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256 Cards in this Set
- Front
- Back
Leaf structure
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function always follows structure
primary function of leaves is photosynthesis have broad/flat surface to capture sunlight |
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Pinnately compound
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one large leaf where blade is broken down into leaflets
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Palmately compound
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all leaflets are attached at a certain point
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How can we tell the difference?
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by the presence of axillary buds; all leaflets in compound leaves are in the same plane
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Cuticle
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non cellular layer of wax - used to minimize water loss
Use wax to minimize water loss because it is a hydrocarbon |
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Hydrocarbons
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composed of hydrogen and carbon - have same electronegativit and thereofre all bonds are nonpolar
But water is polar so can't pass through |
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Palasade mesophyll
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elongated cells, where most of chloroplasts are found - where photosynthesis takes place
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veins
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xylem on top and phloem on bottom - way it is arranged in the stem
Also have parenchyma and sclerenchyma Most of the time do NOT contain chloroplasts |
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Spongy mesophyll
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also have chloroplasts - not as much (bc it is farther away from the surface)
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Why is mesophyll widely spaced?
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plant requires CO2 - can diffuse around these cells
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Bundle sheath function
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regulates water and sugar into and out of veins
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Stoma
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function is to allow CO2 to diffuse into the leaf
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How to tell high plant from low plant?
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by layers of palasade mesophyll - more layers in high plant
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Mesophytes
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plants which grow in intermediate moisture (lilac)
Have collenchyma instead of sclerenchyma to allow for flexibilty |
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Collenchyma
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thicked PCW at edges of cells - provides flexible support - has pectin rather than lignin
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Why do smaller leaves have lower temperatures than large leaves?
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smaller leaves have larger SA to volume ratio, so can get rid of heat easier - air is also a factor: able to conduct heat away from leaves
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Epidermal cells shape:
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not rectangular - have interdigitated shape - which allows it to be stronger
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Xerophytes
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plants that grow in very dry conditions
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Agave
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desert plants - only out cell wall on outside to minimize water loss
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Trichomes Functions
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Protection - against insects
Increases reflectance Reduces transpiration Secrete compounds onto leaf surface Insulation - reduces heat loss |
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Increased reflectance
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when too much light is absorbed it will overheat
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Reduces transpiration
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increases boundary layer which slows water loss
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Insulation
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Keeping stilla ir near leaf reduces heat loss
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Lamb's ear
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has dense covering for defence, increased reflectance, slows transpiration
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Hydrophytes have
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sclereids
very large air spaces stomata only on upper surface |
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Sclereids
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large, star shaped, thick cell walls - defence
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air spaces
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for storage of oxygen (aerenchyma tissue)
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Xerophytes have
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thick cuticle
stomatal crypt multiple layers of epidermis reduced air spaces |
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Stomatal crypt
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on lower leaf surface to reduce water loss because traps humid air inside crypt
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Monocot leaves
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all spongy mesophyll
stomata on top and bottom because grass leaves are at an angle and both sides are exposed to light |
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Bulliform cells
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found next to midrib - store water - when loses water leaves fold up in grasses because they are found in dry environments and therefore will transpire less
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Epidermal cells in monocots
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linear arrangement of cells - dicot is randomly
cells are still integrated to increase strength |
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C4 plants
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have no distinction between palasade and spongy mesophyll
have well developed bundle sheaths with chloroplasts Krantz anatomy - mesophyll is aranged around bundles |
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Modified leaves for food storage
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Onion
bulb underground for root storage |
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Modified leaves for water storage
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leaves are rounded to increase volume and decrease SA to minimize transpiration
sometimes have large epidermal cells to store water Lithops - stone plant |
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Modified leaves for defence/protection
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cactus - green part is stem and prickles are leaves
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Modified leaves for carnivory
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venus fly trap
trichomes on surface sense movement and send impule to cells to decrease water content and fold up other cells secrete enzymes to digest fly - get N and other minerals |
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Modified leaves for support
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pea leaf - has tendrils (modified leaves) to coil around surrounding plant and support its weight
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Modified leaves for water collection
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epiphytes -plants that grow on top of other plants (problem because not very rooted so need to get moisture from rain - form cup to collect water)
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Water potential
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Ability of water to do work or diffuse - always moves from high to low potential
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Why does pressure develop within plant cells?
