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Right ANSWER is (c) Oxygen

The BEST EXPLANATION: The process of photosynthesis has TWO stages-the light reaction and the DARK reaction. The products of the light reaction are oxygen, ATP and NADPH. Oxygen diffuses out of the chloroplast.

Correct CHOICE is (a) True

Easiest explanation: It is a true statement. The photolysis of water (2 molecules) produces four electrons that are required for the reduction reactions of photosynthesis which is NEEDED for non-phosphorylation.

The CORRECT answer is (c) Oxygen BINDS to RuBisCO

To EXPLAIN I would say: The active SITE of RuBisCO can bind to both oxygen and carbon dioxide. When oxygen binds to RuBisCO, carbon dioxide FIXATION is reduced as the active site of RuBisCO is not able to bind to carbon dioxide.

The correct CHOICE is (B) 3-PGA

Easiest explanation: 3-PGA or 3-phosphoglyceric ACID is the product of carboxylation. It is a 3-carbon organic acid. RuBP or ribulose bisphosphate is the primary carbon DIOXIDE acceptor which UNDERGOES carboxylation.

Right answer is (C) OAA

For explanation I would say: CARBON dioxide ASSIMILATION during PHOTOSYNTHESIS is of two types depending upon the first STABLE product of carbon dioxide fixation. the first product of CO2 fixation in the C4 pathway is OAA.

The correct option is (d) NADP

Easiest explanation: The process of photosynthesis has TWO stages-the light reaction and the dark reaction. The PRODUCTS of the light reaction are OXYGEN, ATP and NADPH. The light reaction requires light to carry out its REACTIONS.

Correct answer is (a) Melvin Calvin

For explanation: Melvin Calvin has CONTRIBUTED GREATLY to PHOTOSYNTHESIS studies. The Calvin CYCLE was named after him. He first identified the compound PGA or 3-phosphoglyceric acid as a PRODUCT of photosynthesis.

Correct ANSWER is (a) Z scheme

Best EXPLANATION: The scheme is called Z-scheme. This name was given DUE to the shape of the sequence. The transfer of electrons from PS II to NADP^+ produces this scheme when the carries are PLACED in the order of the redox potential scale.

Right answer is (c) Leaf orientation

The best I can explain: VARIOUS internal and external factors affect the rate of photosynthesis, which in TURN affects the overall productivity and YIELD of the plant. SUNLIGHT, temperature and CO2 CONCENTRATION are external factors.

The correct choice is (d) Water

The EXPLANATION: Various INTERNAL and external FACTORS affect the rate of photosynthesis, which in turn affects the overall PRODUCTIVITY and yield of the plant. SIZE, age and number are internal factors while water is an external factor.

The correct answer is (C) Carboxylation

To EXPLAIN I WOULD say: The Calvin cycle is a pathway of light independent reactions of photosynthesis. The most crucial step of the Calvin cycle is carboxylation, where CARBON dioxide is FIXATED into a stable organic intermediate.

Correct ANSWER is (d) ADP, H2O, and NADP

The best explanation: ADP, H2O, and NADP are the main required materials for light REACTION. The water undergoes PHOTOLYSIS i.e. it splits into HYDROGEN and oxygen. ADP gets converted into ATP and NADP to NADPH.

The CORRECT answer is (b) PS II

To explain: During the photolysis of WATER, two electrons are produced. These electrons ENTER into PS II and it TRANSFERS the electron to Pheophytin (the primary electron acceptor). These electrons mainly help during reduction REACTIONS.

Correct OPTION is (d) A SINGLE chlorophyll a molecule

To elaborate: The reaction center in the light-harvesting complex is formed by a single “chlorophyll a” molecule. This chlorophyll a molecule has the CAPABILITY to absorb different WAVELENGTHS of light energy. It is mainly known for the process called photoionization of chlorophyll.

