Exams › NEET › Biology › Mineral Nutrition
75 questions with worked solutions.
Q1. The most important mineral for blood coagulation is
Answer: Calcium
Calcium is essential for multiple steps in the coagulation cascade, including activation and binding of clotting factors to phospholipid surfaces. Without it, normal blood clot formation is impaired.
Answer: (b) (iii) (iv) (ii) (i)
Zinc is needed for IAA biosynthesis, iron is required for chlorophyll biosynthesis, boron supports pollen germination, and manganese is involved in photolysis of water. Putting these in order gives (b)-(iii), (iv), (ii), (i).
Q3. In which of the following forms is iron absorbed by plants?
Answer: (c) Both ferric and ferrous
Plants can absorb iron in more than one ionic form depending on soil conditions and root chemistry. Both ferric (Fe3+) and ferrous (Fe2+) forms can be taken up, which is why the correct choice includes both.
Q4. In which of the following, all three are macronutrients?
Answer: (d) Nitrogen, calcium, phosphorus
Nitrogen, calcium, and phosphorus are all required by plants in relatively large quantities, so they are macronutrients. The other choices list elements that are mainly micronutrients and needed only in trace amounts.
Q5. Minerals known to be required in large amounts for plant growth include:
Answer: (d) phosphorus, potassium, sulphur, calcium
Plants require certain minerals in large amounts, called macronutrients. Phosphorus, potassium, sulphur, and calcium are all needed in relatively high quantities, unlike the trace elements listed in the other choices.
Q6. Which of the following elements is responsible for maintaining turgor in cells?
Answer: (d) Potassium
Potassium is the major cation in plant cells and helps maintain osmotic potential, which draws water into the vacuole and keeps cells turgid. Magnesium, sodium, and calcium do not play the primary role in maintaining turgor.
Q7. Which of the following elements is a constituent of biotin?
Answer: (a) Sulphur
Biotin contains a sulfur atom as part of its heterocyclic ring structure, which is essential to its chemical identity. The other listed elements are not characteristic constituents of biotin.
Q8. Best defined function of Manganese in green plants is:
Answer: (a) Photolysis of water
Manganese is essential in the oxygen-evolving complex of photosystem II, where it catalyzes photolysis of water during the light reactions. This releases electrons, protons, and oxygen, making it the best-defined function among the options.
Q9. Which one of the following is correctly matched?
Answer: Potassium - Readily immobilisation
Potassium is correctly associated with readily immobilisation because K+ can be quickly fixed by certain clay minerals, making it less available to plants. The other pairs are incorrect: passive transport does not use ATP, apoplast is not plasmodesmata, and bakane disease is linked to gibberellins, not F. Skoog.
Q10. The function of leg haemoglobin in the root nodules of legumes is:
Answer: oxygen removal
Leg haemoglobin keeps free oxygen levels very low in root nodules. This protects nitrogenase, which is highly oxygen-sensitive, while still allowing enough oxygen for respiration.
Q11. Nitrifying bacteria:
Answer: oxidize ammonia to nitrates
Nitrifying bacteria carry out nitrification, which converts ammonia first to nitrite and then to nitrate. This is an oxidation process, not nitrogen fixation, ammonification, or denitrification.
Q12. An element playing important role in nitrogen fixation is:
Answer: Molybdenum
Molybdenum is a key component of nitrogenase, the enzyme complex responsible for biological nitrogen fixation. It helps catalyze the reduction of atmospheric nitrogen (N2) to ammonia.
Q13. Which of the following is a symbiotic nitrogen fixer?
Answer: Azolla
Azolla is a symbiotic nitrogen fixer because it contains the cyanobacterium Anabaena in a mutualistic association, which fixes atmospheric nitrogen. Azotobacter is free-living, Frankia is symbiotic but not the given correct choice here, and Glycine is a plant genus, not a nitrogen-fixing symbiont.
Q14. One of the free-living, anaerobic nitrogen-fixer is:
Answer: Rhodospirillum
Rhodospirillum is a free-living, anaerobic photosynthetic bacterium that can fix nitrogen. Azotobacter is free-living but aerobic, Rhizobium is symbiotic in root nodules, and Beijerinckia is free-living but not the classic anaerobic choice here.
Q15. Nitrogen fixation in root nodules of Alnus is brought about by:
Answer: Frankia
Alnus (alder) forms actinorhizal root nodules, which are colonized by the filamentous nitrogen-fixing bacterium Frankia. This symbiosis enables atmospheric nitrogen fixation in the nodules.
Q16. Which one of the following mineral elements plays an important role in biological nitrogen fixation?
Answer: Molybdenum
Molybdenum is a key component of the nitrogenase enzyme complex that catalyzes biological nitrogen fixation. Without it, many nitrogen-fixing organisms cannot efficiently convert atmospheric nitrogen into usable forms.
Q17. Enzyme involved in nitrogen assimilation:
Answer: nitrate reductase
Nitrate reductase catalyzes the first step of nitrate assimilation by reducing nitrate to nitrite, making nitrogen available for further incorporation into biomolecules. Nitrogenase is for nitrogen fixation, not assimilation from nitrate.
Q18. Which of the following is a free-living aerobic nonphotosynthetic nitrogen fixer?
Answer: Azotobacter
Azotobacter is a free-living, aerobic, nonphotosynthetic bacterium capable of fixing atmospheric nitrogen. Rhizobium is symbiotic, Azospirillum is typically associative, and Nostoc is photosynthetic.
Answer: Application of iron and magnesium to promote synthesis of chlorophyll
Premature yellowing usually reflects reduced chlorophyll, which lowers photosynthesis and seed filling. Iron and magnesium are key for chlorophyll synthesis, so supplying them can best restore leaf greenness and maximize yield.
Q20. If by radiation all nitrogenase enzymes are inactivated, then there will be no
Answer: fixation of atmospheric nitrogen
Nitrogenase is the enzyme complex responsible for fixing atmospheric nitrogen (N2) into ammonia. If all nitrogenase enzymes are inactivated, that process stops completely, so atmospheric nitrogen cannot be fixed.