Mineral Nutrition - Class 11 Medical Biology - Extra Questions

Why is that in certain plants deficiency symptoms appear first in younger parts of the plants while in others they do so in mature organ ?

The mobility of elements plays an important role to determine that deficiency symptoms appear first in younger or older parts of plants. Some elements like N, and K are highly mobile and moves from older parts to younger parts of plants or where they are most needed, so the symptom deficiencies of these elements first appear in older parts of the plants. And another side some elements like as Ca and S are immobile these elements are not transported from the older parts of plants so the symptoms of deficiencies have first appeared in younger parts of the plant.


Prior to sowing rice, a legume crop was cultivated and ploughed back in the field, why? Explain.

Prior to sowing rice, a legume crop was cultivated and ploughed back in the field because leguminous plant posses nitrogen-fixing bacteria (symbiotic bacteria, Rhizobium), it fixes the nitrogen, and the fixed nitrogen makes the soil rich in nitrogen which is essential for the growth of plants.


With the help of examples describe the classification of essential elements based on the function they perform. 

On the basis of function. essential elements can be classified into four categories which are as follows: 
(a) Components of Biomolecules: These are also called structural elements of cells, e.g. carbon, hydrogen, oxygen and nitrogen. 
(b) Components of Energy Related Compounds: Examples: magnesium in chlorophyll and phosphorus In ATP. 
(c) Elements which activate or inhibit enzymes: Examples: magnesium and zinc. 
(d) Elements which can alter osmotic potential of cells, example: potassium.


How are the terms 'critical concentration' and 'deficient' different from each other in terms of concentration of an essential element in plants? Can you find the values of 'critical concentration' and 'deficient' for minerals - Fe & Zn.

The concentration below which plant growth is retarded is called critical concentration for an essential element. Any concentration below the critical concentration is called deficiency 
ElementCritical concentrationDeficient
Zn0.5 - 1% <0.5%
Fe3.5 - 5%<3.5% 


______ nutrients are required in large quantity and called as _____.

Nine nutrients are required in large quantities and are called as macronutrients

The six macronutrients include C, H$$_2$$, N$$_2$$, P, K, O$$_2$$, S, Ca and Mg


From your knowledge of physiology can you think of some method of increasing the life of cut plants in a vase? 

The life of a cut plant can be increased by following methods: 
(a) Immediately put the cut plant in water. 
(b) Some mineral nutrients should be added to water. 
(c) A spray of hormone cytokinin also helps in prolonging the life of the cut plant. 


_____ and _____ are supplied by air to plants. 

Carbon dioxide and Oxygen are supplied by air to plants.

Carbon dioxide is converted to Glucose and Oxygen is used for respiration.



______ nutrients are needed in small quantities by plants and are called ______.

Seven nutrients are needed in small quantities by plants and are called micronutrients
The seven micronutrients include Cl, B, Cu, Mn, Fe, Zn and Mo


Suggest a suitable word for the following statements.
Nitrogen-fixing microorganism present in the root nodules of legumes.

A bacteria called  Rhizobium fixes nitrogen into a form that helps plants to use it in different forms such as nitrate and nitrites. 


Excess of Mn in soil leads to deficiency of Ca, Mg and Fe. Justify. 

Manganese competes with iron and magnesium for uptake and with magnesium for binding to specific enzyme. It also inhibits calcium translocation in shoot apex. Hence, excess of magnesium may induce deficiency of Ca, Mg and Fe. 


Write an essay on Macronutrients.

Macronutrients:Essential elements which are found in a plant in the range of 1.0 to 10.0 mg per gram of dry weight of plant are called macronutrients or mega nutrients.
These are further divided into two categories.
  • Primary macronutrients - Nitrogen, Phosphorus and Potassium are also called as critical elements and soils normally show a deficiency of these elements.
  • Secondary macronutrients - Calcium, Magnesium, and Sulphur are secondary macronutrients.


Write the name of primary macronutrients.

Nitrogen (N), Phosphorus (P), and Potassium (K). are primary macronutrients.


Explain symbiotic nitrogen fixation.

Nitrogen fixation is the conversion of atmospheric nitrogen to Ammonia(NH3) Symbiotic Nitrogen fixation is the process of N2 fixation in presence of microbes. Symbiotic Nitrogen fixation generally takes place commonly in legumes as non-legumes plants. Roots of leguminous plants like Alfa Alfa associate with help of microbes like Rhizobium in case of leguminous N2 fixation. They associate through the help of nodules which are small outgrowths present on the roots. Microbes like Frankia helps to fix nitrogen in non-legumes. Rhizobium and Frankia can easily fix Nitrogen in symbiotic association.


Why is the purification of water and nutrient salts so important in studies involving mineral nutrition using hydroponics?

In hydroponics carefully prepared standardised  nutrient solutions are used for growing plants. These nutrients are taken up by the plroots of the plants. It is essential to purify the water we use and remove any minerals present in it. This is because the preparation of standard nutrient solution has a fixed concentration of minerals and any minerals if present previously and not removed from the water will cause an error in proper resolution. Hence purification of water and minerals is required for obtaining maximum optimum growth of plants.


Deficiency diseases occur in human beings due to lack of nutrients. Does it occur in plants too? Give an example.

Yes deficiency diseases occur in plants too.
Example : 
calcium deficiency in plants happens because of low transpiration rates or overall less accessibility, and also because calcium cannot be transported in the phloem and its local deficiency can cause symptoms like necrosis of the leaves and stunted growth.


Leguminous plants improve soil fertility. How?

Nitrogen fixing bacteria live in roots of leguminous plants and form root nodules. This is a symbiotic relationship between them. The nitrogen fixing bacteria help in nitrogen fixation or conversion of atmospheric nitrogen into forms usable by the plants. Hence they restore the lost nutrition from the soil. Often legumes are grown in fields that have been depleted in their sources of nutrition. Hence they are important in improving the fertility of the soil.


Define hydroponics.

Cultivation of plants by placing the roots in the nutrient solution without any soil is called hydroponics. It is also known as soilless culture/ water culture/ solution culture. It is used to determine which elements are essential for plant growth and what symptoms are produced by the absence or deficiency of essential elements.


What is he agriculture done in fresh water is known as?

Hydroponics is the technique of culturing the plants in a nutrient solution without soil. It is also known as soilless culture. It helps in production of healthy plants without use of traditional methods.


Macronutrient and Micronutrient

On the basis of the relative quantity of elements found in plants, the minerals are divided into macronutrient and micronutrient. Macronutrients are the elements required by the plants comparatively in large quantity. eg. carbon, hydrogen, phosphorus etc. Micronutrients are the elements required by the plant in small quantity eg. zinc, boron, copper etc.


Name the scientist who introduced hydroponics.

William Frederick Gericke was the scientist who introduced hydroponics in the year 1937.


Name the best known symbiotic nitrogen fixing bacterium.

Rhizobium.
It is present in root nodules of leguminous plants.


What are framework elements?

Carbon, Hydrogen and Oxygen: Although these macronutrients elements are not minerals in the true sense, they are still included in the list as they are most essential for plant life. These three elements are also called framework elements. Plants absorb them from air and soil in the form of carbon dioxide and water.


Describe symbiotic nitrogen fixation with the help of a diagram.

Symbiotic nitrogen fixation is the type of biological nitrogen fixation. In this, the atmospheric nitrogen is converted into the nitrogenous compounds through living organisms. It is of 2 types, symbiotic nitrogen fixation and non-symbiotic nitrogen fixation. Microorganisms involved in symbiotic nitrogen fixation includes Rhizobium and Frankia and that in non-symbiotic nitrogen fixation includes Azospirillum, Azotobacter, BGA. Rhizobium is aerobic, gram negative nitrogen fixing bacterial symbionts of Papilionaceous roots. Plants from legume family contain rhizobia within nodules in the root systems. They fix the atmospheric nitrogen and produce nitrogen compounds that help the plant to grow. Plants in turn provides sugars that are utilized by the rhizobia for the energy it requires for nitrogen fixation. Hence, they live in symbiotic association.