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When higher solute conc. inside than outside - water moves into cell
Membranes are semi-permeable so allow water molecules in but not solute molecules - therefore pressure builds |
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Equilbirium
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when water movement stops because potentials are the same
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Turgor
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pressure potential of the cells
Only in cells with rigid cell walls Primary means of physical supprt in herbaceous plants |
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Wilting
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occurs when turgor is lost - pressure is lost
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Hydroskeleton
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use water pressure within body to support their own weight
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Osmosis
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diffusion of water across a semipermeable membrane in response to a change in water potential
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Water movemtent
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from the soil through the xylem into individual cells and through the stomata onto the atmosphere - along a water potential gradient
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Cohesion-adhesion-tension hypothesis
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derived from the idea that water molecules are capable of forming Hbonds because they are polar
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Cohesion
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H-bonding within water molecules
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Adhesion
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H bonding between water and matrices - causes them to adhere to the sides of xylem vessles
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Tension
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evaporation of water in leaves pulls the coninuous water column from the leaves down the roots through teh plant
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Problems
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if air bubble develops within system (cavitation/embolism) the whole system falls apart
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xylem constructed to avoid cavitation
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cells are bigger when formed under wet conditions, but in dry conditions get very narrow because cavitation is more likely to occur - by having narrow diameter can suck up more water
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Bordered pits
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allow water to move from one xylem to another (around the embolism) but embolism cannot move around pits
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How to measure water status of a plant
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meausreing the water status of the shoot - by pressure chamber or scharticoff's technique
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Pressure chamber
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cuts plant stem off and puts in a pressurized chamber - increased pressure in chamber to force water in xylem up to surface - meausre potential of that movement
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How do roots maximize water uptake
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maximize SA - don't become broad bc have to grow through soil - have long tubular structure one cell thick (root hairs)
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Water moves by three routes:
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apoplastic - least resistant
symplastic Transcellular |
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Apoplastic
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movement through the nonliving portion of pant body (cells walls and intracellular matrix)
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Symplastic
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movement through interconnected cytoplasm of cells in the plant body; plasmodesmata
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Transcellular
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movement from cell to cell passing through vacuoles of each
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Apoplastic route ends
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at the endodermis
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When reaches the endodermis
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there are waxes (suberin) and has to travl symplastic route - advantage is to control what goes in and out of cell
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Mineral nutrients are absorbed
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at any point - energy requiring process - bc have a higher conc. in roots than in soil and therefore are moving against a conc. gradient
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As amount of light decreases
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rate of mineral uptake decreases - runs out of energy
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When have a higher solute concentration inside root than outside root
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leads to osmotic uptake of water and the buildup of pressure in the root under conditions of low transpiration - pressure developes inside central vacuole colum -only at night
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Root pressure
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only occurs at areas of low transpiration and does not account for movement of water in xylem under normal conditions
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Guttation
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process that relieves excess pressure in the xylem at night - water comes out of pore in epithelium called hydathode
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Conditions when water moves from plant into soil
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at night because stomata are closed - roots are in two different parts of soil(large tree)
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Hydraulic lift
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when some roots are in ground water and some in dry soil - water leaves tree at higher ground into dry soil
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Evidence of assimilate transport
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when tree is girdled can transport water from roots to shoots - but can't transport sugars because phloem has been removed
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Characteristics of phloem transport:
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can occur in two directions (depending on where in the plant you are)
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Sources
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area of high assimilate concentration (leaves)
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Sins
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areas of low assimilate concentration (roots, meristems)
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Roots
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sinks because they are respiring constantly - are reproductive organs - are growing rapidly
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Assimalate trasport
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very rapid - 50-100 cm/hour
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Pressure flow hypothesis
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Sources and sinks are always in phloem
- water moves from low to high solute concentration Passive process - but we know it requires energy |
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Phloem Loading and unloading
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energy requiring process
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Photosynthesis
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6CO2 +6H20 --> 6C6H12O2 + 6O2
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Light that plants can use in photosynthetic process
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visible light - 400-700 nm
leafs reflect GREEN light |
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PAR
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photosynthetically active radiation - measured in micromoles - measures the number of particles of protons
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Pigments
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chlorophyll a and b and various carotenoids (carotenes and xanothytes)
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Chlorophyll a
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red light and blue light
porphyrin ring containing N and Mg and hydrophobic tain |
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chlorophyll b
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blue light and red light
has CHO bond in place of CH3 |
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Carotenoids
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violet and green and yellow light
cleaved in center to give to VA molecules (beta carotene) VA is converted to retinol |
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Xanthophyll
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have OH group on rings
responsible for colour of corn kernals |
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Where does light dependent reactions take place?
