Chapter 1: What is a Plant? Flashcards
what is the life history of plants?
alteration of generations
what is the chemical composition of plants?
unique sterols (sitosterol and stigmasterol) - membranes tolerate intense temperature fluctuations due to additional methyl group on C-24
what is the cellular structure of plants?
- cell walls, specialized plastids, large vacuole
plasmodesmata
all of plant body is one continuous symplast
what are some plant exceptions?
- xylem don’t have plasmodesmata
- some plants don’t have chloroplasts
what is a model plant?
- are functionally well described and have fully sequenced genomes that can be modified
- small with high resolution genomes, fast life cycles, small physical stature, and representative of a valuable, large complete flowers
cell wall
Cell wall- rigid, principally composed of cellulose microfibrils in a pectin matrix. Primary walls are very thin (<1 um). Secondary walls are thicker (several um) with lignin deposits
vacuole
80-90% of cell volume. Contains water to maintain turgor as well as reserves of
ions, sugars, enzymes and metabolites.
mitochondria
(not a synapomorphy)- Respiration. Number in any given cell is dependent
on the cells function (metabolic activity; many in guard cells). Small (3 um long).
chloroplasts
Specialized plastid for photosynethesis. Usually 20-40 per cell in
photosynthetic tissues. Larger than mitochondria (5-8 um longs).
peroxisomes
(not a synapomorphy, but functionally specialized in plants)- oxidize
compounds and break down peroxide (byproduct of photosynthesis).
plasmodesmata
tubular extensions of the plasma membrane between cells that creates
a continuous cytoplasm. Very tiny (40-50 nm diameter). Inside there is a core that
connects the ER of both cells wrapped in proteins that act as a revolving door
symplast
continuous cytoplasm for all tissues in the plant
apoplast
The cell walls
also create a continuous space (pathway for transport)
apical meristems
Growth in plants is confined to meristems. Primary growth (up and down) is confined to
apical meristems at the top of the shoot and bottom of the roots
parenchyma
- ground tissue
- metabolically active cells (e.g., photosynthesis), with thin cell walls
collenchyma
- ground tissue
- provide structural support (e.g., stem periphery, petiole). Long,
skinny cells. Can bend and stretch as tissues grow
sclerenchyma
- ground tissue
- provide structural support. Thick, lignified secondary cell walls,
often dead at maturity - two types are sclerids and fibers
sclerids
vary in shape from round to branched and occur throughout the plants (e.g., seed coats)
fibers
long and skinny in long parts of the plant (e.g., wood)
xylem
- vascular tissue
- conduct water and nutrients. Composed of tracheids (all plants) and
vessels made up of vessel elements (angiosperms). Both are dead at maturity
with no plasmodesmata and instead are connected by pits.
phloem
- vascular tissues
- conducts sugars and signaling molecules. Composed of sieve cells
(gymnosperms) and sieve tubes made up of sieve elements (angiosperms).
Living at maturity, but minimal organelles and rely on companion cells
what are the dermal tissues?
Epidermis, cuticle, guard cells, root hairs
what is the taxonomic diversity of gymnosperms and angiosperms?
- gymnosperms = more than 700 species
- angiosperms = more than 400,000 species
what are the different forms of plant diversity?
taxonomic, life form, biochemical, and adaptive
what are some forms of biochemical diversity?
C3, C4, CAM, and photosynthesis
what are some forms of adaptive diversity?
light, moisture, and temperature
