NEET Biology Mineral Nutrition Important Questions Set 01

These Class 11 NEET Biology important questions on Mineral Nutrition give 45 questions with step-by-step answers, arranged as very short, short and long answer types, as asked in school and board examinations. They help NEET aspirants revise the definitions, structures, differences and key terms of the chapter.

Very Short Answer Type Questions

Question 1. Name the micronutrient which is the constituent of nitrate reductase.
Answer: Molybdenum

Question 2. Define balanced solution.
Answer: A solution that contains all the essential mineral elements in quantities required for growth and development of plants is called balanced solution.

Question 3. Complete the following : Mn²⁺ is involved in _________ of water.
Answer: Photolysis

Question 4. What is the average concentration of trace elements required by plants?
Answer: Less than 10 mmole/kg of dry matter.

Question 5. Give two examples of free-living N₂-fixing cyanobacteria.
Answer: Nostoc and Anabaena

Question 6. Why nitrifying bacteria are called chemoautotrophs?
Answer: Because they use the energy liberated during nitrification in synthesis of organic substances from CO₂ and a hydrogen donor. They are not dependent on solar energy.

Question 7. Write the overall reaction involved in nitrogen fixation.
Answer: N₂ + 8e− + 8H+ + 16ATP —→ 2NH₃ + H₂ + 16ADP + 16Pi

Question 8. Why the deficiency symptoms of nitrogen appear first in the senescent leaves?
Answer: This is so because nitrogen is a mobile element and can be exported to the young developing tissues after the degradation of nitrogenous compounds present in the senescent leaves.

Question 9. What is the difference between influx and efflux?
Answer: The inward movement of ions into the cells is called influx, whereas the outward movement of ions from the cells is called efflux.

Question 10. Name the root nodule pigment involved in symbiotic nitrogen fixation.
Answer: Leghaemoglobin

Short Answer Type Questions

Question 11. What is hydroponics? Give one application of this technique.

Answer:

The soil-less growth of plants from seeds to maturity in a defined nutrient solution is known as Hydroponics.

Application : It can be employed for the commercial production of vegetables such as tomato, seedless cucumber, lettuce etc.

Question 12. List any three criteria for determining the essentiality of any element.

Answer:

(i) The element must be absolutely necessary for supporting normal growth and reproduction of plants.

(ii) The element must be directly involved in the metabolism of the plant.

(iii) The requirement of the element must be specific and not replaceable by another element.

Question 13. Differentiate between macronutrients and micronutrients. Give three points.

Answer:

Differences between Macronutrients and MIcronutrients :

Macronutrients Micronutrients
1. These are nutrient elements present in 1. These elements are present in plants plants in easily detectable quantities. invery small amounts or intraces.
2. The concentration of–1a macroelement 2. The concentration of a–1microelement is is above 10mmolekg of dry matter. less than10 mmole kg of drymatter.
3. They build up the plant body and 3. They do not have such a role. They are different protoplasmic constituents. generally required in the functioning of enzymes.

Question 14. Name the ionic form in which the following mineral elements are absorbed by the plant roots.
(i) Phosphorus
(ii) Sulphur
(iii) Boron
(iv) Molybdenum
Answer: (i) H₂PO4– or HPO42–
(ii) SO42–
(iii) BO33– or B₄O72–
(iv) MoO22+

Question 15. Identify the mineral element that is a constituent of methionine and cysteine amino acids. State one other physiological role of the same.

Answer:

The mineral element is sulphur.

Role : It is also used in the synthesis of some vitamins, coenzyme A and ferredoxin, which are involved in various metabolic activities.

Question 16. List four common deficiency symptoms observed in plants.
Answer: Four common deficiency symptoms observed in plants are :
(i) Chlorosis
(ii) Necrosis
(iii) Delay in flowering
(iv) Inhibition of cell division

Question 17. State three effects of manganese if it is absorbed in excess by the plants.
Answer: Manganese becomes toxic if it is absorbed in excess by the plants. Toxic effects of Mn are :
(i) Reduction in uptake of Mg and Fe.
(ii) Prevention of binding of Mg with enzymes.
(iii) Inhibition of Ca translocation to shoot apex.