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Name the organism that fixes nitrogen in symbiotic association with a water fern. Where does it live in such plants? 

Anabaena a cyanobacterium is symbiotically associated with water fern  Azolla  pinnata . This bacterium  dwells in ovoid cavities of the leaf in Azolla .
The bacterium fixes atmospheric $$N_2$$ for the plant.


Why are leguminous plants cultivated as green manure crop?

Leguminous plants possess root nodules where atmospheric nitrogen is fixed by symbiotic bacteria- Rhizobium. The fixed nitrogen fertilizers the soil. Moreover, the green plants provide manure by their death and decay. So, leguminous plants are cultivated as green manure crops.



Soil supply _____ nutrients to plants.

Soil supplies 13 nutrients to the plants.

Out of the 16 essential nutrients 3, that is, C, O$$_2$$ and H$$_2$$ are obtained from air, rest of the nutrients are absorbed from soil.


Explain the steps involved in the formation of root module.

Roots of legume release sugars, amino acids which attracted Rhizobium. They get attached to epidermal and root hair cells of the host.
The root hair curl and the bacteria invade the root hair.
An infection thread is produced, carrying the bacteria into the cortex of the root.
Bacteria initiate nodule formation in the cortex of the root. Then the bacteria released from the thread to the differentiation of specialised nitrogen-fixing cells,
The nodule thus formed establishes a direct vascular connection with the host for the exchange of nutrients.

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A total of ______ nutrients are essential to plants.

A total of 16 nutrients are essential to plants.

The sixteen nutrients include, C,H,O, N, P, K,Ca, Mg,S, Cu, Zn, Mn, Fe, B, 
Mo and Cl


_______ is supplied by water to plants.

Hydrogen is supplied by water to plants.

Hydrogen is used to reduce carbon dioxide to glucose and is obtained by splitting of water molecules in presence of light.


What is nitogen fixation and name two microbes which bring about the same.

Nitrogen fixation is defined as the process of reduction of nitrogen to ammonia by the action of some chemical or biological agent. The enzyme, nitrogenase which is capable of nitrogen reduction is exclusively present in prokaryotes. Such microbes are called as Nitrogen-fixers. The microbes bringing nitrogen fixation can be free-living or symbiont. Such as-
Free-living- Azotobacter
Symbiont- Frankia in Alnus leguminous plant roots. 


What are micro nutrients?

The mineral elements required by plants in trace or micro amounts are called micronutrients. They are iron, manganese, boron, zinc, copper, molybdenum and chlorine.


Match column I (Elements) and Column II (Functions).

The chemical elements and compounds that are essential for plant growth and metabolism are classified as macro and micronutrients. All of them are essential for plant growth.
  • Calcium is utilized for continuous cell division and the formation of mitotic spindle fibres.
  • Boron is essential for the proper forming and strengthening of cell walls and calcium metabolism.
  • Phosphorus is involved in a number of vital plant processes and is an important structural component of nucleic acids.
  • Chlorine is necessary for osmosis and ionic balance.
  • Manganese is necessary for photosynthesis and for activating the respiratory enzyme.
So, A-5, B-3, C-2, D-1, and E-4 are the correct match.


What are the steps involved in formation of a root nodule?

  • Root nodules are found in plants belonging to the family Fabaceae or Leguminosae.
  • They include leguminous plants like beans, peas, peanuts etc.
  • It is formed due to the symbiotic association between the leguminous plant and the host-specific bacteria called the rhizobium.
  • The steps involved in root nodule formation are- 
1) Rhizobium bacteria divides to form colonies which surround the root hairs and epidermal cells of the plant.
2) The root hair gets curled and get invaded by the bacteria.
3) After the invasion, it forms an infection thread that carries the bacteria into the cortex of the root. 
  • Later the bacteria gets modified into rod-shaped bacteria called bacteroids.
4) As a result, the cells in the cortex and pericycle undergo cell division, which forms the root nodules.
5) These root nodules get connected with the vascular tissues of the roots for nutrient exchange and help in nitrogen fixation.


Why is purification of water and nutrient salts so important in studies involving mineral nutrition using hydroponics?

Hydroponics is the art of growing plants in a nutrient solution in the absence of soil. Since the plant roots are exposed to a limited amount of the solution, the concentrations of minerals in the plant roots are reduced. Therefore, in studies involving mineral nutrition using hydroponics, purification of water and nutrient salts is essential to maintain the optimum growth of the plants.


Match the followings and choose the correct combination from the options given:

 A. Sulphur 3. Methionine (Sulphur is present in this amino acid)
 B. Zinc 4. Auxin (Zinc is present in this hormone)
 C. Magnesium 1. Chlorophyll (Mg is the central atom in it)
 D. Molybdenum 2. Nitrogenase (it is very important for the working of this enzyme)


 Match the items in Column-I with those in Column-II, and choose the correct answer.

Nitrogen fixation- Nitrogen in earth's atmosphere is converted to ammonia by the nitrogen-fixing bacteria such as Azotobacter.
Ammonification- The process of production of ammonia from organic compounds is known as ammonification. The bacteria that accomplish it are Bacillus, Clostridium, Proteus, Pseudomonas and Stretomyces.
Nitrification- The conversion of soil ammonia to nitrates that are usable by plants is known as nitrification. The bacteria that convert ammonia to nitrates are Nitrosomonas, nitrosporia, Nitrosococcus etc.
Denitrification -The microorganism which converts nitrates in atmospheric nitrogen. The organisms are Thilobacillus denitrificans, Micrococcus denitrificans etc.


Explain the role of the pink pigment in the root nodule of legume plants. What is it called?

There are nodules in the roots of the leguminous plants. The bacterium of the Rhizobium spp. are responsible for the formation of these nodules. The nodules appear pink in colour due to the presence of leghemoglobin. This is an iron-containing pigment which is pinkish in color. The pigment is responsible to scavenge oxygen for the functioning of the enzyme nitrogenase in nitrogen fixation. 


Explain the steps involved in the formation of root nodule.

There are many different type of reactions and interactions occur during the formation of root nodules. The Rhizobium is a soil bacterium which is known to have symbiotic association with the legume plants. There are formation of nodules in the roots of this plant by the bacterium. The bacterium penetrates the cells of the root, divide in the cortical cells and the form the colonies. 
The bacteria first gets attached to the root hairs and then enter the epidermal cells. The root hairs are invaded by the bacteria. The bacteria then moves into the cortex of the root. The bacteria get transformed into rod-shaped cells which are known as the bacteroides. The cells in the cortex undergo division, leading to the formation of root nodules. The nodules finally get connected with the vascular tissues of the roots for the purpose of nutrient exchange.


What is holdfast? What is its use? Mention the species of spirogyra having holdfast.

The basal cell in certain species of the aquatic plant Spirogyra is modified. The modified cell which helps the plant to attach to the substratum is known as the holdfast. The cell allows the attachment of the plant to a fixed surface. Spirogyra fluviatilis, S. rhizoides and S. dubia are the examples of the species of the Spirogyra which have the holdfast for the attachment. 


Explain the role of the pink color pigment in the root nodules of legume plants. What is it called?

There are nodules in the roots of the leguminous plants. The bacterium of the Rhizobium spp. are responsible for the formation of these nodules. The nodules appear pink in colour due to the presence of leghemoglobin. This is an iron-containing pigment which is pinkish in color. The pigment is responsible to scavenge oxygen for the functioning of the enzyme nitrogenase in nitrogen fixation. 


