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Harvesting Light

sophie waddington 16 preguntas Actualizado el 16 may 2018

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Preguntas del test (16)

  1. 1Background
    - [blank_start]sun[blank_end] warms the surface of the plant to a desirable [blank_start]temperature[blank_end] range for supporting life as we know it
    - constitutes the ultimate source of [blank_start]energy[blank_end] that sustains life on earth and utilisation of this light driven energy by [blank_start]photosynthesis[blank_end]
    - there are a few exceptions that don't rely on utilising light e.g. [blank_start]chemosynthetic[blank_end] bacteria that obtain energy by [blank_start]oxidising[blank_end] inorganic substances such as ferrous ions and sulfur or H2S released through volcanic action
    1. Asun
    2. Btemperature
    3. Cenergy
    4. Dphotosynthesis
    5. Echemosynthetic
    6. Foxidising
  2. 2When we talk about light it is important to remember that the [blank_start]electromagnetic[blank_end] (EM) spectrum comprises a very wide length of wavelengths
    - the visible range of light (400-[blank_start]700[blank_end] nm wavelength) is a small section which we can see (stands blue, green, red)
    - plants are dependent on the [blank_start]visible[blank_end] range of the electromagnetic spectrum

    Most energy is in wavebands [blank_start]above[blank_end] 800 nm
    - the [blank_start]human[blank_end] eye is restricted to 450-640nm = strict definition of light
    - green plants and the pigments they contain ([blank_start]chlorophyll[blank_end], carotenoids) can absorb light between [blank_start]400[blank_end]-700nm = the visible range of the electromagnetic spectrum, which is know as the photosynthetically [blank_start]active[blank_end] radiation (PAR)

    PAR is the spectral range that photosynthetic organisms can use for [blank_start]photosynthesis[blank_end]
    1. Aelectromagnetic
    2. B700
    3. Cvisible
    4. Dabove
    5. Ehuman
    6. Fchlorophyll
    7. G400
    8. Hactive
    9. Iphotosynthesis
  3. 3Adaptations of Leaves
    - very [blank_start]efficient[blank_end] at harvesting light
    - upper epidermal cells on top of leave are slight [blank_start]convex[blank_end] in shape = so they reflect light down onto the tissues below = 'harvesting light', this acts like a [blank_start]magnifying[blank_end] glass
    - when light hits the periphery of palisade cells light is [blank_start]split[blank_end] up which maximises the capture of light by chloroplasts
    - [blank_start]chloroplasts[blank_end] are mostly found in the [blank_start]peripheral[blank_end] (near the edges) on cells and closer to the upper side (top)
    - this structure of leaves is designed to optimise the capture of [blank_start]light[blank_end] energy

    1. Aefficient
    2. Bconvex
    3. Cmagnifying
    4. Dsplit
    5. Eperipheral
    6. Fchloroplasts
    7. Glight
  4. 4How many types/forms of [blank_start]chlorophyll[blank_end] do we know exist today?
    - there are [blank_start]5[blank_end] forms of chlorophyll recognised today

    chlorophyll a and b in [blank_start]higher[blank_end] (^) plants
    chlorophyll c in [blank_start]diatoms[blank_end]
    chlorophyll d in [blank_start]red[blank_end] algae
    bacteriochlorophyll in some [blank_start]ancient[blank_end] prokaryotes
    1. A5
    2. Bchlorophyll
    3. Chigher
    4. Ddiatoms
    5. Ered
    6. Fancient
  5. 5[blank_start]Chloroplast[blank_end] Structure
    - double membrane forms an [blank_start]envelope[blank_end] with an inner and outer membrane
    - [blank_start]stroma[blank_end] = contains enzymes for carbon assimilation
    - [blank_start]granum[blank_end] (sing.) = stacks of [blank_start]thylakoid[blank_end] membranes throughout the chloroplasts > these grana provide a big [blank_start]surface[blank_end] area for pigments to be embedded, they serve the major function of a large surface area to capture [blank_start]light[blank_end] with
    1. AChloroplast
    2. Benvelope
    3. Cstroma
    4. Dgranum
    5. Ethylakoid
    6. Fsurface
    7. Glight
  6. 6[blank_start]Grana[blank_end] (plural)
    - surface of grana are covered by chlorophyll a and [blank_start]b[blank_end] (if a higher plant)
    - pigments do not absorb across the whole [blank_start]visible[blank_end] spectrum; pigments only absorb at specific [blank_start]wavelengths[blank_end] in blue and purple wavelengths of the spectrum and the [blank_start]red[blank_end] end of the spectrum ([blank_start]extremes[blank_end] of the visible light spectrum) > this means if every plant was only reliant on [blank_start]chlorophyll[blank_end] a and b a lot of light energy would be not utilised and therefore [blank_start]wasted[blank_end]

