Biology Chapter 12 Mineral Nutrition

usually occurs through ion-channels,

1. The mineral elements are absolutely necessary for supporting normal growth and reproduction. 

2.  The minerals are components of protoplasm. The elements having variable valency bring oxidation and reduction reactions e.g. Fe, Cu.

3. K⁺ ions help in the opening and closing of stomata.

4. Salts of weak acids and weak bases act as buffers.

5. Minerals maintain osmotic potential of cell sap and permeability of plasmalemma.

6. Minerals also act as cofactors and thus bring catalytic reactions.

7. K⁺ and boron help in transportation of food in the phloem tissue.

1. Chlorosis
 2. Necrosis
3. Abscission 
4. Fall of leaves
5. Leaf curl 
6. Wilting

1. Through hydroponic gardening; plants can be grown anywhere as long as their growth  requirements are met .

2. Plants produced are free from soil pathogens and diseases as no soil is involved.

3. Plants grown are free from harmful chemicals as fertilizers and pesticides are not used.

4. The plants can be produced at those places where there is scarcity of land and the soil is thin or infertile.

5. The plants grown by this method are more healthy.

Disadvantages of hydroponics :

1. The initial set-up is very costly.

2. It needs the help of expert scientists to prepare the required nutrient medium and its maintenance.

Mineral absorption through carrier molecules

(1) Weathering of rocks.

(2) Decomposition of fallen leaves, twigs, dead plants and animals and excreta and their convertion to humus.

(3) Biological nitrogen fixation.

(1) By adding farm yard manure or animal excreta to the soil.

(2) By adding fertilizers, manure.

(3) By green manuring.

(4) By crop rotation.

(5) By controlling over-grazing.

1. The essential elements should be necessary for growth and reproduction of the plant. It should be indispensable. The plant should not be able to complete its lifecycle in the deficiency of the element. 

2. The element should not be replaceable and its requirement should be specific. The deficiency of the element should not be met by supplying some other element. 

3. There should be direct involvement of the element in the metabolism of the plant. 

Magnesium-  is a constituent of chlorophyll. It is required in fat synthesis and nucleic acid synthesis. It activates enzyme in phosphate metabolism.

Role of copper :

Copper is absorbed as cupric ions (Cu2+). It is essential for the overall metabolism in plants. It is associated with certain enzymes involved in redox reactions. 

Macronutrients - Nitogen, carbon
Micronutrients - Zinc , molybdenum. 

1. Boron is involved in pollen germination and cell elongation, cell differentiation.

2. It is required in the translocation of scarbohydrates. 

3. It is required for the uptake of Calcium ions. 

4. It helps in membrane functioning. 

(2) Zinc : Due to the deficiency of zinc, young leaves and internodes become extermely small, resulting in little leaf rosette and mottled leaf condition .

Calcium : It's deficiency produces necrosis in the leaf and stem. Plants have a stunted growth with suppressed flowering. Flowers fall immaturely and this process is called premature fall of flower.

Micronutrients : These are present in amount less than 10m mole kg^-1.

Soil fertility. It is the ability of soil to provide good growth of plants. It is dependent upon pH value, size of soil particles, presence of minerals, presence of  air , optimum temperature etc.

Depletion of soil fertility is due to the following reasons :

1. Non-rotation of crops causes deficiency of minerals.

2. Precipitation of salts due to change of pH value.

3. Leaching of salts.

4. Over use of the land for cropping.

5. Over grazing.

7. Deforestation.

Significances of culture experiment :

1. It tells the essentiality of an element.

2. It also tells the toxicity of an element when present in excess amount.

3. It can tell the result of interaction between different elements.
4. It tells us about the effects of the deficiency of a particular element. 

Deficiency symptoms of Nitrogen:

1. Deficiency of nitrogen interferes with protein synthesis and hence all forms of growth are affected.

2. An early symptom is yellowing of leaves and development of chlorosis.

3. Older leaves turn light brown in colour and gradually dry.

4. Flowering is delayed or completely suppressed.

Deficiency symptoms of Phosphorous :
The deficiency of phosphorus causes :

1. disruption of general metabolism
2. abnormalities in the shape and size of chloroplast.

