Important Questions for CBSE Class 11 Biology Chapter 12 - Mineral Nutrition

Very Short Answer Questions: (1 Marks)

1. Name a soil bacterium which is capable of converting ammonia to nitrates.

Ans: The bacteria that convert ammonia to nitrates are called Nitrosomonas and Nitrobacter. The process starts with converting the nitrites into nitrates and then Nitrosomonas transmute ammonia to nitrites.

2. Which macronutrient is essential for the synthesis of auxin.

Ans: The macronutrient used for the synthesis of auxin is Zinc ions. Auxin is the plant hormone that is synthesized at the shoot tip.

3. What do you mean by “chlorosis”?

Ans: Chlorosis is the deficiency of chlorophyll which in result makes the leaves turn yellow. Chlorophyll deficiency requires magnesium, iron, and nitrogen.

4. Name any two elements having a toxic effect on protoplasm?

Ans: Elements that have toxic effects on protoplasm are lead and mercury. These elements are heavy metals which in turn are not good for the soil.

5. What is hydroponics?

Ans: Hydroponics is the method for plantation without soil. In the abstraction of soil, the nutrients are compensated from water.

6. Give the function of enzyme nitrate reductase.

Ans: Nitrate reductase is the prominent enzyme for nitrogen accession by plants, algae, yeasts, and fungi that reduces nitrate ions to ammonia.

7. Name essential components of biomolecules.

Ans: Biomolecules are organic molecules for the existence of the living cells and these are composed of 4 elements i.e. carbohydrates, protein, lipids, and nucleic acids.

8. Name the enzyme that can reduce nitrogen to ammonia.

Ans: Nitrogenase enzyme that can reduce nitrogen to ammonia. Biological nitrogen fixation (BNF) is the result of conversion to ammonia.

9. What are micronutrients?

Ans: Micronutrients are the elements used for the process of photosynthesis by plants. These are the small amounts of nutrients used by plants for metabolic systems. Eg. Cu, Fe, and Mo are the micronutrients

10. Name one symbiotic nitrogen-fixing bacteria.  

Ans: Rhizobium is a nitrogen-fixing bacterium that is found in soil connected to the root to form the nodules.

11. Give two examples of photosynthetic microorganisms, which also fix atmospheric nitrogen.

Ans: Nitrogen-fixing bacterium is found in soil connected to the root to form the nodules. Photosynthetic organisms are photoautotrophs that are capable of photosynthesis. The examples related to photoautotrophs are Azotobacter and archaea.

12. Name two organisms each that fix nitrogen symbiotically and symbiotically.

Ans: Nonsymbiotic or symbiotically nitrogen fixers are free-living bacteria that include Azotobacter and Bacillus.  Rhizobium is an example of a symbiotic nitrogen fixer. Rhizobium is an aerobic bacterium. Also, Azolla and the blue-green alga Anabaena azollae are in symbiotic relationships.

13. Which substance imparts pink colour to the root nodule of a leguminous plant and also mentions its role?

Ans: Leghemoglobin is the substance that reflects the pink color of a leguminous plant and it also plays the part of oxygen scavenger. It protects the enzyme by oxygen and it coordinates between the host plant and the bacteria.

14. What is the term used for mineral deficiency symptoms in plants in which leaves become yellow in different patterns?

Ans: Necrosis is the condition that defines the lack of body tissue in plants that cannot be repudiated.

15. Define hydroponics.

Ans: Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. This is an expensive technique used with chemical fertilizer.

Short Answer Questions: (2 Marks)

1. A farmer adds azotobacter culture to the soil before sowing maize. How does it increase the yield of maize?

Ans: Azotobacter is a free-living nitrogen-fixing bacteria that converts free nitrogen into nitrous and nitrites. It fixes atmospheric nitrogen in the soil and increases the fertility of the soil. So it increases the yield of maize.

