Course Map, chapter five tissues and the primary growth of stems (vascular…
chapter five tissues and the primary growth of stems
cells closest to the metaxylem
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young cells of xylem and phloem
refers to epidermal cells that are in the early stages of differentiation
similar process occurs in the outer part of each vascular bundle. the exterior cells mature
these cells have had the longest time for growth before differentiation, they develop into the largest tracheary elements of all
visible differentiation begins; certain cells stop dividing and start elongating and differentiating into the first tracheid or vessel elements of the vascular bundles
the region just below the apical meristem, its cells are also dividing and growing, producing cells for the region below
stems grow longer by creating new cells at their tips
external organization of stems
at the extreme tip of each stem
stem area just above the point where a leaf attaches
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fatty substance that makes the wall impermeable to water
in shady environments, it may be advantageous for axillary buds to remain dormant so that all resources are concentrated in the growth of the vertical main shoot
horizontal like rhizomes, but they grow for only a short period and are mainly a means of storiing nutrients(potatoes). the word "tuber" is often used informally for any bulky underground plant organ
fleshy horizontal stems that allow a plant to spread underground(bambbo, irsies, and canna lilies).
vertical, thick stems that have thin, papery leaves and gladiolus;
short shots that have thick, fleshy leaves
the bud is covered by small, corky, waxy
miniature shoot with a dormant apical meristem and several young leaves; either a vegetative bud if it will grow in to a branch or a floral bud if it will grow into a flower or group of flowers.
a miniature shoot with a dormant apical meristem and several young leaves
where leaves are attached
also called runners, their internodes are especially long
the regions between nodes
circular bordered pits
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in vessel elements, howevere, an entire region of both primary and secondary wall is missing. during the final stages of differentiation, a large hole.
the aligned set of pits is a pit-pair, and the set of primary walls and middle lamella between them constitues
in such tracheary elements, virtually all of the primary wall is underlain by secondary wall. the pits that allow water movement are weak points in the wall, but the weakness is reduced
the most derived and strongest tracheary elements
the secondary wall is deposited in the shape of a net, as the name suggests.
provides much more strength because the secondary wall underlies most of the inner surface of the primary wall and is fairly extensive
the secondary wall exists as one to three helices interior to the primary wall
a small amount of secondary wall, organized as a set of rings
which conducts water and minerals
which distributes sugars and minerals
a bit more complex than either hornworts or liverworts. always have a stem with leaves and in those with taller stems or larger leaves, some cells deposit a thicker wall and resemble sclerenchyma fibers.
about as simple as hornworts.
rare froup of tiny plants whose bodies look like bits of green cellophane, often no larger than 2 to 5 mm in diameter and only a few cells thick. they have no epidermis, no stomata, no collenchyma, no sclerenchyma, no cortex, no pith, no xylem, and no phloem
short and wide with rather perpendicular end walls; most contain one or two perforations. dead at maturity. found almost exclusively in flowering plants. among non-flowering plants, only a few ferns, horsetails, and gymnosperms have vessels.
long and narrow with tapered ends; contain no perforations. dead at maturity. found in all vascular plants.
sclerenchyma and mechanical sclernchyma
more or less isodiametric; often dead at maturity.
long, many types are dead, other types remain alive and are involved in storage
both a primary wall and a thick secondary wall that is almost always lignified
early angiosperms diversified into several groups
broadloaf plants such as roses, asters, maples, and others,
body of an herb contains three parts
primary plant body
plant that never becomes woody and covered in bark
secondary plant body
grasses, lilies, cattails, palms, philodendrons, bromeliads
waterlilies, magnolias, and laurels
the flowering plants discussed here are formally classicfied as the division magnoliophyta
at frist these areas are low depressions in the developing secondary wall, but as wall depostition continues, these areas become narrow in the secondary wall
the pits of adjacent sclerenchyma cells must meet, the pits of one cell met areas of secondary wall in the neighboring cells, no water or sugars could be transferred and the protoplasts would starve
a primary wall that remains thin in some areas but becomes thickened in other areas, most often in the corners.
mass of parenchyma cells. this is the most common type of cell and tissue, constituting all soft parts of a plant. soft leaves, petals fruits, and seeds are composed almost completely of parenchyma
cell that have only primary walls that remain thin
in basal angiosperms and eudicots, vascular bundles are arranged in one ring surrounding
specific patterns that are too complex to be recognized easily.
large proportion of xylem parenchyma and even mechanical sclerenchyma in the form of xylem fibers
it is part of the primary plant body
located just interior to the cortex.