Deficiency symptoms of Sulphur :

1. Deficiency symptoms first appear in young leaves.

2. They become reduced, chlorotic followed by anthocyanin pigmentation in certain species.

3. Root system becomes extensive and stems become hard and woody.

Deficiency symptoms of Potassiam :

1. Deficiency symptoms are first observed on the older, lower leaves. Spots of dead tissue on older leaves are seen. 

2. Potassium deficiency in cereal crops develop weak stalk. These plants easily bent to the ground by wind or rain.

Deficiency symptoms of Calcium :

1. Calcium deficiency brings about decomposition of root epidermis, roots become mucous, the growing zone and lateral roots rapidly die off.

2. Its deficiency terminates growth of meristematic regions.

3. Margins of younger leaves show chlorosis which become nacrotic.

4. Twig or stalk just below the tip and seed head is often unable to stand erect.

Deficiency symptoms of Magnesium :

1. Extensive interveinal chlorosis of the leaves resulting in defoliation;

2. Yellowing of the leaves start from basal to younger ones;

1. Manganese (Mn) :

Physiological role.
i.  As a Cofactor : Mangenese primarily functions as activator of several enzymes involved in photosynthesis. 

ii.  It helps in the splitting of water and liberation of oxygen 

iii. Synthesis of chlorophyll : It is also involved in the synthesis of chlorophyll.

Deficiency symptoms

Deficiency of manganese causes chlorosis, nacrosis in the interveinal areas of leaves, the veins remain green, the chloroplasts are devoid of chlorophyll and starch grains become yellow green in colour, vacuolated and finally disintegrate.

2. Copper :

Physiological role.
Copper is a component of many enzymes involved in redox reactions. It plays a as a key role in the electron transport chain in photosynthesis. 

Deficiency symptoms.

i. Deficiency of copper causes necrosis.

ii. Under severe conditions the whole plant may appear wilted and the leaves may be lost.

3. Zinc :

Physiological functions.
Zinc plays an important role in the activation of many enzymes especially carboxylases
It is involved in the synthesis of auxin. s

Deficiency symptoms.
Deficiency of zinc causes

(i) shortening of internodes with the result plant become stunted;

(ii) reduction in the size of leaves so that the leaves become very small.

(iii) chlorosis of older leaves starting at tip and extending to the margins.

(i) Macronutrients are generally present in plant tissues in large amounts in excess of 10m mole kg^–1 of dry matter. For example - Carbon, hydrogen, nitogen, phosphorous, and oxygen 

(b) Micronutrients : Micronutrients or trace elements are needed in less than 10mmole kg^–1  of dry matter eg. iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel.

(c) Toxic elements : Any mineral ion or element which reduces dry weight by 10% of plant is called toxic element. Toxicity of element differs from plant to plant. The elements when present in large amounts much more than what is needed becomes toxic. 

(d) Essential elements : These are the elements which are essential for the growth of the plants. The plant cannot complete their lifecycle in the absence of it.  They are C, H, O, N, P, S, K, Ca, Mg, Fe, Mn, Cu, Mo, Zn, B, CI and NL

Foliar Nutrition—In this type of process fertilizers, growth hormones, mineral nutrients and several other chemical substances are directly applied to the plants on their leaves. They are dissolved in water and sprayed on the leaves of plants. Such an application of nutrients is called foliar nutrition.

Advantages of Foliar Nutrition—The foliar nutrition has several advantages—

1. It reaches the desired tissues more quickly as compared to the soil nutrients. 

2. It is more economical means of fertilizing crop plants particularly costly micronutrients.

3. It is a useful method for accelerating growth and development during flowering and fruiting. 

(1) Nutrients. The chemical substance that works as a raw material for body building and maintaining its function is termed nutrient.