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mesophyll cells of leaves - not in epidermal cells
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Thylakoid
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all are interconnected to each otehr
all pigments are found in thylakoid membrane - light dependent takes place within the thylakoid membrane - light independent within the stroma |
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Photosystems
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collections of pigments - usually 200-300 molecules
pigments are found in antennae have two parts - antennae and rxn center |
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rxn center
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only has two chlorophyl molecules
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Purpose of pigments in antennae
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to absorb light over a broad wavelengths and convert all t o one type of light - rxn center only absorbs either 680 or 700
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Energy of a photon is called
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a quantum
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Flourece
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when photons fall back down to lower energy level and reemit light - not 100% efficent
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Longest and shortest wavelength
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blue light has shortest wavelength - red light has longest
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NADP
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nicotinamide adenine diphosphate
can accept electrons |
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Difference between photophosphorillation and respiration
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in ppl use light energy, non cyclic, electrons used over and over
respiration use O2 |
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ATP and NADPH
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products of light dependent rxns - then go on to other photosynthetic processes
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Problem with Z-scheme
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produces same ATP as NADPH, but subsequent reactionsneed more ATP than NADPH - therefore cyclic comes in
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Cyclic
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does not get electrons from water - PSII is not involved
not as efficient |
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Cyclic takes place
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in the mesophyll within the thylakoid membrane - NOT within the stroma
starch is stored within the chloroplasts |
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Chemiosmosis
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synthesis of ATP using chemical and electrical gradient - occurs in the thylakoid membrane
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Chemiosmosis
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the synthesis of ATP using an electrical and chemical gradient - occurs in both resp. adn photo - in thylakoid membrane
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Light independent reactions
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calvin cycle
converts energy to sugars using energy produced in light dependent reactions |
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Rubisco
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also functions as an oxygenase (can load O2 to RuBP as well as carbon)
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Oxygen is
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a competitive inhibitor of photosynthetic process - under low CO2 conditions this is a problem
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Conditions that enchance oxygenase activity and photorespiration process
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high light
high temperatures water stress |
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Rubisco cannot
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distinguish between O2 and CO2, so sometimes adds an O2 molecule to RuBP to get 1 PGA and 1 phosphglycalate
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Photorespiration
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takes O2 to get CO2 - occurs in light only, does not give ATP
Converts phosphoglycalate to PGA |
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C4
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evolved in hot dry conditions
plants do not use Rubisco but PEP carboxylase - never functions as an oxygenase |
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C4 pathway gives off...
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CO2 wich then goes to the cabon cycle
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In order for the C4 pathway to work
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there has to be spatial separation between initial and final fixation of CO2 - so occurs in the bundle sheath and mesophyll
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How do C4 plants avoid photorespiration?
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mesophyll chloroplasts fix CO2 which the goes to bundle sheath chloroplasts - have a high CO2 concentration so Rubisco will never function as an oxygenase
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Mesophyll vs. Bundle sheath
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granum are extremely well developed in mesophyll - less well developed in bundle sheath but more stroma
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CAM pathway
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crassulation acid metabolism
Addaptation to extremely dry environments |
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CAM plants
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live int he desert
diurnal acidity levels all store water within their leaves NO Krantz anatomy |
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CAM pathway
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identical to C4 pathway
oxaloacetates and malates accumulate temporal separation between initial and final fixation all occurs within one cell |
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Night vs. day
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C4 takes place at night
Calvin cycle takes place during the day |
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Temporal separationa advantage?
