24: plant form & function I Flashcards
(27 cards)
difference between tissue and an organ?
- tissues are groups of cells of one or more types that have a specialized function
- organs are several types of tissues that together carry out particular functions
where does growth occur?
primary growth occurs in the apical meristems! in the tips of the root
the apical meristem of the shoot has dense staining because?
there is a lot of metabolic energy
why are leaves arranged in a spiral?
it maximizes surface area to absorb sunlight
types of meristems?
- shoot apical meristem (SAM)
- root apical meristem (RAM)
lateral: - vascular cambium (VC)
- cork cambium (CC)
function of lateral meristems?
add thickness to woody plants during secondary growth
vascular cambium
adds layers of vascular tissues
- secondary xylem (wood)
- secondary phloem (inner bark)
cork cambium
the bark of the tree
- replaces epidermis w/ periderm
- thicker and tougher
what are the SAM and RAM responsible for?
- primary growth
- axial growth (up and down)
what primary tissues make up the SAM and RAM?
ground, vascular, and dermal
in non-woody plants, the dermal tissue system consists of?
the epidermis, with a waxy cuticle that prevents water loss
what does the periderm replace in woody plants?
the epidermis
trichomes
hair-like structures that come out of the shoot epidermis - helps w/ reducing water loss and insect defense
- can also increase relative humidity closer to the leaf or stem surface
the vascular tissue of a stem or root is called the ?
stele : central column w/ xylem and phloem
in angiosperms, the stele of a root is?
a solid central cylinder
what are the ground tissues internal and external to the vascular tissue?
- internal: pith
- external: cortex
ground tissue cells specialize in?
- storage
- photosynthesis
- support
- transport
which cells are the least specialized?
parenchyma cells
what type of walls do parenchyma cells have?
thin and flexible primary walls that are made of:
- cellulose
- other sugars
- proteins
and lack secondary walls
which cells preform metabolic functions and retain the ability to divide?
parenchyma cells
what type of walls do collenchyma cells have?
thicker uneven cell walls that provide young stems flexible support
- also alive
which cell helps celery stand straight?
collenchyma cells
what type of walls do sclerenchyma cells have?
thick secondary walls that are strengthened w/ lignin, dead at maturity
two types of sclerenchyma cells?
- sclereids
- fibers