The CORRECT choice is (c) CO2

The best I can explain: During the process of PHOTORESPIRATION, the active site of RuBisCO binds to oxygen. ATP is not formed but is UTILIZED. NADPH and sugars are not synthesized. CARBON dioxide is released as a result of this process.

The correct CHOICE is (a) RuBP and CO2 give PGA

Explanation: The first step of the Calvin pathway is the carbon dioxide fixation step. The carbon dioxide acceptor molecule RuBP combines with carbon dioxide to give 2 MOLECULES of 3PGA with RuBisCO as the catalyst.

The CORRECT CHOICE is (c) 2

Best explanation: 3-PGA or 3-phosphoglyceric acid is the PRODUCT of CARBOXYLATION. It is a 3-carbon organic acid. RuBP or RIBULOSE bisphosphate undergoes carboxylation to produce two molecules of 3-PGA or 3-phosphoglyceric acid.

Right choice is (C) 10

The explanation: Light is an EXTERNAL factor that affects the rate of photosynthesis. Light saturation OCCURS at 10% of FULL SUNLIGHT. At high light intensities, the rate of photosynthesis does not increase linearly.

The CORRECT option is (d) PHOSPHOGLYCOLATE

Easiest explanation: When oxygen binds to RUBISCO, carbon dioxide fixation is reduced as the ACTIVE SITE of RuBisCO is not able to bind to carbon dioxide. Phosphoglycerate and phosphoglycolate are formed instead.

Correct option is (C) 3

Explanation: For EVERY carbon dioxide molecule used up in the Calvin cycle, 3 molecules of ATP are REQUIRED. SIX cycles are required to produce one glucose molecule; hence 18 ATP molecules are required to produce one molecule of glucose.

The CORRECT answer is (b) ATP

Explanation: ATP is the only product in cyclic photophosphorylation. PS II is not involved in this process. So, there will be no creation of reducing power i.e. NADPH + H^+. And the only source of ENERGY is ATP in cyclic photophosphorylation.

Correct choice is (a) RUBP CARBOXYLASE

To explain: The most crucial step of the Calvin cycle is CARBOXYLATION, where CARBON DIOXIDE is fixated into a stable organic intermediate, known as ribulose bisphosphate. RuBP carboxylase catalyses carboxylation.

The correct choice is (c) A Fe-S PROTEIN

The best I can explain: The first electron acceptor in PHOTOSYSTEM 1 is a Fe-S protein. It is a STABLE complex of iron and sulfur atoms BONDED to a protein. It primarily ACCEPTS the electrons and passes onto NADP^+.

Right CHOICE is (b) Bacterial

For explanation: PS I is the only PHOTOSYSTEM PRESENT in bacterial photosynthesis. It LACKS PS II SINCE it is having less complexity for photosynthesis, they only require one photosystem.

The correct choice is (b) 18

The explanation is: To make one molecule of glucose six MOLECULES of carbon dioxide are required. Hence, six CYCLES of the Calvin cycle are required. To make THREE molecules of glucose, 18 molecules of carbon dioxide are required.

Right option is (d) 360 μlL^-1

Easiest explanation: C3 plants and C4 plants show different carbon DIOXIDE concentration saturations. At HIGH intensities of light, C4 plants show carbon dioxide saturation at 360 μlL^-1 while C3 plants show saturation at 450 μlL^-1.

The correct answer is (a) Its active site can bind to OXYGEN and CARBON dioxide

For EXPLANATION I would SAY: RuBisCO or Ribulose-1,5-bisphosphate carboxylase oxygenase is the most abundant ENZYME in the world. The active site of RuBisCO can bind to both oxygen and carbon dioxide. It has a higher affinity for carbon dioxide.

The CORRECT choice is (b) INCREASE in METABOLISM

For explanation: When there is a water stress, its effects can be seen on the plant. Water stress closes STOMATA hence carbon dioxide availability reduces. The LEAVES wilt to reduce surface area and metabolism.

