12-bio-botany -unit-v & VI Plants Physiology, Biology In Human Welfare

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12-bio-botany -unit-v & VI Plants Physiology, Biology In Human Welfare - Quiz

Prepared by
Mr. D. Rajamani, M. Sc.,M. Ed., P. G. Asst Botany A. C. S Mat. Hr Sec. School, Arni. Tiruvannamalai Dist
  ; &nbs p; &
www. Padasalai. Net


Questions and Answers
  • 1. 

    Photosynthesis takes place in  

    • A.

      Chloroplasts

    • B.

      Ribosomes

    • C.

      Mitochondria

    • D.

      Peroxisomes

    Correct Answer
    A. Chloroplasts
    Explanation
    Photosynthesis is the process by which plants convert sunlight into energy. It occurs in specialized organelles called chloroplasts, which contain chlorophyll, the pigment that captures sunlight. Chloroplasts are unique to plant cells and are responsible for carrying out photosynthesis. Ribosomes are involved in protein synthesis, mitochondria are responsible for cellular respiration, and peroxisomes are involved in various metabolic processes. Therefore, the correct answer is chloroplasts.

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  • 2. 

    During cyclic electron transport, which one of the following isproduced  

    • A.

      ATP only

    • B.

      NADPH2 only

    • C.

      NADH2 only

    • D.

      Both ATP and NADPH2

    Correct Answer
    A. ATP only
    Explanation
    During cyclic electron transport, ATP is produced. This process occurs in the thylakoid membrane of the chloroplasts during photosynthesis. Cyclic electron transport involves the movement of electrons in a circular pathway, which generates a proton gradient across the thylakoid membrane. This proton gradient is then used by ATP synthase to produce ATP through chemiosmosis. NADPH2 is not produced during cyclic electron transport, as it is generated in the non-cyclic electron transport pathway.

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  • 3. 

    Which one of the following is a five carbon compound?  

    • A.

      Ribose

    • B.

      fructose

    • C.

      erythrose

    • D.

      DHAP

    Correct Answer
    A. Ribose
    Explanation
    Ribose is a five carbon compound. It is a type of sugar that is an important component of RNA (ribonucleic acid) molecules. It plays a crucial role in the synthesis and function of RNA, which is involved in protein synthesis and gene expression. Ribose is a pentose sugar, meaning it has five carbon atoms in its structure. Therefore, ribose is the correct answer to the question.

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  • 4. 

    Which one of the following is a C4 plant?  

    • A.

      Sugarcane

    • B.

      rice

    • C.

      Wheat

    • D.

      Potato

    Correct Answer
    A. Sugarcane
    Explanation
    Sugarcane is a C4 plant because it utilizes the C4 photosynthetic pathway. This pathway allows the plant to efficiently fix carbon dioxide by initially converting it into a four-carbon compound before entering the Calvin cycle. C4 plants like sugarcane are adapted to hot and dry environments, as this pathway helps them minimize water loss and maximize their photosynthetic efficiency.

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  • 5. 

    The essential component for the formation of chlorophyll  

    • A.

      Mg

    • B.

      Fe

    • C.

      Cl

    • D.

      Mn

    Correct Answer
    A. Mg
    Explanation
    Magnesium (Mg) is the essential component for the formation of chlorophyll. Chlorophyll is the pigment responsible for capturing light energy during photosynthesis in plants. Magnesium is a central atom in the chlorophyll molecule, and it plays a critical role in capturing and transferring light energy to convert carbon dioxide and water into glucose and oxygen. Without magnesium, plants would not be able to produce chlorophyll and carry out photosynthesis effectively, leading to stunted growth and poor plant health. Therefore, Mg is necessary for the formation of chlorophyll.

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  • 6. 

    The pigment which is highly efficient in absorbing solar energy is  

    • A.

      Chlorophyll

    • B.

      Phycobilins

    • C.

      Carotinoids

    • D.