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Stomata are open at night to so the transpiration rate at night is lower than during the day - thereofre there is decreased water loss
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Difference between C4 and CAM
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phosphenol pyruvate in CAM comes from stored strach instead of reactions as in C4
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Algae
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largely aquatic, photosynthetic organisms
most are microscopic/single celled |
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Algae belongs to two separate kingdoms
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prokaryotae and protista
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Kingdom Protista
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includes: animal like, fungus like, and plant like species
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Groups of photosynthetic protists:
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euglenophyta
rhodophyta dinophyta bacillariophyta chrysophyta phaeophyta chlorophyta |
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Euglenophyta
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900 species
mostly heterotrophs chlorophylls a, b, and carotenoids 2 unequal flagella no cell wall but have pellicle |
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Carb reserve
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paramylon
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Origin of Eukaryotic cells
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Endosymbiotic
photosynthetic or aerobic prokaryotes englufed by phagocytosis and persists as endosymbionts |
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outer membrane and inner membrane
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outer - food vacuole
inner - plasma membrane of prokaryotes |
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Chloroplsts of euglenophyta
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have three membranes
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Rhodophyta (red algae)
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4000-6000 species
chla, phycobillins, carotenoids no flagella mostly marine |
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carb reserve
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floridean starch
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Cell wall
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cellulose microfibrils embedded in matrix, deposits of CaCO3
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Life cycle
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2 or 3 separate generations:
haploid gametophyte, diploid carposporophyte, diploid tetrasporophyte |
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Dinophyta (dinoflagellates)
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2000-4000 species
cha, c, and carotenoids, some heterotrophic one transverse and one longitudinal flagella cellulose plates beneath cell membrane produce deadly toxins |
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Three known stages in life cycle
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biflagellated cell
amoeboid stage amoeboid cyst |
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Bacillariophyta
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100,000 species
heterotrophic and autotrophic w/ cha,c and carotenoids cell wall composed of silica no flagella unicellular or colonial |
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Carb storage
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chrysolaminarin
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Centric and pennate diatioms
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centric - radially symmetical
pennate - bilaterally |
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Frustrules
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cell walls of diatoms
composed of silicon oxide consists of two overlapping halfs contain many pores and channels in ornate paterns |
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Diamotaceous earth
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earth compose of shells of these diatoms
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Asexul reproduction
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diminishing reproduction
when divides in two halfs pulls apart - can only reconstruct bottom part - one will be the same size as parent and one will be smaller - when becomes so small can no longer make a viable cell then undergoes meiosis and goes to sexual reproductoin |
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Phaeophyta (brown algae)
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1500 species
cha,c and focoxanthin two flagella in reproductive cells truly multicellular |
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Carb storage
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laminarin, manitol
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Cell wall
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cellulose embedded in a matrix of mucilaginous algin, plasmadesmata in some
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three parts of body
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holdfast
stipe blade |
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Life cycle
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alternation of generations
either heteromorphic or isomorphic |
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Oogonia
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where meiosis takes place to produce the egg
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antheridia
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where meiosis takes place to produce the sperm
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Isogamy
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gametes are the same, both move
call + and - mating strands |
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Anisogamy
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one large motile and one small motile
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Oogamy
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one small motile and one large immotile
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Heteromorphic
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haploid and diploid generation are different
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Chlorophyta (Green algae)
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gave rise to otehr species of higher plants bc have same chlorophylls (a,b) and same cell walls and store starch the same way
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Carb storage
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starch
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Cell walls
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cellulose, glycoproteins, noncellulose polysaccharides
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Three major classes of green algae
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Chlorophyceae
Ulvophyceae Charophyceae |
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Chlorophyceae
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motile and non motile
colonial and unicellular largest class |
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Zygospore
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resting state of zygote with thick cell wall
isogamous life cycle |
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+- mating strains
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do not equal gametes
but form gametes |
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Plasmogamy
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the joining of the cytoplasm of two cells
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Class Ulvophyceae
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mostly marine
siphonous - no cell walls connecting adjacent cells composed of flat sheets of cells |
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Life cycle
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isogamous - haploid and diploid look identical
sporic life cycle |
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meiosis occurs in
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the sporangia to produce spores
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Charophyceae
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most similar to land plants
unicellular, filimentous, parencymal, and colonial generations |
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Desmids
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unicellular forms, freshwater
constricted cells - have a rigid shape like diatoms |
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Spirogira
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circular, coiled chloroplast
has +- mating strains, makes a zygospore |
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Chrysophyta (Golden brown algae)
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1000 species
cha,c and carotenoids no flagella or 2 apical flagella (1 tinsel and 1 whiplash) no cell wall or silica scales |