chapter six leaves
leaf blade ( also called lamina)
dorsal surface ( under side)
ventral surface (upper side)
petiole ( stalk)
the petiole bears two small flaps of tissue at its base
which serve various function
vascular tissues are the most variable: one, three, five, or more vascular bundles
branch from stem vascular bundles and diverge toward the petiole
if leaves are small or very long and narrow, self-shading is not a problem, and there may be no petiole
holds the blad out into the light. this prevents shading of leaf blades by those above them; self-shading would defeat the basic usefulness of the leaf
(basal angiosperms and eudicots) reticulate venation
at the base of the meristem, cells just interior to the protoderm grow outward, forming a protrusion
extends upward as a narrow cone, growing so rapidly that it becomes taller than the shoot apical meristem
blade of just one part
blade divided into serveral individual parts
sheathing leaf base
emerge that branch into narrow
also called a midvein
the most important for releasing water from xylem and loading sugar into phloem, whereas the midrib and lateral veins are involved mostly in conduction
bundle sheath extension
veins, especially larger ones, often have a mass of fibers above, below, or both
such fibers help give rigidity to the blade and are believed to provide an additional means by which water moves form the bundle out to the mesophyll
they both conduct and support the leaf blade,they may have many fibers arranged as a sheath
are initiated by the expansion of some shoot apical meristem cellls to form a leaf primordium
the cell becomes involved until the primordium is a cylinder that completely or almost completely encircles the shoot apical meristem
apical meristem cells adjacent to the primordium grow upward along with it, becoming party of the primordium and giving it a hood-like shape
numerous adaptation permit plants to survive in desert habitats, one of the most common being production of succulent leaves
this is characteristic of species in the families crassulaceae(contains Kalanchoe and Sedum), portulacaceae, and Auziaceae(ice plant), among other.
Succulent leaves are thick and fleshy, a shape that reduces the surface-to-volume ratio and favors water conservation. some leaves are cylindrical or even spherical, the optimal surface-to-volume shape,
the upper surface of most leaves is a layer of cells
open, loose aerenchyma that permits carbon dioxide to diffuse rapidly away from stomata into all parts of the leaf's interior
ground tissues interior to the leaf epidermis
leaves of conifers
in almost all species of conifers, leaves are sclerophylls: they have a thick cuticle, and their epidermis and hypodermis cells have thick walls.
most conifer leaves contain unpalatable chemicals. conifer leaves are always simple, never compound, and have only a few forms.
sclerophyllous foliage leaves
foliage leaves must produce more sugars by photosynthesis than are used in their own construction and metabolism, or the plant would lose energy every time it produced a leaf.
chapter 16 genetics
a plant's own pollen is used to fertilize its own eggs
f1 or first filial gerneration
the off spring from the interbreeding of the first filial generation
the off spring of their crossbreeding of the parental generation
neither[ parental trait dominates the other, so this pair of alleles are incomplete
ex. a flower receives a dominant allele and a recessive allele making it a heterozygous
each parent is said to be homozygous because each has two identical alleles for this gene
dominant over the recessive trait
the under lining trait that is only dominant if it has two of the same trait
difficult to know what the genotype of any particular plant is unless the plant shows the recessive trait
the homozygous recessives can also be kept as a special line, being selfed and kept pure
a cross involving the plant in question and one that is homozygous recessive for the trait being studied
at least 900 sites exist at which point mutations can occur, and of course, any mutation may involve several nucleotides. consequently, the gene may exist in many forms
only a single character is analyzed and studied; the inheritance of other traits is not considered.
