Photosynthesis- all Flashcards
Photosythesis is a —- or —- process
Physico-chemical or Photobiochemical process
Light energy is converted into — energy in PS
chemical
ps is a redox reaction, where oxidation of —- occurs and reduction of —-
oxy of h2o- light rean
red of co2- dark rean
PS is — and energy absorbing (—-) process
anabolic and endergonic
dark rean is also called
biosynthetic process
____ half leaf exp proved that —- is essential for ps
Molls, co2
1st exp on ps was done by —- 300 years ago called —-
Joseph priestly (1770)
Bell Jar exp
What was observed when lit candle and mice were placed in jar alone individually
Candle light extinguished and mice died
When mint (—) was added into jar with candle and mice?
Mentha bipalaca
Mice/candle- nothing happens
What was the conclusion of Joseph priestly?
Plants restore to air whatever breathing animals and candles remove
All animals including human beings depend on —- for their food.
plants
Green plants, in fact, have to make or rather — the food they need and all other organisms depend on them for their needs.
synthesise
Green plants carry out
‘photosynthesis’, a —- process by which they use light energy to drive the synthesis of — compounds.
physico-chemical
organic
Ultimately, all living
forms on earth depend on — for energy.
sunlight
—- is the basis of life on earth.
The use of energy from
sunlight by plants doing photosynthesis
Photosynthesis is important due to two reasons..
- Primary source
of all food on earth - Responsible for the release of oxygen into the
atmosphere by green plants.
Chlorophyll (green pigment of the leaf), —and — are required for
photosynthesis to occur.
light and co2
Experiment for starch formation in two leaves – a — leaf or a leaf that was partially covered with
black paper, and one that was exposed to light. On testing these leaves
for starch it was clear that photosynthesis occurred only in the — parts of the leaves in the presence of –.
variegated
green, sunlight
Half-leaf experiment is where a part of a leaf is
enclosed in a test tube containing some —-(which absorbs CO2
), while the other half is
exposed to air.
The setup is then placed in light for some time. On testing for — later in the two halves of the leaf, it is found that — was required for photosynthesis.
KOH soaked cotton
starch, CO2
Joseph Priestley (1733-1804) in 1770 performed a series of experiments that revealed the — in the growth of green plants.
essential role of air
—– discovered oxygen in
year (—).
Priestly, 1774
Priestley concluded that
a burning candle or an animal that breathe the air —-
damage the air
Using a similar setup as the one used by Priestley, but by placing it once in the — and once in the sunlight, —- (1730-1799)
showed that sunlight is essential to the plant process that somehow
purifies the air fouled by burning candles or breathing animals.
dark
Jan Ingenhousz
Ingenhousz in an elegant experiment with an — showed that in bright sunlight, small bubbles were formed around the green parts while in the dark they did not. Later he identified these bubbles to be of
—.
aquatic plant (==hydrilla exp)
oxygen
—- showed that it is only the green part of the plants that could release oxygen.
Ingenhousz
It was not until about 1854 that — provided evidence for production of glucose when plants grow.
Julius von Sachs,
Glucose is usually stored as — .
starch
JV Sachs later studies showed that the green substance in plants
(— as we know it now) is located in special bodies (later called —) within plant cells. He found that the green parts in plants is where — is made, and that the glucose is usually stored as starch.
chlorophyll , chloroplasts
glucose
T.W Engelmann, Using a prism he split light into its —- components and then illuminated a green alga, —, placed in a suspension
of aerobic bacteria.
spectral , Cladophora
Acc to JV Sachs, glucose is transported as
Sucrose
The bacteria were used by Engelmann to detect the sites of —.
