Nine-tenth of all photosynthesis of world (85-90%) is carried out by 
85-90% of all photosynthesis of world is carried out by phytoplanktons in ocean.
Pigment acting as a reaction centre during photosynthesis is 
P700 consists of a chl a and chl b molecules and is named after maximum absorption by pigment or photocentre at that wavelength.
Which one occurs both during cyclic and noncyclic modes of photophosphorylation? 
Cyclic photophosphorylation involves only PSI and there occurs only ATP formation.
The specific characteristic of C4-plants is 
Anatomy of leaves of C4– plant is called kranz anatomy. In the mesophyll cells of these plants pallisade tissue is absent.
Photorespiration is favoured by 
Photorespiratory loss of CO2 occurs when RUBISCO starts functioning as an oxygenase instead of carboxylase under conditions of high O2 and low CO2. It involves three organelles chloroplast, mitochondria and peroxisomes. Half of the photosynthetically fixed carbon (in the form of RUBP) may be lost into the atmosphere through this process and no ATP formation occurs.
The principle of limiting factors was proposed by
The principle of limiting factors was formulated by Blackmann (1905). It states that when a process is conditioned as to its rapidity by a number of separate factors, the rate of process is limited by the pace of slowest factor.
Chlorophyll ‘a’ molecule at its carbon atom 3 of the Pyrrole ring II has one of the following [1996, 97]
The empirical formula of chlorophyll molecule is C55H7205N4Mg. It has tadpole like configuration. It is consisted of a porphyrin head and a phytol tail. Porphyrin is a cyclic tetrapyrol structure, having a magnesium atom in the centre. Chlorophyll a methyl group (CH3) is attached to the third carbon in the porphyrin head.
Photosynthetically active radiation is represented by the range of wavelength of [1996, 2004, 05]
Photosynthesis takes place only in the visible part (400 - 700 nm wavelength) of electromagnetic radiations. Hence this component comprises the photosynthetically active radiation.
Which one of the following is represented by Calvin cycle? 
In dark phase of calvin cycle of photosynthesis the CO2 is reduced to Glucose in stroma of chloroplast, making use of the ATP & NADPH2, (available from light phase).
NADPH is generated through 
Photosystem I is the second photosystem in the photosynthetic light reactions of algae, plants and some bacteria. Photosystem I is so named because it was discovered before photosystem II. It produces NADPH2.
Protochlorophyll differs from chlorophyll in lacking 
Protochlorophyll differs from chlorophyll in lacking 2 hydrogen atoms in one of its pyrrole rings.
Which one of the following statements about cytochrome P-450 is wrong? 
Cytochrome P450 (CyP) is a host of enzymes that use iron to oxidize, often as part of the body's strategy to dispose of potentially harmful substances making them more water-soluble. These are found in plants, animals, and microbes and are involved in a variety of oxidative reactions in cells. These catalyse a variety of reactions including epoxidation, /V-dialkylation,o-dialkylation,.v-oxidation and hydroxylation. A typical cytochrome P450 catalyzed reactions is
NADPH + H+ + O2 + RH → NADP- + H20 + R - OH
Which enzyme is most abudantly found on earth?
RUBISCO is the enzyme involved in Calvin cycle. Nitrogenase catalyses nitro- genation. Invertase catalyses breaking of sucrose to glucose and fructose.
The enzyme which fixes CO2 in C4 plants is 
RuBP carboxylase fixes CO2 in C3 plants. Hydrogenase catalyses addition of hydrogen.
The first step of photosynthesis is 
Light reaction is the first step of photosynthesis. Attachment of CO2 to 5 carbon sugar occurs in the next step dark reaction
How many turns of Calvin cycle yield one molecule of glucose ? [1996, 2000]
Each turn of Calvin cycle generates one carbon atom hence six turns of the cycle is required to generate one molecule of hexose sugar glucose.
Fixation of one CO2 molecule through Calvin cycle requires 
2 ATP are required during conversion of PGA to 1, 3-diphosphoglyceric acid and 1 ATP during conversion of glyceraldehyde phosphate to ribulose biphosphate. 2NADH2 molecules are utilised for converting 1, 3-diphosphoglyceric acid to glyceraldehyde phosphate.
Photochemical reactions in the chloroplast are directly involved in 
The photochemical phase of photosynthesis involves fixing light energy and photolysis of water producing ATP and NADPH.
Which pair is wrong? 
Maize is a C4 plant carrying out Hatch and Slack pathway. These plants show Kranz anatomy and overcome photorespiration.
Which pigment system is inactivated in red drop?
The fall in photosynthetic yield beyond the red region of the spectrum (680 runs) is called red drop.
Reaction center of PS-2 is 680 while that of PA-1 is 700.
So the psII system will be inactive.
So the correct option is PS II.
Cytochrome is 
Cytochrome is Fe containing porphyrin pigment. These are electron transferring proteins often regarded as enzymes.
In photosynthesis energy from light reaction to dark reaction is transferred in the form of 
ATP molecules produced in the light reaction are used in the dark reaction to fix CO2 to form organic compound.
Which of the following absorb light energy for photosynthesis? 
Each pigment has its own absorption spectrum, chlorophyll absorbs light energy in blue and red region.
Stomata of CAM plants 
To conserve water, the stomata of CAM plants open during night to take up CO2 and store it in the form of Malic acid which is utilised during the time of photosynthesis.
In sugarcane plant 14CO2 is fixed in malic acid, in which the enzyme that fixes CO2 is 
Sugarcane is a C4 plant in which CO2 is fixed in malic acid by the enzyme phosphoenol pyruvic acid carboxylase present in mesophyll cells.