2. Name the pigment found in root nodules of legumes. What is its function?

Ans: Pigment found in root nodules of legumes is Leghaemogiobi.  It is responsible for carrying oxygen and preventing nitrogenous enzyme nitrogenase from oxidation.

3. What is hydroponics? Mention its uses?

Ans: Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. 

The following are its uses:

• Maximizes Space. Hydroponics requires far less space than plants grown in soil.

• Conserves Water.

• Facilitates a Micro-Climate.

• Produces Higher Yields.

• Require Less Labor.

• Needs No Soil.

• Produces Higher Quality Food.

• Reduces Supply Chain.

4. What is a balanced nutrient solution?

Ans: A solution having all the essential elements in a proper proportion is called a nutrient solution. Essential elements include both macro elements and microelements required in plant growth.

5. What is nitrification? Name any two nitrifying bacteria in soil?

Ans: Nitrification is the process by which ammonia is converted into nitrites. It includes two steps:-

(i) Ammonium ions are oxidized into nitrates by the bacteria like Nitrosomonas and Nitrosococcus.

(ii) Nitrites are converted into nitrates by the bacteria like Nitrobacter.

6. In what form is magnesium absorbed by plants from the soil. Give two functions of magnesium in plants & its deficiency symptoms.

Ans: Magnesium is absorbed by the plants from the soil in the form of Mg2+. It supports the process of respiration and photosynthesis. It is the central atom amid four nitrogen atoms in the chlorophyll molecule.

Functions of Magnesium in Plants are: 

1. Synthesis of DNA and RNA.

2. It activates enzymes in respiration and photosynthesis.

Deficiency Symptoms are:

1. Chlorosis between the leaf veins.

2. Premature leaf abscission.

7. List the four broad groups of essential elements.

Ans: The four broad groups of the essential elements are:

8. How is hydroponics useful?

Ans:  Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. 

The following are its uses:

• Maximizes Space. Hydroponics requires far less space than plants grown in soil.

• Conserves Water.

• Facilitates a Micro-Climate.

• Produces Higher Yields.

• Require Less Labor.

• Needs No Soil.

• Produces Higher Quality Food.

• Reduces Supply Chain.

9. What is mineral nutrition? Name one essential element that is a component of energy-related chemical compounds.

Ans: Mineral Nutrition is known as a naturally occurring inorganic nutrient. It can be found in the soil and food and it is vital for the able functioning of animal and plant bodies. 

Minerals are the vital elements that allow a body to grow and to survive. Minerals are essentially needed by both plants and animals. 

Mg in chlorophyll is an essential component of energy-related chemical compounds.

10. Name the following:

(a) Bacteria which converts ammonia into nitrite.

(b) Bacteria oxidises nitrite into nitrate.

Ans: Nitrosomonas and Nitrobacter are the nitrifying bacteria that convert ammonia. 

(i) Bacteria which converts ammonia into nitrite – Nitrosomonas

(ii) Bacteria oxidize nitrite into nitrate - Nitrobacter.

Short Answer Question (3 Marks)

1. What do you understand about “Donnan Equilibrium''?

Ans: Donnan Equilibrium theory suggests that the passive accumulation of ions which are fixed on is non-diffusible, against an ECP gradient. It is a membrane that separates a cell from the external medium and allows the exchange of some ions and not the other. On the inner side of this membrane are anions (fixed and non-diffusible). The membrane becomes impermeable to these anions. In such conditions (for equilibrium) mobile cations are needed to balance the negative charges of the anions. According to it, Donnan equilibrium is reached, if the product of anions and cations in the internal solution becomes equal to the product of anions and cations in the external solution.

\[\left[ {{\text{C}}{{\text{i}}^{\text{ + }}}} \right]{\text{ }}\left[ {{\text{A}}{{\text{i}}^{\text{ - }}}} \right]{\text{  =  }}\left[ {{\text{C}}{{\text{o}}^{\text{ + }}}} \right]{\text{ }}\left[ {{\text{A}}{{\text{o}}^{\text{ - }}}} \right]\]

Where ${\text{C}}{{\text{i}}^{\text{ + }}}$ = cations inside

${\text{A}}{{\text{i}}^{\text{ - }}}$ = Anions in side

${\text{C}}{{\text{o}}^{\text{ + }}}$ = Cations outside

${\text{A}}{{\text{o}}^{\text{ - }}}$ = Anions outside.