      Xanthophyll

    Correct Answer
    A. Chlorophyll
    Explanation
    Chlorophyll is the pigment that is highly efficient in absorbing solar energy. It is responsible for the green color in plants and is essential for photosynthesis. Chlorophyll molecules are able to absorb light energy from the sun and convert it into chemical energy that can be used by the plant for growth and development. This pigment is found in the chloroplasts of plant cells and is crucial for the process of photosynthesis.

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  • 7. 

    Which of the following bacterium oxidizes ammonia to nitrate  

    • A.

      Nitrosomonas

    • B.

      Rhizobium

    • C.

      Closteridium

    • D.

      E. coli

    Correct Answer
    A. Nitrosomonas
    Explanation
    Nitrosomonas is the correct answer because it is a bacterium known for its ability to convert ammonia into nitrate through a process called nitrification. This bacterium plays a crucial role in the nitrogen cycle, specifically in the first step of nitrification, where it oxidizes ammonia to nitrite. Nitrosomonas is commonly found in soil, water, and wastewater treatment systems, and its activity is important for maintaining nitrogen balance in ecosystems.

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  • 8. 

    Which of the following is a total parasite  

    • A.

      Cuscuta

    • B.

      Viscum

    • C.

      Drosera

    • D.

      Monotropa

    Correct Answer
    A. Cuscuta
    Explanation
    Cuscuta is a total parasite because it lacks chlorophyll and cannot produce its own food through photosynthesis. It relies entirely on other plants for nutrients and water, attaching itself to the host plant and extracting resources from it. This makes Cuscuta completely dependent on its host for survival, making it a total parasite.

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  • 9. 

    Which of the following wavelengths of light is most effective for photosynthesis  

    • A.

      400 nm to 700 nm

    • B.

      100 nm to 200 nm

    • C.

      200 nm to 300 nm

    • D.

      700 nm to 900 nm

    Correct Answer
    A. 400 nm to 700 nm
    Explanation
    Wavelengths of light between 400 nm to 700 nm are most effective for photosynthesis. This range is known as the visible light spectrum and includes colors such as red, orange, yellow, green, blue, and violet. These colors are absorbed by chlorophyll, the pigment responsible for capturing light energy during photosynthesis. Chlorophyll absorbs light most efficiently in the red and blue regions of the spectrum, while green light is reflected, giving plants their green color. Therefore, the wavelengths between 400 nm to 700 nm provide the optimal range of light for plants to carry out photosynthesis.

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  • 10. 

    Dark respiration is the function of  

    • A.

      Mitochondria

    • B.

      Peroxisomes

    • C.

      Chloroplast

    • D.

      Ribosomes

    Correct Answer
    A. Mitochondria
    Explanation
    Dark respiration refers to the process of cellular respiration that occurs in the absence of light. Mitochondria are the powerhouses of the cell and are responsible for carrying out aerobic respiration, which involves the breakdown of glucose to produce energy in the form of ATP. Therefore, mitochondria are involved in dark respiration as they play a crucial role in generating energy for the cell.

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  • 11. 

    The gas evolved during photosynthesis is  

    • A.

      Oxygen

    • B.

      Hydrogen

    • C.

      Carbondioxide

    • D.

      Nitrogen

    Correct Answer
    A. Oxygen
    Explanation
    During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose and oxygen. Oxygen is released as a byproduct of this process and is the gas evolved during photosynthesis.

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  • 12. 

    Dark reaction is also known as  

    • A.

      Calvin cycle

    • B.

      Krebs cycle

    • C.

      Pentosephosphate pathway

    • D.

      Photorespiration

    Correct Answer
    A. Calvin cycle
    Explanation
    The dark reaction is also known as the Calvin cycle. This cycle is a series of biochemical reactions that occur in the stroma of chloroplasts during photosynthesis. It is named after Melvin Calvin, who discovered it in the 1950s. The Calvin cycle uses the energy produced in the light-dependent reactions to convert carbon dioxide into glucose. It is called the dark reaction because it can occur in the absence of light, unlike the light-dependent reactions. The Krebs cycle, pentosephosphate pathway, and photorespiration are all different processes that occur in cellular metabolism and are not related to the dark reaction.