Question 18. Briefly describe the phases involved in the mechanism of mineral absorption by plants.
Answer: The mechanism of mineral absorption can be demarcated into two main phases – Initial phase and Metabolic phase.
(i) Initial phase : In the initial phase, there is a rapid uptake of ions into the outer or free space of the cells, i.e., in the area of apoplast (cell walls and intercellular spaces). The ions are absorbed passively in this phase.
(ii) Metabolic phase : In this phase, the ions pass into the inner space, i.e., the symplast area of the cells (cytoplasm and vacuole). The movement of ions is an active process in this phase. Thus, the entry or exit of ions to and from the inner space requires the expenditure of metabolic energy.

Question 19. (i) What do you mean by nitrogen-fixation?
(ii) How does N₂-fixation occur in the atmosphere?
Answer: (i) The process of conversion of atmospheric nitrogen (N₂) to ammonia is called nitrogen-fixation.
(ii) In the atmosphere, lightning and effect of UV radiations provide enough energy to allow nitrogen to combine with oxygen in order to form oxides of nitrogen (NO, NO₂, N₂O etc.).

Question 20. Give examples of the following :
(i) Free-living aerobic N₂-fixing bacteria
(ii) Free-living anaerobic N₂-fixing bacteria
(iii) Symbiotic N₂-fixing bacteria
Answer: (i) Azotobacter and Beijernickia
(ii) Bacillus and Clostridium
(iii) Rhizobium and Frankia

Question 21. Describe the steps involved in the process of nitrification, giving suitable reactions and the names of microbes involved.
Answer: Nitrification, i.e., conversion of ammonium nitrogen to nitrate nitrogen, involves two steps : Step 1 : Ammonia is oxidised to nitrites by the action of Nitrosomonas and/or Nitrococcus. 2NH₃ + 3O₂ —→ 2NO₂− + 2H+ + 2H₂O + Energy Step 2 : Nitrite is further oxidised to nitrate with the help of Nitrobacter. 2NO₂− + O₂ —→ 2NO₃− + Energy

Question 22. Name the enzyme which is capable of reducing nitrogen into ammonia. Which cells of root divide to form root nodule?
Answer: Nitrogenase enzyme is capable of reducing atmospheric N₂ to ammonia. Division and growth of cortical and pericycle cells lead to nodule formation.

Question 23. Draw a well-labelled diagram of nitrogen cycle.

Answer:

A well-labelled diagram should show these parts: Atmospheric N2; NH; NO2–; NO3–; 3; Soil 'N' Pool; (Ammonification); (Uptake); Decaying biomass; Plant biomass; Animal biomass.

Question 24. What are amides? Give two examples.

Answer:

Amides are organic compounds derived from amino acids in which hydroxyl component of carboxylic group (–COOH) is replaced by another amino group (–NH₂). So, amides contain more nitrogen than amino acids.

Examples : Asparagine and Glutamine

Question 25. Give three functions of potassium in the body of plants.

Answer:

(i) Potassium helps to maintain an anion-cation balance in cells.

(ii) It helps in opening and closing of stomata.

(iii) It helps in maintaining turgidity of the cells.

Question 26. Name atleast two mineral elements responsible for the following deficiency symptoms in plants.
(i) Inhibition of cell division
(ii) Late flowering
(iii) Necrosis

Answer:

(i) N, K, S and Mo

(ii) N, S and Mo

(iii) Ca, Mg, Cu and K

Question 27. Give reasons for the following :
(i) Iron is not a constituent of chlorophyll but its deficiency causes chlorosis.
(ii) Rhizobium can fix nitrogen only in the presence of leghaemoglobin.

Answer:

(i) Iron is needed during the synthesis of chlorophyll. Therefore, its deficiency causes chlorosis.

(ii) Leghaemoglobin acts as oxygen-scavenger and creates anaerobic condition which is essential for the activity of N₂-fixing enzyme, nitrogenase.

Question 28. (i) Identify A and B in the following equation :
α-Ketoglutaric acid + A + NADPH —d Glutamate—→ B + H O + NADP ehydrogenase 2
(ii) What is the significance of this equation?