when achlorophlllous palnt is crossed with a green, chlorophyll-bearing plant, the outcome depends on which plant is the pollen parent and which is the ovule parent
the presence of sports or sectors that are white, reed, or orange on a plant that is otherwise green
the phenotypic result of a mutation can vary in severity from almost undetectable
be difficult to detect if its effect occurs early. if it affects basic metabolic functions such as respiration, DNA replication, cellulose synthesis, or the structure of histones, plants homozygous for it probably die while still very young; in some instances, the gametes die even before fertilization
two genes are on separate chromosomes, the alleles of one gene move independently of the alleles of the other gene
parental type chromosomes
an unexpected feature of both plants and animals is that during fertilization, the sperm cell loses most of its cytoplasm and only the sperm nucleus enters the egg. consequently, the zygote obtains all its plastid and mitochondrion genomes form the maternal parent
map unit or one centimorgan
quantitative trait loci
an intermediate is part of several metabolic pathways and is produced by only one enzume, a mutation in tha tenzyme's gene affect5s all of the pathways and alters several different traits.multiple phenotype affects of one mutation
extremely complex crosses, involving hundreds or thousands of progeny, may have to be performed to determine what fraction of a particular phenotype is correlated wiht a particular gene; the genes or other portions of DNA
having multiple genes for each trait
all plants with more than two sets of chromosomes
a change in chromosome
gene are still so similar to the wilds-type allele that they can be recognized as having originated as duplicates of it
ex. five histone proteins that make up nucleosomes are needed in such abundance tha teach nucleus may have up to 600 paralogs of the genesk, not just two as for most traits;
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each replication fork runs into runs into one of th eadjacent replicons' replicons
as DNA uncoils and then separates, it has a forked appearance
method of replication, in which each strand of DNA acts as the template for making the complementary stand
enters and adds deoxyribonucleotides onto the end of the primer RNA using the open DNA as a guide
ribonucleotides, not deoxyribonucleotides, and are polymerized into short pieces while also acting as a substrate for DNA-synthesizing enzyme
one strand of the DNA double helix is cut, and the two strands separate from each other in a short region, forming a small "bubble"
the expression of those alleles in the individual's size, shape, or meatbolism
types of alleles that a single individual has
the science of inheritance, the chemical basis of genetic inheritance is the gene, the sequence of DNA nucleotides that guides the construction of RNA and proteins and also controls construction of more copies of the genes themselves.
the alleles of a particular gene differing form each other in their sequence of nucleotides
chapter 25 populations and ecosystems
nonliving and are physical phenomena: climate, soil, latitude, altitude, and disturbances such as fires, floods, and avalanches.
living factor: the plant itself, other plant species, and the species of animals, fungi, protists, and prokaryotes
pollinators are critically important aspects of the habitat for the plant species they pollinate, and any disease organisms or predators that prey on those pollinators are also important to the plant.
between the low and high extremes
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autotrophs, they are the first step of any food web
the steps of how the food energy level goes down each losing the energy they gained/lose
basically feeding levels
refers to the number and diversity of species that coexist in an ecosystem, and it depends on whether the climate is mild or stressful, the soil is rich or poor, and the species' tolerance ranges are broad or narrow
trees, shrubs, and herbs are the three most useful categories
the changes that an ecosystem undergoes with time; the time span can be as short as a day or can encompass season or decades
the physical size and shape of the organisms and their distribution in relation to each other and to the physical environment
the set of conditions in which an organism completes its life cycle
rather coexists with numerous populations of other plant species as well as populations of animals, fungi, protists, and prokaryotes
an individual plant never exists in isolation in a habitat; instead , there are other individuals of the same species
boundaries of the geographic range
used whenever there is no obvious, identifiable pattern to the position of individuals
those in which the spacing between plants is either small or large, but rarely average
the length of time from the birth of one individual until the birth of its first offspring, affects the rapidity of population growth: annuals have a generation time of 1 year or less and can increase rapidly, whereas most conifers and angiosperm trees must be several years old before they produce their first seeds
intrinsic rate of fnatural increase or biotic potential
the number of offspring produced by an individual that actually live long enough to reproduce under ideal conditions.