Plants and animals are interdependent. Do you agree with this statement?  Comment.

Plants produce food and oxygen through the photosynthesis and these are used up by animals for nutrition and respiration. They are hence called producers and occupy the first trophic level. These animals use oxygen and the food prepared by plants as sources of energy and release carbon dioxide. Carbon dioxide is used by plants for photosynthesis. Also when animals excrete or are degraded after death, the minerals and nutrients from their bodies are absorbed by the plants again. Hence they are inter dependent on each other. 


Why do plants depend on organisms like Nostoc and Rhizobium?

Nostoc improves the texture and stability if the soil aggregates and protects it from floods and dessication. They also help in reducing pollution. They have very important roles in the environment as they help in nutrient cycling.
Rhizobium is a Nitrogen fixing bacteria live in roots of leguminous plants and form root nodules. This is a symbiotic relationship between them. The nitrogen fixing bacteria help in Nitrogen fixation or conversion of atmospheric Nitrogen into forms usable by the plants. Hence they restore the lost nutrition from the soil. Often legumes are grown in fields that have been depleted in their sources of nutrition. Hence they are important in improving the fertility of the soil.


$$NH_{4}^{+} + 30_{2} \xrightarrow {Nitrosomonas}$$ ____ $$+ 2H_{2}O + Energy$$.

Nitrosomonas species is responsible for the transformation of ammonium into nitrite. They increase the availability of nitrogen to plants and hence play an important role in the nitrogen cycle.
$$\underset{Ammonium}{2NH_4^+}+3O_2\xrightarrow{nitrosomonas} \underset{Nitrite}{2NO_2^-} + 2H_2O + 4H^+$$


........... bacterium is found in the roots of leguminous plants.

Rhizobium bacterium is found in the roots of leguminous plants. It forms a mutual association with the roots of the leguminous plants. This bacterium forms nodules in the cortical cells of the roots. They perform nitrogen fixation with the help of nitrogenase enzyme. They are commonly used as biofertilizers because their activity of nitrogen fixation causes an increase in the yield of the legume plants. 


The bacterium involved in symbiotic nitrogen fixation is ____________.

Nitrogen-fixing bacteria such as Rhizobium live in the root nodules of the leguminous plants. They are capable of converting atmospheric gaseous nitrogen into available forms such as ammonia. So, rhizobium is the most important bacterium involved in the symbiotic nitrogen fixation.


Explain hydroponics (soil-less culture) with diagram. Write its two advantages.

Cultivation of plants by placing the roots in the nutrient solution without any soil is called hydroponics. It is also known as soilless culture/ water culture/ solution culture. The solution is aerated at regular intervals by means of an inlet tube.
Advantages-
1) It is used to determine which elements are essential for plant growth. 
2) The symptoms produced by the absence or deficiency of essential elements.

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What are the indications for mineral deficiency in plants?

1. Chlorosis is a physiological disorder that occurs due to deficiency of the mineral elements (eg; Mn, K, Zn, Fe, Mg, P, S). Leaves become abnormally yellow.
2. Mottled is surface marked with colored spots eg Due to deficiency of N, Mg, P, S.
3. Necrosis refers to a patch of dead tissue, due to deficiency of Mg, K, Zn, Ca and No.


If a plant shows symptom which could be due to deficiency of more than one nutrient, how would you find out experimentally the real deficient mineral element?

In plants, the deficiency of a nutrient can cause multiple symptoms. 
For eg the deficiency of nitrogen (N) causes chlorosis, dormancy of lateral buds, delaying of flowers.
In a similar way, deficiency of a nutrient can cause the same symptom as that caused by the deficiency of another nutrient. For eg, necrosis is caused by a deficiency of calcium, magnesium, copper, and potassium. Also, different plants respond in a different way to deficiency of the same nutrient.
Hence, to identify the nutrient deficiency in a plant all the symptoms developed in its different parts must be studied and compared to actually know the real deficient mineral.


Differentiate between essential and nonessential mineral elements ?

Essential elements are that elements which we need to take it from the food or another external medium, it can not be synthesized in body e.g., N, K, S etc.
Whereas nonessential elements are those elements which are synthesized in body, and also provided by food in the small amount e.g., Al, Br, Co etc. 


What are various steps involved in biological nitrogen fixation in plants?

The various steps involved in Nitrogen fixation are:
1. Nitrogen fixation : It is the conversion of atmospheric nitrogen into forms usable by the plants. Certain bacteria like cyanobacteria can perform this process by using nitrogenase enzyme. These convert nitrogen gas to ammonia.
2. Nitrification : It is the conversion of Ammonia to Nitrates. Nitrosomonas and Nitrococcus convert it into nitrites which are inturn converted to nitrates by Nitrobacter. 
3. Assimilation : It is the incorporation of ammonia and nitrates formed by nitrogen fixation and nitrification into the plants. Their roots absorbs these and it gets assimilated into the plant body.
4. Ammonification : It is the conversion of organic nitrogen into ammonia. This ammonia is then released into the environment and reused.
5. Denitrification : It is the process of breaking down of nitrates back to nitrogen gas by the action of anaerobic bacteria. 


Which is the most abundant element in the plant body?

Carbon is the most abundant element present in the plant body. It is present in amino acids, nucleic acids, lipids, carbohydrates. 


Why are leguminous plants useful for maintaining soil fertility?

Leguminous plants have root nodules that contain nitrogen fixing bacteria. A symbiotic relationship between the plant and rhizobium gives rise to these. These bacteria convert atmospheric nitrogen into forms that are usable by the plants such as ammonia. They restore the lost nitrogen content of the soil.


What type of condition is created by leghaemoglobin in the root nodule of a legume?

The leghaemoglobin is responsible for creating anaerobic conditions in the root nodules of the legume plant. It acts as oxygen scavenger and protects enzyme nitrogenase from oxygen and helps in proper functioning of the enzyme.


Name the respective mineral nutrient element that: 
(i)   Forms the core constituent of the ring structure of chlorophyll 
(ii)  Activates carboxylases 
(iii) Forms the component nitrogenase 
(iv) Synthesizes middle lamella of plant cells

1) Magnesium (Mg)
2) Manganese (Mn) 
3) Molybdenum and Iron  (Mo & Fe) 
4) Calcium (Ca)


What is hydroponics? Give an application of this technique .  

The practice of growing plants in nutrient-enriched water without soil is called soilless growth or hydroponics.
Application:
It is a special technique used in nutritional studies of plants. The plants are raised in large tanks made of borosilicate glass or natural polythene, containing a nutrient solution and are supported by wire netting. Tanks are provided with a solution regulating and pumping systems and are placed under controlled conditions. Iron is added as Fe-EDTA to keep the metal in soluble water (chelating agent or ligand). Because the plants are grown in large tanks, the process of soilless cultivation is also known as tank farming. Hydroponics is useful in areas having thin, infertile and dry soils.


Name a chelate. Why is iron added in hydroponics along with chelating agent ? 

Ethylene diamine tetra acetic acid (EDTA) is a chelate. Iron prevent the solution form getting participated so iron added in hydroponics along with chelating agent.


How are mineral elements absorbed by the plants?

ElementAbsorbed as
Nitrogen
Mainly as nitrates
Phosphorus As phosphate ions 
PotassiumPotassium Ions
CalciumCalcium ions
SulfurSulphate 
IronFerric ions
Mineral elements are absorbed by plants.


What are the steps involved information of root nodule?

Following are the steps involved in the formation of root nodules.

1) Plant and bacterium recognize each other for root hair attachment.

2) Nod factor is oligosaccharide signalling molecules that are secreted by the bacterium.

3) Root hair gets invaded by bacteria.

4) Infection thread is formed and bacteria get transferred to the main root.

