Xylem / Phloem / Transpiration

Question 1

give the function of xylem

Answer 1

to carry water and minerals from roots to the stems and leaves

Question 2

give 3 examples of structures that help the xylem with transpiration

Answer 2

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

Question 3

how do the hollow tubes aid transpiration in xylem

Answer 3

continuous tubes allow water to move through plant easily

Question 4

how does lignin help transpiration in xylem

Answer 4

prevents water leaking

Question 5

how do the lignin spirals help transpiration in the xylem

Answer 5

strengthens the plant

Question 6

what is the function of phloem

Answer 6

to transport dissolved sugars and amino acids from leaves to the rest of the plant for immediate use or storage

Question 7

give 2 examples of special structures in the phloem that helps with translocation

Answer 7

sieve tubes with perforated ends to connect to other sieve tubes

companion cells that stratify to sieve tubes to provide energy for translocation

Question 8

how do sieve tubes help phloem with translocation

Answer 8

sieve tubes connect together to transport dissolved sugars and amino acids

Question 9

how do companion cells help phloem with translocation

Answer 9

companion cells provide energy which is required for translocation

Question 10

what happens during transpiration

Answer 10

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

Question 11

what is the cohesion tension theory

Answer 11

water molecules are attracted to each ither so they move up in one continuous column

Question 12

what do guard cells do during transpiration

Answer 12

guard cells swell and become turgid so stomata opens and water can evaporate

Question 13

what are 4 factors that affect transpiration

Answer 13

light
temperature
humidity
air movement

Question 14

how does light affect transpiration

Answer 14

stomata open in the light and close in the dark as there is no photosynthesis so there is more transpired in the day time

Question 15

how does temperature affect transpiration

Answer 15

water particles have more kinetic energy so more transpiration occurs at higher temperatures

Question 16

how does humidity affect transpiration

Answer 16

more humidity means less transpiration as there is more water in the air so there is a lower concentration gradient

Question 17

how does air movement affect transpiration

Answer 17

moves humid layer of air away which increases the concentration gradient which increases transpiration

Question 18

give two ways to measure the rate of transpiration

Answer 18

measure the decrease in mass due to water loss

measure the volume of water dissolved

Question 19

what is used to measure the volume of water dissolved

Answer 19

a potometer

Question 20

what is a potometer made up of (4)

Answer 20

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

Question 21

what does it mean if the bubble moves fast in the potometer

Answer 21

the faster the bubble moves , the greater the rate of water uptake

Question 22

why is the capillary tubing in the potometer small and thin

Answer 22

to make measurements more accurate and give a higher resolution / accuracy

Question 23

what is the equation for rate of transpiration

Answer 23

distance
—————
time