(2) Micronutrients. These are needed in very small amounts, equal to or less than 0. lmg per gram of dry matter.

(3) Macronutrients. These must be present in plant tissues in concentrations of 1 to 10 mg per gram of dry matter.

(4) Active absorption. It is the movement of ions or molecules against concentration gradient or towards concentration gradient by taking energy directly or indirectly through metabolism.

(5) Passive absorption. It is the movement of minerals from higher concentration to lower concentration by physical processes not involving direct expenditure of energy.

(6) Symplastic pathway. It is the movement of ions across the cytoplasm of cortex, endodermis of pericycle through plasmodesmata.

(a) Reductive amination. In this process ammonia reacts with -Ketoglutaric acid and forms glutamic acid as indicated below : 

(b) Transamination. This process involves the transfer of amino groups from one amino acid to the keto group of a keto acid. Glutamic acid is the main amino acid from which the transfer of NH₂ group takes place and the other 17 amino acids are formed through transamination. The enzyme required for such raction is called transaminase.

The macronutrients are: carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, potassium, calcium and magnesium.

Functions of carbon, hydrogen and oxygen :
These are the components of protoplasm and all organic componds found in plants.

Functions of nitrogen.

It plays a major constituent of proteins, nucleic acids, vitamins and hormones. 

Functions of phosphorous.
Phosphate plays a key role in energy metabolism. Incorporated into ATP it is part and parcel of the universal energy currency of all types of living systems.

Fuctions of sulphur.

Sulphur is present in amino-acids - cysteine and methionine. 

Essential elements can be grouped into four broad categories on the basis of their diverse functions. These categories are :

1. Structural elements

2. Energy related molecules 

3. Activators or inhibitors of enzymes.

4. Elements which alter the osmotic potential. 

Nodulation : It is the process of formation of nodules. It can be described in in following points.

1. Rhizobiua multiply and colonise the surroundings of roots and get attached to the epidermal and root hair cells. 
2. The root hairs curl and bacteria invede it.
3. An infection thread is produced that carries the bacteria to the cortex of the root. 
4. Bacteria is then released into the cells and this leads to the differentiation of specialised nitrogen fixing cells. 
5. The nodule establishes a direct vascular connection with the root for exchange of nutrients.

2. Die back: It is the withering of stem from apex downward. It is due to the deficiency of copper.

3. Necrosis : It is the death of the tissues.  The leaf tips develop dead areas or necrotic areas. It may be also due to Ca, Mg, Ni, Cu and K.

4. Whiptail disease : It occurs in cauliflower. It is due to the deficiency of Mo.

5. Little leaf disease: It is due to the deficiency of Zn. It also causes rosette of apple and peaches.

Heterotrophic nutrition : It is the nutrition in which organisms do not manufacture their own food but take food from external sources such as other living organisms or from dead and decaying matter. For example - animals are heterotrophic 

Conditions for N₂ fixation : There are following conditions necessary for N₂ fixation :

(1) A strong reducing agent like NADPH : It supplies hydrogen to N₂.

(2) ATP as source of energy : It provides energy. For fixation of NH₃ molecules, 8 ATP molecules are needed.

(3) The enzyme system : Nitrogenase is necessary for N₂ fixation.

(4) Compound for trapping ammonia : Ammonia is very toxic and needs to be trapped in the form of amino acids.

(5) Leghaemoglobin : It is O₂ scavenger and maintains anaerobic environment otherwise in the presence of O₂ the enzyme nitrogenase is toxicated.

Passive mineral absorption : It is the absorption which occurs without expenditure of energy. It occurs by following methods :

(A) Diffusion (B) Mass flow 

(A) Diffusion : It is the movement of minerals down the concentration gradient .

Types of Diffusion : It is of Two types as :

(a) Passive Diffusion : It occurs either by dissolving of minerals in matrix cell membrane or through pores. It is a physical process which needs no energy. Water, 0₂, C0₂, etc. diffuse by passive diffusion. Sodium in Nitella is absorbed by passive diffusion.

