RBSE Class 11 Biology Important Questions Chapter 12 Mineral Nutrition

Rajasthan Board RBSE Class 11 Biology Important Questions Chapter 12 Mineral Nutrition Important Questions and Answers.

RBSE Class 11 Biology Chapter 12 Important Questions Mineral Nutrition

Multiple Choice Type Questions

Question 1.    
The hydroponic method was discovered by:
(a) Sachs
(b) Hogland
(c) Knop    
(d) Webster
Answer:
(d) Webster

Question 2.    
‘Die back’ disease is caused due to deficiency of:
(a) K    
(b) Cu
(c) B    
(d) Fe
Answer:
(b) Cu

Question 3.    
The insectivorous plants catch insects to fulfil their need of:
(a) O    
(b) C
(c) N    
(d) K
Answer:
(c) N    

Question 4.    
Nitrogen is the essential component of:
(a) carbohydrates    
(b) fat
(c) protein    
(d) oil
Answer:
(c) protein

Question 5.    
The brown colour of leaves of cabbage is due to the deficiency of:
(a) boron    
(b) nitrogen
(c) sulphur    
(d) calcium
Answer:
(a) boron

Question 6.    
Tracer element is:
(a) microelement    
(b) macroelement
(c) radioisotope    
(d) vitamin
Answer:
(c) radioisotope

Question 7.    
In green plants, the boron helps in:
(a) photosynthesis
(b) translocation of sugar
(c) activation of enzyme
(d) as co - factor of enzyme
Answer:
(b) translocation of sugar

Question 8.
Which of the following is component of vitamin B₁₂?
(a) Ni    
(b) Cu 
(c) Hg     
(d) Co
Answer:
(d) Co

Question 9.    
Yellow leaf disease in tea plant is caused due to:
(a) deficiency of sulphur 
(b) excess of sulphur 
(c) deficiency of nitrogen 
(d) None of these
Answer:
(a) deficiency of sulphur

Question 10.    
Which element plays an important role in opening and closing of stomata?
(a) Oxygen    
(b) Nitrogen
(c) Potassium    
(d) Calcium
Answer:
(c) Potassium

Question 11.    
The main component of middle lamella in plant cell is:
(a) Ca    
(b) Mg
(c) Co    
(d) Mn
Answer:
(b) Mg

Question 12.    
“Criteria of essentiality of elements” was proposed by:
(a) Morgan    
(b) Arnon
(c) Lang    
(d) Smith
Answer:
(b) Arnon

Question 13.    
Which one of the following is not essential?
(a) Co    
(b) Ni
(c) Mo    
(d) Cd
Answer:
(d) Cd

Question 14.    
Mycorrhiza helps in:
(a) respiration
(b) water absorption
(c) nutrients absorption
(d) phosphate absorption
Answer:
(c) nutrients absorption

Question 15.    
Which is present in plastocyanin?
(a) Cu    
(b) Fe
(c) Ca    
(d) K
Answer:
(a) Cu

Question 16.    
Copper (Cu) is found in:
(a) plasmalemma    
(b) plastocyanin
(c) plastoquinone    
(d) vitamin
Answer:
(b) plastocyanin

Question 17.    
What prevents the inactivation of nitrogenase from the toxic effect of oxygen during nitrogen fixation?
(a) Leghaemoglobin    
(b) Xanthophyll
(c) Carotene    
(d) Cytochrome
Answer:
(a) Leghaemoglobin    

Question 18.    
The element essential for auxin synthesis is:
(a) zinc    
(b) phosphorus
(c) sulphur    
(d) potassium
Answer:
(a) zinc

Question 19.    
Deficiency symptoms of nitrogen and potassium are visible first in:
(a) buds    
(b) senescent leaves
(c) young leaves    
(d) roots
Answer:
(b) senescent leaves

Question 20.    
Plants absorb N₂ in the form of:
(a) Nitrate    
(b) Nitrite
(c) Urea and NH₃    
(d) NH₃
Answer:
(a) Nitrate

Question 21.    
Which of the following is a free living nitrogen fixing bacterium?
(a) Azotobacter    
(b) Pseudomonas
(c) Nitrosomonas    
(d) Rhizobium
Answer:
(a) Azotobacter

