Roots Chapter 5 (Week 2 Lecture 2) Flashcards
What are the four main functions of roots?
Anchor plants into soil
Absorption of water and minerals
Store food or water
Other specialized functions
Where does a root arise from?
embryonic root or radicle
A ______ root system belongs to monocots while a ______ root system belongs to dicots.
Fibrous, taproot
Why does a fibrous root plant not have a single large taproot?
Because the embryonic
root dies back when the plant is still young
______ roots are roots that arise from anything other than a radicle.
Adventitious (corn, poison ivy)
What are the four regions of the root? Order them from bottom to top.
Root cap
Region of cell division (apical meristem)
Region of cell elongation
Region of maturation
______ cells make up the root cap covering each root tip.
Parenchyma
Root cap functions in _____ (gravity perception).
gravitropism
True or False: The root cap secretes mucilage that acts as lubricant
True
The region of cell division is composed of what 3 meristematic areas?
Protoderm, ground meristem, procambium
On average, how many times does the apical meristem cells divide per day?
Once or twice per day
True or False: The region of elongation does not merge with the apical meristem.
False, the region of elongation does merge with the apical meristem
If a cambium is present, how does increase in girth happen?
Through the addition of secondary tissues
What happens to tiny vacuoles during the region of elongation?
Tiny small vacuoles merge into 1 or 2 large vacuoles, occupying more than 90% of volume of each cell
What happens to cells during the region of maturation?
Cells differentiate into various distinctive cell types
The region of maturation consists of what 5 cell structures?
Root hairs Cortex Endodermis Pericycle Vascular cylinder
What is the the function of root hairs?
Absorb water and minerals
Adhere tightly to soil particles
Increase total absorptive surface of root
How are root hairs formed?
Formed from epidermal cell extensions with thin cuticle
True or False: The cuticle does not exist on root but does on root hairs.
False, cuticle exists on root but not on root hairs
What cells is the cortex is made up of?
Parenchyma cells between epidermis and vascular cylinder
What is the main function of the cortex?
Mostly stores food
What cells is the endodermis is made up of?
Inner boundary of cortex, consisting of a single-layered cylinder of compact cells
In the endodermis, cell walls with suberin bands called ______ ______ on radial and tangential walls
Casparian strips
In the endodermis, eventually inner cell walls become thickened with suberin, except for ______ ______.
Passage cells
What is the function of casparian strips?
Forces water and dissolved substances entering and leaving the central core to pass through endodermis
Regulates types of minerals absorbed
Where is the pericycle located?
Outer boundary of vascular cylinder
True or False: The pericycle stops dividing after it matures.
False, the pericycle continues to divide, even after mature
What does the pericycle eventually form?
lateral (branch) roots and part of the vascular cambium
Most of cells of ______ ______ are primary xylem or primary phloem
Vascular cylinder
Where is the vascular cylinder located?
Lies inside endodermis
Vascular cambium develops from parts of the ______
and other ______ cells between the xylem arms
and phloem patches in most dicots and conifers.
Pericycle, parenchyma
______ ______ forms secondary phloem
to the ______ and secondary xylem to the ______.
Vascular cambium, outside, inside
In dicots, the solid core of xylem are in the shape of “______” in cross section.
Arms
In monocots, xylem surrounds the ______.
Pith
What is determinate growth?
Growth that stops after an organ is fully expanded or after a plant has reached a certain size
What is indeterminate growth?
New tissues are added indefinitely, season after season
Starch and other carbohydrates like sweet potatoes have ______ ______ roots.
Food storage
The pumpkin family, especially in arid regions have ______ ______ roots.
Water storage
Fruit trees are an example of ______ ______ roots.
Propagative roots
In propagative roots, the adventitious buds on roots develop into ______ (aerial stems)
Suckers
What do pneumatophores function as?
Spongy roots that extend above the water’s surface and enhance gas exchange between atmosphere and subsurface roots
Where are pneumatophores found?
In plants with roots growing in water (black mangrow)
Orchids have aerial ______ roots, with epidermis several layers thick to reduce water loss.
Velamen
Corn has aerial ______ roots to support plants in high wind.
Prop
Aerial roots in ivies (English ivy, Virginia creeper) aid in what?
Plant climbing
______ roots pull plants deeper into soil such as lily bulbs and dandelions.
Contractile
______ roots have stability in shallow soil such as tropical tress
Buttress
______ roots have no chlorophyll and are dependent on chlorophyll-bearing plants for nutrition such as dodder.
Parasitic
What is mycorrhizae?
Fungi that form a mutualistic association with plant roots
True or False: Both fungus and root benefit and are dependent upon association for normal development.
True, mutualistic association
How does the mutualistic relationship work between fungi and roots?
Fungi facilitate absorption of water and nutrients, especially phosphorus for roots and the plant furnishes sugars and amino acids to fungus.
______ ______ contain large number of nitrogen-fixing bacteria.
Root nodules
What type of plants contain root nodules?
Legume family (Fabaceae)
What are the 7 types of specialized roots?
Water storage, buttress, food storage, parasitic, pneumatophores, propagative, contractile