(b) Facilitated diffusion : It occurs by special protein molecules. 

(B) Mass flow : Large amount of water is absorbed daily by the plant. Along with the water minerals from soil are absorbed into roots. More the rate of transpiration, more would be water absorption and thus more minerals pass into the roots and then ascend upwards into stem.

The purification of water and nutrient salts in hydroponics is very important because of the following reasons:

1. Impure water contains impurities, which will interfere in the growth of plant and make the study for the essntiality difficult.

2. Impurities may be toxic to the plant.

3. Impurities may compete with other minerals.

4. Impurities may inhibit some enzymes.

Therefore, only pure water and nutrients should be taken for hydroponics.

Absorption of minerals : The minerals are absorbed by the plants in two ways.

1. Passive absorption through the apoplast pathway - The movement of ions generally take place through the ion channels that is the transmembrane protein that function as selective pores. It does not require energy. 

2. Active absorption through the symplast pathway - It requires the expenditure of energy. The ions are slowly into  the inner space.

1. True. Boron deficiency leads to stout axis.
2. False. Every mineral element present in the cell is not needed by the plant.

3. False. Nitrogen is highly mobile.

4. False. It is very difficult to establish essentiality of micronutrients because they are required in traces.

To find out if the deficiency symptom is due to the deficiency of which nutrient , in the case when more than one nutrient can cause the symptom, a number of wide mouthed bottles is taken. Each is fitted with split cork.
One of them has the normal culture and is called control. While the other bottles have deficiency of one mineral each. For example necrosis is caused by the deficiency of Ca, Mg or K. 
Thus three bottles having defieciency of Ca, Mg and K respectively is taken and the plant is grown in each.
The plants in the three bottles are checked if they have developed chlorosis. If the symptom is corrected by the supply of the particular mineral. Then it is concluded that the deficiency was because of that mineral. 

Steps of root nodules :
(1) Rhizobium bacteria makes contact with a susceptible root hair and divide near it. 
(2) After successful infection of the root hair causes the root hair curls,
(3) Infected thread carries the bacteria to the inner cortex. The bacteria  modifies into rod-shaped bacteroids and cause inner cortical and pericycle cells to divide. Division and growth of cortical and pericycle cells lead to the nodule formation,
(4) A mature nodule forms with vascular tissues continuous with those of the root.

Macronutrients - Those nutrients that are needed by the plants in large quantities are known as macronutrients. They are generally present in the plant tissues in large amounts i.e. in excess of 10 mmole Kg^-1  of dry matter. For e.g - carbon, hydrogen etc. 
Micronutrients - Are the elements which are needed by the plants in very small quantities i.e less than 10 Kg^-1  of dry matter. For e.g. zinc, boron etc. 
Beneficial elements - The elements are plant nutrients that may not be essential, but are beneficial to plants. For e.g/ - Selenium is  beneficial to higher plants.

Toxic elements: Micronutrients are required by plants in small quantities. An excess of these nutrients may induce toxicity in plants. For example, when manganese is present in large amounts, it induces deficiencies of iron, magnesium, and calcium by interfering with their metabolism.

Essential element - The elements that are absolutely necessary for plant growth and reproduction. The requirement of these elements is specific and non-replaceable. For example carbon, magnesium , phosphorous , zinc etc. 

C.

Nitrogen, nickel, phosphorous

Option c is the most appropriate as it has two macronutrients. 

B.

ammonia

The process of conversion of nitrogen (N₂) to ammonia is termed as nitrogen fixation.

In reductive animation, ammonia reacts with alpha-ketoglutaric acid and forms glutamic acid alpha-ketoglutaric acid +NH₄⁺ +NADPH

A.

Leghaemogolobin

During biological nitrogen fixation, inactivation of nitrogenase  by oxygen poisioning is prevented by leghaemoglobin.
It is a  red-pigment that is filled outside the peribacteroid space in the cytosol of nodule cells. It has the ability to combine very rapidly with oxygen and thus acts a very efficient O₂ scavenger. 