typically are annuals or small shrubby perennials because the disturbed habitat gradually changes back into a crowded one that is no longer suitable for the pioneer
a population close to its carrying capacity, select for phenotypes very different from those that are beneficial in a disturbed habitat
the number of individuals in each population that can live in a particular ecosystem is limited
although most habitat components act on the plant simultaneously and most should be considered important, at any given time and locality, one factor alone determines the health of the plant
the first plants that invades a new soil
uppermost and is sometimes called the zone of leaching; it consists of litter and debris, and as this breaks down, rainwater washes nutrients from it downward into the next layer
zone of deposition, is the area where materials for the a horizon accumulates. it is rich in nutrients and contains both humus and clay
composed mostly of parent rock and rock fragments
when several individuals, of either just one or several species, occur together, the possibility for interaction is created. if the interaction is basically benficial for both organisms
a situation in which tow populations do not grow as well together as they do separately because they use the same limited supple of resources
whichever species is les adapted is excluded form the ecosystem by superior competitors
each species is assumed to be adapted to a particular set of conditions
which one species benefits and the other is unaffected, are also common between plants and animals
browsing or grazing
ex. beans frown in rich soil with adequate water are strikingly different from those grown in poor soil with little water and other stresses. to test whether ecotypes really exist
plants form each site are transplanted to the alternate site, and plants from both sites may be grown together
many interrelationships between plants and fungi or bacteria are harmful to the plant, but the fungi and bacteria
seed dispersal by fruit-eating animals, also benefits both species as long as the animal does not chew the seeds and digest the embryos
this could be the beginning of divergent speciation, of course, but long before the various subpopulations could be called subspecies
a relationship in which one species benefits and the other is harmed
but more likely known as browsing or grazing
the roots of one individual may establish a zone that prevents the germination or growth of others. zones can also be established, at least theoretically, by the release from the plant of chemicals that inhibit other plants
chapter 7 roots
they were once thought to represent passagewys for the absorption of minerals; it is now suspected that they are merely slow to develop
the bands of altered walls, are involved in controlling the types of minerals that enter the xylem water stream
between the vascular tissue and the endodermis are parenchyma cells that constitute an irregular region
make contact with the soil, they transport additional nutrients and water to the stem,just as importantly, they contract slightly and place some tension on the stem, thus acting as stabilizers, much like guy wires on tall television antennas
upper side grows more rapidly than other parts of the root. buttress roots brace the trunk against being blown over by winds
in the zone of maturation, minerals do not have free access to the vascular tissues because the innermost layer of cortical cells differentiates into a cylinder
lateral roots or branch roots
seed plants have a single prominent taproot that is much larger than all the rest and numerous
this taproot develops from the embryonic root
fibrous root system
these roots do not arise on pre-existing roots and because they are not radicles
dictyosomes of root cap cells secrete a complex polysaccharide
root apical meristem
zone of elongation
root hair zone
form only in a part of the root that is not elongating; otherwise, they would be shorn off
a region in which many of the epidermal cells extend out as narrow trichomes
zone of maturation
Beginning at the first root hair is the zone of cell maturation where the root cells differentiate into specialized cell types
the region in which newly formed cells by the activity of apical meristem start elongating. Different regions of growth are very distinct in growing roots
is a small region at the tip of a root in which all cells are capable of repeated division and from which all primary root tissues are derived
A region in the apical meristem of a root where cell division proceeds very slowly or not at all, but the cells are capable of resuming meristematic activity should tissue surrounding them be damaged
the absorption of minerals in the root hair zone causes a powerful absorption of water, and a water pressure
the root apical meristem is protected by a thick layer of cells
most monocots and some eudicots have a mass of many similarly sized roots; this arises because the radicle dies during or immediately after germination
carrots, beets, and radishes, are the plant's main site of carbohydrate storage during winter.
ectomycorrhizal relationship( woody forest plants)
hyphae penetrate the root cortex as far as the endodermis; they passs through th ewalls of the cortex cells but cannot pass the casparian strip
a form of symbiotic relationship that occurs between a fungal symbiont, or mycobiont, and the roots of various plant species.
is a symbiotic association between a fungus and a plant, refers to the role of the fungus in the plant's rhizosphere, its root system
a slender projection from the root of a parasitic plant, such as a dodder, or from the hyphae of a parasitic fungus, enabling the parasite to penetrate the tissues of its host and absorb nutrients from it.
a swelling on a root of a leguminous plant, containing nitrogen-fixing bacteria
formation is most often initiated when rhizobia become trapped between two root hair cell walls. This usually occurs when a deformed root hair forms a sharp bend or curl, and bacteria bound to the root hair become trapped between appressed cell walls
the chemical processes by which atmospheric nitrogen is assimilated into organic compounds, especially by certain microorganisms as part of the nitrogen cycle.
chapter 10 energy metabolism: photosynthesis
a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.
organisms that gather energy directly from light and use it to assimilate small inorganic molecules into their own tissues.
organisms that cannot do this but instead take in organic molecules and respire them, obtaining the energy available in them.
which also carries high-energy phosphate bonds.
