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155 Cards in this Set
- Front
- Back
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phloem transport is driven by
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an osmotically generated pressure flow
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why can't transport in phloem be explained by diffusion followed by cytoplasmic streaming
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because velocity of assimilates (~50-100 cm/h) are too great for either phenomena to account for long distance transport via sieve tubes
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what is the pressure flow hypothesis
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erns munch 1972. assimilates are transported form source to sink along a turgor pressure gradient developed osmotically
(phloem transport) |
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what is a source
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area of supply or exporters of assimilates. sources are photosynthesizing leaves and also storage tissues
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what are sinks
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all parts of plants that cannot meet their own nutritional needs. sinks are roots and storage tissue
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what two factors does the source and sink relationship depend on;
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physiological and developmental factors.
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sink/source in younger seedlings
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1. younger seedlings - source to sink is simple and direct in young seedlings: that is where cotyledons are SOURCE as they contain reserve food and the growing roots are SINK
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sink/source in older seedlings
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older plants - the upper most recently matur eleaves commonly exports assimilates to the shoot tip, the lower leaves export to the roots and those in between export both directions
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sink/source change form begetative to reporductive growth
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developing fruits are highly competitive sinks that monopolize assimilates from nearest as well as distant leaves
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during reproductive growth, the ______growth declines
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vegetative
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what direction is phloem transport?
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it is not exclusively upward or downward. the direction of phloem transport is determined by the demands of the organ
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what are the steps in phloem translocation
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1. phloem loading - sucrose produced in mesophyll cells is ACTIVELY LOADED to sieve tubes (higher sucrose concentration in sieve tubes).
2. increase concentration of sugars --> decrease in water potential thus water from xylem goes to the sieve tubes. 3. unloading - sugars are removed at the sink, water potential is increased, and thus water leaves sieve tube. |
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where does passive movement of sugars occur?
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with the movement of water into the sieve tube at the source and out of it at the sink, sugars are carried passively by water along concentration gradient between source and sink.
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where does active movement of sugars occur?
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when the sugars are loaded into and unloaded out of the sieve tube at the source and the sink
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is the rate of translocation sensitive to the energy supply
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yes, b/c laoding and unloading require energy!!
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so phloem loading is symplastic or aploplastic?
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can be both
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what is proton gradient pump?
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this is a plasma membrane h+ ATPase that utilizes the energy form hydrolysis of atp to transport H+ across the membrane. this proton gradient is used by specific carries in the plasma membrane to couple movement of proton back to symplast ot the transport of sucrose
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what is growth?
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an irreversible increase in size by a combination of cell division and cell elongation
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does cell division by itself consititute growth?
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NO!
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morphogenesis
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the process during growth and development in which the plant assumes a particular shape/form
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what determines morpholog?
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plane of cell diviison and expansion
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differentiation
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the prcoess by which cells with identical genetic material cebome different from one another
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differentiation is controlled by
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1. gene expression - companion cell and sieve tube from same mother clel, but due to differential gene expression they have become distinct form on another.
2. by the position in the developing organ: if an undifferentiated cell is displaced it will differentiate appropriate to its new position also: determination and competency |
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what is determination
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progressive commitment to specific course of devleopment, thus reducing the capacity to resume growth
e.g. plants always grow, animals don't |
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competency
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the ability to maintain the capacity to differentiate, divide and have progeny that differentiate into any cell type.
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what is secondary growth
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increase in diameter of regions that no longer elongate
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secondary growth results from 2 lateral meristems, what are they?
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vascular cambium, cork cambium
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secondary growth in roots and shoots consist of?
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1. secondary vascular tissue - xylem and phloem from vascular chambium
2. periderm composed mostly o cork tissue form cork cambium |
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which group of plants undergo secondary growth? annual, biennial, perennial
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annuals = no
biennials = a little maybe? perennials = alot (they all have diff life cycles) |
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what is the life cycle of a plant?
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seed --> vegetative plant --> flowering plant --> seed
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annuals
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complete life cycle in one year. many weeds, wild and graden flowers, and vegetables
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biennials
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complete life cycle in two years
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perennials
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grow over more growing seasons. all gymnosporms, some monocots and many dicots
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what is vascular cambium? how is it different from procambium?
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it produces 2 xylem and phloem, which procambium produces primary xylem and phloem
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cork + cork cambium + phelloderm =
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periderm
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fasicular cambium + interfasicular cambium =
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vascular cambium
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where is fasicular cambium?
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within bundles
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where is interfasicular cambium
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between bundles
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what is pith and pith ray?
