Q1.
Assertion (A): In photosynthesis there is synthesis of glucose but it is stored in form of starch.
Reason (R): Glucose is osmotically active while starch is osmotically inactive.
Q2.
Assertion (A): When Cladophora is placed on suspension of aerobic bacteria, bacteria accumulate in region of red and blue light of split spectrum.
Reason (R): In Cladophora there is maximum absorption of Blue and red light.
Q3.
Assertion (A): Biosynthetic phase of photosynthesis is known as dark reaction.
Reason (R): It takes place in absence of light.
Q4.
Assertion (A): Nomenclature of pigment systems as PS-I and PS-II is based on their functioning during light reaction.
Reason (R): During light reaction PS-II works first and PS-I works later.
Q5.
Assertion (A): The whole scheme of transfer of electrons starting from PS-II to NADP⁺ is called z-scheme.
Reason (R): When all the carriers of this scheme are placed in sequence on a redox potential scale. They appear like Z.
Q6.
Assertion (A): Both PS-I and PS-II are located on same face of thylakoid membrane.
Reason (R): Photolysis of water and reduction of NADP⁺ takes place in stroma site.
Q7.
Assertion (A): Like respiration in Photosynthesis too, ATP synthesis is linked to development of proton gradient across a membrane.
Reason (R): Proton gradient is the strongest source of potential energy which can be used in joining of ADP and Pi.
Q8.
Assertion (A): Biosynthetic phase of photosynthesis is also termed as dark reaction.
Reason (R): Biosynthetic phase is not directly dependent on light but it is supported by products of light reactions.
Q9.
Assertion (A): In all photosynthetic plants first fixation product during biosynthetic phase of photosynthesis is PGA.
Reason (R): PGA is the most stable product and is synthesized from both RuBP and PEP, whenever they act as first CO₂ accepting substance.
Q10.
Assertion (A): To make one molecule of glucose 6 turns of Calvin cycle are required.
Reason (R): In each turn of Calvin cycle there is fixation of one CO₂ only while 6CO₂ are required for each glucose.
Q11.
Assertion (A): C4 plants can tolerate high temperature conditions.
Reason (R): Enzyme pepcase and PPDK work only on high temperature.
Q12.
Assertion (A): In C4 plants there is no photorespiration.
Reason (R): In C4 plants photolysis of H₂O and Rubisco activity show space differentiation.
Q13.
Assertion (A): In mesophyll cells of C4 plants there is no sugar formation after fixation of CO₂.
Reason (R): In mesophyll cells there is no Rubisco so C₃ cycle events can not operate.
Q14.
Assertion (A): The basic pathway that results in formation of sugars, the Calvin pathway is common to the C3 and C4 plants.
Reason (R): C3 path is the only biosynthetic path which yields sugar from CO₂.
Q15.
Assertion (A): Photorespiration is one of the wasteful processes.
Reason (R): In Photorespiration there is no synthesis of ATP and NADPH.
Q16.
Assertion (A): In C4 plants Rubisco selectively shows carboxylase activity no oxygenase activity.
Reason (R): In C4 bundle sheath cell malic acid is broken down to increase intracellular CO₂ concentration.
Q17.
Assertion (A): In Aquatic conditions usually CO₂ concentration regulates the rate of photosynthesis.
Reason (R): In Aquatic conditions generally CO₂ is available at suboptimal level.
Q18.
Assertion (A): In terrestrial conditions CO₂ usually acts as main determining factor of photosynthesis.
Reason (R): Usually CO₂ is available at sub optimal level in terrestrial conditions.
Q19.
Assertion (A): C4 Plants were evolved to adapt for low atmospheric CO₂ concentration.
Reason (R): C4 plants have minimum CO₂ compensation point.
Q20.
Assertion (A): C3 plants do not show rise in photosynthesis at higher temperature.
Reason (R): Enzymes of C3 plants are high temperature sensitive as compared to low temperature sensitive enzymes of C4 plants.
Q21.
Assertion (A): Indirectly water stress leads to decrease in photosynthesis.
Reason (R): Water stress leads to wilt to leaves and minimize their surface area.
Q22.
Assertion (A): Photorespiration decreases the rate of photosynthesis.
Reason (R): RUBISCO can also behave as an oxygenase.
Q23.
Assertion (A): During photophosphorylation light energy is utilized to produce the proton gradient that is required for ATP synthesis.