5) Bacteroids that are modified bacterial cells are formed within the cell. This leads to the development of Nitrogen fixation stage. The bacteroids result from rapid multiplication of rhizobia inside plant cells. They form a swollen tumour-like structure. Bacteroids are surrounded by plant cytoplasmic membrane and the whole structure is called symbiosome. After formation of symbiosome, the nitrogen fixation stage starts.

6) Mature root nodule is formed by cell division of plant and bacteria.



Define the terms : (i) Hydroponics (ii) Micronutrients (iii) Macroelements (iv) Carnivorous plants (v) Nutrient .

(i) Hydroponics: Hydroponics is a method of growing plants without soil with their roots exposed to the mineral solution e.g., Asparagus, beans, beets etc.
(ii) Micronutrients: Minerals and vitamins these two types of micronutrients, Which required in the small amount to the living organism for their survival e.g., Al, Mo, Ni etc.
(iii) Macroelements: Macroelements are those essential elements which are required in the large amount to the body for their survival e.g., K, Ca, Mg etc.
(iv) Carnivorous plants: Carnivorous plants are that plants which nutrients are some or most trapping or consumption protozoan or some insects. They catch insects or protozoan to complete their nutrient nitrogen e.g., Nepenthes lowii.
(v) Nutrient: A essential materials or substances which provide for the development and growth in the life cycle of the living organism is called nutrient e.g., vitamins, carbohydrates, fats, proteins, minerals etc.


Your advice is sought to improve the nitrogen content of the soil to be used for cultivation of a non-leguminous terrestrial crop.
(a) Recommend two microbes that can enrich the soil with Nitrogen.
(b) Why do leguminous crops not require such enrichment of the soil?

(a) Two microbes that can enrich the soil with Nitrogen are:-
        1.  Nostoc
        2. Azotobacter
(b) Leguminous plants are capable of Nitrogen fixation by virtue of their partnership with the bacterium. The Nitrogen fixation in leguminous plants starts with nodule formation in the roots. A common soil bacteria, Rhizobium invades the roots and multiplies within the cortex (thus forming nodules). It fixes the atmospheric Nitrogen in the leguminous roots, whereas the legume provides the bacteria with energy and nutrition. Hence, due to the symbiotic relationship between the leguminous plants and the Nitrogen fixating bacteria, the soil does not require Nitrogen enrichment.


What are micronutrients? Write two examples of it? 

Micronutrients are the essential nutrients which are required in traces i.e. equal to or less than 0.1 mg/g of dry matter by the plants. There are six micronutrients.
Micronutrients are mainly involved in the functioning of enzymes as cofactors or metal activator. They become toxic if there is the increase in their concentration.
Examples of micronutrients are Zinc(Zn) , Copper(Cu).


Differentiate between macro and micro element.

MACROELEMENTMICROELEMENT
They are present in the plant in large quantity.They are present in the plant in small quality.
They build up plant body and different protoplasmic constituents.They do not build up the plant body.
They are not toxic when in slight excess.
They are toxic when in slight excess.
Examples include carbon, potassium, sodium, oxygen.Examples include zinc, boron, copper, nickel.


Very short answer type.
Name the nitrogen fixing bacterium of root nodule in a leguminous plant.

The nitrogen-fixing bacterium in root nodule shows the symbiotic relationship and these plants belong to the genus Rhizobium.


Premature leaf fall is caused due to the deficiency of ..........

nitrogen


Very short answer type.
Name any two macronutrients and state their importance in plant nutrition.

(i) Nitrogen : an integral part of amino acids, proteins, vitamins, coenzymes, nucleotides, alkaloids and chlorophyll.
(ii) Magnesium : a constituent of chlorophyll molecule; an activator for many enzymes like ATPase, helps in photosynthesis and carbohydrate metabolism.


Short / Long answer type questions.
Differentiate between:
(a)Sap wood and heartwood,  (b) Cork cambium and vascular cambium,  (c) Phellem
and phelloderm,  (d) Soft wood and hardwood,  (e) Fascicular cambium and interfascicular cambium

 SapwoodHeartwood 
 Lighter in colourDarker in colour 
 Helps in the conduction of water and minerals from root to leaf in old trees Does not conduct water but gives mechanical support to the stem due to its hard and durable nature
 Cork cambium Vascular cambium
 Develops from secondary lateral meristemDevelops from apical meristem 
 Give rise to bark and secondary cortexGive rise to secondary xylem and phloem 
 Produces the lenticelsProduces the medullary rays 
 Provides protection against the damage and prevents water lossProvides vascular tissues for water and minerals conduction 
 PhellemPhelloderm 
 Called as corkCalled as the secondary cortex 
 Composed of dead cellsComposed of living cells 
 Cells are closely packedCells are densely packed 
 Highly suberizedNot suberized 
 Impermeable to water due to the presence of suberin Permeable to water
 Produced by phellogen towards the outer sideProduced by phellogen towards the inner side 
 SoftwoodHardwood 
 Usually less denseUsually denser 
 They are gymnosperms that remain evergreenThey are angiosperms that come from deciduous trees 
 Examples include: Pine, redwood and larchExamples include: Eucalyptus, beech and Blackwood 
 Fascicular cambium Interfascicular cambium
 The meristematic tissue which develops within the vascular bundles. The meristematic tissue which develops between the vascular bundles.
 It is a primary meristem. It is a secondary meristem.


Fill in the blanks with approriate words.
Growing plants in aqueous nutrient medium is known as ..........

hydroponics


Short / Long answer type questions
Why are the elements Mn, Zn, B, Cu, and MO referred to as trace elements?

Elements that are present at low concentrations in the soil is called as trace elements
Mn, Zn, B, Cu, and MO are the trace elements act as essential micronutrients and involved in the catalytic enzymatic reactions
Ecosystem productivity and community structure may be impacted by trace elements either as limiting nutrients or as toxicants


Differentiate between micronutrients and macronutrients of plants.

The roots of green plants absorb a large number of elements from the soil. Some of these elements are absolutely necessary for normal growth and development of the plant. These elements, said to be macronutrients, are potassium, calcium, magnesium, iron, carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus. Macronutrients must be present in plant tissues in concentration of at least one milligram per gram of dry matter. There are other elements which are specifically required by the plant in very minute quantities, and these elements are known as micronutrients. Manganese, copper, molybdenum, zinc and boron are essential micronutrients.


Fill in the blanks with approriate words.
Elements required by plants in relatively large amounts are .......... and in very small amounts are ..........

macronotrients, micronutnents


Very short answer type.
What is chlorosis?

Yellowing of leaves due to low chlorophyll contents is called chlorosis.


Differentiate between
Guttation and bleeding.

The loss of liquid drop from the hydathodes present on the margins of leaves is called as guttation, while the exudation of cell sap from an incision made in a plant is called bleeding.


Very Short Answer Type :
Explain why salt is added in excess to pickles.

Excess salt is added to pickles to avoid the growth of micro-organisms. The growth is retarded due to exosmosis.


Very Short Answer Type :
Jamming of wooden doors and windows takes place during rainy season. Give reason.

During rainy season, wooden doors and windows quickly absorb water from the atmosphere and swells up considerably. This swelling up as a result of absorption of water is called imbibition. Hence, jamming of wooden doors and windows takes place during rainy season.


Short / Long Answer Type Questions :
What are biofertilizers? What are their main sources? What is biological nitrogen fixation? Name two organisms each which fix nitrogen asymbiotically and symbiotically.