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cortex between bundles = pith ray, cortex in middle of all bundles = pith
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what are fusiform initials
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they make up the axial system of the vascular tissue. they are vertically oriented, many times longer than wide.
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what are ray initials
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they divide to form radial system of the vascular tissue. radial system = vascular ray system. lays at a right angle to fusiform initials. they lay horizontally oriented and are slightly elongated.
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what are the funciton of ray initials
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pathway for movement of food from phloem to xylem and water form xylem to phloem.
storage sites for starch, proteins and lipids. |
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how is secondary xylem and phloem produced
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through periclinal devisions of fusiform and ray initials. that is, cells from these divisions are formed parallel to the surface of roots and stems.
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when secondary xylem is formed, cambium is displaced outward thus increasing circumfrence. thus new cells are added to the cambium by ________ division of initials
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anticlinal
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the periderm(part of bark) is made up of
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phellem, cork cambium, phelloderm
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the functions of the periderm are
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inhibits water evaporation
protects against insect and pathogen invasion |
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what is bark
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protective covering over wood of tree. everything between vascular cambium and outside of woody stem.(phloem + periderm + cortex) composition varies depending on age of tree
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young tree composition of bark
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secondary phloem, few cortex cells, 1 or 2 increments of periderm
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old tree composition of bark
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layers of secondary phloem and several layers of periderm
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what are annual rings
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rings in which tell you how many years old the tree is. they are rings of cells of secondary xylem.
irregular growth of rings in tripical rain forests |
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earlywood/spring wood
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cells in inner part of annual ring, cells larger in diameter, formed during first growth spurt of new season
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latewood/summerwood
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cells smaller in diameter, formed later in growing season.
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heartwood
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darker wood in center
cells blocked with resins and other materials no longer funcitons in transport vessel members may be blocked DEAD |
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sapwood
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ligher wood near periphery
secondary xylem has funcitonal xylem cells where actual transport of water and dissolved minerals takes place LIVING |
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what factors determine the width of annual rings
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light, temperature, length of growing season, water availability: rainfall, available soil water
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what are the two types of factors controlling plant growth and development
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endogenous factors
exogenous factors |
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endogenous factors
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hormones: chemical messenger from one cell to another. plant hormone= phytohormone.
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auxin
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phytohormone
(to increase) functions: apical dominance tropic responses differentiaion of vascular tissue promotion of cambial activity induction of adventitious roots on cuttings inhibition of fruit and leaf abcission promotion of fruit development |
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chemical name of auxin
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indoleacetic acid (IAA)
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site of auxin biosynthesis
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prinarily in leaf primordia
young leaves developing seeds |
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polar transport of auxin
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always towards base
from shoot tips and leaves downwards in stem, via vascular parenchyma cells from root tips towards base of root |
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non polar transport of auxin
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auxin reach root tip in the sieve tubes non polarly at much fast rate than the polar movement
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you can use auxin to grow _____
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fruit
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cytokins
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phytohormone
founded in cocoanut milk functions: cell division promotion of shoot formation in tissue culture delay of senescence promotion of cambial activity release of lateral buds from apical mersitem |
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transport of cytokinins is accomplished by ____ from roots to shoots thus, cytokinins are primarily produced in ________
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xylem
root tips |
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the most common cytokinin in plants is
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zeatin
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ethylene
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phytohormonoe
c2h4 gas synthesized from methionine. founded in gas lamp produced in most tissues as a response to stress, senescene and ripening functions: fruit ripening senescene leaf and fruit abscission |
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ethylene is moved by ______ because its a gas
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diffusion
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abscisic acid (ABA)
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phytohormono
founded in buds of ash and potatoes functions: stomatal closure induction of photosynthate transport form leaves to developing seeds induction of protein synthesis in seeds maintenance of dormancy in seeds |
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site of synthesis of ABA
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in mature leaves and roots, wspecially in response to water stress
potentially in seeds |
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transport of ABA
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exported from leaves in phloem from roots in xylem
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gibberellins (gibberellic acid GA)
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phytohormonoe
founded in rice disease functions: associated w/ dwarfism and hyperelongation of shoots... can affect fruit development (grapes e.g.) effective in breaking dormancy and seed germination stimulates flowering in long day plants |
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biosynthesis of GAs
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in young tissues of the shoot and devloping seed
uncertain if it is produced in roots |
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transport of GA
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probably in phloem and xylem
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the mechanism of action of hormones: 3 things
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1. hormones control gene expression
2. hormones regulate cell expansion and cell division 3. hormones function via alteration of signal transduction pathway |
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exogenous factors
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light
gravity biological clock temperature mechanical stimuli water nutrients |
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waht happens when a plant is grown in the dark?
