Q7. In which of the following forms is iron absorbed by plants?
[2018]
Correct Answer: (a)
Plants mainly absorb iron in the form of ferric ions (Fe3+).
Q8. Which one of the following is essential for photolysis of water ?
[2011M]
Correct Answer: (a)
Manganese and Chlorine are both essential for the oxygen-evolving complex (photolysis of water).
Q9. Nitrifying bacteria :
[2011]
Correct Answer: (a)
Nitrification is the biological oxidation of ammonia to nitrites and then to nitrates.
Q10. Which one of the following mineral elements plays an important role in biological nitrogen fixation ?
[2003]
Correct Answer: (a)
Molybdenum is part of the Mo-Fe protein of nitrogenase.
Q11. Which one of the following is correctly matched ?
[2012]
Correct Answer: (c)
Potassium is a highly mobile element that is easily redistributed (immobilized from older tissues to younger ones). Note: Apoplast is cell wall space, Bakane is associated with Gibberellins/Kurosawa.
Q12. One of the free-living, anaerobic nitrogen-fixer is:
[2010]
Correct Answer: (b)
Rhodospirillum is a free-living, anaerobic nitrogen fixer; Azotobacter and Beijerinckia are aerobic.
Q13. The plants grown in magnesium-deficient but urea sprayed soil would show
[2000]
Correct Answer: (c)
Lack of magnesium prevents chlorophyll synthesis, leading to chlorosis (yellowing), regardless of nitrogen supply.
Q14. Deficiency symptoms of nitrogen and potassium are visible first in:
[2014]
Correct Answer: (a)
Nitrogen and Potassium are mobile elements; they are translocated from older (senescent) leaves to young tissues.
Q15. Which one of the following is not an essential mineral element for plants while the remaining three are?
[2011M]
Correct Answer: (c)
Cadmium is a heavy metal and not an essential element; it is often toxic to plants.
Q16. The association between blue-green algae and fungi occurs in
[1995]
Correct Answer: (a)
Lichens are a symbiotic composite of an alga (often blue-green) and a fungus.
Q17. Which of the following is a free living aerobic nonphotosynthetic nitrogen-fixer?
[1997]
Correct Answer: (b)
Azotobacter is a heterotrophic (non-photosynthetic), free-living, aerobic nitrogen-fixing bacterium.
Q18. Which of the following elements is a constituent of biotin?
[NEET Kar. 2013]
Correct Answer: (a)
Sulphur is a component of vitamins like thiamine, biotin, and Coenzyme A.
Q19. The function of leg haemoglobin in the root nodules of legumes is :
[2011]
Correct Answer: (b)
Leg-haemoglobin acts as an oxygen scavenger to protect the oxygen-sensitive nitrogenase enzyme.
Q20. Boron in green plants assists in
[2003]
Correct Answer: (a)
Boron is essential for translocation of carbohydrates (sugar transport) through phloem.
Q21. Which aquatic fern performs nitrogen fixation?
[2001]
Correct Answer: (a)
Azolla pinnata is an aquatic fern used as biofertilizer due to symbiotic N-fixation.
Q22. Manganese is required in:
[2009]
Correct Answer: (b)
Manganese acts as an activator for the splitting of water in Photosystem II.
Q23. Which one of the following elements in plants is not remobilised?
[2011]
Correct Answer: (b)
Calcium is a structural element of the cell wall (calcium pectate in middle lamella) and cannot be remobilized.
Q24. Enzyme involved in nitrogen assimilation
[2001]
Correct Answer: (a)
Nitrogenase is the primary enzyme responsible for reducing N2 to ammonia.
Q25. In which of the following, all three are macronutrients?
[2016]
Correct Answer: (d)
Macronutrients include C, H, O, N, P, K, S, Ca, and Mg. Option (d) lists N, Ca, and P which are all macronutrients.
Q26. Which one of the following is not a micronutrient?
[2010]
Correct Answer: (b)
Magnesium is a macronutrient required as a constituent of chlorophyll.
Q27. For its activity, carboxypeptidase requires
[2012M]
Correct Answer: (a)
Zinc (Zn2+) is an essential cofactor for the enzyme carboxypeptidase.
Q28. Which of the following elements is responsible for maintaining turgor in cells?
[2018]
Correct Answer: (d)
Potassium (K+) ions play a crucial role in maintaining osmotic potential and turgidity of cells, especially in guard cells.
Q29. In plants inulin and raphides
[2001]
Correct Answer: (a)
Inulin is a storage carbohydrate. Raphides are calcium oxalate crystals often classified with ergastic substances (metabolic reserves/wastes).
Q30. Which one of the following elements is not an essential micronutrient for plant growth?
[2007]
Correct Answer: (c)
Calcium (Ca) is a macronutrient, not a micronutrient.
Q31. Best defined function of Manganese in green plants is :
[2012]
Correct Answer: (a)
The best defined function of Mn is the splitting of water (photolysis) to liberate oxygen during photosynthesis.
Q32. The deficiencies of micronutrients, not only affects growth of plants but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list given below, which group of three elements shall affect most, both photosynthetic and mitochondrial electron transport:
[2005]
Correct Answer: (d)
Iron, Copper, and Manganese are essential components of electron carriers (Cytochromes, Plastocyanin, Mn-complex) in both processes.