Question 22.    
The first used enzyme in nitrogen fixation is:
(a) nitrogenase    
(b) nitroreductase
(c) transferase    
(d) transaminase
Answer:
(a) nitrogenase

Question 23.    
Roots absorb minerals in the form of:
(a) solid state    
(b) liquid state
(c) ionic state    
(d) gaseous state
Answer:
(c) ionic state

Question 24.    
Nitrifying bacteria are:
(a) autotrophs    
(b) chemotrophs
(c) saprophytes    
(d) parasites
Answer:
(b) chemotrophs

Question 25.    
The conversion of nitrate into N₂ is called:
(a) nitrification
(b) denitrification
(c) ammonification
(d) nitrogen fixation
Answer:
(b) denitrification

Question 26.    
A free living nitrogen fixing cyanobacteria that forms symbiotic association with aquatic fern Azolla is:
(a) Tolepothrix    
(b) Chlorella
(c) Nostoc    
(d) Anabaena
Answer:
(d) Anabaena

Question 27.    
The nitrogen fixation in root nodules of Alnus takes place by:
(a) Bradyrhizobium    
(b) Clostridium
(c) Frankia    
(d) Azorhizobium
Answer:
(c) Frankia

Question 28.    
The ion which helps in opening and closing of stomata is:
(a) Mn⁺    
(b) Mg⁺
(c) Ca²⁺    
(d) K⁺
Answer:
(d) K⁺

Question 29.    
The cause of white patches in barley is:
(a) Zn    
(b) Mo
(c) Cu    
(d) Fe    
Answer:
(b) Mo

Question 30.    
Which of the following is a micronutrient?
(a) Mg    
(b) Ca
(c) S    
(d) Cu
Answer:
(d) Cu

Very Short Answer Type Questions

Question 1. 
Define mineral nutrition.
Answer:
The process which involves absorption and utilization of mineral elements by green plants for their growth and development, is called mineral nutrition.

Question 2. 
What is sand culture?
Answer:
To grow plants in pure sand is called sand culture. Nutrient solution is putting in this culture.

Question 3. 
Zinc (Zn) is essential to synthesis of which plant hormone?
Answer:
IAA - Indol acetic acid.

Question 4. 
What is the number of essential mineral elements for growth and development of plants?
Answer:
Seventeen.

Question 5. 
What are frame work elements of plant body? 
Answer:
C, H and O are called frame work elements.

Question 6. 
Which is constituent nutritive element of chlorophyll?
Answer:
Magnesium (Mg).

Question 7. 
By deficiency of which element, internal cork disease of apple fruits is caused?
Answer:
Deficiency of boron (B).

Question 8. 
Which are critical elements?
Answer:
Nitrogen, phosphorus and potassium.

Question 9. 
Which nutrient element is necessary to auxin synthesis? 
Answer:
Zinc (Zn).

Question 10. 
What are catalytic elements?
Answer:
Mg, Cu etc. are function as cooperative of enzymes. Enzymes become inactive in the absence of them. They are called catalytic elements.

Question 11. 
Dalton considered which new element as essential element?
Answer:
Nickel (Ni).

Question 12. 
Write one function of iron element.
Answer:
The iron element is main component of respiratory enzyme cytochrome.

Question 13. 
What is hydroponics?
Answer:
The method of growing plants in medium water solution instead of soil is called hydroponics.

Question 14. 
Write two examples of nitrogen fixing blue green alge.
Answer:
Anabaena and Nostoc.

Question 15. 
Which element takes part in photolysis of water in photosynthesis?
Answer:
Chlorine and manganese.

Question 16. 
Who has proposed criteria of essentiality of elements?
Answer:
Arnon (1938).

Question 17. 
What is the symptom called in which leaves begin yellow due to loss of chlorophyll?
Answer:
Chlorosis.

Question 18. 
Which are protoplasmic elements?
Answer:
Nitrogen, sulphur, phosphorus etc., are called protoplasmic elements because they combine with C, H and O to form main part of protoplasm.