A biofertilizer is a substance which contains living microorganisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. The main sources of biofertilizers are bacteria, fungi, and cynobacteria (blue-green algae). Plants have a number of relationships with fungi, bacteria, and algae. 
Biological nitrogen fixation (BNF) is the process whereby atmospheric nitrogen (N=N) is reduced to ammonia in the presence of nitrogenase. Nitrogenase is a biological catalyst found naturally only in certain microorganisms such as the symbiotic Rhizobium and Frankia, or the free-living Azospirillum and Azotobacter.
 All the nitrogen-fixing organisms are prokaryotes (bacteria). Some of them live independently of other organisms - the so-called free-living nitrogen-fixing bacteria. Others live in intimate symbiotic associations with plants or with other organisms (e.g. protozoa).The most familiar examples of nitrogen-fixing symbioses are the root nodules of legumes. In these leguminous associations the bacteria usually are Rhizobium species, but the root nodules of soybeans, chickpea and some other legumes are formed by small-celled rhizobia termed Bradyrhizobium.  Free-living aerobic bacteria of soils, such as Azotobacter and Beijerinckia.



Short / Long answer type questions .
Why is osmotic potential given a negative sign ?

Osmotic potential is the free energy of the water in a system due to the presence of solute particles. This value of osmotic potential is always negative because the presence of solute will always make a solution have less water than the same volume of pure water (means no solute particles are present). Though the osmotic potential is numerically equal to the osmotic pressure.


Match the element with its associated functions/roles and choose the correct option given among below.

Boron - Zinc
Manganese - Boron
Molybdenum - Molybdenum
Zinc - Manganese
Iron - Iron
So, the correct option is 'A-4,B-1,C-3,D-2,E-5'.


Which one among the following can fix atmospheric nitrogen? Why?
  • Mycorrhiza of Pinus
  • The coralloid root of Cycas

  • Mycorrhizal fungi themselves do not fix nitrogen but bacteria that may associate with them can. Generally, mycorrhiza improves the health of the plant and their roots so diseases may cause less damage.
  • Within the colloidal root is the cyanobacterial zone, which is the region inhabited by cyanobacteria. All cyanobacteria in symbiosis with cycas have the ability to fix nitrogen.


Discuss in short about symbiotic nitrogen fixers.

Anabaena, Nostoc, Rhizobium , Frankia, Xanthomonas, Aulosira

  • Anabaena or Anabaena azollae are phototropic cyanobacteria (blue-green algae) which fixes the atmospheric nitrogen to provide nutrients to plants.

  • Nostoc is a genus of cyanobacteria which also fixes atmospheric nitrogen.

  • A Rhizobium is a group of bacteria present in the root nodules of leguminous plants which fix atmospheric nitrogen.

  • Frankia is a genus of filamentous bacteria which helps in fixing nitrogen and shows symbiotic association with different plants. 

  • Xanthomonas is a genus bacteria which causes plant diseases.

  •  Aulosira is also a genus of filamentous cyanobacteria which are active nitrogen fixers in paddy fields.



Enlist essential elements?

The elements which are needed by the plants to carry out normal physiological functions are called essential elements. 13 elements, are considered as essential elements. There are two types essential elements
1. Macronutrients or major elements: These elements are required by the plants in large quantities. They are Nitrogen, Pottasium, Phosphorous, Calcium, Sulphur, Magnesium.
2. Micronutrients or trace elements: The remaining 7 elements are required in small quantity. They are Iron, Zinc, Manganese, Copper, Molybdenum, Boron, Chlorine.


What are macro-nutrients and micro-nutrients?

 MACRONUTRIENTS MICRONUTRIENTS
 Macronutrients are the nutrients that are required in a huge amount for a living being like fats proteins carbohydrates. Micronutrients are the nutrients that are required in less amount for a living.
 
Chemical elements that are required in large amount by plant's body like potassium, calcium, magnesium.
Chemical elements that are required in less amount by plant's body like Copper, Iodine 


Carnivorous plants like $$Nepenthes$$ and Venus flytrap have nutritional adaptations. Which nutrients do they especially obtain and from where?

Nepenthes and venus fly trap grow in nitrogen-deficient soil. So, they make' up their nitrogen deficiency by trapping insects for which they have developed special adaptations




Read the following statements and mark them as True (T) or False (F).

(a) Plants can assimilate ammonium ions only 
(c) Rhizobium is an obligation anaerobe
(c) In legumes, the nodule is formed by the inner cortex and pericycle cells.

(a) Plants can assimilate ammonium ions only- False
(b) Rhizobium is an obligation anaeroba -False
(c) In legumes, the nodule is formed by the inner cortex and pericycle cells- True


Give reason for the following.
Sodium and potassium are stored in Kerosene.

Sodium and potassium are stored in kerosene because they are highly reactive elements. They can easily catch fire even when in contact with air.
  • Concept insight: sodium and potassium are so highly reactive that they react with water vapour present in air. So they are stored in kerosene.


Describe the nodule formation in leguminous plants.

Rhizobium is a certain bacteria that shows symbiotic association with the root nodules of leguminous plants to help fix nitrogen present in the air. These bacteria get attached to the root hairs of the plant and divide to form several colonies. They now form an infection thread and enter the cortex of the root cells. This causes the cortex and the pericycle to divide and form root nodules and the bacteria to move towards the vascular bundles and help in the exchange of nutrients.


Name the element that activates the enzyme nitrogenase

The biological nitrogen fixation is done by bacteria or cyanobacteria and symbiotic bacteria. 
In symbiotic relationship bacteria provides fixed nitrogen to host and gets carbohydrates from other. 
In this process atmospheric nitrogen is reduces in presence of nitrogens to form ammonia.

Molybdenum activates nitrogenase.


What is biological fixation? How is it different from nitrification? Give examples of organisms involved in each of these.

Biological fixation is the process of converting atmospheric nitrogen into the nitrogenous compounds which plants require. This process occurs in the presence of the bacteria associated with the plants.
Examples include Azotobacter, Rhizobacterium, Anabena, etc.

Nitrification is the process of conversion of ammonia into its nitrites and nitrates as plants take nitrogen mostly in the form of nitrates.
Examples include Nitrobacter, Nitrosomonas, etc.


Why micronutrients and macronutrients are called so ?  What role do they play?

Plants require 16 elements in small or large quantities for proper growth and development.
These elements are obtained from air and from soil, dissolved in water.
Micronutrients - are elements required by plants in very small quantities to be utilized for their growth and development process.
These are seven elements namely, Boron, Chlorine, Zinc, Copper, Molybdenum, Iron and Manganese.
Macronutrients: are elements required by the plant in large quantities for their growth and development.
These are nine elements namely - Nitrogen, Phosphorus, Potassium, Hydrogen, Carbon, Oxygen,Calcium, Magnesium and Sulfur


It is observed that deficiency of a particular element showed its symptoms initially in older leaves and then in younger leaves. 
Does it indicate that the element is actively mobilized or relatively immobile?

This indicates that the element is actively mobilized. Elements which are actively mobilized show deficiency symptoms first in older parts of a plant. 


Name the macronutrient which is a component of all organic compounds but is not obtained from soil. 

Carbon is the macronutrient that is not obtained by soil but is taken in through the stomata in the form of Carbon dioxide gas.


Give the biochemical events occurring in the root nodule of a pulse plant. What is the end product? What is its fate? 

The root nodule contains all the necessary biochemical components required for nitrogen fixation. For example: it contains the enzyme nitrogenase and a pigment leghaemoglobin. Nitrogenase is Mo-Fe protein. It catalyses the conversion of atmospheric nitrogen into ammonia. Ammonia is the first stable product of nitrogen fixation. Conversion of atmospheric nitrogen into ammonia can be shown by following equation:
$$N_2 + 8e^- + 8H^- + 16 ATP \rightarrow 2NH_3 + H_2 + 16 ADP + 16 P_i$$
The following figure shows the conversion of nitrogen into ammonia: 
Fate of Ammonia: Ammonia gets converted into ammonium ion. Most of the plants can assimilate nitrate and ammonium Ions. But ammonium ion is quite toxic and cannot accumulate in plants. Hence, ammonium Ion is converted into amino acids; through transamination and reductive amination. 
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Write an essay on micronutrients.