Answer:

(i) A – NH4+

B – Glutamate
(ii) The above equation is an example of reductive amination where an ammonium ion combines directly with an organic acid to form an amino acid.

Question 29. What is denitrification? Give the name of two microbes responsible for denitrification.

Answer:

The reduction of nitrates present in the soil to gaseous nitrogen by the action of microorganisms is called denitrification.

Denitrification is carried by :

(i) Pseudomonas denitrificans

(ii) Thiobacillus denitrificans

Question 30. Briefly describe the mechanism of nitrogen fixation.

Answer:

An enzyme nitrogenase is responsible for fixing atmospheric nitrogen under anaerobic conditions. Steps involved in N₂-fixation are :

(i) A nitrogen molecule gets attached to the Mo-Fe component of the enzyme.

(ii) The molecule of nitrogen is reduced by the addition of hydrogen atoms which are provided by a reducing agent like NADPH₂.

(iii) This results in formation of dimide (N₂H₂), hydrazine (N₂H₄) and finally ammonia is formed.

Substrate Product [nitrogen gas (N )] [ammonia (NH3)] 2

Reduction

Reduction Reduction Releaseof products

Enzyme Binding H +2 H +2 H (nitrogenase) of substrate ⁺² Freecan nitrogenase bind anotherof N molecule 2

The overall reaction involved in N₂-fixation is N₂ + 8e− + 8H+ + 16ATP —→ 2NH₃ + H₂ + 16ADP + 16Pi

Long Answer Type Questions

Question 31.

Carefully observe the figure given below.

Twig

Nutrient solution

(i) Name the technique shown in the figure and the scientist who demonstrated this technique for the first time.
(ii) What is the significance of aerating tube and feeding funnel in this set up?
(iii) Name three plants for which this technique can be employed for their commercial production.

Answer:

(i) Technique is Solution culture/Hydroponics. This technique was demonstrated by Julius Von Sachs in 1860 for the first time.
(ii) Aerating tube : It aerates the solution so that plant roots are able to obtain oxygen from the air for their optimum growth and functioning. Feeding funnel : It is meant for supplying the nutrient solution which is being absorbed by the growing plant. The nutrient solution has to be replaced regularly.
(iii) Tomato, seedless cucumber and lettuce.

Question 32. State three physiological roles and two deficiency symptoms of potassium in plants.
Answer: Physiological role :
(i) It helps to maintain an anion-cation balance in cells.
(ii) It is involved in protein synthesis.
(iii) It helps in opening and closing of stomata. Deficiency symptoms :
(i) Chlorosis, i.e., loss of chlorophyll leading to yellowing of leaves.
(ii) Necrosis, i.e., death of leaf tissue.

Question 33. Fill in the blanks :
(i) Phosphorus is a _________ while chlorine is a _________.
(ii) In plants, sodium is a _________ element.
(iii) The mineral element which is a constituent of middle lamella is _________.
(iv) Any mineral ion concentration that reduces the dry weight of tissues by about 10% is said to be _________.
(v) _________ is the path of translocation of minerals.
Answer: (i) Macronutrient, micronutrient
(ii) Non-essential
(iii) Calcium
(iv) Toxic
(v) Xylem

Question 34. With the help of examples, describe the classification of essential elements based on the function they perform.
Answer: Essential elements can be grouped into four broad categories on the basis of their functions. These are :
(i) Structural elements : Some essential elements are components of biomolecules and hence are the structural elements of cells. They are carbon, hydrogen, oxygen and nitrogen. For example, C, H and O are components of cellulose and many other biomolecules.
(ii) Components of energy-related compounds : Some essential elements become components of energy- related chemical compounds in organisms. For example, magnesium is a component of chlorophyll that takes part in conversion of light energy into chemical energy.
(iii) Enzyme activators or inhibitors : Many essential elements are responsible for activating or inhibiting enzymes. For example, Zn²⁺ is an activator of alcohol dehydrogenase enzyme.
(iv) Maintaining₊ osmotic potential : Most of the osmotic potential of cell sap is due to inorganic salts such as K etc. Osmotic potential is required for water absorption and maintenance of cell turgidity.

