Mineral Nutrition Class 11 Notes CBSE Biology Chapter 11 (Free PDF Download)

Section–A (1 Mark Questions)

1. What do you mean by “chlorosis”?

Ans. Chlorosis is the lack of development of chlorophyll in the leaves which leads to their yellowing. 

2. What is hydroponics?

Ans. The technique of growing plants in a nutrient-rich liquid culture medium is known as hydroponics.

3. Name essential components of biomolecules.

Ans. Essential elements as components of biomolecules are carbon, hydrogen, oxygen and nitrogen.

4. Name the enzyme that can reduce nitrogen to ammonia?

Ans. The nitrogenase enzyme is capable of reduction of nitrogen to ammonia.

5. What are micronutrients?

Ans. Elements that are required by the plants in very small or trace quantities (less than 10 mmole Kg –1 of dry matter) are termed micronutrients, e.g., zinc, copper, etc.

Section–B (2 Mark Questions)

6. (a) Name the pigment that imparts pink color to the root nodules of legumes. What is its function?

 (b) Give two examples each of free-living and symbiotic nitrogen-fixing bacteria.

Ans. (a)The root nodules of leguminous plants contain pigment leghemoglobin which is responsible for their pink color. Its function is to protect nitrogenase from oxygen. The enzyme nitrogenase is highly sensitive to oxygen and requires anaerobic conditions. To protect these enzymes, leghemoglobin acts as an oxygen scavenger.

(b) Free-living nitrogen-fixing bacteria– Azotobacter, Beijerinckia. Symbiotic nitrogen-fixing bacteria– Rhizobium, Frankia.

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

Ans. Plants require mineral nutrients for their growth and development which do not occur in the plant body in a free state. The utilization of these elements by the plants for their growth and development is called mineral nutrition. Phosphorus is an essential component of energy-related chemical compounds as it is involved in the production of ATP.

8. How is hydroponics useful?

Ans. Hydroponics is essential to know the following-

(i) Essentiality of the mineral element.

(ii) Deficiency symptom due to non-availability of specific nutrients.

(iii) Toxicity to plant if an element is present in excess.

(iv) Role of essential elements in the metabolism of a plant.

9. (i) Name the following:

(a) Bacteria which convert ammonia into nitrite.

(b) Bacteria which oxidizes nitrite into nitrate.

 (ii) A farmer adds Azotobacter culture to the soil before sowing maize. How does it increase the yield of maize?

Ans. (i)(a) Bacteria which convert ammonia into nitrite – Nitrosomonas

(b) Bacteria which oxidizes nitrite into nitrate – Nitrobacter

(ii)Azotobacter is a nitrogen-fixing bacteria that convert free nitrogen into ammonia. It increases soil fertility. So, it increases the yield of maize.

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

Ans. Nitrification is the process of conversion of ammonia into nitrites and then nitrates.

It involves two steps:-

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

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

11. In what form is magnesium absorbed by plants from the soil. Given two functions of magnesium in plants and its deficiency symptoms?

Ans. Magnesium is absorbed by the plants from the soil in the form of divalent Mg2+.

Functions –

1) It is involved in the synthesis of DNA and RNA.

2) It activates enzymes of respiration and photosynthesis.

Deficiency symptoms –

1) Chlorosis between the leaf veins.

2) Necrosis or death of the tissue.

PDF Summary - Class 11 Biology Mineral Nutrition Notes (Chapter 11)

Mineral Nutrition

Definition of Mineral Nutrition in Plants:

Carbohydrates, proteins, lipids, water, and minerals are required for all living creatures to survive. Plants, too, require nutrients for growth and development.

Methods to study the mineral requirement of plants

Hydroponics is a method of growing plants in nutrient solutions rather than soil. This method is employed in the commercial cultivation of vegetables. It's also used to research plant mineral deficiency disorders.

Aeroponics is a method of growing plants by spraying nutrients floating in the air.

Essential Mineral Elements

a) Mineral needs vary depending on the plant. There is a criterion for determining whether or not an ingredient is necessary. 

b) It contains the following items:

• The element must be required for proper development and reproduction. If such a component is missing, the

• Plants won't be able to finish their life cycle.

• The element's need must be precise, and no other element should be able to substitute it.

• The element must play a direct role in plant metabolism.

There are Two Types of Mineral Elements Required By Plants: Macronutrients and Micronutrients.

Macronutrients

The plants require a high amount of these components. Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, potassium, calcium, and magnesium are all found in it. CO2 and H2O are the most common sources of carbon, hydrogen, and oxygen. Others are received as mineral nourishment from the soil.