A.

Photolysis of water

Photolysis of water requires light energy, an Oxygen-Evolving Complex (OEC) and electron carrier 1/2. OEC complex was formerly called Z-enzyme. It has four Mn ions. Light energy brings about changes in Mn (Mn⁺²,  Mn³⁺,  Mn⁺⁴) which helps in removing electrons from OH- component of water forming oxygen. Liberation of oxygen also requires Cl^- and Ca^+2.

C.

Golden rice

Golden rice is a variety of Oryza sativa (rice) produced through genetic engineering to biosynthesize Beta-acetone, a precursor of vitamin-A in the edible part of rice (i.e., endosperm). The research that led golden rice was conducted with the goal of helping children who suffer from vitamin-A deficiency. Because many children in countries where there is a dietary deficiency in vitamin-A rely on rice as a staple food, the genetic modification of rice to produce the vitamin-A precursor beta-carotene is seen as a simple and less expensive alternative to vitamin supplements. 

A.

high input of energy

The enzyme nitrogenase is a Mo-Fe protein and catalyses the conversion of atmospheric N₂ to NH₃ as

Enzyme nitrogenase functions under anaerobic condition and the pigment leghaemoglobin protect it from oxygen. 

A.

phosphorus, potassium, sulphur, calcium

Minerals known to be required in large amounts for plant growth are macronutrients. According to question, option (a) is correct, i.e., phosphorus, potassium, sulphur, calcium.
Macronutrients are consumed in large quantities and are required for plant tissue from 0.2% to 0.4% (on dry matter weight basis). Following are the rest of the macronutrients as:
carbon, hydrogen, oxygen, nitrogen, magnesium, silicon. 

A.

Calcium

An element like calcium are a part of a structural component of the cell and hence, are not released. The deficiency symptoms tend to appear first in the young tissue whenever the elements are not demobilised.

C.

Cadmium

Cadmium is not essential elements to plants

A.

Molybdenum

Molybdenum is absorbed as molybdate by plants. It is involved in nitrogen metabolism including nitrogen fixation. It is a component of enzyme nitrogenase and acts as an enzyme activator. Its deficiency cause chlorosis and necrosis, whiptail of cauliflower and premature leaf fall. 
Copper is absorbed by the plant in ionic form. Its deficiency causes necrosis, die back in Citrus, reclamation in legumes.
Manganese is absorbed by the plants as a bivalent ion. It acts as the enzyme activator. Its deficiency causes interveinal chlorosis as well as yellowing of starch and their subsequent degenerate. 
Zinc is needed for biosynthesis of IAA and also acts as the enzyme activator. Its deficiency causes chlorosis, little leaf, rosette, the white bud of maize and mottling of leaves.

A.

Molybdenum

The essential elements, which are required by plants in comparatively large amounts are called as macro elements, e.g, C,H, O, N, P,K,Ca,S,Mg,Fe. The elements, which are required in very small amount by the plants are called micro elements, e.g, Zn, Mn, B, Cu, Mo and Cl

B.

Rhodospirillum

Rhodospirillum is free - living, anaerobic, nitrogen fixer. Both Beijerinckia and Azotobacter are free-living, nitrogen - fixing, aerobic microbes. Rhizobium is a symbiotic, nitrogen-fixer.

D.

Nitrogenase is insensitive to oxygen

Root nodules of leguminous plants harbour symbiotic bacteria, Rhizobium, which fixes atmospheric nitrogen and provides the plant with most or all of its nitrogen requirements. In return, they have access to a rich supply of carbohydrate. The fixation of atmospheric nitrogen (N₂) to ammonia (NH₃) occurs within the nodules, using the enzyme nitrogen cut this enzyme is very sensitive to oxygen and gets inhibited in oxygen rich environment. This problem is solved by leghaemoglobin, a pinkish-red, oxygen-binding, iron-containing protein present in root nodules. It functions as oxygen buffer, scavenges oxygen and provides the enzyme nitrogenase, a low oxygen environment in which nitrogen fixation can occur.