Question 35. (i) Why is an element said to be essential for plants?
(ii) How many elements have been found to be essential for plants? Name them.
(iii) Classify them as micronutrients and macronutrients.
(iv) Mention the name of two non-mineral elements.
Answer: (i) An element is said to be essential for plants if it has a specific structural or physiological role and without which plants cannot complete their life cycle.
(ii) 17 elements have been found to be essential for plants. These are C, H, O, N, P, K, Ca, Mg, S, B, Mo, Mn, Ni, Cl, Fe, Cu, Zn.
(iii) Out of these, nine are macronutrients as they are required in large quantity by the plants. They are C, H, O, N, P, K, S, Ca and Mg. There are eight micronutrients which are required in traces. These are Fe, Mn, Cu, Mo, Zn, B, Cl and Ni.
(iv) C, H and O are non-mineral elements.

Question 36. Name the ionic form in which manganese and zinc are absorbed by the plant roots. Give two significant functions performed by each of them in the plants.
Answer: (i) Manganese is absorbed in the form of manganous ions (Mn²⁺) from the soil. Physiological role of manganese :
(1) It activates several enzymes involved in photosynthesis, respiration and nitrogen metabolism.
(2) It plays a major role in the splitting of water to liberate oxygen, during photosynthesis.
(ii) Zinc is absorbed as Zn²⁺ ions from the soil. Physiological role of zinc :
(1) It activates various enzymes, especially carboxylases. Hence, it is essential for a large number of metabolic processes.
(2) It is also required in the synthesis of auxin.

Question 37. State four deficiency symptoms which are commonly observed in plants. Also, give the names of deficient mineral elements (atleast two) responsible for each of these symptoms.

Answer:

The most common deficiency symptoms observed in plants are :

Question 38. It is observed that deficiency of a particular element showed its symptoms initially in older leaves and then in young leaves.
(i) Does it indicate that the element is actively mobile or immobile?
(ii) Name two elements which are mobile and two which are immobile.
(iii) How is the aspect of mobility of elements important to horticulture and agriculture?
Answer: (i) The element is actively mobile. In case of deficiency, the mobile element is released from the older leaves and reaches the younger leaves. Therefore, initially the older leaves show symptoms of deficiency while the younger leaves appear normal. However, as deficiency persists, the younger leaves also do not receive the element and develop deficiency symptoms.
(ii) Mobile elements : Potassium, zinc Immobile elements : Calcium, sulphur
(iii) The appearance of deficiency symptoms first in older or younger leaves will indicate the mobile or immobile nature of the deficient element. Further study of symptoms can tell the horticulturist/agriculturist the possible deficient element. Supplying the deficient element in the soil will increase the yield of plants.

Question 39.

Match the element with its associated role.

Answer:

a(iv), b(i), c(iii), d(ii), e(v)

Question 40. Write short notes on the following :
(i) Symbiotic biological nitrogen fixation
(ii) Ammonification

Answer:

(i) Symbiotic biological nitrogen fixation : It refers to the conversion of atmospheric N₂ into biologically usable form by the action of symbiotic microbes. Several types of symbiotic biological nitrogen-fixing associations are known. The most prominent amongst them is the legume-bacteria relationship. Species of rod-shaped Rhizobium live symbiotically within the roots of several leguminous plants such as alfalfa, sweet clover, sweet pea, lentils, garden pea, broad bean, clover bean, etc. These bacteria produce small outgrowths (spherical) on the surface of legume roots, called as nodules. These nodules contain nitrogenase enzyme which help in fixing atmospheric N₂ into NH₃ under anaerobic conditions.
(ii) Ammonification : Decomposition of organic nitrogen (proteins, nitrogenous excretions etc.) of dead plants and animals into ammonia is called ammonification. It is carried out by decay causing organisms such as Bacillus ramosus, B.vulgaris, Actinomyces etc. Proteins are first broken up into amino acids. The latter are deaminated to release organic acids which are then used by the microbes for their own metabolism.

Question 41. (i) Trace the events involved in formation of a root nodule.
(ii) Also write a note on the significance of leghaemoglobin.