Micronutrients

These are the nutrients that plants require in tiny quantities. Iron, manganese, copper, molybdenum, zinc, boron, chlorine, and nickel are all present.

Essential Elements

1. Essential elements like carbon, hydrogen, oxygen and nitrogen serve as components of numerous biomolecules such as amino acids, lipids, and therefore structural elements of cells and are classified into distinct groups depending on their unique activities.

2. Essential elements, such as magnesium ion in chlorophyll and phosphorous in ATP, are key components of chemical compounds associated with energy.

3. Essential elements operate as both activators and inhibitors of enzymes, influencing their function. Both ribulose bisphosphate carboxylase oxygenase and phosphoenolpyruvate carboxylase are activated by Mg2+. Both of these are required for carbon fixation to occur. During nitrogen metabolism, Zn2+ activates alcohol dehydrogenase, while Mo is required for nitrogenase activity. 

4. The osmolarity of a cell is controlled by a few key components. The stomata are open and close in response to potassium ions.

Role of Macronutrients and Micronutrients

The role of different macro and micronutrients are-

Nitrogen

• Plants require a considerable amount of this essential ingredient.

• It is taken by plants as nitrate ions (NO3), with certain plants also absorbing it as nitrate ions (NO2) or ammonium ions (NH4)+.

• It is an essential component of vitamins and is required by plants for actively developing tissues such as meristematic tissues.

• Plays a direct role in photosynthesis.

Phosphorus

• Phosphate ions (PO4)3+ are absorbed by plants.

• It is found in large quantities in cell membranes, proteins, nucleic acids, and nucleotides.

• Encourages the development and growth of roots.

• Seed formation needs the presence of this nutrient.

• Involved in the storage and transport of energy.

Potassium

• It is rich in actively developing tissues such as meristematic tissues, buds, leaves, and root tips. 

• It is necessary for sustaining osmotic potential in a cell that is responsible for stomatal opening and closing.

• Increases photosynthetic rates.

• The protein synthesis is dependent on it.

Calcium

• Calcium ions (Ca2+) are absorbed by plants and are required for ongoing cell division and development.

• Plays a part in nitrogen metabolism.

• It exists in the form of calcium pectate in the middle lamella.

• It is also necessary for the mitotic spindle to develop.

• It is also necessary for the activation of certain enzymes.

Magnesium

• It is necessary for the activation of enzymes involved in respiration and photosynthesis. 

• It is absorbed by plants in the form of magnesium ions (Mg2+).

• It aids in the production of RNA and DNA.

• It's a crucial component of chlorophyll, as well as maintaining ribosome structure.

Sulfur

• An essential component of amino acids like methionine; 

• An essential component of amino acids like methionine; 

• Contributes to seed production 

• It is necessary for chlorophyll creation

Iron

• Iron is absorbed mostly in the form of ferric ions (Fe3+) by plants and is necessary for cell division and development.

• Assists in the transport of electrons during a variety of metabolic processes.

• It is necessary for the activation of the catalase enzyme, which is essential for chlorophyll synthesis; it also functions as an oxygen transporter.

Manganese

• Manganese is absorbed in the form of ions (Mn2+).

• One of the components of the nitrogenase enzyme, which is essential for nitrogen metabolism.

• It is engaged in the photolysis of water during non-cyclic photophosphorylation.

Zinc

• Zinc ions (Zn2+) are absorbed by the body.

• Essential for the production of chlorophyll.

• Plays a role in the activation of numerous enzymes, including carboxylases.

• Required for carbohydrate synthesis.

Copper

• It is absorbed in the form of cupric ions (Cu2+) by plants.

• During metabolic processes, it is engaged in redox reactions.

• Performs photosynthesis and reproductive functions in plants.

• Contributes to the flavor of fruits and vegetables.

• Increase the amount of sugar in the plants.

Boron

• Boron is absorbed in the form of BO33 or B4O72- by the plants. 

• It plays a role in calcium absorption.

• Assists in the development of pollen tubes.

• Plant carbohydrate transport

• Plays a part in cell differentiation.

Molybdenum

• It is obtained by plants as molybdate ions (MoO2)2-.

• Nitrogenase enzyme's main component. It, together with iron, forms the enzyme's catalytic site.

• It's a crucial part of the nitrate reductase enzyme. Nitrate reductase is a nitrogen assimilation enzyme 

• Nitrate reductase is a nitrogen assimilation enzyme that also plays a role in nodule development.

Chlorine

• Ions of chloride are absorbed (Cl1-).

• Maintains the cell's osmotic potential.

• It is engaged in the photolysis of water, which results in the production of oxygen.