Micronutrients:
The essential elements which are found less than 1.0 mg per gram of dry weight of plant are called micronutrients. Although these are found in low amount, they play an important role in plant metabolism. These are also called trace elements. These are eight in number. Example: B, Cu, Cl, Mn, Mo, Zn, Fe and Ni.


Describe plant ash analysis.

  • This method is used to determine the presence of a relative amount of various elements in the plant.
  • In this method when fresh plants are dried at $$70 - 80^0$$C in the oven for one or two days so that, all water present in the plant is driven off.
  • The remaining part is weighed and the dry weight of the plant is obtained.
  • The main constituents of the dry matter are the polysaccharides, lignin, proteins, fats, organic acids and some other elements.
  • This dry matter is burnt in a furnace at $$600^0$$C, as a result, all organic compounds are oxidized and are driven off in the form of gases ($$CO_2$$, $$NH_3$$ and $$SO_2$$ etc.)
  • The remaining material is called plant ash and contains only mineral elements.
  • The relative amount of various minerals can be determined by analysis of this ash. However, the extent of their utilization and essentiality cannot be determined by this method.


Explain Chlorosis and Necrosis.

  • Chlorosis: Due to the degradation of chlorophyll, the leaves become decolourized and become pale yellow coloured. This effect is called chlorosis. Deficiency of Mg, N, Fe, and Mn etc. result in chlorosis.
  • Necrosis: Death or degradation of cells of plant tissue is called necrosis. Due to this effect, the leaves show spots, rotting, or blight symptoms. Deficiency of Ca, Mg, Cu, and K etc. causes necrosis of cells.


What are the conditions necessary for fixation of atmospheric nitrogen by Rhizobium. What is their role in N$$_2$$ fixation?

Rhizobium is a symbiotic bacteria present in the root nodules of leguminous plants. The basic requirements for Rhizobium to carry out nitrogen fixation are as follows :
(a) Presence of the enzyme nitrogenase
(b) Presence of leg-haemoglobin
(c) Non-haem iron protein, ferrodoxin as the electron-carrier
(d) Constant supply of ATP
(e) $$Mg_{2+}$$ ions as co-factors
Rhizobium contains the enzyme nitrogenase – a Mo-Fe protein – that helps in the conversion of atmospheric free nitrogen into ammonia.
The reaction is as follows :
$$N_2 + 8e^– + 8H+ + 16 ATP → 2 NH_3 + H_2 + 16ADP + 16Pi$$
The Rhizobium bacteria live as aerobes under free-living conditions, but require anaerobic conditions during nitrogen fixation. This is because the enzyme nitrogenase is highly sensitive to molecular oxygen. The nodules contain leg-haemoglobin, which protects nitrogenase from oxygen.


Explain with examples : macronutrients, micronutrients, beneficial nutrients, toxic elements and essential elements.

Macronutrients : They are the nutrients required by plants in large amounts. They are present in plant tissues in amounts more than 10 mmole kg–1 of dry matter. Examples include hydrogen, oxygen, and nitrogen.
Micronutrients : They are also called trace elements and are present in plant bodies in very small amounts, i.e., amounts less than 10 mmole kg– 1 of dry matter. Examples include cobalt, manganese, zinc, etc.
Beneficial nutrients : They are plant nutrients that may not be essential, but are beneficial to plants. Sodium, silicon, cobalt and selenium are 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 elements : These elements are absolutely necessary for plant growth and reproduction. The requirement of these elements is specific and non-replaceable. They are further classified as macro and micro-nutrients.


Which process will be affected when coralloid roots are removed from a cycas plant? Give reasons.

There are coralloid roots in the Cycas plant. These roots contain the cyanobacteria called as Anabaena. These are blue-green algae which are responsible for the fixation of the atmospheric nitrogen. The algae help the plants by providing nitrogen in the forms which can be used by the plant. If the coralloid roots are removed from the Cycas plant, the association with the algae will be lost. This will result in the deficiency of nitrogen which will affect the growth of the plant. 


Describe the internal structure of the leaflet of cycas and list out the xerophytic adaptations seen in it.

The leaflets in the plant of cycas are termed as pinnule. There is upper and lower epidermis which have the compactly arranged cells and below is the layer of the hypodermis. There are stomata on the upper and lower epidermis. The mesophyll is divided in two tissues, palisade and the spongy tissue. The palisade tissue contains long cells which are arranged compactly. There is spongy tissue which has the loosely arranged cells. The vascular bundles are conjoint and collateral. The protoxylem is towards the lower epidermis and the metaxylem is towards the upper epidermis. The xylem is central and centrifugal in the arrangement. There is phloem tissue arranged near the lower epidermis. 
There are certain adaptations in these plants similar to the xerophytic plants. There is a thick cuticle which protects from excessive transpiration. There are sunken stomata which reduce the loss of water. There are certain thick walled cells of hypodermis which does not allows the passage of water and prevents water loss. The last leaflets are modified to form the spines which reduce the surface area for transpiration. 

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Name atleast five different deficiency symptoms in plants. Describe them and correlate them with the concerned mineral deficiency.

Five different deficiency symptoms are:- 
1. Chlorosis- chlorosis is the term which refers to the loss of chlorophyll causing yellowing of leaves. Caused due to N, K, Mg etc 
2. Necrosis- the death of tissue particularly leaf is called necrosis. Caused due to Ca, Mg etc. 
3. Whiptail- degeneration of lamina but not of petiole and midrib Causes due to Molybdenum 
4.little leaf disease- small sized leaves. Caused due to Zn. 
5. Dieback - it is the killing of the shoot apex i.e stem tip and young leaves. Caused due to Cu and K.


Match the words in Column I with phrases in Column II.

So the correct answer is ' A-2, B-4, C-1, D-6, E-3'.
 A. Magnesium 2. Structural component of Chlorophyll ( central atom)
 B. Sulphur 4. Found in some amino acids (like cysteine)
 C. Calcium 1. Found in middle lamella (maintain rigidity of cell wall)
 D. Iodine 6. Not important for plants
 E. Manganese 3. Required for enzymatic activity (work as co factors)


Name the pigment found in the root  nodules of the leguminous plant .

The name of the pigment found in the root nodules of the leguminous plant is leghaemoglobin that helps in nitrogen fixation by symbiotic association with bacteria..


Why do farmers use leguminous crops to provide nitrogen to the soil ? Explain .

Farmers use leguminous crops to provide nitrogen to the soil because nitrogen-fixing bacteria found in roots of leguminous plants like as peas, pulses crop etc. These bacteria (like rhizobium) atmospheric nitrogen fixed in the soil. 


Differentiate between macroelements and microelements .

Some minerals (elements) are required for growth and development of a living organism, these elements are called essential elements. It is divided into two groups on the basis of their requirement. 
1. Macroelements
2.Microelements 
Macroelements are that elements which are required in the large amount to the living organism for the normal physiological process of their body e.g., C, H, N, O, Ca, K, S, P, Mg and Fe.
Whereas microelements are that elements which are required in the small amount to the living organism for the normal physiological process of their body e.g., Zn, Mn, B, Mo, Cl and Ni. 



How can the nutrient requirements of a plant be determined?

The soil nutrients, carbon dioxide and water, along with sunlight, which allows plants for their grow. Plant absorbs nutrients from soil through their root system. Climatic changes and mode of soil content helps for the plant growth.
Approximately 17 macronutrients and micronutrients are deemed essential nutrients to support all the biochemical needs of plants.




