transport in plants (topic 8) Flashcards
function xylem
transporting water and dissolved mineral ions from the roots, through the stem and to the leaves
providing support for the plant and helping to keep it upright.
function phloem
transport sucrose and amino acids
structure of xylem and their adaptations for their function
thick walls with lignin for support
no cell content (hollow) and cells joined end to end with no cross walls to form a long continuous tube to transport water
in roots how are phloem and xylem
x- xylem
phloem rest
in stems how are phloem and xylem
xylem towards inside and phloem towards outside
in a leaf vascular bundle
xylem on top phloem on bottom
root hair cells
Type of cell in plant roots that has a large surface area for the absorption of water and mineral ions from the soil, increases surface area of root
pathway of water in plants
soil- root hair cells- root hair cell cortex- xylem- stem- mesophyll cells- air spaces- stomata (as vapour)
how can you investiagte the pathway of water in plants
cut celery stalk, place in water with food coloring, you should see the stain of the water movement in the stalk
transpiration
the loss of water vapour from leaves
how does water leave the leaf
evaporation at surface of spongy mesophyl cells to form water vapour evaporates to air spaces, and then diffuses out of the leaves through the stomata as water vapour
what increases rate of transpiration and why
increasing temp, water molecules gain energy the rate of evaporation of water from the mesophyll cells increases the diffusion of water through the stomata increases the rate of transpiration increases.
wind speed increasing- wind removes water vapour from just outside the stomata so the diffusion gradient is maintained and water continues to diffuse out.
what decreases rate of transpiration
humidity increasing- leaf is surrounded by moist air, the concentration gradient decreases resulting in less transpiration at a higher humidity.
explain relationship between surface area, number of stomata, and transpiration
the bigger the surface area of a leaf, more stomata it contains, which results in a faster rate of transpiration
explain transpiration pull
this is a suction force, draws water in xylem upwards from roots to leaves, that draws up a column of water molecules, held together by forces of attraction between
water molecules
cohesion- water molecules stick to each other
adhesion- force sticking water to xylem walls