Carbon dioxide joins the photosynthetic pathway in 
Photosynthesis is completed in two phases-light and dark phases. In dark phase (Blackman’s reaction or biosynthetic phase) carbohydrates are synthesised from carbon dioxide in stroma of chloroplast using ATP and NADPH products of light reactions.
NADP+ is reduced to NADPH in 
Non cyclic photophosphorylation is not only connected with ATP synthesis but also production of NADPH. It involves two photosystems—PSI and PSII. PSII (680) receive electrons from photolysis of water and transfer it to PSI (700) to form NADPH from NADP+. The hydrogen required for reduction comes from breaking of water molecules.
The size of chlorophyll molecule is 
Chlorophyll has a tetrapyrrole porphyrin ring as head (15 × 15Å) and a long hydrocarbon tail called phytol (20 Å) tail attached to the ring structure.
The substrate for photorespiration is 
Light dependent uptake of O2 and release of CO2 in C3 photosynthetic cell is called photorespiration. Glycolate (Glycolic acid) is the chief metabolite of photorespiration and also its substrate. Other important metabolities are the amino acids glycine and serine. But phosphoglyceric acid (PGA) is a lipid and is not substrate of photorespiration.
In C4 plants, Calvin cycle operates in 
C4 plants are specialised plants for better CO2 assimilation found in hot environment. They have a characteristic leaf anatomy called kranz anatomy showing two distinct choloroplast containing cells mesophyll and bundle sheath cells. Mesophyll cells are located very near to bundle sheath cells and are the site for C4 cycle i.e. CO2 is first fixed as a 4 carbon compounds oxalocetic acid by the action of PEP carbooxylase. The second carboxylation event occur in stroma of chloroplast of bundle sheath cell through C3 cycle.
Greatest producers of organic matter are 
Phytoplanktons (algae) of oceans are the highest producers of organic matter.
A very efficient converter of solar energy with net productivity of 2-4 kg/m2 or more is the crop of 
C4 cycle occurs in C4 plants like sugarcane, maize. C4 cycle provides a more efficient way of CO2 fixation than C3 cycle and hence give more productivity. Rest are C3 plants.
Kranz anatomy is typical of 
C4 plants have a characteristic leaf anatomy called kranz anatomy with two distinct choloroplast containing cells mesophyll and bundle sheath cells.
The first carbon dioxide acceptor in C4-plants is [1990, 92]
The primary acceptor of CO2 in C4 plants is phosphoenol pyruvate or PEP. PEP in mesophyll cells combine with CO2 and converted into 4 carbon compound Oxaloacetic acids by PEP carboxylase. In C3 plant Ribulose 1, 5–diphosphate is primary acceptor of CO2.
Photosynthetic pigments found in the chloroplasts occur in 
Photosynthetic pigments occur on photosynthetic thylakoids of chloroplasts. A stack of thylakoids is called granum.
Dark reactions of photosynthesis occur in 
Dark reaction occurs in the stroma or matrix of chloroplasts. It is independent of light but depends on the products of light reaction (ATP and NADPH– assimilatory process).
Which technique has helped in investigation of Calvin cycle? 
In 1954-55 Calvin traced the pathway of carbon fixation by using radioactive isotope method by using 14CO2 and gave the Calvin cycle.
During monsoon, the rice crop of eastern states of India shows lesser yield due to limiting factor of 
According to law of limiting factors given by Blackman, when a process depends upon a number of factors which are separate, the rate of the process is limited by the pace of the slowest factor. Rate of yield is dependent on light as photosynthesis is dependent on light.
During monsoon, the light is dim and so this reduces rate of photosynthesis and hence yield
Ferredoxin is a constituent of 
In PSI, when the electron passes from ferredoxin and plastoquinone, the electron loses sufficient energy to form ATP from ADP and inorganic phosphate.
Formation of ATP in photosynthesis and respiration is an oxidation process which utilises the energy from 
Electrons provide energy for the formation of ATP in photosynthesis and respiration.
The enzyme that catalyses carbon dioxide fixation in C4 plants is 
In C4 plants, the primary acceptor of CO2 is phosphoenol pyruvate. It combines with carbon dioxide in the presence of PEP carboxylase to form oxalo-acetic acid in mesophyll cells.
Photosystem II occurs in 
Photosystem II is a photosynthetic pigment system that is located in the appressed part of grana thylakoids.
All types of plastids possess essentially the same structure because they 
Depending upon their colour, plastids are of three main types – leucoplasts, chromoplasts and chloroplasts.
Chlorophyll a occurs in 
Chlorophyll a is found in all photosynthetic plants except bacteria. Hence, it is termed as universal photosynthetic pigment.
Translocation of carbohydrate nutrients usually occurs in the form of 
Translocation of organic solutes occur through sieve tubes in the form of sucrose. Transportable form of sugar is sucrose.
Which one is a C4-plant? 
Maize, Sugarcane, Sorghum, Atriplex, Panicum are examples of C4 plants.
The carbon dioxide acceptor in Calvin cycle/ C3-plants is [1993, 95, 96, 99]
The primary CO2 acceptor in C3 plants is Ribulose-1, 5-diphosphate (RuBP) which forms a 3 carbon compound 3-phosphoglyceric acid.
Maximum solar energy is trapped by 
Algae are the most efficeint photosynthesizing organisms.
A photosynthesising plant is releasing 18O more than the normal. The plant must have been supplied with 
The phenomenon of breaking up of water into hydrogen and oxygen in the illuminated chloroplasts is called photolysis. Oxygen comes from photolysis of water was verified by Ruben & Kamen (1941).
C4-cycle was discovered by 
C4 cycle was worked out by Hatch and Slack (1966). C4 cycle occured in C4 plants.