lecture 13 Flashcards
what are the major functions of roots?
- anchoring the plant in the soil
- absorption of water and nutrients
- transport of water and nutrients to the rest of the plant body
what are the other functions of roots?
- nutrient storage
- gas exchange
- plant propagation
- communication
- secretion into soil to signal to other plants and animals
- help the plant orient itself
where do roots originate?
formed in the embryo as the radicle, growth initiates at the root apical meristem
what is the site of lateral root formation?
pericycle
what is the role of the root cap?
secretion of mucilage and protection
how do lateral root primordia form?
in response to chemical signals (plant hormones)
what are the functions of root hairs?
increase the root’s surface area for uptake of water and nutrients
how do adventitious roots form?
form from stems and leaves; usually form out of cell division in stem cortical cells
what are the functions of water in plant cells?
- structure (turgor)
- cooling
- photosynthesis
- transport
how does water move within plants?
- cell to cell: apoplast and symplast
- vascular tissue (between organs): xylem and phloem
what are the cell types involved in water movement?
- vessel elements and tracheids (xylem)
- sieve tubes and companion cells (phloem)
- root hairs
- guard cells
- endodermis
what influences water balance in plants?
the physical properties of water and the solutes dissolved in it
what is the casparian strip?
a hydrophobic barrier in the transverse (upper and lower) and radial (side) walls of the endodermal cells
what is the function of the casparian strip?
preventing water and minerals from entering the root vascular cylinder through the apoplast
what is osmosis?
the movement of water through a semi-permeable membrane from an area of low solute concentration to one of higher solute concentration. this is a physical process driven by the chemical potential energy