Question 19. 
Write one characteristic of bacteria Rhizobium.
Answer:
Rhizobium is aerobic in free state and anaerobic in root nodules.

Question 20. 
Write name of an anaerobic nitrogen fixing bacteria.
Answer:
Rhodospirillum.

Question 21. 
Who protect nitrogenase enzyme?
Answer:
Leghaemoglobin.

Question 22. 
Write the name of most moveable and least moveable element.
Answer:
Most moveable - Potassium (K).
Least moveable - Iron (Fe).

Question 23. 
Name the metallic component of nitrogenase enzyme.
Answer:
Molybdenum.

Question 24. 
Give an example of photosynthetic bacterium.
Answer:
Chlorobium.

Question 25. 
Name the disease which is caused by the deficiency of molybdenum in cauliflower.
Answer:
Whip tail disease.

Short Answer Type Questions - I

Question 1. 
Name the minerals which produce catalytic effect.
Answer:
Catalytic effect: Iron (Fe), copper (Cu), zinc (Zn) etc., elements function as prosthetic group of some enzymes. Conversely ions of manganese (Mn), magnesium (Mg), cobalt (Co) etc., function as activators or inhibitors for processes of many enzymes.

Question 2. 
What do you understand by fresh weight and dry weight of plant?
Answer:
When the weight of a plant or its part when taken it is called fresh weight of plant. The dry weight is an estimate of a body or a body sample of plant weight when all water has been removed by heating it at 100°C.

Question 3. 
What are criteria of essentiality of element proposed by Arnon?
Answer:
According to Arnon (1938), the essential elements are those:

• That take part in metabolism directly.
• Disease are caused due to deficiency of them.
• The diagnose of their deficiency is fulfilled by only same element.

Question 4. 
What is denitrification? What are suitable conditions for it?
Answer:
Denitrification: A group of bacteria break up nitrates and ammonium compounds into molecular nitrogen (N₂) which is released into the atmosphere. This process is called denitrification and the bacteria are called denitrifying bacteria, such as Pseudomonas, Thiobacillus etc. The suitable conditions for denitrification is anaerobic environment.

Question 5. 
What is nitrification? Name two nitrogen fixing bacteria.
Answer:
The conversion of ammonia into nitrate is called nitrification.

Nitrite is converted into nitrate
2NO₂^- + O₂ → 2NO₃^- (Nitrate)
Nitrifying bacteria: Nitrosomonas and Nitrobacter.

Question 6. 
Differentiate between Trace element and Tracer element.
Answer:
Difference between Trace and Tracer elements

Trace element	Tracer elements
1. Plants require these elements	1. These are radioactive elements which are introduced into the plants from outside to trace out the path of a metabolic process and are metabolized by plants as usual.
2. Their presence can not be observed in plants.	2. As they are radioactive elements their presence can be marked.
3. Examples: B, Mn, Zn, Cu, Cl and Mo.	3. Examples: C14, N13, K42, S35, Na24 etc.

Question 7. 
What do you understand by mineral and non - mineral elements?
Answer:
Mineral and non - mineral elements: Those essential elements which are obtained by plants from soil are called mineral elements, where as those essential elements such as carbon, hydrogen and oxygen which are obtained by plants from air or water are called non - mineral elements.

Short Answer Questions - II

Question 1. 
Write the composition of Knop’s nutrient solution.
Answer:
Knop’s nutrient solution: 
Calcium nitrate : 0.8 g/L
Magnesium sulphate : 0.2 g/L
Potassium nitrate : 0.2 g/L
Potassium dihydrogen phosphate : 0.2 g/L
Ferrous phosphate : A few drops

Question 2. 
What is the function of nitrogen and potassium in plants?
Answer:
Nitrogen: Plants absorb nitrogen in the form of NO₂, NH₃, NH₄. Nitrogen is essential to the synthesis of protein, coenzyme, nucleic acid (DNA and RNA) and other organic compounds. It is main component of protoplasm and chlorophyll. Nitrogen is helpful in opening and closing of stomata and movement and balance of water.

Potassium: It is important to cell growth, growth of leaves, and formation of secondary roots. It requires to sustain viability of protoplasm. It plays an important role in opening and closing of stomata. It is cofactor of enzyme.

