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