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  • 13. 

    C4 pathway is otherwise known as  

    • A.

      Hatch-Slack pathway

    • B.

      EMP pathway

    • C.

      Photorespiration

    • D.

      Electron transport chain

    Correct Answer
    A. Hatch-Slack pathway
    Explanation
    The C4 pathway is also known as the Hatch-Slack pathway. This pathway is a biochemical process used by certain plants to efficiently fix carbon dioxide and minimize photorespiration. It involves the initial fixation of carbon dioxide into a four-carbon compound and its subsequent conversion into a three-carbon compound for entry into the Calvin cycle. The Hatch-Slack pathway is named after the scientists Marshall Davidson Hatch and Roger Slack, who first described the process in the 1960s.

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  • 14. 

    Photorespiration is otherwise called as  

    • A.

      C2 cycle

    • B.

      C3 cycle

    • C.

      C4 cycle

    • D.

      C5 cycle

    Correct Answer
    A. C2 cycle
    Explanation
    Photorespiration is also known as the C2 cycle. This is because during photorespiration, a two-carbon compound called glycolate is produced as a byproduct instead of the normal three-carbon compound, phosphoglycerate, in the Calvin cycle. The glycolate then undergoes a series of reactions in the peroxisome and mitochondria, ultimately leading to the release of carbon dioxide. This process is called photorespiration because it occurs in the presence of light and consumes oxygen while releasing carbon dioxide.

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  • 15. 

    An example for insectivorous plant is  

    • A.

      Drosera

    • B.

      Viscum

    • C.

      Monotropa

    • D.

      Vanda

    Correct Answer
    A. Drosera
    Explanation
    An example of an insectivorous plant is Drosera. Insectivorous plants are plants that have adapted to attract, trap, and digest insects as a source of nutrients. Drosera, also known as sundew, is a genus of carnivorous plants that use sticky hairs on their leaves to trap and digest insects. They secrete a sticky substance that attracts insects, and once an insect lands on the leaf, the hairs bend and trap the insect. The plant then releases enzymes to digest the insect and absorb its nutrients.

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  • 16. 

    Which of the following is regarded as primary pigment?  

    • A.

      Chlorophyll ‘a’

    • B.

      Carotenoid

    • C.

      Xanthophyll

    • D.

      Chlorophyll ‘b’

    Correct Answer
    A. Chlorophyll ‘a’
    Explanation
    Chlorophyll 'a' is regarded as the primary pigment because it is the main pigment involved in the process of photosynthesis. It absorbs light energy from the sun and converts it into chemical energy, which is then used by plants to produce glucose and oxygen. Chlorophyll 'a' is responsible for the green color of plants and is essential for their growth and survival. Carotenoids and xanthophylls are accessory pigments that assist chlorophyll 'a' in capturing light energy, while chlorophyll 'b' is another type of chlorophyll that also contributes to photosynthesis but is not considered the primary pigment.

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  • 17. 

    The dark reactions of photosynthesis were discovered by  

    • A.

      Melvin Calvin

    • B.

      Embden and Meyer

    • C.

      Krebs

    • D.

      Parnas

    Correct Answer
    A. Melvin Calvin
    Explanation
    Melvin Calvin is credited with discovering the dark reactions of photosynthesis. He conducted experiments using radioactive carbon-14 to trace the pathway of carbon dioxide during photosynthesis. Through his research, Calvin was able to identify the series of chemical reactions that occur in the absence of light, which are responsible for converting carbon dioxide into glucose. This process is known as the Calvin cycle, named after him. His discovery significantly contributed to our understanding of how plants convert sunlight into energy and played a crucial role in the development of modern biochemistry.

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  • 18. 

    Which of the following is a 5C compound?  

    • A.

      RuBP

    • B.

      Glucose

    • C.

      Fructose

    • D.

