Plants Flashcards
(46 cards)
Plants
● Multicelled, eukaryotic, photosynthetic autotrophs
● Their cell walls are mad of cellulose, and their surplus carbohydrate is stored as starch
Sporopollenin
● A tough polymer, is resistant to almost all kinds of environmental damage and protects plants in a harsh terrestrial environment
- Found in the walls of spores and pollen
Gametangia
● A protective jacket of cells that gametes and zygotes form within some plants
● Prevents them from drying out
Cutin
● The waxy coating on the leaves
● Helps prevents water loss
Stomates
● Open to exchange gases
● Close to minimize water loss
Mycorrhizae
● A symbiotic fungus that lives on some roots
● Increases hte amount of water hte plant absobrs
Lignin
● Embedded in xylem and other plant cells
● Provides support
Leaf
● Organized to maximize sugar production while minimizing water loss
● Epidermid is covered by a waxy cuticel made of cutin to minimize water loss
- Guard cells control the opening of the stomates
● Inner part consists of palisade and spongy mesophyll
- Vascular bunders/veins are located here
Guard cells
● Modified epidermal cells that contain chloroplasts
● Photosynthetic
● Control the opening of the stomates
Palisade mesophyll cells
● Photosynthesis
● Pakced tightly
Spongy mesophyll cells
● Photosynthesis
● Packed loosely to allow for diffusion of gases into and out of these cells
Vascular bundles/veins
● Loaed int he mesophyll cells
● Carry water and nutrients from the soil to the leaves
● Carry sugar, the product of photosynthessi, from the leaves to the rest of the plant
Bundle sheath cells
● Specialized mesophyll cells
● Surround the veins and separate them from the rest of mesophyll
● Involved in special C4 photosynthesis
Stomatal crypts
● Some platns have stomates nestled in these
● THey further minimize exposure of the stomate to air
● This reduced water loss even more
Osmosis
● The diffusion of water across a membrane
● The direction in which water idffuses in determined by water potential
● Responsibled for short-distance transport of water
Water potential
● Free water, water not bound to solutes, diffuses from regions of higher water potential to lower water potential
Aquaporins
● Speical transport proteins that facilitate the rapid osmosis of water across emmbranes
● THe opening and closing of these selective channels affect the rate at which water flow, not its direction
Bulk flow
● The movement of liquid in response to pressure gradient
● Always occur from higher to lower pressure
● Independent of slolute concentration
● Occur within vascular tissue (phloem and xylem)
Phloem
● Transports sugars produced by photosyntehssis from leaves to all parts of a plantf or immediate use or storage
Xylem
● Transports fluid, water and minerals from the soil, rises in a platn against gravity but requires no energy
● The fluid can be pushed up by root pressure or pulled by transpirational pull
Root pressure
● Results from water flowing into the stele from the soil as a result of the high mineral content in the root cells
● It push xylem sap upward only a few yard
● Known as guttation
Transpirational pull
● Evaporation of water from leaves
● Causes negative pressure (tension) to develop int eh xylem tissue from the roots to the leaves
● The cohesion of water due to strong attraction between water molecules makes it possible to pull a column of water from above within the xylem
● The absorption of usnlight drives this
Transpirational pull-cohesion tension theory
● States that for each molecule of water that evaporates from a leaf by transpiration, another molecule of water is drawn in at the root to replace it
Plant hormones
● Help coordinate growth, development, and responses to environemntal stimuli
● Produced in very small quantities, but they have a profound effect ont eh plant because the hormone signal is amplified