Q33. Passive absorption of minerals depend on
[2001]
Correct Answer: (a)
Passive absorption is a physical process influenced by temperature but not affected by metabolic inhibitors.
Q34. The first stable product of fixation of atmospheric nitrogen in leguminous plants is :
[NEET 2013]
Correct Answer: (a)
Nitrogenase reduces dinitrogen gas directly into ammonia, which is the first stable product.
Q35. Grey spots of oat are caused by deficiency of
[2003]
Correct Answer: (d)
Grey speck or grey spots of oats is a classic Manganese deficiency symptom.
Q36. Match the following concerning essential elements and their functions in plants :
(a) Iron
(i) Photolysis of water
(b) Zinc
(ii) Pollen germination
(c) Boron
(iii) Required for chlorophyll biosynthesis
(d) Manganese
(iv) IAA biosynthesis
Select the correct option
[2020]
Correct Answer: (b)
Iron is essential for chlorophyll biosynthesis. Zinc is required for IAA (Auxin) biosynthesis. Boron is involved in pollen germination. Manganese is involved in the photolysis of water during photosynthesis.
Q37. Which one of the following is not an essential element for plants ?
[1996]
Correct Answer: (c)
Iodine is an essential element for animals but not for higher plants.
Q38. Which one of the following is wrong statement?
[2012]
Correct Answer: (c)
Phosphorus is found in nucleic acids and membranes but is generally not a component of proteins (sulphur is the main mineral in proteins).
Q39. A plant requires magnesium for
[2007]
Correct Answer: (b)
Magnesium is the central metallic ion of the chlorophyll molecule.
Q40. Which of the following is not caused by deficiency of mineral nutrition?
[1997]
Correct Answer: (c)
Etiolation is caused by lack of light, not by mineral deficiency.
Q41. The product(s) of reaction catalyzed by nitrogenase in root nodules of leguminous plants is/are
[2020]
Correct Answer: (c)
Nitrogenase reaction produces 2 molecules of ammonia (NH3) and 1 molecule of hydrogen (H2) per N2 fixed.
Q42. Read the following four statements (A-D). (a) Both, photophosphorylation and oxidative phosphorylation involve uphill transport of protons across the membrane. (b) In dicot stems, a new cambium originates from cells of pericycle at the time of secondary growth. (c) Stamens in flowers of Gloriosa and Petunia are polyandrous. (d) Symbiotic nitrogen-fixers occur in free-living state also in soil. How many of the above statements are correct?
[2012M]
Correct Answer: (c)
According to the key, three statements are correct. (c) is likely the incorrect one depending on specific botanical classification contexts, but the key explicitly says (b) which corresponds to three correct statements.
Q43. The major portion of the dry weight of plants comprises of
[2003]
Correct Answer: (a)
C, H, and O make up about 94% of the dry weight of plants.
Q44. Mycorrhiza is a symbiotic relationship between roots of higher plants and
[1995]
Correct Answer: (b)
Mycorrhiza is the association between a fungus and the roots of a plant.
Q45. Which of the following can fix atmospheric nitrogen ?
[1995]
Correct Answer: (d)
Anabaena is a nitrogen-fixing cyanobacterium; the others listed are fungi.
Q46. Which two distinct microbial processes are responsible for the release of fixed nitrogen as dinitrogen gas (N2) to the atmosphere?
[NEET Kar. 2013]
Correct Answer: (a)
Denitification and Anammox (Anaerobic ammonium oxidation) both return nitrogen to the atmosphere as N2 gas.
Q47. Thiobacillus is a group of bacteria helpful in carrying out:
[2019]
Correct Answer: (d)
Thiobacillus species are primarily involved in denitrification and sulphur oxidation.
Q48. The major role of minor elements inside living organisms is to act as
[2003]
Correct Answer: (b)
Micronutrients (minor elements) primarily function as co-factors for various enzymes.
Q49. For its action, nitrogenase requires
[2012M]
Correct Answer: (c)
Nitrogen fixation requires 16 molecules of ATP for every molecule of N2 fixed.
Q50. Which of the following bacteria reduce nitrate in soil into nitrogen ?
[2019]
Correct Answer: (d)
Thiobacillus denitrificans and Pseudomonas carry out denitrification (Nitrate → Nitrogen gas).
Q51. Which one is an essential mineral, not constituent of any enzyme but stimulates the activity of many enzymes
[1989]
Correct Answer: (c)
Potassium (K) activates over 60 enzymes but is not a structural part of their organic components.
Q52. Phosphorous and nitrogen ions generally get depleted in soil because they usually occur as
[1989]
Correct Answer: (b)
Nitrate (NO3-) and Phosphate (H2PO4-) are anions. Since soil particles are also negative, they leach away easily.
Q53. A free living nitrogen-fixing cyanobacterium which can also form symbiotic association with the water fern Azolla is
[2004]
Correct Answer: (d)
Anabaena azollae is a cyanobacterium that lives symbiontically in Azolla leaves.
Q54. Minerals known to be required in large amounts for plant growth include :
[2015 RS]
Correct Answer: (d)
Large amounts (macronutrients) are required at >10 mmole kg-1 of dry matter. These include P, K, S, and Ca.
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