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Carb storage
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chrysolaminarin
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Green algae and plants similarities
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photosynthetic pigments (cha, c and carotenoids)
store carbs as starch cellulose is major component of cell walls cell division is similar - formation of cell plate chloroplasts have thylakoid membranes staked into grana |
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Plants evolved in terrestrial environments
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characteristics are adaptatiosn
angiospermsa are best adapted plants to dry environments |
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Problems terrestrial plants face
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obtaining enough water -roots
transporting water from soil to above ground parts and photosynthate to below ground parts - vasc. system prevent excessive water loss - cuticle and stomata support plant body - sclerenchyma exchange gases - stomata |
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Reproduction in terrestrial plants
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don't have flagellated cells so have wind or inset pollination
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Four types of terrestrial plants
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mosses and other bryophytes
fern and fern allies gymnosperms angiosperms |
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Bryophytes
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liverworts, hornworts and mosses
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Bryophytes
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need to be moist because have flagellated sperm cell
lack well developed vasc. tissue so can't get very large have rhizoids for water and nutrient absorbtion multicellular sex organs with a layer of sterile cells to protect from dessication gametophyte dominant - sporophyte parasitic |
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Thallus
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means it has a two dimensional strcution - thalloid liverwort
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antheridiophores
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stemlike structures produced on top of liverwort where sperm is produced
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Pores (stomata)
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when bryophytes have a cuticle they have pores - which are multiple layers of guard cells but have same function as stomata
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Anthocerophyta (Hornworts)
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have thallus and long horn like structure growing up
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Horns
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are sporophyte, parasytic on gametophyte generation
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Bryophyta (mosses)
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two growth forms found: cushiony and feathery forms
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Germination of mosses: why related to green algae
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when spores first germinate form a structure that resembes a green algae (protonema) - then forms a bud which becomes a gametophyte
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Gametophyte stage
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is dominant
sporophyte is parasitic on gametophyte stage |
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Primitive conducting tissue
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epidermis, cortex and conducting strand - has hydroids in middle and leptoids outside (start of evolution of xylem and phloem)
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Life cycle
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gemetic life cycle
spends most of its time in the gametophyte generation |
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Antheridia
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produces sperm by mitosis
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Sporophyte generation
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foot
capsule calyptera |
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foot
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produced inside archegonium and absorbs nutrients
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Capsule
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has sporangium
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Calyptera
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falls off and spores are released
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Guard cells
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only have one guard cell with two different nuclei and a single stomata inside
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Seedless vasc. plants
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fern and fern allies
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Characteristics
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protective sterile jackets around reproductive organs
multicellular embryos in archegonium cuticle on above ground parts xylem and phloem dominant sporophyte all have true stems |
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Dominated Earth
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during the Silurian period
grew woody in carboniferous period |
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Microphylls
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generally smaller
grows as an outgrowth of the stem that was vascularized but only have a SINGLE vasc. strand |
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Megaphylls
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leaf developed from an entire branch - arranged in 2-D space perpendicular to light to maximize light interception
has well developed vascular system |
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Homosporous
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only one type of spore produced - gives rise to sporophyte generation
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Heterosporous
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have separate male and female spores which gives rise to antheridia and archegonia
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Psilophyta
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only two living genera - Psilotum and Tmesipteris
resemble earliest land plants in terms of structure - lack true roots and leaves and have dichotomous branching reduction evolution |
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Psilotum
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subterranean generation - because wants to find a moist place
saprophytic not parasitic |
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Lycophyta
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Lycopodiacea
selaginellacea isoetacea |
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characteristics
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middle of Devonian period, but not the first land plants (Rhinophyta was)
extinct plants were large trees - only small plants today true roots and true leaves (microphylls) |
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Gametophyte generation
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saprophytic in soil
form a symbiotic relationship with fungi so gametophyte gen. is able to live in teh soil - this ensures fertilization takes place |
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Sporophylls
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major advantage over psilotum, they are leaves which bear sporangia on surface - gives rise to seeds
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Stroboli
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groups of sporophylls clustered together in a club
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Selaginella
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can grow in very dry environments
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Isoetes
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called the quill plant because of quill-like microphylls
have a cuticle but lack a stomata - they are CAM plants - take CO2 through roots and transport it as inorganic acid |
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Spenophyta
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arose during Devonian period
only 1 genus - Equisetum |
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Equisetum
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unchanged since carboniferous
found in moist, damp places hollow jointed stems with whorled microphylls Souring rush Underground rhizomes with adventicious roots |
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Scouring rush
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collects silica from soil and deposits it in leaves - leaves have sandpaper like texture
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Sporangiosphores
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stem that is specialized for reproduction