O2 evolution
Engelman observed that the bacteria accumulated mainly in the region
of — and —- light of the split spectrum.
blue and red
A first —- of photosynthesis was thus described. It resembles roughly the — spectra of chlorophyll a and b
action spectrum, absorption
By the middle of the —century the key features of plant photosynthesis were known, namely, that plants could use light energy to make —from CO2 and water.
nineteenth
carbohydrates
The empirical equation
representing the total process of photosynthesis for oxygen evolving
organisms was then understood as:
co2 + h20 —> ch2o + o2
ch2o - represented carbohydrate
A milestone contribution to the understanding of photosynthesis was
that made by a —-, —- (1897-1985), who,
based on his studies of purple and — bacteria, demonstrated that
photosynthesis is essentially a light-dependent reaction in which hydrogen from a suitable —- compound reduces carbon dioxide
to carbohydrates.
microbiologist,
Cornelius van Niel
green
oxidisable
Eq as observed by Neil can be expressed by:
2HA + CO2 —> 2A + CH2O + H2O
In green plants — is the hydrogen donor and is oxidised to O2.
H2O,
Some organisms do not release – during photosynthesis.
O2
When H2S, instead
is the hydrogen donor for — and — bacteria, the
‘oxidation’ product is sulphur or — depending on the organism and not O2
purple and green sulphur
sulphate
Hence, — inferred that the O2 evolved by the green plant comes from H2O, not from carbon dioxide. This was later proved by using
— techniques.
Cornelius Von Neil
radioisotopic
The correct equation, that would represent the
overall process of photosynthesis is therefore:
6CO2 + 12H2O —-> C6 H12 O6 + 6H2O +6O2
___ did exp on isolated chloroplast of plant ===
Robert Hill and Bendolf
==Stellerium
Hills reagent are
Benzoquanone, Ferrocyanide (used a H+ donors instead of water)
Who proved Neil’s exp and supported hills reaction
Ruben and Kamen by O18 Radiolabelled isotope
In the absorption spectrum of —-, —- absorbs more light in blue and red region respectively
Engelman
Chlb- in blue
Chla- in red
diff b/w absorption spectrum and action spectrum
absorption- represents amt of light absorbed at diff wavelengths
action- rate of ps at different wavelengths
based on action and absorption spectrums it was concluded that
chl a is most abundant pigment in higher plants
emersons enhancement exp was done on —
it showed that?
chlorella
rate of ps is more when exposed 2 diff wavelengths (680 and 700 nm) of light than the sum individual rates in each wavelength
Red drop mechanism means
Reduction in the rate of photosynthesis with increase in wavelength (More wavelength, towards red light— hence ‘‘red drop’’)
___ concluded that plants have 2 photosystems
Emerson
PS1 and PS2 are also called
quantasomes
(Photosystem==grp of photosynthetic pigments)
PS1 and PS2 can absorb till — wavelength of light
PS1- 70nm
PS2- 680 nm
Photosynthetically active radiation belongs to — range
400-700 nm (Visible range)
Photosystem has reaction centre containing —- pigment and is surrounded by
Chl a,
Antenna pigments==Caratenoids (Accessory pigments)
Photosynthesis take place in the green leaves of plants but it does so also in — of the plants.
other green parts
— cells in the
leaves, have a large number of chloroplasts.
Mesophyll
Usually the chloroplasts align themselves along the walls of the mesophyll cells, such that they get the —- of the incident light.
optimum quantity
___ parenchyma in mesophyll cells have most chlorophyll?
Palisade
(Spongy have very less)
During high intensity of chloroplasts are arranged — to light
Parallel== Parastrophe
If there’s less intensity of light, chloroplasts are arranged —-
perpendicular to light– epistrophe
in — intensity, irregular arrangement of chloroplast is seen
medium intensity
Within the chloroplast there is the —- consisting of grana, the stroma lamellae, and the fluid stroma
membranous system
There is a clear division
of — within the chloroplast.
labour
The membrane system is responsible for
—–and also for the synthesis of — and —
the trapping of light energy
ATP and NADPH
In stroma, —- incorporate CO2 into the plant leading to the synthesis of —, which in turn forms starch.
enzymatic reactions, sugar
The membrane reactions, are called —reactions.
The stroma reactions are not directly light driven but are dependent on the —–). Hence, they are called as dark reactions. However, this should not be construed to mean that they — or —
light
products of light reactions (ATP and NADPH)
occur in darkness or that they are not light dependent.
