Chapter 9 Flashcards
What is the need for plant transport systems?
metabolic demand- internal and underground parts of a plant need glucose and oxygen transported to them and all cells need metabolic waste removed
size -plants and multicellular so diffusion would be too slow and unable to reach inner cells due to their size
surface area to volume ratio -as plants multicellular they have a small surface area to volume ratio making diffusion slow and innefective
What is a herbaceous dicotyledonous plant
A herbaceous dicotyledonous plant is a flowering plant with a non woody stand
What is the vascular system
The vascular system is a system of transport vessels in animals or plants
Draw the transverse section of a stem root and leaf in a herbaceous dicotyledonous plant
Check with notes
How can you dissect and observe plant tissue
Use a scalpel to cut a thin cross section either transverse or longitudinal of the stem
Using tweezers transfer it to a dish containing a stain
Mount onto a slide and observe the position and structure of the xylem
What is the function of the xylem
It is a function of the xylem transports water and mineral ions
What is the structure of the xylem
long tube-like structures formed from cells joined end-to-end
No end walls
Dead cells with no cytoplasm
Walls are thickened by spirals of lignin to support the vessel
They have small non-lignified pits for transport
What is the function of a phloem
Phloem transport organic solutes around a plant
What is the structure of the phloem
Phloem is formeds of cells arranged in tubes
They have sieve tube elements living cells with holes in no nucleus and few organelles and little cytoplasm
They also have companion cells which carry out their living functions
How does water enter a plant at the roots
water enter plant root hair cell each microscopic hair has a large surface area to volume ratio and is able to penetrate between soil particles they also have a thin surface cell and a tiny concentrated cytoplasm allowing water to move in by osmosis down a water potential gradient
How does water move through the root
Water can move through the route in two ways
the symplast pathway water move through the cytoplasm of each cell through the plasmodesmata by Osmosis
The apoplast pathway water moves through the cell walls by diffusion and cohesive forces
when it reaches the endodermis the wax experience strip blocks the water in the apoplast pathway and forces it into the symplast pathway
How does water move up the xylem and how does transpiration take place
Water molecules evaporate from the mesophyll cells and move out of the stomata down a concentration gradient
this lowers the water potential of mesophyll cells so water news in by osmosis which repeats across the leaf and in the cytoplasm drawing more water molecules in
This creates a tension and as water molecules are cohesive and adhesive water moves up against gravity in the xylem in a transpiration stream
Why does transpiration happen
transpiration is a consequence of gas exchange the plant needs to open it’s stomata to gain CO2 but there’s also loses water down the water potential gradient
What are the factors affecting transpiration
Light is needed for photosynthesis so when it’s light the stomata open to diffuse in CO2
temperature increases kinetic energy of particles so they evaporate faster increasing water potential gradient
Humidity increases the amount of water particles around a plant so water potential gradient decreases
Air movement by the way surrounding water molecules increasing water potential gradient
How can you measure transpiration
Cut a shoot underwater at a slant
Assemble potometer and insert shoot underwater
Remove but ensure capillary tube is submerged in a beaker
Dry leaves and allow time to acclimatize
Shut the tap and remove the end until one bubble forms
Record starting position of the bubble and start stopwatch
to estimate the rate of transpiration divided the distance moved by the time