involves light energy in photosynthesis; animals, fungi, and nonchlorophyllous plant tissues cannot perform photophosphorylation because they lack the necessary pigments and organelles
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small proteins that contain a cofactor, heme, which holds an iron atom
cytochromes, transport electrons over short distances within a membrane
a small protein that carries electrons on a metal atom in this case copper
cytochrome b6/f complex
which in turn gets electro from a molecule of plastoquinone
a molecule of quinone, receives electrons
actually a chlorophyll a molecule that does not contain a magnesium atom, becomes oxidized as it donates an electron to Q
the reaction center of photosystem 2 and has the name P680
electron transport chain
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light dependent reactions
water and light, however, do not act on carbon dioxide directly; instead, they create the inermediates ATP and NADPH
ATP and NADPH interact with carbon dioxide and actually produce carbohydrate
electromagnetic radiation spectrum
which encompasses gamma rays, X-rays, ultraviolet light, infrared light, microwaves, and radio waves, in addition to visible light
quanta (singular, quantum)
radiation can be thought o fand treated physically either as a set
also called photons
as a set of waves
any material that absorbs certain wavelengths specifically and therefore has distinctive color
it absorbs only some red and some blue light, letting most of the rest pass thorugh, especially high energy radiation
quality of sunlight
regers ot the colors or wavelengths it contains. sunlight is pure white because it contains the entire visible spectrum
quantity of light
refers to light intensity or brightness, is affected by several factors. more light is available for photosynthesis on a clear than on a cloudy day
light compensation point
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this energy is trapped in the earth/atmosphere system and warms our world
the concentration of carbon dioxide is increasing the atmosphere, and the average temperature is also
global climate change
wind patterns are being changed such that certain areas areas are beoming
a colorless unstable toxic gas with a pungent odor and powerful oxidizing properties, formed from oxygen by electrical discharges or ultraviolet light. It differs from normal oxygen (O2) in having three atoms in its molecule (O3)
chapter 8 structure of woody plants
contain conducting tissues, their accumulation gives plants a greater capacity to move water and minerals upward and carbohydrates downward
connects on each side with the fascicular cambia
irregularly, without any horizontal pattern
fusiform initials may occur in regular horizontal rows
in a woody species, the cells located in this position never undergo cell cycle arrest; they continue to divide instead of maturing.
horizontal, rectangular cells that look somewhat like parenchyma cells but have secondary walls, circular bordered pits, and protoplasts that degenerate quickly after the secondary wall is completed
when a fusiform initial undergoes longitudinal cell division with a wall parallel to the circumference of the cambium, it produces two elongate cells
vascular cambium cells must occasionally divide longitudinally
develops form the ray initials
the arrangement of secondary xylem cells reflects that of the fusiform and ray initials
derived from the fusiform initials
though in many instances they are actually much harder than many hardwoods
wood of all basal angiosperms and eudicots, even those that lack fibers, making them strong, tough, and useful for construction
all cells formed to the interior of the vascular cambium
one of the meristems that produce the secondary plant body
wood that is formed late in a tree's growing season and which forms the darker part of the annual ring of growth
having vessels more numerous and usually larger in cross section in the springwood with a resulting more or less distinct line between the springwood and the last season's wood
having vessels more or less evenly distributed throughout an annual ring and not varying greatly in size
cork cell (phellem cell)
defined as the meristematic cell layer responsible for the development of the periderm, Cells that grow inwards,
teh corky outer layer of a plant stem formed in secondary thickening or as infection
made up o fcells prodced inwardly by the cork cambium, in woody plants the epidermis is eventually replaced by a tougher, protective layer called bark
tissue in the stem of a plant that gives rise to cork on it s outer surface and containing chlorophyll on its inner surface
one sperm and one egg are brought together, forming a new signle diploid cell, the fertilized egg
sporophyte phase or generation
in plants, the life cycle is more complex. the plants you are familiar with--trees, shrubs, and herbs--aare all just one phase of the plant life cycle.
always diploid, like most adult animals, and they have organs (located in the flowers in angiosperms) with cells capable of undergoing meiosis.
in animals, meiosis result in haploid gamestses, but in plants, its results in haploid
syngamy or fertilization
gametes can fuse with other gametes in a process; producign the diploid zygote. a gamete that does not undergo syngamy dies because it cannot live by itself and usually cannot grow into a new, haploid individual ( unfertilized eggs of some insects such as bees are exceptional develop into sterile workers).
plant spores are just the opposite: they cannot undergo syngamy,l but each undergoes mitosis and grows into an entire new haploid plant
small sperm cells that swim
large that do not
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in oogamous plants, just as in oogamous mammals, sperms are produced by one type of individual and eggs by a different type of individual;
a large spreading or vining plant grows to several meters in length, and individual parts becomes itself sufficient by establishing adventitious roots
haploid sex cells
sperms or eggs
by meiosis individuals that produce sperms(male) and individuals that produce eggs(females)
fusion of the protoplasts of the gametes
fusion of the nuclei. as a pollen tube grows downward through the style toward the ovule, it is guided to the ovuel's micropyle by some means
in angiosperms only, the seond sperm nucleus releases form the pollen tube migreates form the synergid into th ecentral cell. in undergoes karyogamy with both polar nuclei,
because both sperm nuclei undergo fusions-one with the egg nucleus and the other with the polar nuclei
which pushes the embryo deep into the endosperm. usually delicate and ephemeral in angiosperms; it is crushed by the later growth of the embryo and is not easily detectable in a mature seed.