Question 3. 
Give some examples of symbiotic nitrogen fixers.
Answer:
Symbiotic Nitrogen Fixers

• Rhizobium bacteria found in root nodules in leguminous plants.
• A microorganism, Frankia found in root glands of Alnus.
• Anabaena and Nostoc (cyanobacteria), in coralloid roots of Cycas.
• Anabaena in leaves of a fern Azolla.
• Blue green algae (cyanobacteria) in thallus of lichen.

Question 4. 
Write the symptoms produced in plants which growing in deficiency of potassium and nitrogen.
Answer:
Deficiency of Protein: Due to deficiency of potassium dead necrosis are formed on leaves. The process of protein synthesis is reduces. Resistance capacity also reduces. The mechanical tissues are less developed. Plants become bushy.

Deficiency of Nitrogen: The leaves of plant becomes yellow. Cell division, respiration, protein synthesis etc., reduce. The growth of plant re tarts and delayed flowering. The grains shrink.

Question 5. 
Write common functions of minerals.
Answer:
Common Functions of Minerals

• The mineral elements are framework elements of plant body. Such as - C, H and O form the framework of plants.
• Nitrogen, phosphorus, sulphur etc., build protoplasm along with carbon hydrogen and oxygen.
• Mg, Cu etc., function as cofactor of enzyme hence called catalytic elements.
• Cu, Mg, K etc., reduce toxic effect of other minerals.

Question 6. 
Explain required conditions for a normal nutrient solution.
Answer:
It should be kept mind in the time of preparation of soil that less nutrient solution that it includes all the essential nutrients. Besides following conditions are required:

• All essential elements are soluble.
• The solution should be dilute and it can be change time to time.  
• The solution should has reasonable aeration arrangement.
• The pH of solution should be maintain.

Question 7. 
What is Hydroponics? What is its importance. 
Answer:
A famous German botanist, Julius von Sachs (1860) demonstrated first that plants could be grown to mature in a nutrient solution instead of soil. The term “Hydroponics” was first of all coined by William F. Gericke of California University in 1920. Hydroponics is a Greek word which literally means, ‘working with water’. Therefore, all those methods of growing plants in them some other medium are used instead of soil are called hydroponics.

It is also called water culture e.g., tank farming, soil less culture, test tube farming etc. Several methods have been used to determine the essentiality of an element, from time to time. Besides, the study of various symptoms produced due to the deficiency of a particular mineral element in plants, the effect of excess of a particular element and interaction of the particular element with other element etc., is made by these methods. Hydroponics includes two main methods:

• Solution Culture
• Sand Culture

Question 8. 
In which form phosphorus is absorbed by plants? Where phosphorus utilizes in plants? Write two symptoms of phosphorus deficiency in plants.
Answer:
Plant absorb phosphorus mainly in the form of phosphate ion (PO₄^3-) and dihydrogen phosphate H₂PO^-₄. Phosphorus is utilized in formation of cell membrane and leaves and growth of roots. Phosphorus is also utilized in synthesis of protein, nucleoprotein, nucleotide etc. Due to deficiency of phosphorus, the patches of anthocyanin appear on leaves and leaves fall down early.

Question 9. 
Write examples of symbiotic nitrogen fixing microorganisms.
Answer:
Free living or symbiotic nitrogen fixing microorganisms are generally aerobes or anaerobes. Examples: Rhodospirillum is anaerobic and Azotobacter. Beijerinckia are aerobic bacteria. Free living blue green algae such as Anabaena, Nostoc, Tolypothrix etc. Some species of yeast also help in nitrogen fixation.

Question 10. 
Write difference between haemoglobin and leghaemoglobin.
Answer:
Difference between Haemoglobin and Leghaemoglobin.

Haemoglobin	Legahaemoglobin
1. It is found mainly in vertebrate animals.	1. It is found in root nodules of leguminous plants.
2. It is bright red pigment.	2. It is dull brown.
3. It acts as oxygen carrier.	3. It combines rapidly with oxygen and helps in nitrogen fixation.
4. It takes part in respiration.	4. It protects nitrogenase enzymes.