      Phosphoglyceric acid

    Correct Answer
    A. RuBP
    Explanation
    RuBP (ribulose-1,5-bisphosphate) is a 5C compound. It is an important molecule in the Calvin cycle, which is involved in the fixation of carbon dioxide during photosynthesis. RuBP has a total of five carbon atoms in its structure, making it a 5C compound. Glucose, fructose, and phosphoglyceric acid are not 5C compounds.

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  • 19. 

    In C3 plants light reactions and dark reactions occur in  

    • A.

      Mesophyll cells

    • B.

      Bundle sheath cells

    • C.

      Epidermal cells

    • D.

      vascular cells

    Correct Answer
    A. Mesophyll cells
    Explanation
    In C3 plants, light reactions occur in the thylakoid membranes of the chloroplasts in mesophyll cells. During light reactions, light energy is converted into chemical energy in the form of ATP and NADPH. These energy molecules are then used in the dark reactions, also known as the Calvin cycle, which occur in the stroma of the chloroplasts in mesophyll cells. In the dark reactions, carbon dioxide is fixed and converted into glucose through a series of enzymatic reactions. Therefore, both light reactions and dark reactions occur in mesophyll cells of C3 plants.

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  • 20. 

    In C3 pathway acceptor molecule of CO2 is  

    • A.

      RuBP

    • B.

      Phosphoenol pyruvate

    • C.

      PGA

    • D.

      DHAP

    Correct Answer
    A. RuBP
    Explanation
    In the C3 pathway, the acceptor molecule of CO2 is RuBP (ribulose-1,5-bisphosphate). RuBP is a five-carbon molecule that combines with CO2 in the presence of the enzyme Rubisco to form an unstable six-carbon compound. This compound then breaks down into two molecules of PGA (3-phosphoglycerate), which is the first stable product of CO2 fixation in the C3 pathway. Therefore, RuBP acts as the initial acceptor molecule for CO2 in the C3 pathway.

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  • 21. 

    Which of the following is not a C4 plant?  

    • A.

      Wheat

    • B.

      Maize

    • C.

      Tribulus

    • D.

      Amaranthus

    Correct Answer
    A. Wheat
    Explanation
    Wheat is not a C4 plant because it uses the C3 photosynthetic pathway. C4 plants have a specialized mechanism to minimize photorespiration and increase efficiency in hot and dry environments. They have a unique anatomy that separates the initial carbon fixation from the Calvin cycle. Maize, Tribulus, and Amaranthus are all examples of C4 plants.

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  • 22. 

    Vanda plant is a/an ----  

    • A.

      Epiphyte

    • B.

      Total parasite

    • C.

      partial parasite

    • D.

      Saprophyte

    Correct Answer
    A. Epiphyte
    Explanation
    An epiphyte is a type of plant that grows on the surface of another plant, typically a tree, without deriving nutrients from the host plant. It obtains nutrients and water from the air, rain, and debris that accumulate around it. Vanda plants are known to be epiphytes, as they are commonly found growing on trees in tropical regions.

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  • 23. 

    The reducing power produced in the light reaction is  

    • A.

      NADPH2

    • B.

      ADP

    • C.

      NADP

    • D.

      ATP

    Correct Answer
    A. NADPH2
    Explanation
    The reducing power produced in the light reaction is NADPH2. This molecule is formed through the transfer of electrons from water to NADP+ during photosynthesis. NADPH2 is an important molecule in the Calvin cycle, where it acts as a reducing agent to convert carbon dioxide into glucose. It is also used in other metabolic processes that require reducing power, such as lipid and nucleotide synthesis. Therefore, NADPH2 is the correct answer as it is the primary reducing agent produced in the light reaction of photosynthesis.

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  • 24. 

    Which of the following is not accessory pigments?  

    • A.

      Chlorophylls

    • B.

      Phycobilins

    • C.

      Carotenoids

    • D.