Answer:

(i) Formation of root nodules involves a sequence of multiple interactions between Rhizobium and roots of the host plant. Principal stages involved in the formation of nodules are summarised below :
(1) Rhizobium multiply and colonise the surroundings of roots and get attached to epidermal root hair cells. This occurs because legume roots secrete some specific chemicals which attract the bacteria.
(2) Bacteria collect over the root hairs, release Nod factors that cause curling of root hairs and the bacteria invades the root-hair. An infection thread containing the bacteria is produced. Infection thread grows alongwith multiplication of bacteria.

Soil Hook particles

Root hair Infection thread

(3) Infected thread carries the bacteria to the inner cortex where they initiate the nodule formation.
(4) The invading bacteria stop dividing and get modified into rod-shaped structures called bacteroids.

Membrane

Leghaemoglobin

Bacteroids

Host cell

(5) Also, the bacteria release signals that cause inner cortical and pericycle cells to divide.
(6) Division and growth of cortical and pericycle cells lead to nodule formation.
(ii) Leghaemoglobin is a red or pink-coloured pigment present in the root nodules. It acts as a very efficient O₂-scavenger and thus create anaerobic conditions in the root nodules, which is essential for the functioning of nitrogenase enzyme.

Question 42. Name the site of nitrogen fixation in legumes. Describe the biochemical events occurring in this process. What is the end product? What is its fate?

Answer:

The site of N₂-fixation in legumes is the root nodule. The root nodule contains all the biochemical components required for N₂-fixation including the enzyme nitrogenase and a red or pink-coloured pigment called leguminous haemoglobin or leg-haemoglobin (LHb).

Events of nitrogen fixation occurring in the root nodules are :  A nitrogen molecule (N ≡ N) gets attached to Mo-Fe component of the nitrogenase enzyme.  The molecule of nitrogen is reduced by the addition of hydrogen atoms (provided by reducing agents like NADPH₂)

Substrate Product [nitrogen gas (N )] [ammonia (NH3)] 2

Reduction

Reduction Reduction Releaseof products

Enzyme Binding H +2 H +2 H (nitrogenase) of substrate ⁺² Freecan nitrogenase bind anotherof N molecule 2

 It produces dimide (N₂H₂), hydrazine (N₂H₄) and finally ammonia (2NH₃) is formed.  The synthesis of ammonia requires very high input of energy (8 ATP for each NH₃ produced). The energy required is obtained from the respiration of the host cells.  The overall reaction involved in N₂-fixation is N₂ + 8e− + 8H+ + 16ATP —→ 2NH₃ + H₂ + 16ADP + 16Pi Thus, the end product of N₂-fixation is ammonia. Fate of ammonia : Ammonia does not remain in the gaseous form in the soil. It is protonated to form NH4+. Since ammonium ions are toxic to plants, they are quickly assimilated to form amino acids in plants.

Question 43. Give two examples of each of the following :
(i) Essential micronutrients
(ii) Free living N₂-fixing cyanobacteria
(iii) Amides
(iv) Nitrifying bacteria which convert nitrites to nitrates
(v) Beneficial elements

Answer:

(i) Iron, manganese, copper (any two)

(ii) Nostoc and Anabaena

(iii) Glutamine and Aspargine

(iv) Nitrobacter, Nitrocystis

(v) Sodium, silicon, cobalt (any two)

Question 44. Give one word for the following :
(i) Enzyme responsible for fixing atmospheric N₂.
(ii) Transfer of amino group of one amino acid to the keto group of keto acid.
(iii) Pigment which imparts pink colour to root nodules.
(iv) Reduction of nitrates present in soil to gaseous nitrogen.
(v) Phase of mineral absorption in which the ions pass into the symplast area of cells.
Answer: (i) Nitrogenase
(ii) Transamination
(iii) Leghaemoglobin
(iv) Denitrification
(v) Metabolic phase

Question 45.

Complete the following table :

Answer:

A : Macroelement B : It activates the enzymes of respiration, photosynthesis and also involved in the synthesis of DNA and RNA. It is a constituent of chlorophyll pigment. C : Micro element D : It activates many enzymes involved in photosynthesis, respiration and N₂-metabolism. It is required for photolysis of water and liberation of O₂ during photosynthesis. E : Molybdenum