OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www wisedane
OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www. wisedane. com
BIOLOGY PHOTOSYNTHESIS SET 1 MCQ’S
Q 1. The name Melvin Calvin is associated with A. synthesis of ATP during photosynthesis B. release of water during photosynthesis C. carbon fixation during photosynthesis D. capture light energy during photosynthesis www. wisedane. com
ANSWER (C) EXPLANATION • The Calvin cycle (also known as the Calvin–Benson cycle) is the set of chemical reactions that take place in chloroplasts during photosynthesis. • The cycle is light independent because it takes place after the energy has been captured from sunlight. The Calvin cycle is named after Melvin Calvin, who won a Nobel Prize in Chemistry for finding it in 1961. www. wisedane. com
Q 2. The non-polar part of chlorophyll A. phytol B. porphyrin C. pyrrol D. none above www. wisedane. com
ANSWER (A) EXPLANATION Ø Chlorophyll is a term used for several closely related green pigments found in cyanobacteria and the chloroplasts of algae and plants. Ø Chlorophyll is an extremely important biomolecule critical in photosynthesis, which allows plants to absorb energy from light. Ø Chlorophyll is a chlorin pigment which is structurally similar to porphyrin pigments such as heme. The chlorin ring can have several different side chains which includes a long phytol chain and hence is the non polar part of chlorophyll. www. wisedane. com
Q 3. A process that makes important difference between C 3 and C 4 plants is A. Transpiration B. Photorespiration C. Photosynthesis D. Glycolysis www. wisedane. com
ANSWER (B) EXPLANATION Ø Photorespiration is also known as the oxidative photosynthetic carbon cycle, or C 2 photosynthesis. It refers to a process in plant metabolism where the enzyme Ru. Bis. CO oxygenates Ru. BP, causing some of the energy produced by photosynthesis to be wasted. Ø The majority of plants are C 3 plants, which have no special features to combat photorespiration. Ø C 4, end subscript plants minimize photorespiration by separating initial CO 2 Ø fixation and the Calvin cycle in space, performing these steps in different cell types. Ø Crassulacean acid metabolism (CAM) plants minimize photorespiration and save water by separating these steps in time, between night and day. www. wisedane. com
Q 4. Ru. B is CO stands for A. Ribulose phosphate carboxylic oxygenase B. Ribulose bisphosphate carboxylase oxygenase C. Ribulose phosphate carboxylase oxygenase D. None of the above www. wisedane. com
ANSWER (B) EXPLANATION: Ø Ribulose 1, 5 bisphosphate carboxylase/oxygenase, commonly known by the abbreviations Ru. Bis. CO or Ru. BPCase, is an enzyme involved in the first major step of carbon fixation. Ø Carbon fixation is a process by which atmospheric carbon dioxide is converted by plants and other photosynthetic organisms to energy rich molecules such as glucose www. wisedane. com
Q 5. Bacterial photosynthesis involves A. PS I only B. PS II only C. Both PS I and PS II D. Either PS I or PS II www. wisedane. com
ANSWER (A) EXPLANATION Ø Bacterial photosynthesis is different from plant photosynthesis. Bacterial photosynthesis is based on cyclic photophosphorylation mechanism and only one pigment system (PS I) is involved. Ø During the process, bacteriochlorophyll absorbs light and this light energy raises the chlorophyll molecule to an excited state. Excited bacteriochlorophyll gives off an electron and becomes positively charged. Ø Some of the light energy is carried successively to electron transport system via electron. The first energy receiver is ferredoxin followed by ubiquinone, cytochrome b and to cytochrome f and finally back to excited bacteriochlorophyll. Ø An electron thus completes the cycle of energy transfer beginning with and returning to bacteriochlorophyll, hence it is called cyclic photophosphorylation. www. wisedane. com
Q 6. In higher plants, continuity of cytoplasm from one cell to its neighboring cells is established through A. Apoplast B. Chloroplast C. Symplast D. Leucoplast www. wisedane. com
ANSWER (C) EXPLANATION Ø The symplast of a plant is the inner side of the plasma membrane in which water and low molecular weight solutes can freely diffuse from one cell to its neighboring cells. Ø The plasmodesmata allow the direct flow of small molecules such as sugars, amino acids, and ions between cells. Larger molecules, including transcription factors and plant viruses, can also be transported through with the help of actin structures. Ø This allows direct cytoplasm to cytoplasm flow of water and other nutrients along concentration gradients www. wisedane. com
Q 7. In CAM plants, CO 2 required for photosynthesis enters the plant body during A. Daytime through the lenticels B. Night when the hydathodes are open C. Daytime when the stomata are open Symplast D. Night through the stomata which are kept open www. wisedane. com
ANSWER (D) EXPLANATION Ø Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to dry conditions. Ø In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide www. wisedane. com
Q 8. Who enunciated the law of limiting factor for photosynthesis A. Robert Emerson B. Ruben C. Blackman D. Calvin www. wisedane. com
ANSWER (C) EXPLANATION Ø Blackman proposed the law of limiting factors in 1905 for photosynthesis. Ø According to this law, when a process depends on a number of factors, its rate is limited by the pace of the slowest factor. Ø Blackman's law of limiting factors determines the rate of photosynthesis. www. wisedane. com
Q 9. Which one of the following doesn't play any role in photosynthesis A. Phycocyanin B. Xanthophylls C. Phycoerythrin D. Anthocyanin www. wisedane. com
ANSWER (D) EXPLANATION Ø Anthocyanins are water soluble vacuolar pigments that may appear red, purple, or blue depending on the p. H. Ø They belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway; they are odorless and nearly flavorless, contributing to taste as a moderately astringent sensation. Ø Anthocyanins occur in all tissues of higher plants, including leaves, stems, roots, flowers, and fruits www. wisedane. com