What do you understand by symbiotic nitrogen fixation? Describe the role of leghaemoglobin in nitrogen fixation. Outline the process of nitrogen fixation as it takes place in the bacteroid inhabiting a legume nodule.

Symbiotic nitrogen fixation is the process of nitrogen fixation that occurs in plants within their tissues. The best example is the association between legumes and bacteria in the genus Rhizobium. This relationship benefits both the organisms and it is known as mutualism.


The rhizobia and legure are mutually dependant to each other. The legume is helpful to the rhizobia that it supplies nutrients to the bacteroids with which they synthesize the large amounts of ATP which is needed to convert the nitrogen (N2) into ammonia (NH3)

Also, legume supplies one of the critical components of nitrogenase.

The bacteroids require oxygen to make their ATP. However, nitrogenase is strongly inhibited by oxygen. Nodules are filled with hemoglobin. So, the hemoglobin of the legume called the leghemoglobin supplies the required concentration of oxygen to the bacteroids.




The pigment present in the nodules of the rhizobium-legume complex is known as ..........

leghaemoglobin


Long answer type questions.
Why were micronutrients discovered later than macronutrients? With one example each, mention the physiological role and deficiency disease caused by (i) nitrogen, (ii) phosphorus, (iii) copper, and (iv) iron.

Macronutrients are needed in large quantities in comparison to other nutrients which is why they are called “macro” nutrients and are commonly referred to as "macros". Micronutrients are needed only in very small amounts, these substances to not provide any calories but enable our bodies to produce enzymes, hormones, and other substances vital to development, disease prevention, and well-being.
(i) Nitrogen: Plants absorb nitrogen from the soil in three forms: nitrate (NO3- ), Nitrite (NO2-) or Ammonium (NH4+).
Functions:
(i) It is the major constituent of proteins, purines, pyrimidines, vitamins, chlorophyll and hormones, It is also present as a component of coenzymes like FAD, NAD, NADP etc., Older leaves when turning yellow, their nitrogen passes to younger parts in the form of amines and amides.
Deficiency Symptoms:
(i) Stunted growth due to reduced cell division and dormant lateral buds. Chlorosis (yellowing of leaves), Suppressed or late flowering, Increase in starch content but the decrease in protein content, Wrinkling of cereal grains, Purple coloration appears in shoot axis.
 (ii) phosphorus: Soil contains phosphorus in organic and inorganic forms.  
Functions:
It is a constituent of phospholipids (membrane lipids), nucleic acids, nucleotides, coenzymes, ATP, metabolic intermediates, sugar phosphates in photosynthesis etc.
Deficiency Symptoms:
Purple or red pigmentation on leaves, Premature fall of leaves and floral buds
Delay in seed germination, Older leaves affected first and become dark brown, Stunted and slender stem in young plants, Accumulation of carbohydrates in Glycine max (Soybean), Vascular tissues reduce in tomato plants.
(iii) Copper:
Copper is necessary for carbohydrate and nitrogen metabolism and, inadequate copper results in stunting of plants. Copper also is required for lignin synthesis which is needed for cell wall strength and prevention of wilting. Deficiency symptoms of copper are dieback of stems and twigs, yellowing of leaves, stunted growth and pale green leaves that wither easily.
Copper deficiencies are mainly reported on sandy soils which are low in organic matter. Copper uptake decreases as soil pH increases. Increased phosphorus and iron availability in soils decrease copper uptake by plants.
(iv) iron:
Iron is involved in the production of chlorophyll, and iron chlorosis is easily recognized on iron-sensitive crops growing on calcareous soils. Iron also is a component of many enzymes associated with energy transfer, nitrogen reduction and fixation, and lignin formation. Iron is associated with sulfur in plants to form compounds that catalyze other reactions. Iron deficiencies are mainly manifested by yellow leaves due to low levels of chlorophyll. Leaf yellowing first appears on the younger upper leaves in interveinal tissues. Severe iron deficiencies cause leaves to turn completely yellow or almost white, and then brown as leaves die.
Iron deficiencies are found mainly on high pH soils, although some acid, sandy soils low in organic matter also may be iron-deficient. Cool, wet weather enhances iron deficiencies, especially on soils with marginal levels of available iron. Poorly aerated or compacted soils also reduce iron uptake by plants. Uptake of iron decreases with increased soil pH, and is adversely affected by high levels of available phosphorus, manganese and zinc in soils.


What is hydroponic culture? How is it useful in mineral nutrition studies?

Hydroponic culture is cultivating plants without soil and by using mineral nutrient elements in the solution of water solvent. For example terrestrial plants grown only when the roots get exposed to an inert medium or a mineral solution. The hydroponic plants grow almost 50% faster than the plants grown in the soil which will help more in the studies of mineral nutrients according to the plant type


Very short answer type.
How does the segmentation of an annelid worm differ from the repeating units of the body of a tapeworm?

Anndids are metamerically segmented organisms; the metameres are marked externally by grooves and internally by septa. However, tapeworms exhibit pseudo-segmentation.


Long answer type questions
Name the elements that make up most of a plants body. What are essential mineral nutrients and beneficial mineral nutrients?

A plant's body is mostly made up of minerals. Interactions involving weathering of rock minerals, decaying organic matter, animals, and microbes form inorganic minerals in the soil. Roots absorb these mineral nutrients from the soil through the meristematic root tips.


There are actually 20 mineral elements namely,

  • Carbon (C)

  • Hydrogen (H)

  • Oxygen (O)

  • Nitrogen (N)

  • Phosphorus (P)

  • Potassium (K)

  • Calcium (Ca)

  • Magnesium (Mg)

  • Sulfur (S)

  •  Boron (B)

  • Chlorine (Cl)

  • Copper (Cu)

  • Iron (Fe)

  • Manganese (Mn)

  • Sodium (Na)

  • Zinc (Zn)

  • Molybdenum (Mo) 

  • Nickel (Ni)

  • Silicon (Si) 

  • Cobalt (Co)





short / Long answer type questions.
How would you determine whether or not a particular element is essential for plant growth and development?

Criteria to find whether the element is essential or not :

  • The element must be a critical element for the growth of the plant. Without the element, the plant can not complete its life cycle or produce seeds.

  • The element’s requirement must be specific and non-replaceable. The deficiency of the element cannot be compensated by any other element.

  • The element should have a major role in the metabolism of the plant.



short answer type questions.
Briefly describe the use of hydroponics to determine the mineral nutrients of a plant.

Hydroponics is the process of growing plants by suspending them with their roots in a nutrient solution. Hydroponics method allows the plant to grow well if it receives the nutrients it needs from the nutrient solution. The investigator will exclude a mineral and observe how this affects the plant’s growth, and if the growth is affected in a negative way, it is concluded that this mineral was an essential nutrient. 


Rhizobium bacteria are associated with the fixation of __________.

$$\textbf{Solution}$$

$$\bullet$$ Rhizobium bacteria are associated with the fixation of Nitrogen with the process of biological nitrogen fixation.

$$\bullet$$Biological nitrogen fixation occurs when the nitrogen present in the atmosphere, called the atmospheric nitrogen is converted into ammonia with the help of nitrogenase enzyme.
$$\bullet$$ This process is carried out by a specialist group of prokaryotes which utilizes the enzyme nitrogenase in order to catalyse the atmospheric nitrogen into ammonia because plants can easily assimilate ammonia to produce nitrogenous molecules.
$$\bullet$$This process requires a huge amount of energy and nitrogen is enzyme to break the covalent bond of Nitrogen atom and add three hydrogen atoms to each nitrogen atom.


Explain the formation of root nodules in legumes.

