Chapter 5 Roots and Soil Flashcards
embryo
(em′bree-oh) an immature sporophyte that develops from a zygote within an ovule or archegonium after fertilization
radicle
(rad′i-kuhl) the part of an embryo in a seed that develops into a root
root cap
(root kap) a thimble-shaped mass of cells at the tip of a growing root; functions primarily in protection
parenchyma
Parenchyma is a type of simple permanent tissue that makes a major part of ground tissues in plants,
amyloplast
(am′uh-loh-plast) a colorless, starch-forming plastid found in roots and involved in gravity perception
region of cell division
(ree′juhn uhv sel′ dih-vizh-uhn) area of actively dividing cells at an apical meristem
apical meristem
apical meristem, region of cells capable of division and growth in the root and shoot tips in plants. Apical meristems give rise to the primary plant body and are responsible for the extension of the roots and shoots.
protoderm
(proh′tuh-durm) the primary meristem that gives rise to the epidermis
ground meristem
(grownd mair′i-stem) meristem that produces all the primary tissues other than the epidermis and stele (e.g., cortex, pith)
procambium
(proh-kam′bee-um) a primary meristematic tissue that differentiates into primary xylem and phloem
region of elongation
(ree′juhn uhv ih-lawng-gey′shuhn) area near an apical meristem in which cells grow in length and width
secondary tissue
(sek′un-der-ee tish′yu) a tissue produced by the vascular cambium or the cork cambium (e.g., virtually all the xylem and phloem in a tree trunk)
region of differentiation
(ree′juhn uhv diff-uhr-en-tee-a′shun) area of maturing cells near an apical meristem
root-hair zone
(root′ hair zohn) area of cells in a root in which protuberances of epidermal cells can be found
root hair
(root hair) a delicate protuberance that is part of an epidermal cell of a root; root hairs occur in a zone behind the growing tip
cortex
(kor′teks) a primary tissue composed mainly of parenchyma; the tissue usually extends between the epidermis and the vascular tissue
endodermis
(en-doh-dur′mis) a single layer of cells surrounding the vascular tissue (stele) in roots and some stems; the cells have Casparian strips
Casparian strip
(kass-pair′ee-un strip) a band of suberin around the radial and transverse walls of an endodermal cell
passage cell
(pas′ij sel) a thin-walled cell of an endodermis
vascular cylinder
(vas′kyu-lur sil′in-der) a core of tissues, including xylem and phloem, that lies to the inside of the endodermis
pericycle
(per′uh-sy-kul) tissue sandwiched between the endodermis and phloem of a root; often only one or two cells wide in transverse section; the site of origin of lateral roots
adventitious
(ad-ven-tish′uss) said of buds developing in internodes or on roots, or of roots developing along stems or on leaves
pneumatophore
(noo-mat′oh-for) spongy root extending above the surface of the water, produced by a plant growing in water; pneumatophores facilitate oxygen absorption
aerial root
(air′ee-uhl root) root formed above the ground
Contractile Roots
A contractile root is a thickened specialized root at the base of a corm, bulb, rosette or other organ which is designed to shrink vertically under conditions of seasonal drought that helps position this plant part at an appropriate level in the ground.
Buttress Roots
Buttress roots are large, wide roots on all sides of a shallowly rooted tree. Typically, they are found in nutrient-poor tropical forest soils that may not be very deep. They prevent the tree from falling over while also gathering more nutrients
Parasitic Roots
Parasitic or Haustorial roots : Plants which depend on plant partially or totally for their food material are known as parasites
haustorium
(pl. haustoria) (haw-stor′ee-um; pl. haw-stor′ee-uh) a protuberance of a fungal hypha or plant organ such as a root that functions as a penetrating and absorbing structure
saprophyte
(sap′roh-fyte) an organism that lacks chlorophyll and obtains nutrients from dead or decaying organic matter
epiphyte
(ep′uh-fyt) an organism that is attached to and grows on another organism without parasitizing it
epiparasite
(ep′uh-par-uh-sahyt) a parasite that feeds upon another parasite
myco-heterotroph
(my-co-het′-ur-oh-trohf) a plant that obtains its carbon from a fungus rather than from photosynthesis
mycorrhiza
(pl. mycorrhizae) (my-kuh-ry′zuh; pl. my-kuh-ry′zee) a symbiotic association between fungal hyphae and a plant root
root nodule
(root nodd′yewl) a small swelling associated with nitrogen-fixing bacteria that invade the roots of leguminous plants and alders
hygroscopic water
(hy-gruh-skop′ik waw′tuhr) water that is chemically bound to soil particles and therefore unavailable to plants
gravitational water
(grav-uh-tay′shun-ul waw′tuhr) water that drains out of the pore spaces of a soil after a rain
capillary water
(kap′i-lair-ee waw′tuhr) water held in the soil against the force of gravity; capillary water is available to plants
phytoremediation
(fahy-toh-ri-mee-dee-ey′shuhn) use of plants to facilitate removal of toxins from the soil
phytochelatin
(fahy-toh-kee′la-tin) polypeptide that sequesters and detoxifies heavy metals
Taproot system
taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward.
Fibrous root system
A fibrous root system is the opposite of a taproot system. It is usually formed by thin, moderately branching roots growing from the stem. A fibrous root system is universal in monocotyledonous plants and ferns. The fibrous root systems look like a mat made out of roots when the tree has reached full maturity.