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it grows taller trying to reach the light
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how is light absorbed by plants?
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by plant photoreceptors
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what is a photoreceptor?
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a pigment (chromophore) contianing protein.
a chromophore is the light absorbing portion of a molecule |
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plant photoreceptor types
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phytochrome - abosorbs light in far red 660-750
phototropins - blue region, kinase, 450 cryptochromes - blue region, not a kinase 450 |
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what is etiolation
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causing a plant to grow white by eliminating light
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phytochromes Pr
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regular red light. inactive when perceiving red light.
when activated for 30 secs converts to Pfr |
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phytochromes Pfr
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far red light. active form. absoarbs far red light.
bio activity breaks down back into Pr |
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so if the last light seen is Pr will plant germinate?
what if last light seen is Pfr |
yes because will convert into active Pfr and remain there.
no becuase will convert into Pr (inactive form) |
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how do plants avoid shade
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they grow taller and compete with their neighbors for more light
they respond to far red light for elongation (fr exposed plants will be taller??) |
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what is tropism
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growth response of plants towards or away form an external stimuli
towards = positive tropism away from = negative " |
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what is phototropism?
phototropism is controlled by |
caused by elongation of the cells under shaded side of the tip by plant hormone auxin
auxins and light |
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role of light in phototropism
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light decreases the auxin sensitivity on the lighted side
light destroy auxin light drives auxin to the shaded side of the growing tip |
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what is gravitropism
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redistribution of auxin from the upper to the lower side
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how do plants perceive gravity
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by sedimentation of amyloplasts (starch containing plastids)
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the coordination of both _____ factors and _____ factors control __________
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endogenous and exogenous
plants growth and development |
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what are the 5 division(phlya) of fungi
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chytridiomycota
zygomycota glomeromycota ascomycota basidiomycota |
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what is mycology
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the study of fungi
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fungi are more closely related to which? plants or animals?
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animals
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6 characteristics of fungi
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1. composed of hyphae (mass of hyphae = a mycelium)
2. hyphae of most species are separated by septa 3. hyphae lacking septa are coenocytic 4. cells walls of fungi contain chitin 5. fungie are hetertrophic and obtain their food by absortption (enzymes) 6. fungi have zygotic life cycle that includes separate steps of plasmogamy and karyogamy |
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zygomycota
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1100 named species
economically important as food storage eproduce sexually with meiospores called zygospores and asexually with sporangiospores e.g.=rhizopus - common break and fruit mold |
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ascomycota
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32000 species
many familiar and economically important species: human diseases - athletes foot, pnuemocystis plant diseases - powder mildew, dutch elm disease parasites - cordyceps (mind control of ants) medicines - penecillin, cyclosporin food delicacies - truffles, morel mushrooms botrytis - "the noble root" yeast - bread, beer, wine, importnat reserach organism other info: form meiotic spores called ascospores, which are enclosed in a special sac-like structure called an ascus have only been observed undergoing asexual reproduction. Because the products of meiosis are retained within the sac-like ascus, several ascomyctes have been used for elucidating principles of genetics and heredity |
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basidiomycota
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26000 species
produce meiospores called basidiospores on club-like stalks called basidia. Most common mushrooms belong to this group, as well as rust (fungus) and smut fungi, which are major pathogens of grains. Amanita (poisonous) mushrooms - the death cap, puffballs many edible mushrooms too psliocybe muschrooms |
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what is fungal symbioses
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the living together of two dissimilar fungi??
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types of fungal symbioses
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1. mycorrhizae - endomycorrhizae(glomeromycota), ectomycorrhizae (some asco, and basidio)
2. lichens - mutualistic symbiotic relationship between a fungal partner (usually asco and green alga or cyanobacteria) |
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what are oomycota
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previously grouped w/ fungi, but now it is clear they are unrelated. water moldes, slime molds.
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waht is taxonomy?
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identifying, naming, and classifying species
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what is phylogeny
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evolutionary relationships among organisms
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cladistics
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a set of quantitative methods and concepts for exploring the evolutionary relationships between taxa
(phylogeny trees?) |
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chytridiomycota
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1000 species
possess flagellated swimming cells disease caused by one chytrid species is implicated in mass amphibian die-offs |
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glomeromycota
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157 species
use to be goruped w/ zygomycota form symbiotic associations w/ 80% of wild plants sexual reproduction is unknown. asexual reproduction = miltospores |
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what are monera?