2. What are essential mineral elements?

Ans: Mineral elements are often found in soil which may enter into the plants through their roots. More than 60 essential mineral elements of 105 discovered so far occur in different plants. Some accumulate selenium but some others gold. Also, some plants growing near nuclear test sites take up radioactive strontium.

3. Differentiate between active & passive absorption.

Ans: The difference between active & passive absorption is as follows:

4. List the criteria for the essentiality of elements as nutrients in plants. 

Ans: Criteria for essentiality of element are following-

1) A plant cannot complete its life cycle without the element; 

2) The element is directly involved in plant nutrition.

3) The requirement must be specific and not replaceable by another element.

5. Describe the process of nitrogen fixation in plants. Mention the site where this process actually occurs is such plants.

Ans: Nitrogen fixation normally occurs in nodules in legume plants such as gram and arhar. 

They act as sites for it. The legume plants like pea, gram show symbiosis or mutualism with the bacterium, Rhizobium leguminosarum. 

Nitrogen fixation occurs with the help of enzymes nitrogenase and leghaemoglobin. 

Leghaemoglobin act as Oxygen scavenges and nitrogenase catalyse the conversion of Nitrogen into ${\text{N}}{{\text{H}}_3}$

${{\text{N}}_2} + 8{{\text{e}}^ - } + 8{{\text{H}}^{\text{ + }}} + 16{\text{ATP}} \to 2{\text{N}}{{\text{H}}_3} + {{\text{H}}_2} + 16{\text{ADP}} + 16{\text{Pi}}$

Long Answer Questions: (5 Marks)

1. Describe the process of development of root nodules in the leguminous plants. Name the oxygen scavenger molecule present in root nodules?

Ans: Legumes are the seeds of the plant and when these seeds are dried out, they are used for the pulses. These are the edible seed pods that include lentils, peas, chickpea, gram, etc.

Root nodules are the organs developed by the main plant, mostly legumes, in which the symbiotic microorganism reduces the nitrogen to ammonia.

The root nodules in legume plants are produced due to the bacteria Rhizobium. The purpose is to fix the nitrogen and enrich the soil with fertilizers. It is basically the connection between the rhizobium and plant

Formation of root nodules in a leguminous plant:

(1) The root nodule is formed when a root hair of a leguminous plant comes in contact with Rhizobium.

(2) Bacteria occupy and increase with the root hair.

(3) To unfurl the bacteria, Bacteroides enlarge to become membrane

(4) Infection thrust made of the plasma membrane is formed by the host that distinguishes the infected cell from the tissue.

(5) Cell division is gorged in the infected tissue that directs more bacteria to enter the newly formed cells.

(b) Leghaemoglobin (Lb) is the oxygen scavenger found in root nodules of legume plants.

2. Write the role of different elements in a plant?

Ans: The essential elements of the plant include micronutrients and macronutrients for plant growth and development. The Plants various elements for growth including carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn)

(1) Maintaining the osmotic pressure in the plant cells.

(2) Nitrogen, sulfur, and phosphorus are required for compounds of proteins. Magnesium plays a vital part in the constituents of chlorophyll.

(3) Balancing pH levels.

(4) Elements increase or decrease the permeability of the plasma membrane.

(5) They have balancing functions reactions – some of the minerals balance the effects of the other.

3. Mention the role of micronutrients in plant life?

Ans: Micronutrients are the nutrients that the plant needs in smaller amounts. Micronutrients play a vital part in the process of photosynthesis in plants.  A plant that lacks an essential nutrient cannot complete its life cycle that includes germination of seeds, quality harvest, etc.

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