      Xanthophylls

    Correct Answer
    A. Chlorophylls
    Explanation
    Chlorophylls are not considered accessory pigments because they are the primary pigments involved in photosynthesis. They are responsible for capturing light energy and converting it into chemical energy. On the other hand, accessory pigments such as phycobilins, carotenoids, and xanthophylls play a secondary role in photosynthesis by absorbing additional wavelengths of light that chlorophylls cannot capture effectively. These accessory pigments help to expand the range of light that can be utilized for photosynthesis.

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  • 25. 

    The photosynthetic pigments are located in  

    • A.

      Thylakoid

    • B.

      Stroma

    • C.

      Cristae

    • D.

      Cisternae

    Correct Answer
    A. Thylakoid
    Explanation
    Thylakoids are the correct answer because they are the site of photosynthesis in plant cells. Thylakoids are flattened, membrane-bound structures found within the chloroplasts of plant cells. They contain the photosynthetic pigments, such as chlorophyll, which capture sunlight and convert it into chemical energy through the process of photosynthesis. The pigments are embedded within the thylakoid membranes, allowing them to absorb light and carry out the necessary reactions for photosynthesis to occur. Therefore, the photosynthetic pigments are located in the thylakoids.

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  • 26. 

    Which of the following is the common respiratory substrate?  

    • A.

      Carbohydrates

    • B.

      Proteins

    • C.

      Lipids

    • D.

      Vitamins

    Correct Answer
    A. Carbohydrates
    Explanation
    Carbohydrates are the common respiratory substrate because they are the primary source of energy for cellular respiration in most organisms. During cellular respiration, carbohydrates are broken down into glucose, which is then used to produce ATP, the energy currency of the cell. Proteins and lipids can also be used as respiratory substrates, but carbohydrates are the most common and preferred source due to their efficient conversion into energy. Vitamins, on the other hand, are not respiratory substrates as they do not provide energy through cellular respiration.

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  • 27. 

    The number of high energy terminal bonds present in ATP is  

    • A.

      Two

    • B.

      One

    • C.

      Three

    • D.

      four

    Correct Answer
    A. Two
    Explanation
    ATP (adenosine triphosphate) is a molecule that stores and releases energy for cellular processes. It consists of three phosphate groups attached to an adenosine molecule. The high energy terminal bonds in ATP are the bonds between the phosphate groups. ATP has two high energy terminal bonds, which are easily broken to release energy when needed.

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  • 28. 

    The first step in aerobic respiration is  

    • A.

      Glycolysis

    • B.

      Krebs cycle

    • C.

      Terminal oxidation

    • D.

      Cyclic photophosphorylation

    Correct Answer
    A. Glycolysis
    Explanation
    The first step in aerobic respiration is glycolysis. This is the process where glucose is broken down into two molecules of pyruvate in the cytoplasm of the cell. It is an anaerobic process, meaning it does not require oxygen. Glycolysis is the initial step in both aerobic and anaerobic respiration, and it produces a small amount of ATP and NADH. The pyruvate molecules produced in glycolysis then enter the mitochondria to continue the aerobic respiration process.

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  • 29. 

    Glucose is phosphorylated to glucose-6-phosphate by the enzyme  

    • A.

      hexokinase

    • B.

      Pyruvic kinase

    • C.

      Aldolase

    • D.

      Enolase

    Correct Answer
    A. hexokinase
    Explanation
    Hexokinase is the enzyme responsible for phosphorylating glucose to glucose-6-phosphate. This phosphorylation step is important in the first step of glycolysis, as it traps glucose within the cell and prepares it for further metabolism. Hexokinase catalyzes the transfer of a phosphate group from ATP to glucose, forming glucose-6-phosphate. This reaction is irreversible and is an important regulatory step in glycolysis.

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  • 30. 

    Fructose 1,6-bisphosphate is cleaved to two molecules of 3 carbon compounds by  

    • A.

      Aldolase

    • B.

      Enolase

    • C.

      Pyruvic kinase

    • D.

