Quiz 4: leaves Flashcards
what are leaves?
- outgrowth of the stem
function of leaf
-primary organ of photosynthesis
petiole
leaf stalk
petiolate
leaf with a petiole
sessile leaf
directly attached to stem
stipule
leaf- like appendages (at base of petiole on some leaves)
simple
leaf is a single unit
compound
leaf divided into smaller units- leaflets
compoundly pinnate
- leaflets along both side of a common axis
rachis
- axis from which leaflets attach
compoundly palmate
leaflets radiate from one point
venation
- arrangement of veins (vascular bundles)
pinnate, palmate venation
- reticulate- net-like
parallel venation
- linear, monocots
simple leaf
one balde
what are 3 adaptation plants have for protection
- thorns
- spines
- prickles
thorns
modified sharp stem or branch
- grow from axillary buds at the node - where branch would develop
spine
- modified sharp pointed leaf
- occurs in relative position of a leaf
prickle
- woody epidermal outgrowth of stems, leaves and some fruit
- arise randomly from internodes
conifer
a tree with needle or scale like leaves
fascicle
- dense cluster of leaves or needles
broadleaf
- a tree with wide, flat leaves
describe entire leaf margin
leaf margin that is smooth without teeth or lobes
describe undulate leaf margin
- leaf margin that is wavy
serrate leaf margin
- leaf margin that has pointed teeth directed upward
doubly serrate
- serrate leaf margin where the primary teeth support another set of teeth
crenate
- a leaf margin that has rounded teeth
lobed
segmented leaf having pointed or rounded extensions separated by sinuses that do not extend more than half way down midrib
sinus
the space or indentation between lobes of leaf blade
acute leaf tip
slightly pointed
acuminate leaf tip
sharply pointed
bristle- tipped leaf point
sharply pointed tip
truncate leaf tip
squared/ abruptly cut off
obtuse leaf base
rounded
cuneate leaf base
wedge- shaped
obtuse leaf base
rounded
cordate leaf base
heart shaped
truncate leaf base
squared or abruptly cut off
oblique leaf base
asymmetrical, unequally sided
compound leaf
type of leaf that has three of more leaflets attached to a common stalk
palmately compound
-arrangement of leaflets radiating from a central point
pinnately compound
-arrangement of leaflets attached laterally along the rachis of a compound leaf
palmately
- veins or lobes of a leaf radiating from a central point
saying to detect poison ivy
leaves of 3 let it be
hairy rope- dont be a dope
berries white- take flight
describe tendrils
leaf divided into ordinary leaflets and grasping tendrils, enabling plant to scramble over grasses and other herbs despite weak stem
what is a plastid?
tiny organelle containing pigments
chloroplast
-plastid containing green pigment –> major site for photosynthesis
chromoplast
-yellow- orange red pigments –> masked by chlorophyll
mesophyll , contains what 2 cells
- tissue of leaf between upper and lower epidermis
- palisade cell, spongy cell
palisade cell
- primary site of photosynthesis
spongy cell
-large spaces for diffusion of CO2
cuticle
- waxy coating to epidermis
- barrier to prevent water loss from leaves
- reflects sunlight
- barrier to allow water entry
hirsute
-hairy coating of epidermis
guard cells
- location
- how functions
- pair cells surrounding stoma
- when opens, inner walls of 2 guard cells move apart
- inner wall which surrounds pore thicker than outer wall –> as water moves into vacuoles of guard cells content increased and so is pressure of cytoplasm against cell wall
- cell wall begins to stretch
- difference of thickness of wall causes the outer wall to stretch more than inner
- outer wall pulls inner walls away from each other causing pore to open
stoma
- function
- main location
- pore in epidermis of leaves and herbaceous stems which allows atmospheric gas (CO2) to enter leaf
- outlet for escape of water vapour
- usually found on lower epidermis
- open during day for gas entry, close at night due to lack of photosynthesis
- can be closed during day to prevent regulate water loss
- hot, dry windy days
- drought conditions
epidermal hairs
- reduce evaporative water loss
- deterrent to insect predation
- reflect sunlight
describe what is happening when stoma closes and opens
closing: water leaves, guard cells shrink, stoma closes
opening: water enters, cells swell, stoma opens
what are 4 factors that influence stoma opening/ closing
- light causes stoma to open and darkness close
- exception succulents, opposite –> take advantage of cooler evening for gas exchange to reduce water loss - wilting or water deficit causes the stomata to close to prevent further water loss from leaves
- increase in CO2 = stoma closure
- increase in temperature = stomata open
describe what happens when stomata opens
- only epidermal cells with chloroplasts
- stomata opens, CO2 can enter leaf
1. chloroplasts make sugar via photosynthesis
2. guard cells actively pump in K+ ions
how is water lost through stomata
- evapo-transpiration
- source of the pull of water conduction through xylem