Deficiency Symptoms of Essential Elements

• One of the most crucial necessary elements is nitrogen. Yellowing of the leaves is caused by a nitrogen deficiency.

• Phosphorus shortage results in burned leaf tips and yellowing of the tips.

• Potassium shortage results in interveinal chlorosis and wilting of older leaves.

• Blossom end rot is caused by a calcium shortage.

• Magnesium causes older leaves to become yellow, a condition known as chlorosis, which occurs when chlorophyll is degraded.

• Sulphur shortage causes younger leaves to yellow more than older ones.

• Chlorosis of young leaves is caused by an iron deficit. Dieback disease is a common symptom of an iron shortage in plants.

• Manganese causes yellowing between the veins of the leaves and creates dead patches on plant components.

• Zinc causes the plant to develop rosettes, yellowing between the veins, and reduced growth.

• Copper shortage results in the weakening of cell walls, as well as stem and twig dieback.

• Boron has an effect on plant reproductive and vegetative development, as well as meristem death.

• Molybdenum causes growth retardation. 

• Chlorine produces wilting, chlorosis, and a highly branching root system, as well as necrosis in the tissues.

Metabolism of Nitrogen

Nitrogen is made up of two nitrogen atoms that are linked together by a triple covalent bond (N ≡ N). Nitrogen fixation is the process of converting nitrogen into ammonia.

The conversion of nitrogen to ammonia can be done in two ways. The following are the details:

• Physical nitrogen fixing happens when lightning strikes. In the presence of lightning, N2 and O2 in the atmosphere react to create nitric oxide (NO). NO is then oxidized further to create nitrogen peroxide (NO2).

• Ammonification is the process of producing ammonia from the decomposition of dead plants and animals. Nitrification is the process of converting ammonia to nitrite and ultimately to nitrate. Nitrite is formed in the presence of Nitrosomonas bacteria, whereas nitrate is formed in the presence of Nitrobacter bacteria.

1. $\mathrm{N}_{2}+\mathrm{O}_{2} \stackrel{\text { lighthing }}{(\text { Nitric oxide) }}{2 \mathrm{~N} O_{2}}$

2. $2 \mathrm{NO}+\mathrm{O}_{2} \quad$ oxidation

(Nitrogen per oxide)

3. $2 \mathrm{NO}_{2}+\mathrm{H}_{2} \mathrm{O}$

$\mathrm{HNO}_{2}+\mathrm{HNO}_{3}$

4. $4 \mathrm{NO}_{2}+2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2} \longrightarrow 4 \mathrm{HNO}_{3}$

(Nitric acid)

5. $\mathrm{CaO}+2 \mathrm{HNO}_{3} \longrightarrow \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}+\mathrm{H}_{2} \mathrm{O}$

(Calcium nitrate)

6. $\mathrm{HNO}_{3}+\mathrm{NH}_{3} \longrightarrow \mathrm{NH}_{4} \mathrm{NO}_{3}$

mmonium nitrate)

7. $\mathrm{HNO}_{2}+\mathrm{NH}_{3} \longrightarrow \mathrm{NH}_{4} \mathrm{NO}_{2}$

(Ammonium nitrite)

Biological nitrogen fixation happens when nitrogen-fixing microorganisms like Rhizobium are present. Diazotrophs are prokaryotes that fix nitrogen in a biological way. Rhizobium is a symbiotic bacteria that dwells in the roots of leguminous plants. Nitrogenase is the enzyme responsible for biological nitrogen fixation. Both free-living and symbiotic nitrogen-fixing bacteria exist. Azotobacter, Rhodospirillum, Anabaena, and Nostoc are examples of free-living nitrogen-fixing aerobic bacteria.

Leguminous plants, such as peas, beans, clover, alfalfa, and others, have a symbiotic relationship with Rhizobium. Nitrogen-fixing is accompanied by the development of distinctive nodules. The contact of Rhizobium with the roots of the plants is the first step in the development of nodules. Certain compounds are released by these plants, which attract bacteria to the plant's roots. Rhizobium produces a root hair curling component that aids the bacteria's invasion of the roots. The nitrogenase enzyme, which catalyzes nitrogen fixation, is oxygen sensitive. During nitrogen fixation, the enzyme leghemoglobin (a member of the hemoglobin family) scavenges oxygen.