C.

photolysis of water during photosynthesis

In plants, manganese is absorbed in the form of manganous ions (Mn²⁺). It activates many enzymes involved in photosynthesis, respiration and nitrogen metabolism. The best-defined function of manganese is in the splitting of water to liberate oxygen during photosynthesis, ie, photolysis of water.

C.

Frankia

Casuarina tree has nitrogen-fixing root nodules that harbour a filaments streptomycete like symbiotic nitrogen-fixing organism, called Frankia.

C.

Frankia

Nitrogen is the most critical element. The atmosphere is the greatest reservoir of nitrogen. Molecular nitrogen cannot be utilised directly by plants. It has to be fixed or converted into compounds prior to utilisation. symbiotic nitrogen fixation is accomplished by Rhizobium species, which occurs on the roots of leguminous plants. Certain non-leguminous plants also form nodules to fix nitrogen. The best-known example in the temperate region is alder (Alnus sp.). The bacteria involved in nodule formation is an Actinomycetes, the frankia.
Clostridium is anaerobic saprotrophic free-living nitrogen-fixing bacteria.
Bradyhizobium is symbiont in plants of parasponia and soybean.
The azohizobium forms both stem and root nodules in Sesbania (aquatic plant).

C.

Manganese

Magnesium is required in leaves, growing areas of root and stem protein synthesis hence, withdrawn from ageing. It is a constituent of chlorophyll, middle lamella, and connects with phosphate transfer in respiration, binding of ribosomes and DNA and RNA synthesis.
Manganese activates enzymes of respiration, photosynthesis and nitrogen metabolism performing oxidation, reduction decarboxylation. photolysis of water etc.
Copper is an activator of plastocyanin cytochrome oxidase, RuBP carboxylase and many other enzymes. It functions in electron transfer, maintenance of carbohydrate/nitrogen balance, chlorophyll synthesis etc.
Calcium is a constituent of middle lamella, an activator of enzymes connected with chromosome formation and many aspects of metabolism.

D.

Ca

Ca is essential macronutrient for plant growth. It is constituent of middle lamella, activator of enzymes, connected with chromosome formation and many aspects of metabolism

D.

Iron compounds

Anaemia refers to any condition in which there is an abnormally low haemoglobin concentration and/or blood cell count. The most common cause is deficiency of iron which is an essential element of haemoglobin molecule.
Thus, the iron compounds in the diet will help to alleviate the symptoms of anaemia.
Thiamine (vitamin B₁), deficiency causes beri-beri.
Riboflavin (vitamin B₂) deficiency causes cheilosis and skin diseases.

A.

pulse crops

Sulphur is constituent of certain amino acids. The amino acids form the protein by polymerisation. The pulses are rich in protein.

B.

ammonia

$\underset{\mathrm{Nitrogen}}{{\mathrm{N}}_2} \stackrel{ }{\to }\underset{\mathrm{Dimide}}{{\mathrm{N}}_2{\mathrm{H}}_2 }\stackrel{ }{\to }\underset{\mathrm{Hydrazine}}{{\mathrm{N}}_2{\mathrm{H}}_4} \stackrel{ }{\to }\underset{\mathrm{Ammonia}}{2{\mathrm{NH}}_3}$

The fixation of atmospheric nitrogen to ammonia is given as

$$\begin{gathered} {\mathrm{N}}_2 + 8{\mathrm{e}}^{-} + 8{\mathrm{H}}^{+} + 16\mathrm{ATP} \underset{\mathrm{Nitrogenase}}{\overset{\mathrm{MO} -\mathrm{Fe}}{\to }} \\ 2{\mathrm{NH}}_3 + {\mathrm{H}}_2 + 16 \mathrm{ADP} + 16\mathrm{Pi} \end{gathered}$$

The process in which atmospheric nitrogen rates concerted into inorganic nitrogenous (nitrate, ammonia) compounds through microorganisms is called biological nitrogen fixing.