Question 11. 
Differentiate between Micronutrients and Macronutrients.
Answer:
Difference between Micronutrients and Macronutrients

Micronutrients	Macronutrients
1. These elements are required by plants in small quantity.	1. These
2. Micronutrients form minor portion of dry weight of a plant.	2. Macronutrients form major protein of dry weight of a plant.
3. These are called trace elements.	3. These are called elements.
4. These are usually used as co - factors or metal activators in the functioning of enzymes.	4. They enter into structure macromolecules of the cell.

Question 12. 
What is critical concentration of elements? When a mineral ion becomes toxic?
Answer:
On limiting supply of essential elements, the growth of plants is inhibited. The concentration of essential elements whose deficiency inhibits the growth of plants is called critical concentration.

An element becomes limiting below its critical concentration. It is termed as deficient element. Growth declines and deficiency symptoms become visible if element concentration is above the level of critical concentration, it is termed as adequate. The growth is not increased if concentration is increased. Toxicity appears of sufficiently high element level. Any mineral ion concentration in tissues that reduces the dry weight of tissues by about 10 percent is considered toxic.

Long Answer Type Questions

Question 1. 
Describe nitrogen cycle in nature with diagram.
Answer:
Nitrogen (N₂) constitutes 78% of the atmosphere. This gas cannot be utilized by the higher plants in the free state. The plants take it in the form of nitrates and nitrites from the soil. Therefore the gaseous nitrogen is converted in various nitrogenous compounds. The ratio of nitrogen between the earth and atmosphere remain constant, which is possible by nitrogen cycle.
The nitrogen cycle can be studied under four convenient headings:

• Nitrogen Fixation
• Ammonification
• Nitrification
• Denitrification

1. Nitrogen Fixation: A number of micro-organisms and blue green algae are, however, capable of fixing the atmospheric nitrogen in the form of compounds nitrogen is also fixed by lightning and rain fall.

(i) Non - biological Nitrogen fixation: Under thunderclap, the atmospheric nitrogen combines with oxygen to form nitrogen peroxide and nitric acid. These come on the earth with rains and reaching in soil in form of nitrates and nitrites compounds.

(ii) Biological Nitrogen Fixation: The atmospheric free nitrogen is converted into nitrogenous compounds by freeliving bacteria, symbiotic bacteria and blue green algae. Azotobacter, Rhodospir ilium, Clostridium etc., bacteria and Nostoc, Anabaena etc. Cyanobacteria are free living nitrogen fixers. Rhizobium bacteria are found in root nodules present in roots of leguminous plants as symbiotic forms.

2. Ammonification: Plants synthesis organic nitrogenous compounds with the help of the nitrogen pool of the soil. In leguminous and certain non - leguminous plants atmospheric nitrogen can also be fixed up directly. Animals drive their nitrogen requirement from the plants. When the plants and animals die, their protein contents are decomposed into ammonia by a variety of micro - organisms.

The bacteria which bring about protein decomposition are termed as ammonifying bacteria, e.g., Bacillus ramosus, B. vulgaris and B. mycoides. Ammonia is added to the nitrogen pool of the soil or to water (in the form of soluble ammonium compounds). Some of the ammonia goes out into the atmosphere. Ammonia can be directly taken up by the plants or can be converted to nitrates by the process of nitrification.

3. Nitrification: Ammonia or the ammonium compounds formed by ammonification are converted into nitrite and then into nitrate by a group of bacteria called nitrifying bacteria. Ammonia is oxidized to nitrite by Nitrosomonas and nitrite is further oxidized to nitrate by Nitrobacter.



Once nitrate is formed it is taken up by the plants in which it gives rise to ammonia.

4. Denitrification: A group of bacteria called denitrifying bacteria (Bacillus denitrifleans, Thiobacillus, Pseudomonas etc.) break up nitrates, and ammonium compounds into molecular nitrogen (N2) which is released into the atmosphere. Such bacteria are thus responsible for reducing the nitrogen contents and therefore, the fertility of the soil. It should be noted that loss of nitrogen into the biosphere due to denitrification and sedimentation (in aquatic ecosystem) is more than compensated by gains by nitrogen fixation, nitrification, volcanic release of ammonia, oxidation of atmospheric nitrogen by lightening and the weathering of the rocks.

