plant transport Flashcards
what is the function of xylem
to transport water and mineral salts from the roots to leaves
what is the 4 types of cell in xylem
tracheid, xylem vessels, parenchyma and fibres
describe what the tracheid are/do/ have
they hv a smaller diameter than xylem vessels and pointed ends
they have pits to allow water to flow
they transport water in-between cells
describe what xylem vessels are/do/ have
long tubes that join end to end
lignin for strength and permeability
what does parenchyma and fibres do
parenchyma- store food
fibres- support
what are the adaptations of xylem vessels and tracheid
lignin- strength & prevents food entry
open ends to allow water flow
pit to allow mineral salt and water pass through
open ends join to form hollow tubes - water and mineral salt pass sideways
what is the function of phloem
to transport products of photosynthesis from leaf to storage and growing areas
what are the 4 types of cells in phloem
sieve tubes, companion cells, parenchyma and fibres
describe what sieve tubes are
they have no nucleus and are dead cells
long cells that join end to end with no lignin
sieve plate lets substances pass through
what is companion cells
have nucleus and help sieve tubes
produces mitochondria
provide protein and energy
describe root pressure
high concentration of ms in cell, active transport from soil to cell. lower wp in cell so osmosis. causes root pressure
adaptation of root
has root hair cells which is just elongated cytoplast to increase surface area
has root cap to protect root
describe the pathway of water
soil - root- root hari-cortex- cell -xylem - leaf
describe the pathway of water
soil - root- root hair-cortex- cell -xylem - leaf
compares villus and root hair
similarities
both use active transport
absorb nutrients
have structures to increase surface area
differences
root hair absorb water and ms but villus absorb amino acid
root use AT to get nutrients but villus use diffusion
root hair has cytoplasm, nucleus and vacuoles but villus has lacteal and vein
why is root pressure not enough to bring water up the stem
it is insufficient to over come forces of gravity
what are the 2 types of forces in capillary action and their meaning
cohesive- between water molecules
adhesive- between water molecules and vascular vessels
why do we need transpiration pull
capillary action is only enough to pull upwards the xylem vessel but not enough to pull to leaves
how does transpiration occur
there is excess water is mesophyll cells
the temp rises due to sunlight intensity
water evaporates
concentration of water vapor in atmosphere in air space is higher than atmosphere
water will diffuse out of the lead into atmosphere
define transpiration
loss of water vapour due to the evaporation of water in the mesophyll cell followed by diffusion of water vapour through stomata
what is transpiration pull
force that pulls water vapour up from the xylem vessels into mesophyll cells
describe how the force of transpiration pull is made
the cell has low wp
adjacent cell has higher wp so osmosis
draws water up the xylem vessels
what is the importance of transpiration
maintain turgidity
cool temp - use heat to change liquid to gas
water uptake
what happens if there is too much transpiration
wilting occurs
what does leaves do to avoid too much transpiration
roll inwards t reduce SA and hv less water loss
why is too much transpiration a bad thing
they cant carry out biochemical reactions
what do you use to measure rate of transpiration
potometer
what are the 2 ways to measure rate of transpiration
distance travelled by bubble/ fixed time
measure time for bubble to travel fixed distance
what is the assumption of potometer
volume of water loss from potometer is equal to volume of water transpired
how to set up potometer
place potometer in water place plant and rubber topper lift apparatus up to get 1 bubble measure distance open reservoir to restart
what are the limitation of potometer
not all water taken up will be transpired
use for photosynthesis and absorbed by cells to maintain turgidity
what are the other uses of potometer other than measuring rate of transpiration, and how do you manipulate them
effect on light intensity: distance of lamp
effect of air movement: speed of fan
effect of number of leaves: remove leaves one by one
what are the 6 factors that affect rate of transpiration?
humidity, air movement, light intensity, temperature, number of stomata and water supply
how does humidity affect rate of transpiration
lower the humidity, the faster the rate
less water vapour outside, so steeper gradient
faster diffusion so faster rate
how does air movement affect rate of transpiration
more air movement, faster rate
air will move water vapor away from the leaves
lower concentration outside and thus steeper gradient
increases transpiration rate
how does light intensity affect rate of transpiration
higher light intensity, higher rate of transpiration
stomata opens wider so more co2 and water vapour go out
light intensity simulates stomata to open
how does temperature affect rate of transpiration
higher temp higher rate
more kinetic energy to evaporate and diffuse out the stomata
rate of photosynthesis is higher, so more water is drawn up the stem
so more water in air spaces
what is source
region of production
what is sink
region of storage area of places where used for growth and respiration
how does translocation change in potato leaves during changes of seasons
in summer, leaves are source bc photosynthesis, tubers and stem becomes sink
in winter, leaves fall out so tubers, which stored starch becomes source and leaves became sink
how does development of seed and translocation change
when developing, leaves are source and sink so seed
store sucrose is from of starch in cotyledon
when they germinate seed becomes source
list some adaptation to reduce transpiration rate
hairy leave- less air movement
less stomata, less evaporation
waxy cuticle- longer distance to travel for diffusion
small leaves- reduce surface area
rolled leaves- trapped air inside has higher humidity
