The inorganic plant mineral nutrition focuses on the criteria to identify which minerals are essential for plant growth. Here is a collection of all important questions regarding mineral essentiality, their absorption and deficiency symptoms for NEET 2023.
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- Select an incorrect statement regarding hydroponics.
(a) Soil-borne diseases can be prevented
(b) Uniform growth and high yield
(c) Water and fertilisers can be reused
(d) Less expensive than conventional agriculture
Answer: (d)
Explanation: The technique of growing plants in a mineral solution without the presence of soil is known as hydroponics. Because soil is not used in this technique, soil borne diseases can be prevented. This technique ensures that every plant is provided with the proper amount of nutrients and hence uniform growth and high yield are obtained. The advantage of this technique is that the water and nutrients can be reused. It is an expensive technique that requires specialised equipment and hence is considered costlier than conventional agriculture.
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- Which of the following is/are the criteria required for the essentiality of an element in plants?
(a) The element must be directly involved in the metabolism of the plant
(b) The element must be absolutely essential for growth and reproduction
(c) The requirement of the element is specific and cannot be replaced by another element
(d) All of these
Answer: (d)
Explanation: Following are the criteria required for the essentiality of an element in plants –
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- It should be directly involved in metabolism
- It should be essential for both growth and reproduction and in its absence, the plant cannot complete its life cycle and set seeds
- Its requirement is specific and cannot be replaced by another element.
- In plant mineral nutrition, elements are called macro or micro elements depending upon their
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(a) relative presence in plant ash
(b) relative importance in plant growth
(c) relative amount required in plants
(d) relative availability in soil
Answer: (c)
Explanation: Essential elements are of two kinds –
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- Macronutrient: The nutrients required by plants in large quantities are grouped under macronutrients. They include carbon, oxygen, hydrogen, phosphorus, sulphur, nitrogen, calcium, and potassium.
- Micronutrient: These are the nutrients that are required in very small quantities by the plants such as zinc, iron and boron.
- Which among the following is not a main component of the biomacromolecules?
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(a) Carbon
(b) Hydrogen
(c) Nitrogen
(d) Magnesium
Answer: (d)
Explanation: Carbon, hydrogen, nitrogen and oxygen form the backbone of most biomacromolecules. Magnesium, though an essential element, is not the main component of biomacromolecules. It is required for plant growth, activation of certain enzymes, and binding of ribosomal units during protein synthesis.
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- Which among the following are trace elements?
(a) Nitrogen, phosphorus, molybdenum and copper
(b) Manganese, iron, molybdenum and copper
(c) Cobalt, selenium, sodium and silicon
(d) Nitrogen, carbon, oxygen and phosphorus
Answer: (b)
Explanation: Nutrients that are required in large quantities by plants are called macronutrients and they include nitrogen, carbon, oxygen and phosphorus. Nutrients that are required by plants in small amounts are called micronutrients or trace elements. They include manganese, iron, molybdenum and copper. Certain elements are required only by some higher plants, they are called beneficial elements such as sodium, selenium, cobalt and silicon.
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- Which of the following is incorrect?
(a) Chlorine: splitting of water during light reaction
(b) Magnesium: constituent of chlorophyll
(c) Manganese: splitting of water during light reaction
(d) Sulphur: activates catalase enzyme
Answer: (d)
Explanation: Manganese and chlorine are essential during light reactions as they are involved in splitting of water that leads to the release of oxygen molecules. The chlorophyll has a porphyrin ring with magnesium as its central atom. Sulphur is found in two amino acids namely cysteine and methionine. Iron helps in the activation of catalase enzymes.
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- The element responsible for opening and closing of the stomata is
(a) boron
(b) potassium
(c) phosphorus
(d) sodium
Answer: (b)
Explanation: Potassium ion plays a major role in the opening and closing of the stomata. Exchange of gases and transpiration occur through stomatal pores. The opening and closing of the stomata is controlled by the guard cells.
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- Prominent symptom caused by manganese toxicity is
(a) Delay in flowering
(b) Necrosis, i.e., death of tissue in leaves
(c) Brown spots encompassed by chlorotic veins
(d) None of the above
Answer: (c)
Explanation: The onset of manganese toxicity can be observed by the appearance of prominent symptoms like brown spots and chlorotic veins (yellow appearance due to insufficient chlorophyll) in leaves.
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- Select the correct option.
Assertion(A): When there is a deficiency of relatively mobile elements, the deficiency symptoms appear first in young tissues.
Reason (R): Relatively mobile elements like nitrogen and phosphorus are transported from young tissues to old senescing tissues.
(a) Both assertion and reason are correct and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are correct but the reason is not the correct explanation of the assertion.
(c) Assertion is correct but the reason is incorrect.
(d) Both assertion and reason are incorrect.
Answer: (d)
Explanation: Relatively mobile elements in plants are nitrogen, potassium and magnesium. These elements can be actively mobilised from the older to young developing tissues or leaves. Hence, the deficiency symptoms tend to appear first in older leaves.
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- Assertion: Plants exhibit deficiency symptoms
Reason: It receives nutrients below critical concentration
(a) Both assertion and reason are correct and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are correct but the reason is not the correct explanation of the assertion.
(c) Assertion is correct but the reason is incorrect.
(d) Both assertion and reason are incorrect.
Answer: (a)
Explanation: Critical concentration is the level of concentration of any essential element below which the plants exhibit deficiency symptoms.
