Module 5.6 Flashcards
Why is photosynthesis important ?
Photosynthesis is a physiological process used by plants , algae and some types of bacteria to convert light energy from sunlight into chemical energy .
Why is photosynthesis important ? - what is meant by autotrophic nutrition
organisms , can use this chemical energy , to synthesise large organic molecules , which form the building blocks of living cells . From, simple inorganic molecules such as water and carbon dioxide- known as autotrophic nutrition .
What are Photoautotrophs ?
organisms that photosynthesise , as they use light as the energy source for autotrophic nutrition .
-These organisms , are also described as producers , because they are at the beginning (first trophic level ) , o fa food chain and provide energy and organic molecules to other non-photosynthetic organisms .
general equation for photosynthesis
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what is a photon
a photon is a particle of light each photon contain an amount (a quantum( of energy .
what is the main product of photosynthesis
the main product of photosynthesis is monosaccharide sugar which can be converted into disaccharides for transport and then starch for storage .
what is carbon fixation?
-Give an example
-Photosynthesis is an example of carbon fixation - the process by which, carbon dioxide is converted into sugars.
-The carbon for synthesising all types of organic molecules is provided by carbon fixation .
What type of reaction is carbon fixation
endothermic, and so needs energy . Carbon fixation also needs electrons ;the addition of electrons is a reduction reaction .
What is the purpose of carbon fixation
carbon fixation helps regulate , the concentration , of carbon dioxide , in the atmosphere , and oceans .
-Most forms of life on earth rely directly or indirectly on photosynthesis.
respiration
plants, and other organisms , that photosynthesise also respire . During respiration , they oxidise , the organic molecules that they have previously synthesised by photosynthesis and stored, releasing chemical energy .
-non-photosynthetic organisms
such as fungi , animals, many protoctists , and many types of bacteria are described as heterotrophs .They obtain , energy , by digesting , complex organic molecules of food to smaller molecules that they can use as respiratory substrates .They obtain energy from the products of digestion by respiration.
what happens during respiration
glucose , and other organic compounds are oxidised to produce carbon dioxide and water . Respiration releases chemical energy 9IT IS EXOTHERMIC )
-THAT can drive the organismsmetabolism .
how do photosynthesis and respiration interrelate ?
both photosynthesis and aerobic respiration are important in cycling the carbon dioxide and oxygen in the atmosphere. The products of one process are the raw materials for the other process . Aerobic respiration removes oxygen from the atmosphere and adds carbon dioxide while photosynthesis does the opposite .
competition between plants
-fyi - plants respire all the time
-however , plants only photosynthesise during daylight.
-plants often compete with each other for light.
-the i intensity of light has to be sufficient , to allow photosynthesis at a rate that replenishes the carbohydrate stores used up by respiration .
what happens at the compensation point?
when photosynthesis and respiration proceed at the same rate , so that there is no net gain or loss of carbohydrate , the plant is at its compensation point.
-The time a plant takes to reach its compensation point is called the compensation period.
how compensation periods vary in different plants .
-the compensation period is different for different plant species . Shade plants can utilise light of lower intensity than sun plants can .
-When exposed to light after being in darkness , shaded plants reach their compensation point sooner (shorter compensation ) than sun plants , which requeue a higher light intensity to achieve their optimum rate of photosynthesis.
what is granum (plural grana )
inner parts of chloroplast made of stcks of thylakoid memerbanes where the light dependant stage of photosyntheissi takes place .
what is a photosynthetic pigment
pigment that absorbs specfici wavelengths of light and raps the energy associated with light , such pigments include chlorophlls a and b crotene and xanthophyll .
what is a photosytem
system of phtoosytnhetic pigments found in thylakoids and chloroplasts , each photoytem contains aout moelcules of chlorphyll tht traps photons and pass thheir eergy to a primary pigment reaction cener ,a moleucle of chlorphyll , a during the light dependet stage of photosynthesis .
what is stroma
fluid filled matrix of chloroplasts , where the light independent stage of photosyntehsis akes place .
what is a thylakoid
flattneed emmbrane bound sac found isnide chloroplasts contians phtoosyntehtic pigments / photosytems and is the site of the light dependent stage of photosyntehsis ..
structure of chloroplasts
–chlroroplasts are the organelles within plant cells where photosynthesis takes place .