the end of the embryo father form the suspensor initiates two primordia that grow into two cotyledons in basal angiosperms adn eudicots.
the part of a plant embryo that develops into the primary root
the region of an embryo or seedling stem above the cotyledon
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chapter 12 transport processes
the space outside the plasma membrane within which material can diffuse freely. It is interrupted by the Casparian strip in roots, by air spaces between plant cells and by the plant cuticle.
a continuous network of interconnected plant cell protoplasts.
which the vesicles migrate through the cytoplasm and fuse with a another organelle
cells that are not close neighbors
inhibit movement of substances, plants are adept at synthesizing organic polymers impermeable to a variety of substances
involves distances of a few cell diameters or less
plants have only a few basic types of transport processes, and the fundamental principles are easy to understand
membranes don't allow anything to pass through and occur as isolation barriers
selectively permeable membranes
allow only certain substances to pass through: all lipid/protein cell membranes are differenitally permeable
membranes allow all solutes to diffuse through them and have little biological significance
water molcules, even though highly polar, pass through all membranes, but their movement is more rapid if the membranes has protein channels
uses the energy of ATP to force molecules across the membrane, even if that type of molecule is extremely concentrated on the receiving side
which the random movement of particles in solution causes them to move form areas where they are relatively high concentration to areas where they are in relatively low concentration
megaapascals (MPa) or bars
water's adhesion to nondissolved structures such ass cell walls, membranes, and sooil particles. adhesion can only decrease water's free energy, and thus, matric potential is always negative
he effect that soulutes have water potential. in pure water, no solutes are present and osmotic potential is given the value of 0.0 MPa. adding solutes can only decrease water's free energy because water molecules interact with solute molecules and cannot if wate molcules do not interact with the added molecules, the substance does not dissolve
unit of pressure, one megapascal is approximately equal to 10 bars atmospheres of pressure. pure water at one or 10 atmosphere of pressure is defined as having water potential of zero
the effect that pressure has on water potential. if water is under pressure, the pressure potential increases and so does water potential. if pressure decreases, so do the pressure potential and water potential. pressure can be positive or negative
like any other chemical, water has free energy, a capacity to do work. for most chemicals, this energy is called its chemical potential
basically the evolutionary history of each member of the group. some phylogenetic studies attempt to create models of the evolutionary relationships of very large groups, for example, the steps that were involved as plants, animals, and fungi evolved form some early ancestor. other studies focus on the relationships of smaller groups, such as the species of the legume family.
to understand each of these evolutionary lines and to have a system of names
that reflects their relationships accurately; the body or system of names in a particular field.
natural system of classification
a system in ehich closely related organisms are classified together, and assigning plant names on the basis of phylogenetic relationships. the nomenclature would reflect the natural system of classification
which ideally and theoretically is a set of individuals closely related by descent from a common ancestor. members of a species can interbreed with each other successfully but cannot interbreed with individuals of any other species
deciding whether several species are closely related enough to be placed together in the same genus is difficult. no objective criteria exist; the decision is entirely subjective and is often the cause of great dispute.
can be traced directly to Carolus Linnaeus, a professor of natural history at the University of Uppsala in Sweden during the middle and latter part of the 18th century.
binomial system of nomenclature
placed every species into one genus or another. every species had both a genus name and a species epithet
inheritance of acquired characteristics
it was the first major attempt at a natural system of classification , and people could not help but whether some species within each genus had not evolved from others. perhaps similar genera had changed, evolved. science was still dominated by the idea of divinely created types
the critical concern is that the genera are natural, that all of the species included in the genus are related to each other by a common ancestor, and that all descendants of that common ancestor are in the same genus.
members have evolved from different ancestors an may resemble each other only as a result of convergent evolution
the level above genus, being composed of one, several, or often many genera. most families are well defined, with widespread agreement as to which species and genera belong in a particular family.
each of the three traditional divisions (animal, vegetable, and mineral) in which natural objects have conventionally been classified.
below the class, and comprised of families sharing a set of similar nature or character
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a diagram that shows evolutionary pasterns by means of a series of branches.