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- Which of the following nutrient elements cannot undergo remobilisation in plants?
(a) Nitrogen
(b) Potassium
(c) Calcium
(d) Magnesium
Answer: (c)
Explanation: Mobile nutrients are the ones that can be broken down and extracted from the older leaves and are readily transported within the plants. They include potassium, magnesium, nitrogen and phosphorus. On the other hand, immobile nutrients contribute to the structural makeup of the plant and cannot be remobilised easily such as calcium and sulphur.
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- Mineral ions and water are translocated via ____, which is pulled by _______.
(a) phloem, root pressure
(b) xylem, transpiration stream
(c) phloem, transpiration stream
(d) xylem, root pressure
Answer: (b)
Explanation: Transpiration is the loss of water by plants. It results in the pulling of water along with mineral ions into different plant parts, this is called transpiration stream. The mineral ions and water are translocated by the help of xylem tissues.
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- Initial rapid uptake of mineral ions ___________.
(a) is active and it occurs through apoplast pathway
(b) is passive and it occurs through symplast pathway
(c) is active and it occurs through symplast pathway
(d) is passive and it occurs through apoplast pathway
Answer: (d)
Explanation: The initial rapid uptake of ions is passive and it occurs through apoplast. The apoplast pathway is the movement of ions through the outer or free space (outside the cell membrane) between the cells. This passive uptake of ions does not utilise energy.
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- Activation of catalase enzyme, formation of chlorophyll, electron transfer are all associated with which of the following elements?
(a) Zinc
(b) Magnesium
(c) Sulphur
(d) Iron
Answer: (d)
Explanation:
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- Zinc is absorbed by plants as a divalent cation. It is involved in activation of carboxylases and auxin synthesis.
- Magnesium is also absorbed as a divalent cation and is involved in activation of enzymes required for respiration, photosynthesis, and DNA and RNA synthesis. It is also the principal component of chlorophyll and maintains ribosomal structure.
- Sulphur is absorbed by plants as sulphate ions and is found in cysteine and methionine. It is the principal component of coenzymes, vitamins and ferredoxin.
- Iron is obtained by plants in the form of ferrous ions. It is involved in activation of catalase enzymes, formation of chlorophyll and electron transfer proteins like ferredoxin and cytochromes.
- What does A and B represent in the following diagram?
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(a) (A) nitrification, (B) denitrification
(b) (A) ammonification, (B) denitrification
(c) (A) denitrification, (B) ammonification
(d) (A) denitrification, (B) nitrogen fixation
Answer: (c)
Explanation: A represents denitrification and B represents ammonification. Refer to the diagram given below for a better understanding:
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- Match the columns and choose the correct answer.
| I | II | ||
| p | Thiobacillus denitrificans | i | Nitrogen fixation |
| q | Nitrosomonas | ii | Ammonification |
| r | Azotobacter | iii | Nitrification |
| s | Bacillus vulgaris | iv | Denitrification |
(a) p-iv, q-iii, r-i, s-ii
(b) p-iii, q-iv, r-i, s-ii
(c) p-iv, q-ii, r-i, s-iii
(d) p-ii, q-i, r-iii, s-iv
Answer: (a)
Explanation:
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- Denitrification is the conversion of nitrates back to nitrogen with the help of Pseudomonas and Thiobacillus.
- Ammonification is the conversion of ammonia into nitrites by Nitrosomonas and Nitrococcus and eventually into nitrates by Nitrobacter.
- Nitrogen fixation is the conversion of nitrogen into ammonia, nitrites and nitrates in the presence of Azotobacter.
- Ammonification is the conversion of dead plant and animal remnants into ammonia by Bacillus vulgaris and Bacillus ramosus.
- From the options given below, identify the gene responsible for nitrogen fixation.
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(a) Nif
(b) Nitrogenase
(c) Leg-haemoglobin
(d) Both a and b
Answer: (a)
Explanation: The nif genes are genes encoding enzymes involved in the fixation of atmospheric nitrogen. The main enzyme coded by the gene is the nitrogenase complex which converts atmospheric nitrogen to ammonia, which plants can use for various purposes.
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- Frankia produces nodules on the roots of
(a) leguminous plants like Alnus
(b) non-leguminous plants like Alnus
(c) leguminous plants like sweet pea
(d) non-leguminous plants like sweet pea
Answer: (b)
Explanation: Frankia is a nitrogen fixing microbe and it establishes a symbiotic relationship with the roots of trees belonging to the genus Alnus. It produces nitrogen fixing nodules on these non-leguminous plants.
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- If the nitrogenase enzyme has been activated by radiation, there will be no
(a) fixation of atmospheric nitrogen
(b) fixation of nitrogen by microorganisms
(c) conversion of nitrite to nitrate
(d) conversion of ammonia into nitrite
Answer: (b)
Explanation: Reduction of nitrogen into ammonia by microorganisms is called biological nitrogen fixation. This reaction is catalysed by nitrogenase enzymes. Nitrogenase is a Mo-Fe protein found only in some prokaryotes.
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- The pigment protein present in nodulated roots inhabited by Rhizobium is
(a) nitrate reductase
(b) hydrogenase
(c) leg-haemoglobin
(d) plastocyanin
Answer: (c)
Explanation: Leguminous haemoglobin (leg-haemoglobin) is a pink pigment present in the root nodules of leguminous plants and is essential for nitrogen fixation.
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