    BUT; plants have adapted to have a range of different [blank_start]pigments[blank_end] to cover a wider range of wavelengths of the visible [blank_start]light[blank_end] spectrum
    - so grana also contain lots of accessory pigments so expand the range of wavelengths of light to be harvested
    - this improves the absorbance spectra across [blank_start]400[blank_end]-700nm spectrum
    - [blank_start]accessory[blank_end] pigments enhance the capacity of light harvesting
    1. AGrana
    2. Bb
    3. Cvisible
    4. Dwavelengths
    5. Ered
    6. Fextremes
    7. Gchlorophyll
    8. Hwasted
    9. Ilight
    10. Jpigments
    11. Kaccessory
    12. L400
  7. 7[blank_start]Photons[blank_end] (light particles) are harvested by [blank_start]antennae[blank_end] complexes which contain carotenoids, [blank_start]chlorophyll[blank_end] a and b
    - light in channeled through antennae pigments down into specialised [blank_start]reaction[blank_end] centres = focused at wavelength optima of chlorophyll a and b (680 and [blank_start]700[blank_end]nm)

    Photosystem 2= P[blank_start]680[blank_end] nm optimum
    Photosystem 1 = P[blank_start]700[blank_end] nm optimum

    Photosystems are positioned inside the [blank_start]thylakoid[blank_end] membranes; the whole process involves the acidification/movements of [blank_start]protons[blank_end] across the membrane into the lumen, which then can produce massive amounts of energy through [blank_start]photophosphorylation[blank_end] via ATP synthase

    carbon assimilation is completely dependent on [blank_start]ATP[blank_end] and NADPH (products from the light [blank_start]dependent[blank_end] stage of photosynthesis that takes place on the thylakoid membranes)
    1. APhotons
    2. Bantennae
    3. Cchlorophyll
    4. Dreaction
    5. E700
    6. F680
    7. G700
    8. Hthylakoid
    9. Iprotons
    10. Jphotophosphorylation
    11. KATP
    12. Ldependent
  8. 8[blank_start]Light[blank_end] use efficiency (quantum mechanics) =

    net carbon [blank_start]assimilation[blank_end]/fixation = gross photosynthesis - [blank_start]respiration[blank_end]

    The point at which the plateau is reached = light [blank_start]saturated[blank_end] rate of photosynthesis, this is the optimum rate of photosynthesis you can achieve regardless of [blank_start]light[blank_end] intensity

    1. ALight
    2. Bassimilation
    3. Crespiration
    4. Dsaturated
    5. Elight
  9. 9Light [blank_start]compensation[blank_end] point = the amount of light intensity on the light curve where the rate of photosynthesis exactly matches the rate of [blank_start]respiration[blank_end]
    - at this point, the uptake of carbon [blank_start]dioxide[blank_end] through photosynthetic pathways is exactly matched to the respiratory release of [blank_start]carbon[blank_end] dioxide
    - and the uptake of oxygen by [blank_start]respiration[blank_end] is exactly matched to the photosynthetic release of oxygen
    1. Acompensation
    2. Brespiration
    3. Cdioxide
    4. Dcarbon
    5. Erespiration
  10. 10Quantum ratio or quantum [blank_start]requirement[blank_end] = the minimum amount of [blank_start]light[blank_end] required to fuel 2 photosystems = 8 photos per mol. of [blank_start]oxygen[blank_end] or per mol of carbon dioxide assimilated/fixated
    - thus maximum quantum yield = 1 mol (oxygen or carbon dioxide)/8 mol (photons) = [blank_start]0.125[blank_end]

    SO: quantum [blank_start]ratio[blank_end]/requirement is the number of photons per unit oxygen evolved or per unit carbon dioxide assimilated, and this is 8 moles of photons, 0.125

    Measured values for some plants approach the [blank_start]theoretical[blank_end] optimum
    - but the majority of plants are much [blank_start]less[blank_end] efficient (i.e. more energy is trapped in the light reactions diverted to fuel structural and metabolic requirements), so [blank_start]more[blank_end] photons are required to fuel carbon dioxide fixation than theoretical requirement

    e.g. 18 mol of photons per mole of carbon [blank_start]dioxide[blank_end] assimilated or oxygen evolved in higher plants
    - so the [blank_start]maximum[blank_end] quantum yield = 1/18 = 0.06

    1. Arequirement
    2. Blight
    3. Coxygen
    4. D0.125
    5. Eratio
    6. Ftheoretical
    7. Gless
    8. Hmore
    9. Idioxide
    10. Jmaximum

Información

Descripción
Plant Biology Test sobre Harvesting Light, creado por sophie waddington el 16/05/2018.
Idioma
English
Visitas
1
Historial
Creado el 16 may 2018 · actualizado el 16 may 2018
Etiquetas
plant biology
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