The Four zones in a developing root are…
Root cap
Region of cell division
Region of maturation
Region of elongation
The root cap is composed of ______.
parenchyma cells
Within a root, cells in the region of cell ______ divide every 12 to 36 hours.
division
Apical meristems
apical meristem, region of cells capable of division and growth in the root and shoot tips in plants. Apical meristems give rise to the primary plant body and are responsible for the extension of the roots and shoots.
Cells in the region of ____ are responsible for the growth in length of roots.
elongation
Order the four regions in a developing root starting with the tip of the root
- Root cap
- Region of cell division
- Region of elongation
- Region of maturation
In roots, tissue differentiation occurs in which region?
Maturation
Root hairs are tubular extensions of __.
Epidermal Cells
How does the region of elongation contribute to the lengthening of roots?
Cells in the region of elongation become several times longer than wide.
A taproot system is characterized by a single large root with smaller branch roots, whereas a ______ root system is characterized by many smaller roots of similar diameter.
Fibrous
How does the cuticle of root hairs compare to that of stems and leaves?
It is thinner
In growing roots, cells in the region of maturation are differentiating into specific ______.
Cell types
Root cortex
In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation.
Endodermal cells
The endodermis is the innermost layer of primary cortex, which represents a boundary between the vascular cylinder and peripheral root tissues
The cell walls of root endodermal cells are impregnated with lignin and ______
Suberin
Suberin
What is suberin and its function? Suberin functions as a physical barrier, preventing water loss from the tissues it surrounds as well as providing protection against pathogens
The cuticle of stems and leaves typically does not allow passage of water. Root hairs, which are responsible for water and nutrient absorption, also have a cuticle. Which of the following describes the root hair cuticle?
Their cuticle is thin enough to allow water to pass through, but it is thick enough to protect the root hairs from bacterial and fungal infections.
Pericycle
The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants
Where do branch roots and part of the vascular cambium of dicots arise?
within the pericycle
The tissue just inside the root epidermis is called the _____
Cortex
Certain plants such as sweet potatoes produce roots with extra parenchyma cells that are full of carbohydrates. These roots are called _____ _____ roots.
Food Storage
What substances (aside from cellulose) impregnate the cell walls of endodermal cells?
Lignin
Suberin
Some members of the Pumpkin Family that grow in dry regions are able to store _____
in their roots for when the natural supply runs low.
water
Suckers are aerial stems with rootlets at their base that are produced by _________ buds.
adventitious
adventitious buds
Buds arising at any part other than stem are known as adventitious bud.
All functions of the pericycle
Gives rise to lateral roots
Gives rise to parts of the vascular cambium of dicots
Gives Rise to root hairs
Pneumatophores
Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves, banyan figs, the warm-temperate rainforest rata, and pohutukawa trees of New Zealand
Non-parasitic plants that are attached to tree branches and grow unconnected to the ground often have roots that extend into the air called _____ roots.
Aerial
Buds that appear along the roots and produce suckers are called _____
buds.
adventitious
The roots of some bulb plants, called _____ roots, can pull the plant deeper into the soil each year.
Contractile
Suckers are aerial stems with rootlets at their base that are produced by _________ buds.
Adventitious
The contractile roots of some bulb plants ______.
pull the plant deeper into the soil
Some trees growing in shallow soils can gain extra stability by growing ______ roots.
buttress
Haustoria
In botany and mycology, a haustorium is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates the host’s tissue and draws nutrients from it.
Haustoria are produced by ______.
parasitic plants
Most land plants have associated fungi in the soil that are called ______.
mycorrhizae
mycorrhizae
a fungus which grows in association with the roots of a plant in a symbiotic or mildly pathogenic relationship.
epiparasites
Epiparasitism is the situation in which one parasitic species is parasitized by another to which it is related. Epiparasites (or secondary parasites) are thus ‘fellow travellers’, perhaps advantaged by sharing some feature of their hosts (the primary parasites), such as their dispersal agents.
Contractile roots
Contractile roots are responsible for movement of the underground shoot part ofthe plant, e.g., a corm, a bulb, or a. rhizome.
barbasco plant
used as a commercial insecticide and piscicide
Components of soil.
Minerals
Organisms
Air
Organic matter
Soil formation begins when rocks are broken down into ______ material.
parent
Parent material
Parent material is the underlying geological material in which soil horizons form. Soils typically inherit a great deal of structure and minerals from their parent material
Nodules are specialized tissues that surround beneficial bacteria. This symbiotic relationship enables plant to utilize ______.
gaseous nitrogen
Beyond food, in what ways do humans use root crops?
dyes
alcohol
drugs
insecticide
Members of the madder family
Other well-known members of the Madder family include the anti-malarial alkaloid quinine (Cinchona), and the ornamental Gardenia. Most plants of this family grow in the tropics, many of them as shrubs or trees.
Sands are particles that can be seen with the naked eye, whereas
_______ contains particles that can be seen with a lens or a light microscope.
Silt
Living organisms contribute to the soil in what ways?
adding to organic material through wastes
adding carbon dioxide
decomposing organic material
colloidal particles
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance.
What are groups of soil particles that are held together by colloidal particles?
Aggregates
Field capacity
Field capacity is the amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has materially decreased, which usually takes place within 2–3 days after a rain or irrigation in pervious soils of uniform structure and texture.
mycorrhizae
root associated fungi