      Hexokinase

    Correct Answer
    A. Aldolase
    Explanation
    Aldolase is the correct answer because it is the enzyme responsible for cleaving fructose 1,6-bisphosphate into two molecules of 3 carbon compounds. Aldolase catalyzes the aldol cleavage reaction, which breaks the carbon-carbon bond in fructose 1,6-bisphosphate and forms two 3 carbon compounds, dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP). This reaction is a crucial step in glycolysis, the metabolic pathway that converts glucose into energy.

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  • 31. 

    Cisaconitic acid is converted into isocitric acid by the addition of a molecule of water. This reaction is catalyzed by  

    • A.

      Aconitase

    • B.

      Citric acid synthetase

    • C.

      fumarase

    • D.

      Malic dehydrogenase

    Correct Answer
    A. Aconitase
    Explanation
    Aconitase is the enzyme that catalyzes the conversion of cis-aconitic acid into isocitric acid by adding a molecule of water.

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  • 32. 

    A - ketoglutaric acid is a _____ carbon compound  

    • A.

      Five

    • B.

      Four

    • C.

      Two

    • D.

      Three

    Correct Answer
    A. Five
    Explanation
    Ketoglutaric acid is a five-carbon compound.

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  • 33. 

    Complete oxidation of one molecule of glucose yields  

    • A.

      38 ATP

    • B.

      36 ATP

    • C.

      35 ATP

    • D.

      2 ATP

    Correct Answer
    A. 38 ATP
    Explanation
    The complete oxidation of one molecule of glucose yields 38 ATP. This is because during cellular respiration, glucose is broken down through a series of metabolic reactions, such as glycolysis, the Krebs cycle, and oxidative phosphorylation. These reactions generate energy in the form of ATP. The breakdown of glucose ultimately produces a total of 38 ATP molecules, which are used by cells as a source of energy for various cellular processes.

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  • 34. 

    Oxidative decarboxylation of pyruvic acid is catalysed by  

    • A.

      Pyruvic dehydrogenase

    • B.

      Pyruvic kinase

    • C.

      Pyruvic mutase

    • D.

      Pyruvic isomerase

    Correct Answer
    A. Pyruvic dehydrogenase
    Explanation
    Pyruvic acid undergoes oxidative decarboxylation to produce acetyl-CoA, which is an important step in cellular respiration. This reaction is catalyzed by pyruvic dehydrogenase, an enzyme complex located in the mitochondria. Pyruvic dehydrogenase removes a carboxyl group from pyruvic acid and transfers the remaining acetyl group to coenzyme A, forming acetyl-CoA. This acetyl-CoA can then enter the citric acid cycle to generate ATP through oxidative phosphorylation. Therefore, pyruvic dehydrogenase is the correct enzyme responsible for the oxidative decarboxylation of pyruvic acid.

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  • 35. 

    Respiratory quotient of glucose is  

    • A.

      Unity

    • B.

      zero

    • C.

      More than one

    • D.

      less than one

    Correct Answer
    A. Unity
    Explanation
    The respiratory quotient (RQ) is the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed during cellular respiration. In the case of glucose, the RQ is 1 because for every molecule of glucose that is metabolized, one molecule of carbon dioxide is produced and one molecule of oxygen is consumed. Therefore, the correct answer is unity.

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  • 36. 

    Glucose is phosphorylated to glucose-6-phosphate by  

    • A.

      Hexokinase

    • B.

      Mutase

    • C.

      Aldolase

    • D.

      Kinase

    Correct Answer
    A. Hexokinase
    Explanation
    Glucose is phosphorylated to glucose-6-phosphate by hexokinase. Hexokinase is an enzyme that catalyzes the addition of a phosphate group to glucose using ATP as a phosphate donor. This phosphorylation step is important in glucose metabolism as it traps glucose inside the cell and prepares it for further metabolic processes. Hexokinase is found in most tissues and has a high affinity for glucose, ensuring efficient glucose uptake and utilization.

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  • 37. 

    One molecule of NADH2 on oxidation yields  

    • A.

      Three ATP

    • B.

      One ATP

    • C.

