Botany 3rd Exam

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69 terms · Roots, stems, plant metabolism, and growth

Roots....

anchor trees firmly in the soil, usually through an extensive branching network that constitutes about one third of the total dry weight of the plant.\; they also absorb water and minerals in solution, mostly through "feeder" roots found in the upper meter of soil. Some store water or food.

taproot

When the radicle develops into a thick, tapered root from which thinner ranch roots arise.

Adventitious roots

Roots that do not develop form another root but develop instead from a stem or leaf.

fibrous root system

have large numbers of fine roots of similar diameter develops from the adventitious roots.

Dicots have...

a taproot system with one primary root from which secondary roots develop.

Monocots have...

a fibrous root system with adventitious roots developing.

The four regions of a developing root

the root cap, the region of cell division, the region of elongation, the region of maturation.

Root cap

composed of a thimble shaped mass of parenchyma cells covering the tip of each root; it's quite large and obvious in some plants; it functions to protect the delicate tissues

amyloplasts

plastids containing starch grains; act as gravity sensors, collecting on the sides of root cap cells facing the direction of gravitational force

region of cell division

is composed of an apical meristem which is a tissue of actively dividing cells, in the center of the root tip, produce the surrounding root cap.

protoderm

gives rise to an outer layer of cells, the epidermis

ground meristem

the inside of the protoderm; produces parenchyma cells of the cortex

procambium

appears as a solid cylinder in the center of the roots, produces primary xylem and primary phloem

Pith

parenchyma tissue; originates from ground meristem; generally present in stems but absent in most dicot roots.

region of elongation

merges with the apical meristem, usually extends about 1 centimeter or less from the tip of the root.

root hairs

absorb water and minerals, adhere tightly to soil particles with the aid of microscopic fibers they produce and greatly increase the total absorptive surface of the root.

cortex

a tissue composed of parenchyma cells lying between the epidermis and inner tissues; mostly store food.

endodermis

the inner boundary of the cortex; consists of a single layered cylinder of compactly arranged cells whose primary walls are impregnated with suberin

Casparian strips

the suberin bands; on the radial and transverse walls; they prevent water from passing through the otherwise permeable cell walls.

passage cells

some endodermal cells; may remain thin-walled and retain their Casparian strips, but may eventually tend to become suberized.

vascular cylinder

a core of tissues; lies to the inside of the endodermis; most of the cells conduct water or food in solution

pericycle

a layer of parenchyma tissue that lays against the inner boundary of the endodermis

determinate growth

grouth that stops after an organ such as a flower or leaf is fully expanded or after a plant has reached a certain size.

indeterminate growth

occurs in tress and other perennials where new tissues are added indefinitely, season after season.

adventitious buds

buds appearing in places other than stems

pneumatophores

special spongy roots which extend above the water's surface and enhance gas exchange between the atmosphere and the subsurface roots to which they are connected.

epiphytes

nonparasitic plants that grow suspended without direct contact with the ground like orchads.

The ground meristem..

gives rise to parenchyma cells of the cortex

the procambium...

appears as a solid cylinder n the center of the root; produces primary xylem and phloem

node

A region of a stem where a leaf/leaves are attached

internode

a stem region between nodes.

petiole

the "stem" between the leaf and the branch, connecting the two.

axil

the angle between the petiole and the stem which contains a bud.

terminal bud

resembles an axillary bud although it is often a little larger; contain meristems.

stipules

paired, leaflike, appendages that ma remain throughout the life of the leaf.

leaf primordia

tiny embryonic leaves that will develop into mature leaves after the bud scales drop off and growth begins.

secondary xylem

functions the same as primary counterparts; conducts water and soluble nutrients

secondary phloem

functions the same as primary counterparts; conducts, in soluble form, food manufactured by photosynthesis throughout the plant

cork cambium

when a second cambium arises within the cortex or from the epidermis or phloem

suberin

a waxy substance that makes the cells impervious to moisture.

lenticels

one of usually numerous, slightly raised, somewhat spongy groups of cells in the bark of woody plants; they permit gas exchange between the interior of a pant and the external atmosphere.

vascular bundles

herbaceous dicot stems retain these; patches of xylem and phloem; arranged in a cylinder that separates the cortex from the pith

Procambium produces..

only primary xylem and phloem, but later, a vascular cambium arises between these two primary tissues and adds secondary xylem and phloem to the vascular bundles.

Wood is...

secondary xylem.

spring wood

When a typical tree first becomes active in the spring, it usually produces relatively large vessel elements of seconary xylem.

summer wood

The xylem that is produced after the spring wood, and which has smaller or fewer vessel elements and larger numbers of tracheids

annual ring

One year's growth of xylem

vascular rays

lighter streaks or lines can be seen radiating out from the center across the annual rings; consist of parenchyma cells that may remain alive for ten or more years.

xylem ray

any part of a ray within the xylem

phloem ray

a ray that extends into the phloem

Monocots do not...

have a vascular cambium nor a cork cambium and thus produce no secondary vascular tissues or cork.

rhizomes

Horizontal stems that grow below ground, often near the surface of the soil; superficially resemble roots but have scalelike leaves.

Runners

Horizontal stems that grow above ground, generally along the surface; they also have long internodes.

Bulbs

Large buds surrounded by numerous fleshy leaves, with a small stem at the lower end.

Corms

composed almost entirely of stem tissue, except for the few papery, scalelike leaves sparsely covering the outside.

Cladophylls

Stems that appear flattened and leaflike.

photosynthesis

parts of water and air are combined in cells and stored as sugar.

respiration

when stored energy is released

metabolism

the sum of all the interrelated biochemical processes that take place in a living organism which requires energy to occur.

enzymes

proteins that speed up chemical reactions in cells without being used up in the reactions; regulate about every metabolic activity.

catabolism

when enzymes break chemical bonds

cellular respiration

generally catabolic; release energy held in chemical bonds

reduction

gain of one or more elections

oxidation

loss of one or more electrons

light dependent reactions

the first major steps in the conversion of light energy to biochemical energy; the reactions are initiated when units of light energy strike chlorophyll molecules embedded int he thylakoid membranes of chloroplasts.

NADPH

reduced nicotinamide adenine dinucleotide phosphate; caries hydrogen and is used in the second phase of photosynthesis.

light independent reactions

utilizes ATP and NADPH to form sugars; also known as dark reactions because they don't directly require light; take place outisde of the grana in the stroma of the chloroplast

NADP

nicotin amide adenine dinucleotide phosphate; natural elecron acceptor in the light dependent reaction

During light dependent reactions...

water molecules are split apart, releasing electrons and hydrogen ions, and oxygen gas is released; the electrons from the split H2O molecules are passed along an electron transport system; energy-storing ATP molecules are produced; some hydrogen from the split H20 molecules is involved in the reduction of NADP to form NADPH.

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