Loss of nitrogenous compounds in the form of cereal grains, straw, hay etc., or harvested underground storage organs etc., are compensated by the addition of natural manure and artificial fertilizers in the soil. In agriculture, crop rotation involving a leguminous crop is often practised to maintain the pool of available nitrogen in the soil. 



Importance of Nitrogen Cycle

• By nitrogen cycle the balance of nitrogen in atmosphere sustains.
• Nitrogen helps to reduce activeness of oxygen.
• By cycling nitrogen becomes available to plants.
• By the degradation of waste of plants and animals nitrogen releases into atmosphere.

Question 2. 
Write functions and deficiency symptoms of following elements:
(a) Ca 
(b) Mg 
(c) Fe 
(d) P 
(e) S
Answer:
(a) Calcium (Ca): The amount of calcium in plants is approximately 0.1 - 3.5%.
Source: Calcium obtained to soil by weathering of anorthite or CaAl₂ Si₂ O₂. Its other common compound is calcium carbonate (CaCO₃) which obtained from lime. It present also in the form of calcium phosphate in soil. Plant absorb calcium in the form of Ca⁺⁺ ions.
Specific Role

1. It is most important component of cellwall. The middle lamella is made of calcium pectate.
2. It is essential for carry the metabolic process of plant body.
3. It controls the permeability of cell membrane.
4. It is essential for continuous growth of shoot apex and also for cell division.
5. It reduces toxicity converting organic acid to harmless compounds.
6. It helps in transportation of amino acid and carbohydrate.
7. It increases root growth.
8. It is found as calcium oxalate crystals in many plants.
9. It helps in formation of cell membrane.
10. It takes part in photolysis of water and regulating metabolism.

Deficiency Symptoms

• The cell wall does not form during cell division.
• The root and shoot meristem become dead.
• Roots are poorly developed.
• Chlorosis is produced on the margins of young leaves.

(b) Magnesium (Mg): Its amount in dry weight of plant is 0.5 - 0.7%.
Source: It is found in soil mainly as carbonates (MgSO₃) and dolomite (MgCO₃ . CaCO₃). Plants absorb it as magnesium (Mg ⁺⁺) ions.

Specific Role

1. It is the main component of chlorophyll molecule.
2. It is intimately associated with the phosphorus metabolism and is particularly essential for the enzymes involved in the phosphate transfer reaction.
3. It plays an important role in synthesis of ATP from ADP and inorganic phosphate.
4. It activates many enzymes such as carboxilase, hexokinase, phosphorylase dehydrogenase etc.
5. It binds sub - units of ribosome together. The formation of dimers and polymers of ribosome depends upon the concentration of Mg⁺⁺ ions.

Deficiency Symptoms

• Interveinal chlorosis is produced in leaves.
• The older leaves are affected first and the younger leaves are affected later on.
• Anthocyanin pigment begins to form due to which red or violet colour begin to form in chlorotic regions.
• The necrotic area begins to form on leaves.
• The vegetative and reproductive growth of plant are reduced.

(c) Iron (Fe): Its amount is 10 - 100 ppm (mg/L) in plants. Source: In soil iron is found as limonite and pyrite form. It is absorbed by plants in both the forms i. e., ferrous and ferric ions. It is found abundently in acidic soil. The pH of soil controls iron. 

Specific Role

• It is main component of porphyrine, cytochrome, peroxidase and catalase.
• It is essential for chlorophyll synthesis.
• It is important component of ferridoxin.
• Iron play an important role in respiratory mechanism.
• It is a component of several electron carriers.

Deficiency Symptoms

• Chlorosis is produced in leaves and become yellow in colour.
• The decomposition of plastids begins.
• Protein synthesis in plant is reduced.
• The symptoms appear first in younger leaves.
• Its deficiency seriously impairs aerobic respiration and other related processes.
• Petioles become short.