      Two ATP

    • D.

      four ATP

    Correct Answer
    A. Three ATP
    Explanation
    When NADH2 is oxidized, it donates its electrons to the electron transport chain, which leads to the production of ATP through oxidative phosphorylation. Each NADH2 molecule can generate approximately 2.5 ATP molecules. Therefore, one molecule of NADH2 on oxidation yields three ATP.

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  • 38. 

    Formation of ATP during electron transport chain is known as  

    • A.

      Oxidative phosphorylation

    • B.

      Dephosphorylation

    • C.

      Phtophosphorylation

    • D.

      Substate level phosphorylation

    Correct Answer
    A. Oxidative phosphorylation
    Explanation
    Oxidative phosphorylation is the process in which ATP is formed during the electron transport chain. It occurs in the inner mitochondrial membrane and involves the transfer of electrons from NADH and FADH2 to oxygen, generating a proton gradient across the membrane. This proton gradient is then used by ATP synthase to produce ATP. Therefore, oxidative phosphorylation is the correct term for the formation of ATP during the electron transport chain.

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  • 39. 

    Which of the following is referred to as EMP pathway?  

    • A.

      Glycolysis

    • B.

      Krebs cycle

    • C.

      Electron transport chain

    • D.

      Pentose phosphate pathway

    Correct Answer
    A. Glycolysis
    Explanation
    Glycolysis is referred to as the EMP pathway. This pathway is the first step in cellular respiration and involves the breakdown of glucose into pyruvate. It takes place in the cytoplasm of the cell and does not require oxygen. The term EMP stands for Embden-Meyerhof-Parnas, which are the names of the scientists who discovered this pathway.

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  • 40. 

    One molecule of FADH2 on oxidation yields  

    • A.

      two ATP

    • B.

      One ATP

    • C.

      three ATP

    • D.

      Four ATP

    Correct Answer
    A. two ATP
    Explanation
    FADH2 is a molecule that carries high-energy electrons to the electron transport chain in cellular respiration. During the process of oxidative phosphorylation, these electrons are passed down the electron transport chain, generating a proton gradient across the inner mitochondrial membrane. This proton gradient is then used by ATP synthase to produce ATP. Each molecule of FADH2 generates enough energy to produce two ATP molecules. Therefore, the correct answer is two ATP.

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  • 41. 

    The total amount of energy released from one molecule of glucose on oxidation is about  

    • A.

      2900 kJ

    • B.

      1600 kJ

    • C.

      2300 kJ

    • D.

      2500 kJ

    Correct Answer
    A. 2900 kJ
    Explanation
    The total amount of energy released from one molecule of glucose on oxidation is approximately 2900 kJ.

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  • 42. 

    Which of the following is a 5C compound?  

    • A.

      Xylulose phosphate

    • B.

      Phosphoglyceraldehyde

    • C.

      Erythrosephosphate

    • D.

      Sedoheptulose phosphate

    Correct Answer
    A. Xylulose phosphate
    Explanation
    Xylulose phosphate is a 5C compound because it contains 5 carbon atoms in its structure. The other compounds listed, phosphoglyceraldehyde, erythrosephosphate, and sedoheptulose phosphate, do not have 5 carbon atoms and therefore cannot be classified as 5C compounds.

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  • 43. 

    Which one of the following plant hormones was first discovered?  

    • A.

      Auxin

    • B.

      Gibberellin

    • C.

      Cytokinin

    • D.

      Ethylene

    Correct Answer
    A. Auxin
    Explanation
    Auxin was the first plant hormone to be discovered. It was first identified by Charles Darwin and his son Francis Darwin in their experiments on phototropism in 1880. They observed that a chemical substance was responsible for the bending of plant stems towards light, and they named this substance "auxin." Since then, auxin has been extensively studied and found to play a crucial role in various plant growth and development processes, including cell elongation, root formation, and apical dominance.

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  • 44. 

    An example for synthetic auxin is  

    • A.

      NAA

    • B.

      IAA

    • C.

      PAA

    • D.