The correct option is (d) Chemiosmosis

The BEST explanation: There is a pH gradient across the thylakoid membrane, which provides a PROTON MOTIVE force. This creates chemical potential energy for the PRODUCTION of ATP from ADP and inorganic phosphate is CALLED chemiosmosis. Peter Mitchell proposed this theory.

Right option is (d) Oxidation

The explanation: The CALVIN cycle is a PATHWAY of light independent reactions of photosynthesis. It depends on the energy CARRIERS ATP and NADPH and hence, Calvin cycle indirectly depends UPON light.

Right option is (a) It is the THIRD step of the CYCLE

For explanation I would say: Reduction is the SECOND step of the Calvin cycle. It results in the formation of glucose. Reduction utilizes NADPH for reduction and ATP for phosphorylation which results in the PRODUCTION of glucose.

Correct OPTION is (d) PGA

For explanation: Oxaloacetic acid or OAA is the FIRST stable product of carbon dioxide fixation in C4 plants. OAA, along with malic acid and ASPARTIC acid are 4-carbon compounds. HOWEVER, PGA is a 3-carbon compound.

Correct option is (c) RUBP and CO2 GIVE PGA

Explanation: The FIRST step of the Calvin pathway or the Calvin cycle is the carbon dioxide fixation step. The carbon dioxide ACCEPTOR molecule RuBP combines with carbon dioxide to give 2 molecules of 3PGA.

Correct option is (c) Presence of chloroplasts

Easiest explanation: C4 plants show KRANZ ANATOMY in which bundle SHEATH cells surrounds the vascular BUNDLES. They lack photorespiration and show presence of bundle sheaths. HOWEVER, chloroplasts are present in both types of plants.

Right OPTION is (c) Wreath

Best explanation: C4 plants have a special type of anatomy of the leaves. This is known as Kranz anatomy. It is CHARACTERIZED by the presence of large CELLS around the vascular bundles in the FORM of a wreath.

Right option is (b) Radioactive C-14

To ELABORATE: Melvin Calvin used the radioactive isotope of carbon-12 or C-12, carbon-14 or C-14 in algal photosynthesis studies. This helped in DETERMINING the VARIOUS steps of the Calvin cycle or PATHWAY.

Right option is (c) 4

To elaborate: OAA or oxaloacetic acid is a 4-carbon compound. It is an organic acid. OAA or oxaloacetic acid is the first stable PRODUCT of carbon dioxide fixation during PHOTOSYNTHESIS, in some PLANTS.

Right option is (B) 5

To explain I would SAY: RuBP or Ribulose bisphosphate is a 5-CARBON ketose sugar. It is the primary acceptor of carbon dioxide in photosynthesis. It accepts carbon dioxide from the atmosphere for the process of photosynthesis.

Correct option is (a) Two

To EXPLAIN I WOULD say: The PHOTOSYNTHETIC pigments are organized into two GROUPS of light-harvesting systems. They are mainly composed of many pigments bonded to proteins. These light-harvesting systems are present WITHIN PS I and PS II.

Right ANSWER is (a) Thylakoid membrane

For explanation I would say: It is in the thylakoid membrane, in which the ELECTRON TRANSPORT system occurs. Each thylakoid membrane is a closed compartment that GETS protons from stroma by the b6 or f COMPLEX. Also, thylakoid membrane is impermeable to protons.

The correct answer is (d) Both are present in EQUAL PROPORTION

Explanation: In chloroplast, chlorophyll-a is more than chlorophyll B. They are not present in equal proportion. Since chlorophyll-a is the main CHIEF pigment in photosynthesis, it is more in number. Chlorophyll b is LESS in number since it is only an accessory pigment.

Right answer is (C) ATP and NADH are used

For explanation I would say: The biosynthetic phase of photosynthesis DEPENDS upon the products of the LIGHT reaction, which are namely oxygen, ATP and NADPH. It LEADS to the SYNTHESIS of food, which are sugars.