The mechanism of root nodule formation in leguminous plants can be explained by the following steps: 
  • The roots of legume plants secrete lectin protein which attracts specific species of Rhizobium towards it. 
  • The root hair becomes hook-like under the influence of hormones secreted by the plant root and the ‘Nod’ factor secreted by the Rhizobium. 
  • The cell wall of hook-shaped root hair breaks near the tip and the bacterial cells enter into root hair along with mucilaginous substance. 
  • The plasma membrane of root hair becomes folded and forms an infection thread that penetrates the cortex region of the root. 
  • The bacteria continue to divide and induce polyploidy in the nucleus of cells of the outer cortex. 
  • These cells divide continuously and form a nodule. 
  • IAA secreted by the bacteria cause growth in the size of the nodule and soon vascular tissue differentiates in it which gets connected with the main vascular tissue of the root. 
  • The functional nodules appear pink in color due to the presence of leghaemoglobin.


Write names of essential elements of plants and write their function, availability, form in which absorbed and deficiency symptoms of any four.

The elements which have been found to occur in all plants and are necessarily required for the normal growth, development and reproduction of plants are called essential elements. The total number of elements essential for plants is seventeen (17). These are C, H, O, P, K, Ca, Mg, S, B, Cu, Fe, Cl, Mo, Mn, Zn and Ni.

Role of macro and micronutrients in plant nutrition:
  • Essential elements participate in different physiological activities of plants.
  • These elements play important role in, regulating the permeability of the plasma membrane, controlling osmotic pressure, electron transport system, balancing various biochemical reactions with the help of enzymes, storage of reserve food material in storage organs, buffer actions, etc.
Potassium (K):
  • It is found in soil insoluble and exchangeable form.
  • It is absorbed in the form of potassium ion ($$K^+$$).
  • Potassium is not a component of any biochemical compound and is not a structural element.
  • It plays an important role in four biochemical reactions viz cation neutralization, transport across the membrane, enzyme activation and osmotic potential regulation.
  • The best function of potassium is in regulating the opening of stomata.
  • It also plays an important role in photosynthesis and normal growth of seeds and fruits.
Deficiency Symptoms:
  • The first symptom of deficiency of Potassium is marginal chlorosis.
  • The leaves become mottle due to chlorosis.
  • Shortening of internodes results in stunted growth and bushy appearance of plants. Necrotic spots appear on the margins of more mature leaves.
  • Disease resistance of plants decreases.
  • Rate of protein synthesis decreases.
Magnesium:
  • Magnesium is found in soil as magnesium carbonate ($$MgCO_3$$) and is absorbed as magnesium ion ($$Mg^{++}$$).
  • It is an important component of chlorophyll pigment.
  • This element activates the enzymes of respiration, protein synthesis and photosynthesis. It helps in joining the two subunits of ribosomes.
  • It is also involved in the synthesis of DNA and RNA.
  • It is found in abundant amount in oilseeds as it plays an important role in the formation of oil seeds.
Deficiency symptoms:
  • Magnesium deficiency causes extensive interveinal chlorosis.
  • Leaves show reddish and yellow and orange spots due to the predominance of anthocyanin pigments.
  • There is a decline in photosynthesis.
  • In acute cases leaves become nearly white.
Sulphur (S):
  • This is absorbed from soil in the form of sulphate ion ($$SO^{++}_4$$). Besides this sulphur dioxide ($$SO_2$$) present as an environmental pollutant may also be absorbed by plants.
  • It is helpful in the synthesis of amino acids such as cysteine, methionine, etc. needed in protein synthesis.
  • It is also found in vitamin B and coenzyme-A.
  • It is an important component of protoplasm.
  • In the roots of plants of pea family growing in sulphur rich soil, the nodules are better developed.
  • The characteristic pungent odour of cruciferous plants, & onion and garlic is due to sulphur-rich volatile oils.
Deficiency symptoms:
  • Leaves show chlorosis.
  • Shortage of sulphur-containing amino acids occurs.
  • Plants become stunted and fail to form fruits.
  • Plants become stiff and woody due to the formation of more of thick-walled tissue such as sclerenchyma and xylem.
Iron (Fe):
  • Plants absorb iron from the soil in the form of ferric ions ($$Fe^{+++}$$).
  • It plays an important role in cell division, respiration and different steps of the electron transport system.
  • It is an important constituent of cytochrome and ferredoxin and acts as an activator of aconitase, catalase, peroxidase and some Krebs cycle enzymes.
  • It is helpful in chlorophyll synthesis but is not a part of chlorophyll molecules.
  • It is found as fixed protein (Phytoferritin) in leaves and in the chromatin network of the nucleus.
  • In metabolic reactions, it participates as $$Fe^{++}$$ (Ferrous).
Deficiency symptoms:
  • Young leaves show extensive chlorosis and may become white or yellow-white. The derailment of reactions of photosynthesis, respiration and protein synthesis occurs.
  • Cell division activity is inhibited.
  • Plant growth becomes slow..
Zinc (Zn):
  • This element is absorbed from soil in the form of zinc ions ($$Zn^{++}$$).
  • Zinc is required for the synthesis of growth hormone indole acetic acid (IAA).
  • It also controls the absorption of phosphorus.
  • Zinc is a component of several types of enzymes especially carboxylases.
Copper (Cu):
  • It is absorbed from soil by roots in the form of divalent cupric ions ($$Cu^{++}$$) or monovalent cuprous ions ($$Cu^+$$).
  • Copper acts as an electron carrier in oxidation-reduction reactions.
  • It is a component of plastocyanin and cytochrome oxidase which acts as an electron carrier in photosynthesis.
Deficiency symptoms:
  • Wilting and curling of leaves occurs.
  • The leaf tip shows chlorosis and becomes discoloured.
  • In Citrus deficiency of copper causes dieback disease of a leaf.
Molybdenum (Mo):
  • This element is absorbed in the form of molybdenum oxide ($$MoO_2$$).
  • This is required for nitrogen fixation in leguminous plants.
  • Molybdenum ions are part of enzyme nitrogenase and nitrate reductase which are involved in nitrogen fixation.
Deficiency Symptoms:
  • Mottling of leaves is a characteristic symptom of molybdenum deficiency.
  • Chlorosis of leaves and poor flower setting is observed. In cauliflower, the leaves become distorted and subsequently die. This is called whiptail disease and is caused due to molybdenum deficiency.
Chlorine (Cl):
  • Chlorine is absorbed from soil in the form of chloride ions ($$Cl^-$$).
  • This element is not a component of any biochemical substance.
  • It plays an important role in carbohydrate metabolism and in balancing anion-cation concentration in the cell.
  • It is helpful in the photolysis of water leading to the evolution of oxygen.
Deficiency symptoms:
  • Leaves show variegated chlorosis followed by necrosis.
  • Fruit formation is reduced and the size of fruit is also reduced. 
Nickel (Ni):
  • Dalton (1988) included nickel as essential element.
  • It is found in soil in sufficient amount and is absorbed in the form of nickel ions ($$Ni^{++}$$). Nickel is neither a component of any biochemical compound nor its function and deficiency are properly understood.
  • It is an essential part of the enzyme urease. It is probably helpful in the transportation of nitrogenous compounds.
Deficiency symptoms:
  • Plants show chlorosis and formation of necrotic tissue in leaves.
  • Plants growing in soil normally do not suffer a deficiency of nickel because it is required in very minute quantity. Note: It is important to note that deficiency symptoms of mobile elements first appear in old leaves whereas the deficiency symptoms of immobile elements first appear in young leaves.
  • Deficiency symptoms due to deficiency of Ca and B appear in terminal buds.
  • Deficiency symptoms first appear in old leaves due to deficiency of mobile elements such as N, P, K, Mg, Zn, Mo.
  • Deficiency symptoms first appear in young leaves due to deficiency of immobile elements such as Cu, S, Fe, Mn. 


Class 11 Medical Biology Extra Questions