(d) Phosphorus: Its amount in dry weight of plant is 0.2 - 0.8%. Phosphorus is one of the most important element for the plants. It is a vital structural component of the nucleic acid, nucleoprotein, phytin, phospholipids, sugar phosphate, ATP, NADP⁺ etc.
Source: The soil is the main source of phosphorus for plants. Phosphorus is absorbed by the plants from the soil in the form of phosphate ions H₃PO₄^-  and HPO₄^2-.

Specific Role

1. It is component of NAD, NADP⁺ and ATP etc.
2. It is also component of RNA, DNA and phospholipids.
3. It plays an important role in protein synthesis with the help of oxidation, reduction and energy transfer processes. For example, ADP, NADP⁺ and ATP etc., are substance of phosphate act in photosynthesis and respiration.

Deficiency Symptoms

• Root and stem become weak and small.
• There necrotic regions are formed on leaves and fruits.
• Phosphorus deficiency may cause premature leaf fall and purple anthocyanin pigmentation.
• Plant growth is retarted.
• The activity of cambium is decreased.

(e) Sulphur (S): The amount of sulphur in plants is approximately 0.5 - 1%.
Source: Inorganic sulphur is found in soil in the form of minerals such as pyrite, gipsum, ipsonite and cobohite etc. It is soluble in water in the form of sulphate (SO₄). Some bacteria convert sulphur to sulphate. It is absorbed by plant from soil as sulphate ion.

Specific Role

• It takes part in the formation of several amino acids such as cystein, cystine and methionine etc. Besides, it is main component of vitamins such as biotin, thiamine and it is also a major component of coenzyme - A.
• It helps in seed formation.
• In some plants e.g., mustard, onion, garlic etc., it forms glucoside.

Deficiency Symptoms

• There is a deficiency of sulphurous amino acids due to which sulphurous proteins also reduced and the storage of carbohydrates is increased.
• Leaves exhibit chlorosis. This symptom is first seen in young leaves and then in old leaves.
• Due to the storage of carbohydrates, there is increase in the quantity of thick walled tissues, whereby the stem of plant becomes strong.
• The apical growth of the plant is reduced.

Question 3. 
How the effects produced by the deficiency of various nutrient elements are known? Explain. 
Answer:
Study of effects produced by deficiency of nutrients in plants: When we study the usefulness of any nutrient element or the effect produced by the deficiency of any nutrient, then for this plant is grown in liquid medium. For this, prepared medium in many bottles. Out of them, one bottle is filled with complete culture solution. Other bottle lacks such nutrient which is studied. Now plants are left for growing. After few days comperative study is made. Produced effect in plant is symptom of deficient element.
Table for Study of effect of elements

Deficiency of element in Solution	Symptom
1. Control.	1. Normal growth of plant.
2. Deficiency of Mg.	2. Less growth, yellow leaves.
3. Deficiency of calcium (Ca).	3. Weak plant, root undeveloped, spot on leaves.
4. Deficiency of Iron (Fe).	4. Leaves white - yellow, less growth.
5. Deficiency of potassium (K).	5. Less growth, brown leaves, plant death early.
6. Deficiency of phosphorus (P).	6. Roots are affected and finally plant dies.
7. Deficiency of nitrogen (N).	7. Less growth, yellow leaves, weak plant.

Question 4.
Explain absorption of mineral elements by roots.
Answer:
Absorption of Mineral Elements: Mostly mineral elements absorbed by root hairs in their water soluble state. These minerals diffuse freely into the epiblema, cortex and then they reach into the endodermal cells. In the endodermis, casparian strips are found which retard such type of movement. According to Butler (1953) and Epstein (1955) no metabolic energy is required for the movement of minerals across the living cells of the cortex. Suppose the part of cytoplasm has free space, the ions will be translocated passively through the wet cell walls and plasmodesmata of the cells of the cortex and will go to endodermis.

From the endodermis the ion will reach to the xylem through the living cortical cells. Such process is called “symplast theory” of ion uptake. By this active process the ions move from endodermis to non - living elements of xylem. It requires energy which is supplied through respiration. Some special cells called transfer cells take part in the movement of mineral into the xylem. Though in the xylem upward translocation of the nutrients takes place, through the cells of the cambium, these nutrients are radially translocated in the phloem also.