each point at which a cladogram branches
all of the branches that extend from any particular pint represent the descendants of the original group
any ancestor and all of the branches that lead form it
A derived trait distinct to a certain species or group in a phylogenetic tree down to its descendant
most recent common ancestor
the most recent node form the clade (first)
one that does not contain all the descendants of the most recent common ancestor
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chapter 11 energy metabolism: respiration
the process that breaks down complex carbon compounds into simpler molecules and simultaneously generates the adenosine triphosphate(ATP) used to power other metabolic processes
cellular respiration falls into two categories: aerobic and anaerobic. respiration that requires oxygen as the terminal electron acceptor
under certain conditions, oxygen is not available, and an alternative electron acceptor must be used
respiration without oxygen
because animals and plants must have oxygen for their respiration
carry out anaerobic respiration exclusively; such bacteria are actually killed by oxygen
facultatively aerobic ( facultatively anaerobic)
if oxygen is present, they carry out aerobic respiration, but when oxygen is absent or insufficient, they switch to anaerobic respiration
glucose is broken down during anaerobic respiration by a metabolic pathway
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in prokaryotes, similar relationships hold and others also occur. green bacteria, cyanbacteria, and some purple bacteria are photosynthetic
most other bacteria, like animals, take in organic substanecs and use them both for the ATP gereration and for polymer construciton
they absorb and use organic carbon for construction and use photosynthesis almost exclusively to generate ATP.
examples are the colorless (nonphotosynthetic) sulfur bacteria. hydrogen bacteria, nitrifying bacteria, and iron bacteria. as they oxidize hydrogen, sulfur, iron and so forth, the energy goes to make ATP, part of which is used for regular metabolism and part to pump protons, creating a pH gradient that can be used to reduce NADP+ to NADPH.
they get their energy by oxidizing sulfur compounds and they take in organic compounds for structural uses. they do not use carbon dioxide, and apparently they lack the Calvin cycle
citric acid cycle, Krebs cycle, or the tricarboxylic acid cycle
names reflect different facts about the cycle. one of the intermediates is citrate, the anion of critic acid.
carbon dioxide and NADH are produced along with a two-carbon fragment
the carbon dioxide and NADH remain free in the matrix solution, but the acetyl becomes attached to a carrier molecule.
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chapter 17 pop. genetics and evolution
population concept of species
character, ranging of values, Adult height: 1 m to 2.5 m skin color: white, brown, black, yellow, ect., blood type A, B, AB, O. similar ranges of variation occur in all species, and it's just as true of plants as it is of us.
type concept of species
biologists and others thought in terms of one single ideal specimen-- the type--that would represent a species. the concept had several foundations
all offspring greatly resemble the first
the initial gene pool is extremely small; if just one seed is the founder, the original gene pool consistes of its two sets of alleles
if two distinct, unrelated species occupy the same or similar habitats, natural selection may favor the same phenotypes in each. as a consequence, the two may evolve to the point that they resemble each other strongly
although the population is small, it is more subject to accidents, and thus, the gene pool can change rapidly and erratically
total number of alleles in all the sex cells of all individuals of a population
purpose, intention, planning
or voluntary decision making
natural selection does not include these
gene flow does not keep the species homogeneous throughout its entire range, divergent speciation may occur; if alleles that arise in one part of the range do not reach individuals in another part
abiological reproductive barrier
the original species In species is physically divided into two or more populations that cannot interbreed; if speciation results
or geographic speciation
any physical, nonliving feature that prevents two populations form exchanging genes
biological reproductive barrier
when two groups become reproductively isolated even though they grow together
prezygotic isolation mechanisms
prevent pollen form moving from one plant to another, and thus, neither pollination nor fertilization occurs
postzygotic internal isolation barriers
two populations occasionally interbreed or are artificially cross-pollinated and produce viable seeds, but the seed grows into a sterile plant
if cross-pollination occurs, alleles form one parent may code for proteins incompatible with those coded by alleles form the other, and not even a sterile hybrid can result; instead, the zygote or embryo dies early in development
separate two subpopulations that are considered separate species
any biological phenomenon that prevents successful gene flow
millions of years are often required for a species to evolve into a new one
occurs in many ways, such as by pollen transfer, seed dispersal, and vegetative propagation
which one species gradually becomes so changed that it must be considered a new species
natural selection has caused a new species to evolve
the most significant factor causing gene pool changes, is usually described as survival of the fittest
the process in which humans purposefully change the allele frequency of a gene pool
deals with the abundance of different alleles within a population and the manner in which the abundance of a particular allele increases, decreases, or remains the same with time
because hydrogen is such a light gas, most of this first atmosphere was lost into space
all of these are found in vocanic gases and in meterorites that still strike earth. molecular oxygen was absent; it had already combined with other elements, resulting in compounds such as water and silicates
only after all of the free iron in eath's oceans had oxidized did oxygen finally begin to accumulate in the atmosphere. the atmosphere present today was derived from the early second atmosphere by this addition of oxygen from photosynthesis
the most seriously considered hypothesis about the origin of life on earth; basically, the chemosynthetic hypothesis attempts to model the origin of using only known chemical and physical processes, rejecting all traces of divine intervention
chapter 26 community ecology
a group of species that occur together at the same time and place.
