Leaf Anatomy Flashcards
main functions of leaves
traspiration:regulate water levels
photosynthesis
-need large SA for these
How does the leaf form
-Chemical signals (IAA) sent and apical meristem forms LEAF PRIMORDIUM
-proctoderms and procambium produce vascular strand that become midvein and vascular strand
-the meristematic cells thicken leaf and produce lamina(blade) and petiole(stem thing)
The leaf primordium position determined by the
phylotaxy
until when does leaf uses plant resources?
until 40% grown
Cuticle covers the
epidermal layer
epidermis does not usually contain
chloroplasts
do guard cells contain chloroplasts?
yes
what are the openings in the epidermis called? what controls them?
-they are called stomata( stoma singular)
-guard cell controls them, controlling gasses necessary for photosynthesis, and transpiration
why must the stomata close if the gas and water exchanges are important to the plant?
water loss
how do guard cells open and close?
-movement of potassium and water in response to light intensity
-co2 or water concentration triggers these pressure changes
-as potassium ions move, water follows by osmosis, changing shape of guard cells
How does proton pump work
transfers protons out, and then k+ rapid intake
if there is H+, guard cells closed
no H+, guard cells open
what hormone inhibits proton pump
ABA, abscisic acid
what is the internal structure of leaf made of
mesophyll tissue,
intercellular spaces
vascular tissue
monocot vs dicot msophyll
monocot have t type of mesophyll
dicot have 2
Palisade mesophyl
made of 2 layers sof longated cells
80% of chloroplasts
Spongy layer
-intercelular spaces
-most gas exchange is here
-fewer chloroplasts
what is vascular strand surrounded by?
vascular bundle
vacsular tissue composed of
xylem- vessel and tracheids
phloem- sieve cells and companion cells
what does vascular bundle do
helps load sugars to phloem and unloads water from xylem
C3 photosynthesis
-Do not have predominant bundle sheath
-RUBC fixes CO2 to sugar in chloroplasts of mesophyll
bundle sheath
-in C4 plants, has tightly packed mesophyll cells
-aid vascular bundle transport water to epidermis
-aids in converting CO2 to sugar
C4 photosynthesis
-PEP fixes CO2 into C4 molecule in cytosol of mesophyll.
-then transported to bundle sheath, where it is converted back into C3+ CO2
-in calvin cycle, CO2 fixes to C5 to make C6 for sugars in bundle sheath
CAM
at night, PEP binds C3to C4, which accumulates in the vaccuole
during day, C4 diffuses out of vaccuoles and CO2 released for calvin cycle–>rusisco and co2 fixation
What happens if no CO2 intake for photosynthesis? (C3)
Bind O2 to rubisco,
leads to no carbon fixing, however saves plant from oxygen accumulation
–> photorespiration
Photorespiration
dissipates ATP and accumulated elections to prevent photooxidative damage
modified leaves
adapted to trap insects
leaf tendrils(support)
leaf spines(protection)
reduction in transpiration
water or food storage
asexual propogation
specialized to form flowers
leaves modified to reduce water loss thru transpiration
reduction of size
leaf blade rolled
pitted or sunken stomata
