidity increases the rate of transpiration decreases. This is because when there is more water vapour (moisture) in the air concentration gradient for diffusion is smaller
light intensity
as light intensity increases the rate of transpiration increases. This is because the guard cells are turgid and will open when the light intensity is high allowing more water to evaporate via the stomata
Multicellular vs Unicellular Transport Systems
Unicellular Organisms:
rely on diffusion for the movement of substances in and out of the cell because of their large surface area to volume ratio.
Multicellular Organisms:
rely on transport systems for the movement of substances in and out of cells because of their inability to use diffusion due to the small surface area to volume ratio
single circulatory system
found in fish where blood only pumped by the heart one time in a complete circuit of the body
double circulatory system
found in humans where the blood is pumped by the heart two times in a complete circuit.
differences
-fish heart has two chambers rather than 4 -fish heart has less valves -fish heart has no septum -fish heart have similar chamber walls thickness, human heart chamber walls are different thicknesses.-when blood leaves heart it will be deoxygenated and go to the gills
Transport System in Plants (Vascular Bundle)
Phloem
used to transport sugars and amino acids from the leaves to the rest of the plant.
Structure--
flow is up and down made of living cells thin permeable cell wall made of cellulose, companion cells on the side contains nucleus that controls the phloem
Xylem
used to transport water and mineral ions from the roots to the other parts of the plant.
Structure--
flows up transpiration stream, no cytoplasm, made of dead cells, thick cell wall made of lignin
Root Hair Cells
where absorption of water and mineral ions takes place via osmosis and active transport
Adaptations
long and narrow so higher SA:V, large concentration gradient
Xylem on the inside to withstand stretching forces as they take in lots of water & Phloem on the outside to resist this compression
Translocation in Phloem
The phloem is a sieve tube that has cells joined end to end, there are pores between these cells (sieve plates) that allow sugars and amino acids passage from the source (leaf) to the sink (where it will be stored/used)
Investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot.
Method:
1) Set up potometer.
2) Cut the leafy shoot underwater to prevent air bubbles from entering the vascular tissues and insert the potometer.
3) Use Vaseline to seal gaps to make it airtight.
4) Set up environmental factors -temperature controlled room, humidity wrap shoot in plastic bag after spraying water, wind speed set up fan varying distances speed, light intensity set up lamp varying distances.
5) Allow time for apparatus equilibrate.
6) Record starting position of air bubble.
7) Leave for hour.
8) Record final position of air bubble and calculate the distance moved calculate the volume of water absorbed by the plant in the period of time.
9) Repeat and change factor.
10) Plot a graph of the factor (x-axis) against the volume of water uptake.
DORIC
D:volume of water uptake. O:leafy shoot R: repeat with different factors I: environmental factors C: other factors, species of plants
Sources of Error
plant dying when stem cut, some water is used for photosynthesis and cell turgidity, temperature may change with lamp use LED