(Image will be uploaded soon)

Steps of Nodule Formation During Biological Nitrogen Fixation

The reaction catalyzed by the nitrogenase is as follows-

$\mathrm{N}_{2}+12 \mathrm{ATP} \stackrel{\text { nitrogenase }}{\mathrm{ATP}}=2 \mathrm{NH}_{3}+12 \mathrm{ADP}+12 \mathrm{P}_{\mathrm{i}}$

nitrogen ammonia phosphate (atmospheric) (inorganic)

It requires 12 ATPs to breakdown the strong triple bond that exists between the two nitrogen atoms of $\mathrm{N}_{2}\;\text {gas}:{\mathrm{N}}\equiv \mathrm{N}$

The process of nitrogen fixation requires a lot of energy. To transform one molecule of nitrogen into two molecules of ammonia, 16 ATP molecules are required.

Plants are poisoned by the ammonia produced during nitrogen fixation. As a result, this ammonia undergoes further reactions. 

Reductive amination is the reaction of ammonia with alpha-ketoglutaric acid to produce glutamic acid or glutamate, as indicated in the diagram below:-

(Image will be uploaded soon)

Reductive Amination and Transamination

Transamination: When an amino group from one amino acid is transferred to a keto acid. Transaminases are enzymes that catalyze this process. Asparagine amino acids are formed as a result of this process. As a result, poisonous ammonia is transformed into necessary amino acids for plant growth and development.

Notes of Chapter 11 Biology Class 11 Free PDF Download

Contents of Biology Class 11 Chapter 11 Notes

The ch 12 bio class 11 notes contain detailed information about the mineral requirements of plants. The minerals required by plants are usually obtained from the soil. However, hydroponics can also be used to serve the required minerals. Depending on the amount of mineral required for living, minerals are divided into two major groups:

• Macronutrients: These elements are required by living beings in a large quantity and are thus called macronutrients. Some examples of macronutrients are hydrogen, oxygen, and nitrogen.

• Micronutrients: These elements are required in smaller quantities and are therefore referred to as micronutrients. Examples of micronutrients include zinc, copper, and iron.

The class 11 bio chapter 11 notes contain detailed information about the function of each of the important micro and macro elements. The effects that the deficiency of these elements will have on plants are also mentioned in chapter 11 class 11 biology notes. The metabolism of nitrogen and its utilization by plants is also discussed in details to give students a good idea about the chapter as a whole.

Subtopics in Class 11th Biology Chapter 11 Notes 

The subtopics discussed in the class 11 chapter 11 biology notes are listed below:

• What is mineral nutrition in plants?

• What are macro and micronutrients?

• Grouping essential elements according to functions

• The function of important elements, viz: 

• Nitrogen: The main function of nitrogen is that it is required for growth, photosynthesis.

• Phosphorus: It is an important element required for growth, energy transfer, and seed formation

• Potassium: Needed to maintain osmolarity

• Calcium: needed for signal transduction

• Magnesium: Needed for photosynthesis

• Sulfur: needed for protein structuring also an important component of vitamins.

• Iron: Helps is signal transduction and enzymatic reactions.

• Manganese: Helps in photophosphorylation

• Zinc:  Required for chlorophyll formation

• Copper: Required for metabolic reactions

• Molybdenum: Acts as a catalyst for certain reactions

• Boron: Important for reproduction

• Chlorine: maintains the potential of the cell

• Deficiency symptoms of mineral nutrients in plants

• Metabolism of nitrogen by plants

Apart from this, the class 11 bio ch 12 notes also contain model answers to all the related questions of the chapter. Students can easily study through the notes of biology class 11 chapter 11 prepared by experts to get a clear understanding of the chapter 

Tips to Study From Ch 12 Biology Class 11 Notes

The notes of ch 12 bio class 11 are prepared in such a way that anyone carefully studying them can easily score high marks without any trouble. However, there are some tips you can follow to ensure the best possible results. Let’s look at the tips!

• Read the NCERT textbooks very carefully: Most of the questions for the Board exams as well as the competitive exams will come from the textbook directly.

• Identify the segments that are difficult to understand. Read the required segments from the notes of Chapter 11 Biology Class 11. In case you still have doubts, in the Biology Class 11 Chapter 11 notes, you can sign up for the live classes on Vedantu. 

• Answer the questions given at the end of the chapter. Refer to the textbook and correct your own answers.

• After that, refer to the model answers given in the notes. Identify the shortcomings in your answer and try to work on that.

• Before exams, just go through the class 11th biology chapter 11 notes to check all the important topics.

• Make a table for the functions of all the micro and macro elements for better revision.

Why Choose Biology Chapter 11 Class 11 Notes By Vedantu?

The Vedantu chapter 11 biology class 11 notes are written by experts in biology. They have years of experience in teaching CBSE students for both competitive and board exams. This is why the notes are prepared in simple and easy language to ensure that a student can grasp the basic concepts. The notes are available in a chapter-wise manner so it is easier to revise and manage. The model answers are also extremely useful for students who are weak in biology.