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elators
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coiled around spores, are hygroscopic meaning they absorb moisture from air - as gain or loose moisture either coil or uncoil regulating the release of spores
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Gametophyte generation
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only has rhizoids
no vasc. tissue sperm are flagellated |
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Pterophyta (Ferns)
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Arose in devonian and became important in carboniferous
11,000 living species well developed vasc. - true roots, leaves, and stems mostly homosporous |
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Leaves (Fronds)
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megaphylls
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Sporangia
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developed on the undersurface of leaves and are grouped into sori
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Ostrich ferns
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only ferns that can be eaten
fiddle heads |
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Indusium
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covers the sori - sporangia are found underneath
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Annulus
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outer wall of sporangia - as sporangia matures annulus dries out and eventually cracks open with force to disperse spores
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Seed plants share certain traits:
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all are heterosporous
megasporangium protected by integuments gametophyte generation no longer free living - parasitic on sporophyte dont need water for reproduction all have megaphylls |
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Evolution of seed plants
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did not become important until permian and triasic period - surface of earth was covered by shallow seas in carboniferous
climate cooled and water levels fell at this time |
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What are seeds
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multicellular sporophyte embryo
food reserve for germination and establishment outerprotective covering |
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Ovules include
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megasporangium - where magagametopyte is produced by meiosis
integuments |
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Ginko biloba
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has separate male and female generations
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Pine life cycle
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sporophyte (2n) produces male and female cones on different parts of the plant
females produce seeds that disperse and are heavier - males produce pollen which is lighter bc doesn't require much height |
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Why separate places?
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To ensure cross polination and dispersal takes place
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Male cone
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groups that have sporangia on surface
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Female cone scales
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ovuliferous scales
cone contains stem and leaf material |
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After meiosis in males:
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microspore divides by meiosis to produce 4 haploid cells - pollen grain (male gametophyte gen)
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4 cells of male gametophye
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tube cell - ensures growth of pollen tube
2 prothalial cells - degenerate 1 generative cell - divides to produce sperm |
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air bladders
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pollen grain has two air bladders to increase SA to allow it to be carried by wind
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After meiosis in females
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4 megaspores produced - 3 die and only one functional one - gives rise to the female gametophyte generation
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Micropyle
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exudes moisture that binds pollen grain
once pollen grain has landed produces tube = once grown generative cell divides |
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megaspore
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undergoes MITOTIC divisions to produce many cells - some archegonia which have eggs
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Once eggs have developed...
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the spermitogenous cell divides MITOTICALLY to produce sperm which fuzes with the egg
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After fertilization
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fertilized egg divides MITOTICALLY to produce embryo
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Seed strucutre
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has female gametophyte tissue (n) - food storage
embryo - 2n integuments - forms seed coat (2n) |
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Embryophytes
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have multicellular reproductive structures (sporangia and gemetangia) that are surrounded by a layer of residual sterile tissue
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All bryophytes are
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oogamous
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Moss gametophyte
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grows from an apical meristem that consists of a single apical cell
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Phyllids
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leaf-like structure of mosses
one cell thick - no vasc tissue - only have cuticle on upper surface |
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Hydroids resemble
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traechids - but with no lignin of SCW
when have no hydroids water moves along the outer surface of the plant |
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Leptoids resemble
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sieve cells - sugar transport
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Sphagnum
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absorbs 20x its weight in water
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Prothallus
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When FERN spores disperse and germinate form a bisexual gametophyte
produces antheridia and archegonia |
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Prothallus
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formed by the germination of spores
heart shaped gametophyte in pteropyhyta |
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Gymnosperm wood
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soft wood with traechids
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Where is the ovule produced
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develop on exposed surfaces of a modified leaves or braches
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Seed differences in gymnosperms
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not surrounded by a fruit wall
does not have endosperm - gets food from female gametophyte |
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Staminate cones
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male cone
small and short lived scales are modified leaves - microsporophylls that have two sporangia on each scale |
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Seed cone
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ovulate cone
has ovuliferous scales - has two megasporangium |
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pollination occurs
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in the SPRING
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Generative cell
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divides three times produces two non-flagellates sperm
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Lichensq
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are a mutualistic symbiotic assosiation between fungi and green algae
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Fungus' role
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recieves sugars from green algae and fixed nitrogen
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Algae's role
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obtains nutrition form the fungi, enclosed in the fungi hyphae
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Lichen reproduction
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eihter by fragmenting or by producing soredia (small masses of both fungal and algal cells)
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