this more-or-less predictable sequence of changes
the disturbed patch undergoes succession until it becomes spruce-fir forest again, which is the climax community, and stability returns.
such as reintroducing wolves into Yellowstone national park and encouraging the migration of bears and mountain lions across the Rio Grande River from Mexico into Big Bend National Park.
habitat loss and habitat fragmentation
by studying community ecology, we may be able to minimize the damage we do. we already realize that wetlands are extremely valuable; not only do they have high species diversity, but they also filter harmful chemicals out of water, prevent erosion, and produce abundant animal life.
often easier to see than to measure. a first approach to quantifying community diversity is done by measuring species richness, which is simply a count of the species present.
larger areas are more diverse than smaller ones. for example, if we consider the entire earth to be our community, it contains every species, every growth form, and so on, whereas a smaller area-the Americas for example-might still have as many growth forms.
the relationship between area and species richness
species abundance distribution
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optimal foraging theory
examine the interactions between these factors in an attempt ot understand why herbivores eat the plants they do while ignoring others.
optimal diet model
makes four predictions.
resource competition occurs when the organisms actually consume a shared resource, thus making it less available for other organisms.
one organism restricts another organism's access to resources even though the first night not be using it.
if a species can increase from very low population density even with its competitor present, then that species can be invasive
any substance or factor that can lead to increased growth rates as its availability is increased and tha tis consumed by an organism.
thus an increase in one plant species is associated with a decrease in others, and they appear to be in competition. because the plants are not actually competing for and using a resource.
mutualism or mutualistic relationship
if two organisms interact such that both benefit
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chapter 20 nonvascular plants:mosses, liverworts, and hornworts
plants are traditionally divided into those that have neither vascular tissues nor seeds,
have both vascular tissue and seeds, nonvascular plants arose first, and some of their later members were the ancestors of the vascular plants.
many moss plants grow close together, tightly appressed and forming dense mounds. in other species, particularly those of cool wet areas, the plants are more open and loose.
ubiquitous, occurring in all parts of the world and in almost every environment. they are perennial and thrive in many places within cities.
in some mosses, primarily the family polytrichaceous, the innermost cortex is composed of cells
they are elongate, have relatively prominent interconnections with adjacent cells, and lack nuclei at maturity, although they do retain their cytoplasm
small, multicellular trichome-like structures that penetrate the surface of the substrate. rhizoids only anchor the stem; they do not absorb either water or minerals.
this cell undergoes mitosis and produces a branched system of similar cells; the entire network
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dibiontic life cycle
each species has a multicellular gametophyte and also a multicellular sporophyte.
having only one multicellular generation: a zygote undergoes only meiosis, producing more spores tha will grow into new gametophytes. the zygote cannot undergo mitosis and cannot grow into a sporophyte.
postulates that a small sporophyte came into existence when a zygote germinated mitotically instead of meiotically. the sporophyte generation would have gradually evolved in complexity while the gametophyte generation remained small.
postulates that after the dibiontic life cycle originated, both gametophyte and sporophyte became larger, more complex, and vascularized, in a life cycle with alternation of isomorphic generation.
equal dichotomous branching
both branches being of equal size and vigor. plants of cooksonia had an epidermis with a cuticle, a cortex of parenchyma, and a simple bundle of xylem composed of tracheids with annular secondary walls.
as in all plants, only the central cells were sporogenous, and the sporangium had to open to release the spores. plants of cooksonia were homosporous; there were no separate micro-spores and mega-spores. fossils that have these general characters
early vascular plants had tow types of xylem organizations. in both, the center is a solid mass of xylem with no pith
protoxylem is located in the center and meta-xylem differentiates on the outer edge of the xylem mass. protoxylem is the xylem that differentiates while cells are small and narrow, and meta-xylem differentiates after the cells have expanded for a few more hours or days and are larger.
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