      ABA

    Correct Answer
    A. NAA
    Explanation
    NAA is an example of synthetic auxin. Auxins are plant hormones that regulate various growth and developmental processes. NAA, or naphthaleneacetic acid, is a synthetic auxin commonly used in agriculture and horticulture. It is used to promote root development, stimulate fruit formation, and control weed growth. NAA mimics the effects of natural auxins and can be applied externally to plants to manipulate their growth and development.

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  • 45. 

    Apical dominance is due to  

    • A.

      Auxin

    • B.

      ethylene

    • C.

      Gibberellin

    • D.

      Cytokinin

    Correct Answer
    A. Auxin
    Explanation
    Apical dominance is the phenomenon where the terminal bud of a plant suppresses the growth of lateral buds. This is primarily due to the presence of auxin, a plant hormone, in the terminal bud. Auxin inhibits the growth of lateral buds by promoting the elongation of cells in the terminal bud, redirecting the flow of nutrients and energy towards the terminal bud. This allows the plant to prioritize the growth of the main stem, ensuring its upward growth and preventing the lateral branches from competing for resources.

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  • 46. 

    Bakanae disease in paddy is caused by  

    • A.

      Gibberellic acid

    • B.

      Abscissic acid

    • C.

      Phenyl acetic acid

    • D.

      Naphthelene acetic acid

    Correct Answer
    A. Gibberellic acid
    Explanation
    Bakanae disease in paddy is caused by gibberellic acid. Gibberellic acid is a plant hormone that promotes plant growth. In the case of Bakanae disease, the presence of gibberellic acid leads to abnormal elongation of the infected plant, causing symptoms such as excessive height and reduced yield. This disease is commonly found in paddy fields and can cause significant damage to the crop.

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  • 47. 

    In sigmoid curve the rapid growth phase is designated as  

    • A.

      Log phase

    • B.

      lag phase

    • C.

      Dormant phase

    • D.

      Steady state phate

    Correct Answer
    A. Log phase
    Explanation
    The correct answer is "log phase". In a sigmoid curve, the rapid growth phase is known as the log phase. During this phase, the population or system experiences exponential growth, with a constant rate of increase. This is characterized by a steep upward slope on the sigmoid curve.

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  • 48. 

    Auxin prevents  

    • A.

      abscission

    • B.

      parthinocarpy

    • C.

      Apical dominance

    • D.

      Ageing process

    Correct Answer
    A. abscission
    Explanation
    Auxin prevents abscission, which is the process of shedding or dropping of leaves, flowers, or fruits from a plant. Auxin helps in maintaining the attachment of these plant parts to the stem by inhibiting the formation of the abscission zone, a layer of cells that facilitate the detachment. This allows the plant to retain its leaves, flowers, and fruits for a longer period, ensuring their proper growth and development.

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  • 49. 

    “Foolish seedling” disease of rice is caused by  

    • A.

      Gibbrellins

    • B.

      Auxin

    • C.

      Cytokinin

    • D.

      Abscisic acid

    Correct Answer
    A. Gibbrellins
    Explanation
    "Foolish seedling" disease of rice is caused by gibberellins. Gibberellins are a group of plant hormones that regulate various processes in plant growth and development, including stem elongation. In the case of "Foolish seedling" disease, the excessive production of gibberellins leads to abnormal elongation of the rice seedlings, resulting in weak and floppy stems. This disease is a common problem in rice cultivation and can significantly affect crop yield.

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  • 50. 

    Closure of stomata is caused by  

    • A.

      Abscisic acid

    • B.

      Auxin

    • C.

      Gibbrellins

    • D.

      Cytokinin

    Correct Answer
    A. Abscisic acid
    Explanation
    Abscisic acid is responsible for the closure of stomata. Stomata are small openings on the surface of leaves that allow for gas exchange. When plants experience water stress, such as drought or high temperatures, abscisic acid is produced and triggers the closure of stomata. This helps to reduce water loss through transpiration and conserve water within the plant. Auxin, gibberellins, and cytokinins are plant hormones that have various other functions in growth and development, but they do not directly cause the closure of stomata.

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