A.

Nitrogen-containing polysaccharide

Macromolecules chitin is an example of complex structural hetero plysaccharide. It has nitrogen-containing glucose derivatives such as N-acetyl glucosamine.

B.

Both I and II are correct

The earliest organisms that appeared on earth were anaerobic chemoautotrophs. Chemoautotrophs were the first autotrophic organisms. They were unable to perform photolysis of water and never released oxygen, e.g. sulphur bacteria

A.

Epidermal extensions

Epidermal extensions are always unicellular, while epidermal appendages may be uni or multicellular. Root hairs are epidermal extensions formed by outward elongated bulging of a wall of epidermal cells.

C.

Frankia

Nitrogen is the most critical element. The atmosphere is the greatest reservoir of nitrogen. Molecular nitrogen cannot be utilized directly by plants. It has to be fixed or converted into compounds prior to utilization, Symbiotic nitrogen fixation is accomplished by Rhizobium species, which occurs on the roots of leguminous plants. Certain non-leguminous plants also form nodules to fix nitrogen. The best known example in temperate region is alder (Alnus sp.). The bacteria involved in nodule formation is an Actinomycetes, the Frankia.

Clostridium is anaerobic, saprotrophic, free-living nitrogen-fixing bacteria.

Bradyrhizobium is symbiont in plants of parasponia and soyabean.

The Azorhizobium forms both stem and root nodules in Sesbania (aquatic plant).

A.

Silicon

Silicon is a micronutrient/trac element which is found only in few organisms.

B.

Azotobacter

Anabaena, Nostoc and Aulosira are symbiotic Rhizobium Nitrogen fixing microbes, while.

A.

Nife gene

VAM is a symbiotic relationship between fungi and higher plants. Nif gene is responsible for biological nitrogen fixation, which directs the synthesis of the nitrogenase enzyme.

B.

The sufficient amount of sunlight stored in a cell

Green plants are called sun basket because they store solar energy by converting it into chemical energy with the help of chloroplast by the process called photosynthesis.

D.

Mg, N

Magnesium is present in the central position of tetrapyrrole ring of the chlorophyll molecule. Porphyrin is a cyclic tetrapyrrole ring made up of four nitrogen-containing pyrrole rings arranged in a cyclic fashion in the chlorophyll molecule.

D.

Nostoc

Heterocysts are modified vegetative cells specified for nitrogen fixation. These are found in blue-green algae, e.g., Nostoc.

C.

Chlorophyll synthesis

Magnesium is an important constituent of chlorophyll molecule.

B.

Calcium

A.

mottling

Molybdenum causes mottling because of this element deficiency results in sulfite toxicity. Appearance of green and non- green patches.

A.

soilless culture

Hydroponics refers to soil-less cultures of plants and growing them on mineral solution

C.

khesari dal

Lathyrism is a neurological disease causd by khesari dal (Lathyrus odoratus). It carries an ODAP, also known as β-N-oxalyl-amino-L-alanine, or BOAA which is a neurotoxin (glutamate analogue).

A.

nitrogenase

Enzyme nitrogenase plays a key role in N, fixations and remains active only during anaerobic condition. It is made up of two protein subunits :

i) non-heme iron protein or Fe-protein or dinitrogen reductase.

ii) Iron molybdenum protein or Mo-Fe protein or dinitrogenase

C.

nitrogen

The insectivorous plants grow in nitrogen deficient soil and their nitrogen requirement is fulfilled by capturing and digesting the insects.

A.

Cu, Mn, Fe

Micronutrients are minerals obtained from the soil and present in plant tissues at concentrations usually less than 3 $\mathrm{\mu }$ mol g^-1 dry matter. Copper (Cu), Manganese (Mn) and Iron (Fe) are the micronutrients which affect both photosynthesis and mitochondrial electron transport as they are the main constituents of various electron carriers.