Reason (R): Oxidative phosphorylation results as the energy of oxidation-reduction is utilized for phosphorylation.
Q24.
Assertion (A): Chief photosynthetic pigment is chlorophyll a but plants evolved some other pigments also.
Reason (R): Photosynthetic efficiency is increased due to absorption of variety of wavelengths.
Q25.
Assertion (A): Higher rate of photosynthesis is seen when plants are illuminated by wavelengths of visible light.
Reason (R): There is maximum absorption by chlorophyll a in the blue and the red regions of the visible light.
Q26.
Assertion (A): Cyclic photophosphorylation results only in the synthesis of ATP, but not of NADPH + H⁺.
Reason (R): Cyclic photophosphorylation occurs only when light of wavelengths beyond 680 nm are available for excitation.
Q27.
Assertion (A): The protons or hydrogen ions that are produced by the splitting of water accumulate within the lumen of the thylakoids.
Reason (R): The primary acceptor of electron which is located towards the outer side of the membrane transfers its electron not to an electron carrier but to an H carrier.
Q28.
Assertion (A): The primary acceptor of carbon dioxide in C3 plants is a 2-carbon compound.
Reason (R): The first product of carbon dioxide fixation in these plants is a C3 acid.
Q29.
Assertion (A): The light-independent reactions do not require light, but they are most likely to occur during day.
Reason (R): NADPH and ATP from the light-dependent reactions are used in the light-independent reactions.
Q30.
Assertion (A): Except for plants in shade or in dense forests, light is rarely a limiting factor for photosynthesis in nature.
Reason (R): Increase in incident light beyond a point causes the breakdown of chlorophyll and a decrease in photosynthesis.
Q31.
Assertion (A): Current availability of CO₂ levels is limiting to the C3 plants.
Reason (R): Carbon dioxide is the major limiting factor for photosynthesis.
Q32.
Assertion (A): Plants that do not use PEP-carboxylase in carbon fixation are C3 plants.
Reason (R): The primary carboxylation reaction in C3 plants, catalyzed by RuBisCO, produces the three carbon 3-phosphoglyceric acids directly in the Calvin Benson cycle.
Q33.
Assertion (A): ATP acts as the energy currency of the cell.
Reason (R): ATP is a ribonucleoside triphosphate.
Q34.
Assertion (A): It is possible to make calculations of the net gain of ATP for every glucose molecule oxidised; but in reality this can remain only a theoretical exercise.
Reason (R): These calculations can be made only on certain assumptions that are not really valid in a living system.
Q35.
Assertion (A): The alignment of the chloroplasts along the walls of the mesophyll cells vary depending on the amount of incident light.
Reason (R): The alignment of the chloroplasts along the walls of the mesophyll cells is such that they get the optimum quantity of the incident light.
Q36.
Assertion (A): Accessory photosynthetic pigments in higher plants enable a wider range of wavelength of incoming light to be utilised for photosynthesis.
Reason (R): Accessory pigments protect chlorophyll a from photo-oxidation.
Q37.
Assertion (A): The protons and O₂ formed by photolysis of water are released in the thylakoid lumen.
Reason (R): The water splitting complex is associated with the PS I, which itself is physically located on the outer side of the membrane of the thylakoid.
Q38.
Assertion (A): Electron transport via cytochrome b6f is responsible for creating the proton gradient that drives the synthesis of ATP in chloroplasts.
Reason (R): Cytochrome b6f complex functions to mediate the transfer of electrons and of energy between Photosystem II and Photosystem I, while transferring protons from the chloroplast stroma across the thylakoid membrane into the lumen.
Q39.
Assertion (A): Breakdown of proton gradient across the thylakoid membrane leads to the synthesis of ATP.
Reason (R): The gradient is broken down due to the movement of protons across the membrane to the stroma through the transmembrane channel of the CF₀ of the ATP synthase.
Q40.
Assertion (A): Immediately after light becomes unavailable, the biosynthetic process continues for some time, and then stops.
Reason (R): The biosynthetic phase of photosynthesis depends on the products of the light reaction.
Q41.
Assertion (A): The enzyme that catalyses carboxylation of RuBP in Calvin cycle would be more correctly called RuBisCO rather than RuBP carboxylase.
Reason (R): This enzyme also has an oxygenation activity apart from a carboxylase activity.