Q 10. Cyclic photophosphorylation results in the formation of A. ATP B. NADPH C. ATP and NADPH D. ATP, NADPH and O 2 www. wisedane. com
ANSWER (A) EXPLANATION Cyclic photophosphorylation is the photophosphorylation in which electron transport occurs in a cyclic manner. It has the below characteristics. • Only photosystem I is involved • The active reaction centre is P 700 • Electrons travels in a cyclic manner • Electron travels back to PS I • Only ATP is produced • Photolysis or water splitting is absent • Oxygen is not evolved • The system is predominant in bacteria www. wisedane. com
Q 11. The fluid-filled space which surrounds the grana is A. Stroma B. Cristae C. Matrix D. Thylakoid space www. wisedane. com
ANSWER (A) EXPLANATION Ø Chloroplast thylakoids frequently form stacks of disks referred to as grana (singular: granum). Grana are surrounded and connected by intergranular or stroma thylakoids, which join granum stacks together as a single functional compartment. www. wisedane. com
Q 12. Each chloroplast contains a flattened membranous sac called A. Stroma B. Cristae C. Matrix D. Thylakoids www. wisedane. com
ANSWER (D) EXPLANATION Ø A thylakoid is a membrane bound compartment inside chloroplasts and cyanobacteria. They are the site of the light dependent reactions of photosynthesis. Ø Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana (singular: granum). Grana are connected by intergranal or stroma thylakoids, which join granum stacks together as a single functional compartment. www. wisedane. com
Q 13. RUBISCO enzyme is also called as A. carboxytetra mutase B. carboxy di mutase C. carboxytrimutase D. carboxyuni mutase www. wisedane. com
ANSWER (B) EXPLANATION Ø Ribulose 1, 5 bisphosphate carboxylase/oxygenase/ carboxy di mutase, commonly known by the abbreviations Ru. Bis. CO or Ru. BPCase, is an enzyme involved in the first major step of carbon fixation. Ø Carbon fixation is a process by which atmospheric carbon dioxide is converted by plants and other photosynthetic organisms to energy rich molecules such as glucose www. wisedane. com
Q 14. The product of photosynthesis is . A. glucose B. cellulose C. starch D. fructose www. wisedane. com
ANSWER (A) EXPLANATION Ø The products of photosynthesis are glucose and oxygen. Photosynthesis takes in carbon dioxide and water and combine them in the presence of energy from the sun to make food for the organism Ø The main product of photosynthesis is glucose, which is the molecule that produces energy to run the processes of the cell. Oxygen is mainly a byproduct of the process of photosynthesis. Ø Six molecules of carbon dioxide and six molecules of water are needed to produce one molecule of glucose. www. wisedane. com
Q 15. Loculus is the internal space of A. Grana B. Stroma C. Thylakoid D. Quantasome www. wisedane. com
ANSWER (C) EXPLANATION Ø The space bounded by the thylakoid membranes is called the loculus, and solutes are transported across the thylakoids in and out of this intramembrane space. Ø Most chloroplasts of the lower epidermal and sub epidermal cells in mature floating leaves of Nymphoides indica have densely staining thylakoid loculi which contrast markedly with electron translucent loculi of chloroplasts elsewhere in the leave www. wisedane. com
Q 16. Ribbon shaped chloroplast is present in A. Zygnema B. Spirogyra C. Chlorobium D. Chromatinum www. wisedane. com
ANSWER (B) EXPLANATION Ø Chloroplasts' main role is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight and converts it and stores it in the energy storage molecules ATP and NADPH while freeing oxygen from water. Ø They then use the ATP and NADPH to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Ø Spirogyra is a genus of filamentous charophyte green algae of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts. www. wisedane. com
Q 17. Photosynthetic pigments found in the chloroplasts occur in A. Thylakoid membranes B. Plastoglobules C. Matrix D. Chloroplast envelope. www. wisedane. com
ANSWER (A) EXPLANATION Ø Photosynthetic pigments are found in the thylakoids membrane of chloroplasts. The grana lamellae are paired to form sac like structures and form thylakoids. Ø Chlorophylls and other photosynthetic pigments are confined to grana. www. wisedane. com
Q 18. Dark reactions of photosynthesis occur in A. Granal thylakoid membranes B. Stromal lamella membranes C. Stroma outside photosynthetic lamellae D. Periplastidial space. www. wisedane. com
ANSWER (C) EXPLANATION Ø The dark reactions of photosynthesis is purely enzymatic and slower than the primary photochemical reaction. Ø It takes place in stroma portion of the chloroplast and is independent of light i. e. , it can occur either in presence or in absence of light provided that assimilatory power available. www. wisedane. com
Q 17. The enzyme that catalyses carbon dioxide fixation in C 4 plants is A. Ru. BP carboxylase B. PEP carboxylase C. Carbonic anhydrase D. Carboxydismutase. www. wisedane. com
ANSWER (B) EXPLANATION Ø Addition of CO 2 to any compound is called carboxylation. In C 4 cycle, CO 2 combines with phosphoenol pyruvic acid to form oxaloacetic acid. The enzyme is phosphoenol pyruvate carboxylase. Ø The oxaloacetic acid breaks up into pyruvic acid and CO 2 which combines with RUDP to form PGA as in Calvin cycle. www. wisedane. com
Q 20. Photosystem II occurs in A. Stroma B. Cytochrome C. Grana D. Mitochondrial surface. www. wisedane. com
ANSWER (C) EXPLANATION Ø Photosystem II has almost equal number of chlorophyll a and chlorophyll b molecules. Ø It is dark green in colour and located mostly in the appressed parts of grana thylakoids towards the inner surface of membranes. www. wisedane. com
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