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today the kingdom is called prokaryotes.. however it used to be called monera.
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what are the four kingdoms?
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protista, monera, eukaryota, bacteria
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basics of prokaryotes
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structurally simplest and physically smallest and most abundant organisms
evolutionaryily the oldest organisms and most successful form of life capable of living in enviornment that supports no other form of life |
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waht are the two domains?
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prokaryotes and eukaryotes
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why are prokaryotes so successful
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1. metabolic diversity
2. rapid division 3. adaptability |
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how are prokaryotes metabolically diverse
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1. autotroph (both photosynthetic and chemosynthetic)
2. heterotrophs requir organic compounds as a carbon source. majority are saprophytic. important decomposers in the enviornment. |
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why are prokaryotes important
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autotrophic bacteria are major contributers to carbon balance
nitrogen fixation producers of 90% co2 biological decomposers source of ABs commercial use for production of aa's and enzymes food industry potent disease causing agents |
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characterstics of prokaryotic cells
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lack of organized nucleus bounded by nuclear envelope
circular dna in a region of cells called nucleoid they may contain extra dna called plasmids that replicated independent from cells cytoplasm contians 10,000 riobosomes smaller size ribosomes lack of cytoskeleton lacks membrane bounded organelles plasma membrane is formed form lipid bilayer plasma membrane of aerobic bacteria has the electron transport chain that is in the mitochondria of eukaryotes the site of photosynthesis in purple and green photosnthetic bacteria are in plasma membrane usually rigid or flexible cell wall |
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bacteria can be divided into two groups based on their ability to retain the dye crystal violet in their cell wall.
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gram positive - retains dye - PURPLE 90 percent peptidioglycans and is thick
gram negative - do no retain dye PINK- has outer membrane and thinner layer of peptiodioglycans then an inner membrane |
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major forms of prokaryotes
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rod, spiral, spherical
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reproduction through gene exchange
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conjugation, transformation, transduction
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formation of _____ increases the ability of prokaryotes to survive
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endospores
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phylogenetic analysis
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based on sequences of rRNAs there are 17 major bacterial lineages
selected groups: cyanobacteria purple and green bacteria mycoplasmas |
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cyanobacteria
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phylum of bacteria that obtain their energy through photosyntheis (aka blue algae)
phycocyanin gives them their nme they have chlorophyll a and carotenoids unicellular filamentous: linear or branched colonies |
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purple and green bacteria
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grow in light, but under anaerobic conditions because oxygen suppress the synthesis of their pigment, bacteriochlorophyll
contian accessory pigments: yellow and red carotenoids two types 1. sulfur bacterium 2. nonsulfor bacterium |
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mycoplasmas
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bacteria w/o cell wall
smallest organism incapable of independent growth assume various shapes they are plant pathogens chlorosis (yellowing the foliage) movies w/in sieve tubes transmitted form plant to plant by vectors such as aphids. lethal yellowing |
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4 distinct groups of archae
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halophiles
methanogens extreme thermophiles thermoplasma |
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halophiles
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salt loving
high salt limits 02 necessary for respiration they use bacteriorhodopsin, a protein in plasma membrae to conver light energy to atp |
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methanogens
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methane producing
only organism that produce ch4 from h2 and co2 strictly anaerobic use nh4+ as a nitrogen base most gas resserves are produced by activities of methanogens found in the digestive trck of ruminants where they digest cellulose |
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extreme thermophiles
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heat loving
enzyles are stable at 80 to 110 deg c most species metabolize sulfur and are strict anaerobes h2s rising to surface highly acidic |
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thermo plasma
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archaea w/o cell walls
single genus and single species no cell wall, spherical and small occurs in acidic, self heaitng coal |
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what are viruses
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submicroscopic parasites found in animals, plants, fungi and bacteria
it is genome + coat nucelic acids protected by protien coat that also helps virus attach to host outside the cell is called virion and is metabolically inert |
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viruses usually host specific responsible for many infectious diseases such as
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chicken pox, measles, mumps, influenza, polio, aids, herpes, hepatits, ebola virs, west nile virus
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waht do plant diseases do to the plant
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reduce grwoth
yellow the leaves mosaic and ring spots |
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3 types of plant firuses have dan as genetic material
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geminiviruses
badnaviruses caulmoviruses |
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how do viruses invade plants
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by vectors such as aphids, leafhoppers, whitefliet etc etc
transmission thorugh polle tube of an infected pollen into an ovule once inside the cell, virion shed it's coat and it's rna or dna multiplies using the host cell machinery |
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genome of viruses is either composed of...