-algae have chloroplasts but photosynthetic bacteira do not .
-+Most plant chloroplasts are disc shaped and around - 2-10 micrometers long . Each is surrounded by a double membrane , the envelope with an INTERMEMEBRAE SPACE of width 10-20 nanometeres . ebtween the inner and outer memebrane .
OUTER MEMBRAN EIS HIGHY PERMEAE .
there are two distinct region visible on an electron micrograph
the fluid filled matrix called the stroma and the grana that consists of stacks of thylakoid membranes .
-check page 116
grana (1) check page 117
-first stage of photosyntheiss is the light - dependent stage , this takes place in the grana ,
how many membranes do chloroplasts have explain them
chloroplasts have three distinct membranes - outer , inner and thylakoid , giving these separate internal compartmenet s- the intermemebranse space , the stroma , nd the thylakoid space .
–The thylakoids within a granum may be connected to thylakoids within nother granum by intergranal lamellae (also knwon as intergranal thylakoids )
what is the thylakoid membrane of each chloroplast
-the thylakoid membrane of each chloroplasts is less permemable and is foled into flattened dis like sacs called thylKOIDS THAT FORM STACKS .
-eACH STACK , OF THYLAKOIDS , IS called a granum , . One granum may contain 100 thylakoids
with many grana in every chloroplast and with many chloroplasts in each photosynthetic cells , there is a huge surface are for what
-The distribution of the photosytems that contain the photosynthetic pigments that trap sunlgiht energy .
-the electrons carries and ATP synthase enzymened need to conver that lgiht energy into ATP .
why are proteins embedded in the thyLAKOID MEMBRANE >
To hold the photosytems in palce .
-The gana are surroudned by the stroma , so the products of the light dependent stage can easily pass to the stroma to be used in the light independent stage .
what is in the stroma
the strom is the fluid filled matrix , it contins the enzmes needed to catalyse the reactions of light independent stage of photosynhtesis as well as strach grians oil droples , small ribsosomes ismilr to those found in porkaryote cells .
-the loop of dna contains genes that code for some of the porteins needed for photosyntheiss . These proteins are assmled at the chloroplass ribosomes .
where are photosyntheitc pigments and what is their purpose
within the thylakoid membranes of each chloroplasts are funnel shaped strucutures called photsytems . These photosytems contain photosynthetic pigemnts .
-Each pIgement absorbs light o a particular wavelength and reflects other wavelength s of light .
-Each pigment appears to our eyes and brain , the clolour o fthe wavelngth of ligh t it is reflecting .
what happens to the energy associated witht he wavelengths
it is funneled down to the primary pigement reaction cenre cosniting of a type of chlorphyll at the base of the photosytem .
check page 117 figure 3
wgat are chlorophylls
chlorophylls arre a mixture of pigments all hae a similar molecular strucuure consiting of a porphyrin group in which is a magnesiuma tom and a long hdyrocarbon chain .
what is chlorphyll a
there are two forms of chorms of chlorophyll a - both of which appear blue - green . Both are situaated at the center of photosytems , both absorb red ligh t buthey have different absoprtion .
p680
is found in photosytems ii and its peak of absoprtion is lioght of wavelength 680nm .
p700
is found in photosytem I , and its peak of absoption is light of wavelength 700 nm .
-chlrophyll a also aborbs some blue light , of wavelength around 440 nm .
what does chlorphyll b absorb
chlorophyll b absorbs light of wavelengths 400-500nm and 640 nm it appears yellow green .
what are accessory pigments
cartenoids absorb blue light of wavelengths 400-500 nm .
They reflexct yellow nd orsange light .
-XAnthophylls absorb blue and green light sof wavelgnths 375-550 nm they reflect yellow light .
how to separate photosynthetic pigments
using thin layer chromaatorpahy , mashing green leaf to separate pigmens in chlorpjull ,t hen spot oto tlc materia , olven separates the pigments as they hae differeet rf vlaues .
-useing high flammable solvent ehtnol make sure no anked flames .
where does the light dependent stage of photosyntheissi occur and what does it invovle
where does the light dependent stage of photosyntheiss occurs in the grana (thylakoids) of chloroplasts and invovles photosytems - it invovled the direct use of ligh energy .
