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.
What is the purpose of the Casparian Strip?
It keeps harmful things like aluminum from coming into the vascular cylinder and getting into the xylem.
Pericycle
Located immediately inside the endodermis. Retains meristematic capability, aka can still divide.
What does the pericycle produce?
Secondary branch roots and portions of the vascular cambium.
What shape do the xylem form in the dicots?
An x shape, with phloem between the arms.
How are xylem and phloem arranged in monocots?
Patch of pith in the center of the vascular cylinder, and it is surrounded by xylem and phloem.
Why can xylem not decide what can and can’t enter it?
Xylem is dead.
What are plant strategies for reducing aluminum impact?
- Release negatively charged organic acids that will bind aluminum in the soil.
- Aluminum ions can be trapped in the cell walls, by plants building extra cell walls to corral it.
- Produce more specific transporter proteins for other materials.
How does acid rain effect the amount of aluminum in the soil?
The acid rain drops down excess hydrogen which steals the Aluminums “spot” where it was bonded with the dirt. This kicks all the aluminum out to be free floating.
Symbiosis
Organisms living together.
Mutualism
Both members benefit.
Parasitism
One member benefits, the other is harmed.
Commensalism
One member benefits, the other is not effected.
Mycorrhizae
Name for a relationship between roots and fungi.
What do hormones do?
Regulate plant growth and development.
What are hormones?
Chemical compounds produced in one part of an organism that influences development and functions in another part.
In short, hormones are….
MESSAGES
What is the cell that the hormones are being sent to called?
Target cells
What are all over the cell membrane and detect the hormones?
Receptors
What is the process called where a hormones message is bounced from cell to cell to reach the nucleus?
Signal Transduction
What does a hormone do when it reaches DNA?
It turns a gene on or off.
What does the turning on/off of a gene do?
Triggers a response from the cell.
What does the hormone travel through in the cell wall?
Plasmodesmata
What are the 8 plant hormones?
Auxin, ethylene, gibberellins, cytokinins, abscisic acid, brassinosteroids, systemin, salicylic acid
Where is auxin located?
Young leaves, buds, primary meristems
What are the primary effects of auxin?
Promotes cell elongation and enlargement
Promotes apical dominance (makes them grow taller)
What are the secondary effects of auxin? (Not needed for text but still cool)
Inhibits leaf and fruit drop
Initiates root development
Assist growth in response to light
What is tropism?
Growth in response to a particular stimulus.
What is auxins relationship to tropism?
Auxins are produced in reason to different tropisms
What are positive tropisms?
When plants grow towards something.
What are negative tropisms?
When plants grow away from something.
Phototropism
Light stimulus
Hydrotropism
Water stimulus
Gravotropism
Response to gravity
Thigmotropism
Responds to touch
Thermotropism
Responds to temperature.
What times of tropism does a root exhibit?
Gravotropism
Hydrotropism
Thermotropism
What types of tropism does a stem show?
Phototropism
Thermotropism
Gravotropism
Thigmotropism
What is apical dominance?
Auxins produced at tips of plants inhibits growth of lateral buds.
How can one make a plant grow to appear thicker or bushier?
Cut off the tips of the plant to stop apical dominance and make the plant grow horizontally instead of vertically.
What is agent orange and why is it evil?
An auxin that was used in Vietnam to cause the trees to drop their leaves. Ended up getting contaminated and becoming a carcinogen.
Where is cytokinin located?
Root tips, germinating seeds
What are the primary functions of cytokinins?
Stimulating cell division
Secondary functions of cytokinins
Delay leaf aging
Forms root partnership with fungi and nitrogen fixing bacteria
What are root nodules?
Name for the nitrogen fixing bacteria in plants.
Mycorrhizae
Relationship between roots and fungi
Where is ethylene found?
Everywhere, but especially fruits.
Primary function of ethylene.
Fruit ripening
Leaf and fruit dropping
Secondary purpose of ethylene
Promotes flower aging
Promotes cell specialization
Assist in sex determination
Why does “one bad apple spoil the bunch”?
The apple ethylene spreads to all the other apples.
Where are gibberellins located?
Roots, young leaves, embryos, apical buds.
What is the function of Gibberellins?
Promotes cell division of the shoot, promotes cell elongation of the shoot, promotes seed germination, stimulates flowering in some plants.
Where is abscisic acid located?
Buds and seeds
What are the functions of abscisic acid
Stops plant metabolism, promotes dormancy (especially in seeds)
What is the location of brassinosteroids?
Leaves, shoots, fruits, seeds, flower buds
What is the function of brassinosteroids?
Cell elongation, protection from temperature change, salts, and herbicides.
What is the location of systemin?
Wounded leaves
What is the function of systemin?
Sends defensive alerts to neighboring plant structures and tissues.
What is the location of salicylic acid?
Bark and flowers
What is the function of salicylic acid?
Delays flower aging, defense against invading microbes.
Why is it beneficial to put aspirin in with cut flowers?
It slows down the aging of the cut flowers.
What hormones promote growth?
Auxins, gibberellins, cytokinins, brassinosteroids.
What hormones promote senescence?
Ethylene, systemin
What hormones are part defense?
Systemin, brassinosteroids, ABA, salicylic acid
What do light sensing pigments do?
Controls plant response to light stimuli.
What are two kinds of light sensing pigments?
Crypto chrome and phytochrome
What color light does cryptochrome want?
Blue light
What kind of light does phytochrome want?
Red light
What happens when cryptochrome is off?
Seedlings lengthen (plant grows)
Why does the seedling lengthen when light if off?
It is growing taller to stretch towards the light.
What happens when cryptochrome is on?
It creates chlorophyll and grows leaves.
Why is chryptochrome important for plants?
They don’t waste their time growing leaves that can’t photosynthesize.
What happens when phytochrome is off?
No germination
What happens when phytochrome is off?
Seed germination occurs
How is phytochrome an adaptive advantage for plants?
The seeds won’t grow unless they’re close enough to the ground surface to get enough sunlight.
What are short day plants?
Like time shorter than their critical period.
What are long day plants?
Like more sunlight than the critical period.
What are day neutral plants.
They don’t care about how much sunlight they get. They just want to grow.
What is the critical period of a plant?
The around of sunlight it needs to grow.
What is the order of the cell regions, starting at the root cap?
Root cap—> region of cell division —-> region of elongation —-> region of maturation
What does the protoderm become?
Epidermis
What does the ground meristem become?
Parenchyma that’s in the cortex
What does the procambium become?
Produces primary xylem and phloem.
What is the dicot xylem shaped like?
X shape
What is the difference of vascular cylinder in dicots?
Solid core of xylem and phloem
What is the difference in the vascular cylinder of monocot roots?
Pith is present and surrounds xylem and phloem.
How thick are root hairs?
One cell thick
What happens to the vacuoles in the cells in the region of elongation?
The vacuoles merge to one or two large vacuoles which occupy 90% of the cell space
Why does the epidermis have no to low cuticle?
Roots are used for absorption and absorption is hard to do with water resistant suburin.
Why is it important that the proteins on the cell membrane are selective?
So they don’t accidentally absorb aluminum.
What is signal transduction?
A series of chemical reactions happening across a cell to convey the message sent by the hormone.