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dna and rna... single strand or doublestranded
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what are hte stages of the life cycle of a virus
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infection
replication inside the host spread to new host aided by vector organisms |
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movement of viruses within the plant
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short distance movement (cell to cell) through plasmodesmata
long distance movement trough sieve tubes of phloem tissue |
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what is endosymbiosis
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symbiosis in which one symbiont lives within the body of the other.
(eukaryotes) |
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what is an endosymiont
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an organism that lives within another, dissimilar organism
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serial endosymbiosis
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process by which eukaryotic cells originated via a series of events
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what are the protista
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the rest of the eukarya besides animals, plants, and fungi
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evidence in support of serial endosymbiosis
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1. double membrane around organelles. the mt inner membrane rsembles prokaryotic membranes, not eukarytoic membranes
2. mitochondira and hcolorplasts have their own ribosomes and the size matches that of bacterial ribosomes, not eukaryotes 3. dna. circular chomrosome, like bacteria. dna sequences are more closely related to bacteria than eukarya 4. divisoin by binary fission like bacteria |
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protista
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an assemblage of mostly unrelated groups
all aquatic, freshwater and amrine do not need to have much support do not need water conductin tissue no cuticle, stomata, or roots water currents/waves cause more damage than air planktonic (floaters) vs. benthic (attached) life styles |
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the three benthic zones
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bathyal zone, sub-littoral zone, intertidal zone
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living in the inter-tidal zone
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negative- lots of wave action in the intertide zone, drying out, high temperatures, high salt concentrations
---strategies for this: flexible rubbery body, thick walls, water holding wall materials, slime positivies- high light intensity, high sconcentrations of minterals |
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living in the sub-littoral zone
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positives - less wave action, no drying out, heat or salt damage
negatives - less light, less minerals strategies: long stipes (stalks) to get into zone w/ more light. phycoerethrins that absorb light in blue wavelengths |
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planktonic life
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these organisms go w/ the flow (wave action) but ther eis danger of drifting too far out to sea
need to get mineral nutrients from run off form land any that drift out die and fall to bottom need to reproduce rapidly to make up for the organisms that die - have small bodies, single cells or small colonies mostly in two groups - basillariohphyta and dinophyta |
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features of algal cells
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unicellular, filamentous, siphonaceous, colonial sheetlike, or complex thallus
cell wall chloroplast envelops and pigmentation flagella number, placement and type -insertion at tip or along side -tinsel or whiplash types storage reserves life cycle- gametic or zygotic (sporic seen in land plants) |
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3 life cycle types
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gametic life cycle
zygotic life cycle sporic life cycle |
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gametic life cycle
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(metazoons, some algae) entire life spent in diploid state, meiosis at time of gamete production
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zygotic life cycle
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(some algae) entire life spent in haploid state, zygote is the only diploid cell, undergoes meiosis to make body
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sporic life cycle
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(land plants) have both diploid and haploid multicellular bodies. dipploid body is called sporophyte, haploid body is the gametophyte. the two generations alternate during the life of the plant.
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isogamy
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male and female same size both swimmers
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anisogamy
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female larger, both swimmers
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oogamy
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female larger, only male is a swimmer
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dinophyta
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dinoflagellates
related to paramecium (protozoan) fresh water and marine their nuclear membranes do not disintegrate during cell division their chromosomes are always condensed and have no histones have two flagella, on ein groove around cell and another vertical, they spin as the flagella beat they have cullulose plates in vesicles inside the outer cell membrane they cause red tides and toxic blooms in water. gymnodinium breve is the case. large bodies of water can turn reddish brown. toxins cause neurologic damage. have chl a, c and carotenoids, chloroplasts have 4 membranes they can occur as symbionts in coral reefs they can form resting cysts under low nutrient conditions haploid cells-make haploid siwmming gametes that fuse to make diploid zygote. after a resting period the zygote undergoes meiosis. |
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diatoms
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unicellular or colonial
important component of the phytoplankton - primary source of food for aquatic animals first appeared 250 million years ago silica in the cell walls cell walls made of two overlapping parts called frustules pennate and centric duaughter cells start with on half of the parent cell walls - this makes one set of cells smaller and smaller. when cell size below threshold sexual reproductoin occurs - gametes produced by meiosis; zygote is diploid, gians the maximum size for the species by laying down new wall. male gametes have on tinsel flagellum diatomaceous earth has many uses - insulation, polish etc. |