A — separation of the leaf pigments shows that the colour that we see in leaves is not due to a single pigment but due to — pigments.
chromatographic, four
Chlorophyll a (—– in the chromatogram), chlorophyll b (—-), xanthophylls (—) and carotenoids (—-).
bright/ blue green
yellow green
yellow
yellow to yellow-orange
Though chlorophyll is the major pigment responsible for trapping light, other thylakoid pigments like chlorophyll
b, xanthophylls and carotenoids, which are called —- pigments,
also absorb light and transfer the energy to chlorophyll a; enabling a wider range of wavelength of incoming light to be utilised
for photosyntesis but also protect chlorophyll a from —-
accessory
photo-oxidation.
Types of Photosynthetic pigments
Chlorophylls, Carotenoids and Phycobillins
____ is the universal pigment found in all O2 liberating photosynthetic orgs
Chl a
___ are soluble in organic solvents
Chlorophylls
Chl b is accessory pigment found in
euglenoids, green algae and higher plants
Structure of chlorophyll looks like a —-
tadpole
Chlorophyll is made of 2 parts-
Porphyrin head and Phytol tail
Porphyrin head is
Hydrophillic
Tetrapyrole structure with Mg at the centre
15*15 A (size)
Phytol tail properties
C 20, H 39, OH
-20 A size
Hydrophobic
Tail is embedded in lipid bilayer of thylakoidal membrane
Chl a has — grp in 2nd pyrole ring
CH3
Chl b has — grp in 2nd pyrole ring
CHO
Formula of Chl a and b are
a- C 55, H 72, O 5, N 4, Mg
b- C 55, H 70, O 6, N 4, Mg
synthesis of chlorophyll?
Succinyl CoA + Glycine —-> Protochlorophyll —> (in presence of light and 2 H+) forms chlorophyll
Catalyst: Fe
first carotenoid was discovered in
carrot- yellow orange in colour
____ are the common carotenoids found in plants
Beta carotene and Lutein
____ convert lethal nascent oxygen to molecular oxygen. Thus also called?
Carotenoids
Shield pigments
Hot water soluble pigments are
Phycobilins (lack Mg and phytol tail)
Types of phycobillins:
Phycocyanin- blue
Phycoerithrin- red
Allophycocyanin- Light blue
Carotene and Xanthophylls formula
C- C 40, H 56
X- C 40, H 56, O 2
____ are soluble in petroleum esters
Carotenoids and Chl
Light reaction is also —- phase
Phytochemical
Light reaction includes
-Light absorption
-Water splitting
-O2 release
-Formation of high energy chemical intermediates like ATP and NADPH
The pigments are organised into two discrete photochemical —- within the Photosystem I (PS I) and Photosystem II (PS II). These are named in the sequence of their discovery, and not in the
sequence in which they function during the light
reaction.
light harvesting complexes
(LHC)
The LHC are made up of hundreds of — molecules bound to —- .
250-400 molecules of pigment, proteins
Each photosystem has all the pigments (except—-) forming a light
harvesting system also called —
one molecule of chlorophyll a, antennae
LHC pigments help to make photosynthesis more efficient by absorbing— of light.
different wavelengths
The single chlorophyll a molecule forms
the —-. The reaction centre is different in both the photosystems.
reaction centre
(PS= LHC + Rean centre)
Granal thylakoids have
PS 1, 2 and FNR (Ferredoxin NADP reductase)
Stroma thylakoids have
PS 1 only
Photophosphorylation means
Synthesis of ATP from ADP and iP
Non cyclic Photophosphorylation is also called
Z scheme
Primary e- acceptor from PS 2 is
Pheophytin
ETS consists of
Cytochromes
In photosystem II the reaction centre chlorophyll a absorbs —nm wavelength of red light causing electrons to become excited and jump
into an orbit farther from the atomic nucleus. These electrons are picked
up by an —- which passes them to an electrons transport
680, electron acceptor
