Xylem / Phloem / Transpiration Flashcards
give the function of xylem
to carry water and minerals from roots to the stems and leaves
give 3 examples of structures that help the xylem with transpiration
cells due to form hollow tubes that run from roots to the leaves
walls contain lignin, a woody waterproof substance
lignin forms spirals in xylem tube
how do the hollow tubes aid transpiration in xylem
continuous tubes allow water to move through plant easily
how does lignin help transpiration in xylem
prevents water leaking
how do the lignin spirals help transpiration in the xylem
strengthens the plant
what is the function of phloem
to transport dissolved sugars and amino acids from leaves to the rest of the plant for immediate use or storage
give 2 examples of special structures in the phloem that helps with translocation
sieve tubes with perforated ends to connect to other sieve tubes
companion cells that stratify to sieve tubes to provide energy for translocation
how do sieve tubes help phloem with translocation
sieve tubes connect together to transport dissolved sugars and amino acids
how do companion cells help phloem with translocation
companion cells provide energy which is required for translocation
what happens during transpiration
water is absorbed through the roots via osmosis and is moved up the stem in the xylem vessels by the cohesion tension theory to evaporate from the stomata
what is the cohesion tension theory
water molecules are attracted to each ither so they move up in one continuous column
what do guard cells do during transpiration
guard cells swell and become turgid so stomata opens and water can evaporate
what are 4 factors that affect transpiration
light
temperature
humidity
air movement
how does light affect transpiration
stomata open in the light and close in the dark as there is no photosynthesis so there is more transpired in the day time
how does temperature affect transpiration
water particles have more kinetic energy so more transpiration occurs at higher temperatures
how does humidity affect transpiration
more humidity means less transpiration as there is more water in the air so there is a lower concentration gradient
how does air movement affect transpiration
moves humid layer of air away which increases the concentration gradient which increases transpiration
give two ways to measure the rate of transpiration
measure the decrease in mass due to water loss
measure the volume of water dissolved
what is used to measure the volume of water dissolved
a potometer
what is a potometer made up of (4)
a container of water
a capillary tube
rubber tubing that connects capillary tube to stem of leaf
scale to measure the distance travelled by bubble in capillary tube
what does it mean if the bubble moves fast in the potometer
the faster the bubble moves , the greater the rate of water uptake
why is the capillary tubing in the potometer small and thin
to make measurements more accurate and give a higher resolution / accuracy
what is the equation for rate of transpiration
distance
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time
