Chapter 3 Flashcards
(19 cards)
Photosynthesis
The process by which light energy from the sun is converted to sugars
Transpiration
The loss/release of water vapor from the leaf by evaporation through the stomata
Respiration
Exchange of CO2(coming in) and Oxygen (going out)
Tendrils
A type of modified leaf that wrap around objects for support
Ex) Grape vines
Spines.
A type of modified leaf for protection
Thorns or spikes
Bracts
Green or colored leaves that surround flowers. Ex: Poinsettia
Mesophyll
(Parenchyma tissue)
‘Middle’ of the leaf. There are two types..
Palisade: contain most of the chloroplasts in dicot leafs
Spongy: next to the intercellular air spaces to allow for the interchange of gases.
Most monocots only have this type
Dicots have both
Vascular bundles
Tissues that transport materials to and from the leaf
Xylem and phloem
Epidermis
Outer layer of leaf. Upper and lower epidermis. It’s translucent
Epidermal cells are clear to allow light penetration
Cuticle
Waxy layer usually produced by upper epidermis, also prevents moisture loss through epidermis
Stoma (stomata)
Opening in leaf; surrounded by two guard cells.
-stomata controls transpiration and air exchange rates
- mostly found in lower epidermis and occasionally in upper epidermis (for dicots)
- monocots have lower and upper stomata
Hydrathodes
Modified stoma
(Overflow holes)
- openings on leave margins at the end of veins that transpire water droplets instead of vapor
- this type of water secretion is called “guttation”
Often mistaken for dew
Trichomes
Hairlike projections that some leaves have.
For
•protection
•warmth in cold climates
•deflecting hot sun
Described at pubescence
Why are leafs green?
Chlorophyll is abundant in the leaf cells during the growing season
The chlorophylls green color dominates and masks out the colors of any pigment that may be present in the leaf
Why do leaves change in autumn?
- leaves lose chlorophyll as dormancy or death sets in (senescence)
- The chromoplast are always present in the leaf now show through and oranges reds purples yellows,etc.
Chromoplasts
Color plastid that are often found in many flower petals and fruits and dominate in some colored leaves
These are the non-green pigments
Leaf arrangements on the stem
- opposite-two leaves and auxiliary buds at the same node directly across from each other
- alternate-leaves and auxiliary bud’s occur one per node on varying sides of the stem
- subopposite-almost opposite but a little Offset
- whorled-three or more leaves and auxiliary buds are attached at the same node
Petiole
The part that attaches the leaf to the stem
Blade of the leaf
The main part of the leaf that houses mesophyll
