Plants Flashcards
What are cell walls made of?
Cellulose
What do plants cell walls store
Carbohydrates (ex. Starch)
2 types of plants
Bryophytes and tracheophytes
Bryophytes characteristics
- primitive, lack vascular tissue
- must live in moist environments (transport water by osmosis)
- tiny because they lack the lignin fortified tissue necessary to support all plants
Bryophytes ex.
Liverwarts, mosses, hornwarts
Tracheophytes characteristics
- have transport vessels, xylem and phloem
- include seedless and modern plants with seeds
- plants with seeds are divided into gymnosperms and angiosperms
Gymnosperms
Conifers- cone bearing plants that produce seeds on the surface of cones. Have needle shaped leaves, thick and waxy cuticle, and stomates in stomata crypts to reduce water loss
Gymnosperms ex
Cedar, sequoia, redwood, pine, yew, and juniper
Angiosperm
Flowering plants, seeds develop inside ovaries (after pollination ovary becomes fruit)
Angiosperm ex
Roses, daisies, fruits, nuts, grains, and grasses
Monocotyledon
One seed leaf (cotyledon), scattered vascular bundles in stem, parallel leaf venation, floral parts in 3s
Dicotyledon
2 seed leaves, vascular bundles in stem are in a ring, net like leaf venation, floral parts in 4s or 5s
Monocotyledons ex
Grasses (wheat, corn, oat, rice), palm trees
Dicotyledon ex
Daisies, roses, carrots, tree woods
Stomates
Open to exchange photosynthetic gases and close to minimize excess water loss
Cutin
Waxy coating on leaves that helps minimize water loss
Gametangia
The protective jacket of cells that some gametes and zygotes form in to prevent drying out
Sporopollenin
Tough polymer that protects plants in harsh environments, found on walls of spores and pollen
Meristem tissue
Continually divides so that plants grow as long as they live
Primary plant growth
Vertical growth (on root tip and buds of shoots)
Primary plant growth on root tip (3 zones of primary growth)
Apical meristem (zone of cell division, bottom), zone of elongation (middle), zone of differentiation (top). There is root cap after the zone of cell division
Zone of cell division
Produces new cells that grow down into soil
Zone of elongation
Cells elongate and push the root cap deeper into soil
Zone of differentiation
Cells undergo specialization into 3 primary meristems that give rise to 3 tissue systems in plant (epidermis, ground tissue, and xylem/phloem)
Secondary growth
Lateral growth (increase in girth). New cells provided by the lateral meristem. Nonwoody plants don’t have secondary growth
Function of roots
Absorb nutrients from soil, anchor plant, store food
Epidermis
Covers entire SA of root and are for absorption. Root hairs extend from these cells to increase SA
Cortex
For storage. Consists of parenchyma cells that contain plastics to store starch
Stele/Vascular cylinder
For transport. Contains vascular tissues (xylem and phloem), surrounded by pericycle from which lateral roots arise
Endoderm
Surrounds vascular cylinder, selects what minerals enter vascular cylinder
Casparian strip
Wraps each endoderm cell, is a band of waxy material that is impervious to water and dissolved minerals
Lateral movement
Movement of water and solutes across a plant
Symplast
Continuous system of the cytoplasm of cells interconnected by plasmodesmata
Apoplast
Network of cell walls and intercellular spaces that permit extensive extracellular movement of water
Mycorrhizae
Supply the plant with water and minerals in older regions of roots that lack root hairs. Consists of the plants roots intermingled with the hyphae (filaments) of a fungus that increases the quantity of nutrients the plant can absorb
Rhizobium
Bacterium on the nodules of roots in legumes that fixes nitrogen gas from air
Taproot
Single, large root that gives rise to lateral branch roots. Primary root in many dicots.
Fibrous root system
Common in monocots and holds plant in place
Adventitious roots
Arise above ground. Include aerial roots and prop roots
Aerial roots
In trees that grow in swamps and marshes, when root sticks out of water to aerate the root cells
Prop roots
In tall plants, grow from base of stem and help support plant
Leaf overall function
Maximize sugar production while minimizing water loss
Epidermis function
Protection
Want cuticle function
Minimizes water loss
Guard cells
Control the opening of the stomates, respond to changes in water pressure
Palisade mesophyll (tightly packed)
Photosynthesis
Spongy mesophyll (loosely packed)
Photosynthesis, diffusion and exchange of gases into and out of these cells
Veins (in mesophyll)
Carry water and nutrients from the soil to the leaves and carry sugar from leaves to the rest of the plant
Transpiration
Loss of water from the leaf
Dermal tissue
Outer protective covering of plants, cannot photosynthesize (except for guard cells)
Trichomes
Tiny, Spike like projections that protect the leaf
Vascular tissue
Transports water and nutrients up and down the plant (includes xylem and phloem)
What does xylem consist of
Tracheids and vessel elements
What does phloem consist of
Sieve tube elements and companion cells
Ground tissue
All plant tissue besides dermal and vascular
Parenchyma cells
Have a thin and flexible primary cell wall, but no secondary cell wall, typical plant cell, found in all parts of plant
Collenchyma cells
Unevenly thickened primary cell walls, no secondary cell wall
Sclerenchyma cells
Very thick primary and secondary cell walls that are fortified with lignin, purely for support
What does xylem do
Carriers water and nutrients from soil to leaves (against gravity) with no expenditure of energy
What are water and nutrients pulled up by in xylem
Transpirational pull: evaporation of water from leaves
Cohesion: water molecules are attracted to each other and stick together
For each molecule of water that evaporates by transpiration, one is drawn to the root to replace it
How does humidity affect rate of transpiration
High humidity slows transpiration, low humidity speeds it up
How does wind affect transpiration rate
Wind reduces humidity near stomates and increases rate of transpiration
How does light intensity affect transpiration
More light speeds up photosynthesis which will increase the rate of transpiration
Phloem function
Carry sugar from the photosynthetic leaves to the rest of the plant by translocation (this requires energy)
