36 Plants Flashcards
Plants general
Autotrophic organisms which are able to synthesize all required organic compounds from inorganic substances using sunlight. Multicelled and eukaryotic. Beta glucose linkage
Vascular plants
Specialized tissue : xylem and phloem
Xylem
Conducts water and minerals from roots to the rest of the plant in one direction. Support. Xylem transports UP. Xylem makes up wood, xylem rings.
Phloem
Carries sugar from leaves to the rest of the plant. Main conducting cells are called sieve tub members. Sugars that are made by photosynthetic leaves are loaded into the tube members with the help of companion cells.
Phloem can transport up or down.
Cuticle
Waxy coating, hydrophobic. impermeable to CO2, stomata allow CO2 to diffuse through.
Transpiration
H2O evaporation in plants
In most plants, stomata stay ____ during the daylight
Open, when photosynthesis occurs. CO2 can enter, H2O is lost.
At night, stomata closed, CO2 accumulates and water is conserved.
Guard cells
When water builds up, they become swollen and open up to allow water vapor loss and CO2 entry in the leaf.
Soil suited for plant growth characteristics
Aeration and H2O holding capacity
Roots
All begin with a primary root then differentiates into smaller secondary roots. Root surface area is increased by root hairs. Root tip = meristem
Root structures
Epidermis: outermost layer includes root hairs
Cortex: stores starch: contains parenchymal cells
Endodermis: innermost layer of cortex, with a waxy tissue band called casparian strip. Involved in controlling the uptake of water and dissolved nutrients.
Stele/Vascular cylinder: Layer of cells inside the epidermis contain xylem and phloem. Cambium tissue lies between xylem and phloem, to thicken the root. Pericycle is the outer layer of the stele which can initiate development of secondary roots
On roots of legumes we see swelling called root __
nodules. Contain nitrogen fixing bacteria which convert atmospheric N2 to NO3- and NH4+.
Nitrification
Break down of dead organisms to release NH4+ to be oxidized into NO3-
Denitrification
Form N2 and a small amount of N2O as NO3- and NO2- are converted into these products. Nitrogen Cycle
3 types of ground tissue which differ in cell wall structure
Parenchyma, Collenchyma, Scelrenchyma
Parenchyma cells
Most abundant, thin walls in roots, stem, leaves
Storage, secretion, and photosynthesis
Collenchyma
Cell walls are thick, but flexible support for growing stem
Scelerenchyma Cells
Very thick cell walls, contain lignin (2nd most abundant natural polymer in the world) Lignin and cellulose work as a team to provide strength.
Stems
Root system usually beneath the ground, while a shoot system is above the ground.
Stem function
a) Support shoot system structure
b) Transport substances between roots and the leaves
c) Store food
Angiosperms (seed plants)
Flowering plants, pears, strawberry, cherries, raspberries, apples. 90% of plants are angiosperms, most diverse and produces seeds.
As seeds develop from ___ after fertilization
Ovules, the ovary becomes the fruit.