Unit 3 Botany Flashcards
Explain absorption
Absorbs water, nitrogen, phosphorous, sulfur, potassium, sodium, magnesium, etc.
What are the three major functions of roots?
Absorption, storage, anchorage.
Anchorage
Holds in place, keeps it from falling over and blowing away and stuff.
Storage
Stores carbs.
What’s the purpose of keeping carbs underground?
It keeps the food stores safe from predators and in a stable temperature.
How much of the plant is underground?
Roughly 1/3
How deeply can roots penetrate?
Between 10-100 feet!
Food storage roots
Fleshy and thick for storing carbs needed in next season. Ex: sweet potatoes, beats, turnips, radishes.
Adventitious roots
Roots that develop from the stem. There are three specific types.
Three types of adventitious roots?
Prop roots, buttress roots, and aerial roots.
Prop roots
Roots found near the base of stem to provide additional support, like on corn.
Buttress roots
Roots found in tropical areas which are very large. Help plants found in areas with thin soil, like a ficus.
Aerial roots
Roots that emerge above ground from branches. They directly support the weight of large branches. Ex:banyan tree
Pneumatophor
Roots that grow from the soil upward into the air. There are lenticels found on them, and spongy, air filled tissue, both of which are used for gas exchange.
Ex:mangrove trees
Contractile roots
Pull the plant deeper into the soil until stable temperatures are met.
Ex: lily, tulip, and dandelion.
Parasitic root
Roots that invade another plants vascular system and steal their nutrients and sugars
Ex: mistletoe, dadder
What are three ways humans use roots?
Food, spices, medicine/drugs
Biennial
Complete life cycle in two seasons
Biennial root crops examples
Carrot, beet, turnip, radish
Non-biennial crop examples
Sweet potatoes, yams, casava
Examples of root spices
Licorice, sarsaparilla, sassafras
Types of root medicine/drug
Ginseng, gentian, ipecac
Radicle
Embryonic root, located in the seed. Develops the first root after germination. Grows downwards into the soil and matures.
What does the radicle eventually become?
The primary root.
What two root systems occur after germination?
Taproot and fibrous.
Taproot
One large primary root develops. Smaller secondary roots shoot off the primary root.
What kind of plant root system is associated with dicots?
Taproots
Example of a plant with a taproot?
Dandelion.
What are taproots specialized for?
Storage
Fibrous roots
Many smaller roots are present, but there is no one large root.
What root systems do monocots mainly have?
Fibrous
Examples of plants with fibrous root systems?
Grass, corn, lily, iris
What function are fibrous roots specialized for?
Anchorage and absorption
Feeder roots
Produced by both taproot and fibrous roots, they are very small roots found near the surface.
What is the function of feeder roots?
Absorption
What specialized epidermal cells must feeder roots have a ton of?
Root hairs.
What do root hairs increase?
The roots surface area.
Root cap
Thimble shaped mass of parenchyma found only on the tips of roots.
Functions of root caps
Lubrication, protection, gravotropism
What is gravotropism
The root cap can detect gravity telling the root to grow down.
How does the root cap lubricate the root?
It creates mucilage
How does the root cap protect the root?
It protects the apical meristem from damage.
What is the average life span of a root cap cell?
Less than one week.
Region of cell division.
Also called the apical meristem, this is where new cells are created.
Describe the region of cell division.
Inverted, cup shaped dome. Cell division takes place on the edges, but the center is quiescent, aka quiet center with an infrequent cell division.
How frequently do the cells divide?
Every 12-36 hours.
Describe the new cells that are produced.
They are cuboidal in shape, have a large nucleus, and few, if any, small vacuoles.
What are the three primary meristems in the apical meristem?
Protoderm, ground meristem, and procambium.
Protoderm
Makes the root epidermis.
Ground meristem
Makes the parenchyma of the cortex.
Procambium
Creates the primary xylem and phloem.
Region of elongation
The area where cells become longer and begin to differentiate. Cells assume mature shape and size.
Region of maturation
Cells are fully mature in this region, aka fully specialized and fully working.
Root hairs emerge here.
Root hairs
Extremely fragile, don’t live more than 4-5 days. They are only one cell in diameter.
What is the advantage of root hairs being so narrow?
Lots of surface area.
What happens as root hairs develop?
Their cell membranes become more and more selective so that they don’t accidentally absorb aluminum.
What is the root epidermis missing and why?
Cuticle, because if it had a cuticle the absorption would be severely limited.
Cortex
Made up of parenchyma, functions in food storage. Area outside the vascular cylinder.
Endodermis
Layer of compact cells surrounding vascular cylinder. Coated with the casparian strip.
Casparian Strip
The endodermis cells that are coated with suberin between the cells to keep things from slipping through.