Lecture 8 Flashcards
what is a protoplast
a plant cell without a cell wall
what is a callus
a mass of undifferentiated cells which may either continue dividing or undergo differentiation
what makes the plant cell change from spherical to oval
secretion of a cell wall by the protoplast
what is cellulose
complex linear polysaccharide polymer made up of glucose monomers
- major component of the cell wall
what is a microfibril
several cellulose chains arranged in parallel arrays
what is cellulose synthase
rosette structures complex at the plasma membrane that moves as it extrudes microfibrils
what is hemi-cellulose
smaller chains of cellulose which help link together the microfibrils and other components of the cell wall
what is pectin
sticky, acidic, heteropolysaccharide that binds various cell wall components together
- it is this which helped keep single celled primitive plant cell things together (first lecture)
what is the primary cell wall (PCW)
characteristic feature of every cell that is able to divide and differentiate and facilitates cell expansion and elongation
what is parenchyma tissue
cells with thin, flexible cell walls
what are secondary cell walls
primary cell walls which have laid down internal subsequent cell wall layers and are largely cellulosic to increase structural rigidity
what is collenchyma tissue
strategic points of layering of the PCW which gives rise to different levels of strength and flexibility
what is lignin
a complex, hydrophobic, phenolic polymer which aids in structural rigidity of the cell wall
what is growth
irreversible increase in size due to division and enlargement
what is development
growth and differentiation occurring over time
what is morphogenesis
the genesis and development of morphology (form)
is a strict embryonic lineage maintained during post-germinative development
no
what is totipotency
cells can go back to being meristematic after differentiating (unlike eukaryotic stem cells)
how is plant growth under normal conditions
modular (zygote develops into a unit which produces more units like itself)
what is the protoderm
epidermis
what is the procambium
vascular tissue
what is the ground meristem
pith and cortex
what is the tunica
outer layers (L1 and L2) created mainly by anticlinal divisions
what is the corpus
Layer 3 (L3), made by periclinal divisions
what is the central zone
the pro-meristem and shows infrequent division. It is surrounded by the peripheral zone
what is the peripheral zone
gives rise to leaf primordial
what causes stem elongation
internode elongation
what causes stem thickening
periclinal divisions and cell enlargement
what is the lamina
leaf blade
what is the petiole
stalk, connects the blade to the stem
what is a sessile leaf
when the petiole is absent, leaf forms a sheath
what are stipules
scale-like or green leafy appendages at the base of some leaves
what is a dorsiventral leaf
then upper and lower surfaces can be told apart
what is a isobilateral leaf
when it isn’t possible to distinguish between the two sides of the leaf
what is adaxial
the side of the leaf adjacent to the axis
what is abaxial
the side of the leaf facing away from the axis
what is phyllotaxy
pattern of organ initiation at the shoot apex or the arrangement of leaves on the stem
alternate arrangement
single leaves at each node and alternating along the sides of the stem (ex grasses)
decussate/ opposite arrangement
leaves arranged with each succeeding pair at right angles to the pairs below and above them (ex maple)
what is whorled
when several leaves appear to arise from one node
what is spiral
alternately arranged leaves in which each succeeding node and attached leaf is rotated slightly (ex aloe)
what is rosette
leaves arranged in a cluster near the soil at the base of the plant (ex dandelion)
what is heteroblasty
plants which exhibit major differences between young and mature leaves
what is a phyllode
flattened leaf stalk/petiole that looks like a leaf
what is heterophyllous
leaves of different sizes or shapes on the same plant
what is phyllocade/cladode
flattened stem that take over leaf functions (cactus)
what are pavement cells
large epidermal cells
what are trichomes
epidermal hair
what contains chloroplasts
palisade layer of mesophyll, guard cells, epidermal pavement cells
what is the venation in dicots vs monocots
reticulate in dicots, parallel in most monocots
what is the midrib
largest vein along the long axis of the leaf which forms a ridge on the abaxial side
what is the bundle sheath
layers of compact cells around the veins
what is kranz anatomy
a wreath like arrangement of photosynthetic cells around the veins in leaves which creates a bundle sheath and creates a low O2 environment due to being surrounded by a layer of mesophyll cells, it is characteristic of C4 plants
what is the palisade layer of leaves
it is made up of tightly packed columnar cells that contain chloroplasts and are the main spot for photosynthesis
