Case Study Questions Class 11 Biology Chapter 12 Mineral Nutrition
CBSE Class 11 Case Study Questions Biology Mineral Nutrition. Important Case Study Questions for Class 11 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Mineral Nutrition.
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CBSE Case Study Questions Class 11 Biology Mineral Nutrition
CASE 1
Only a few elements have been found to be absolutely essential for plant growth and metabolism. These elements are further divided into two broad categories based on their quantitative requirements are as, Macronutrients and Micronutrients
Macronutrients are generally present in plant tissues in large amounts (in excess of 10 mmole Kg –1 of dry matter). The macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorous, sulphur, potassium, calcium and magnesium. Of these, carbon, hydrogen and oxygen are mainly obtained from CO2 and H2O, while the others are absorbed from the soil as mineral nutrition.
Micronutrients or trace elements, are needed in very small amounts (less than 10 mmole Kg –1 of dry matter). These include iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel. In addition to the 17 essential elements named above, there are some beneficial elements such as sodium, silicon, cobalt and selenium. They are required by higher plants.
Essential elements can also be grouped into four broad categories on the basis of their diverse functions. These categories are:
- Essential elements as components of biomolecules and hence structural elements of cells (e.g., carbon, hydrogen, oxygen and nitrogen).
- Essential elements that are components of energy-related chemical compounds in plants (e.g., magnesium in chlorophyll and phosphorous in ATP).
- Essential elements that activate or inhibit enzymes, for example Mg2+ is an activator for both ribulose bisphosphate carboxylase- oxygenase and phosphoenol pyruvate carboxylase, both of which are critical enzymes in photosynthetic carbon fixation.
- Some essential elements can alter the osmotic potential of a cell. Potassium plays an important role in the opening and closing of stomata.
1.) Identify the incorrect statement
Statement 1 – Micronutrients are also called as Trace elements.
Statement 2 – Macronutrients are also called as Trace elements
Statement 3 – Elements are divided into two categories based on their quantitative requirements
Statement 4 – Micronutrients are needed in very small amounts
a.) Statement 1 is incorrect
b) Statement 2 is incorrect
c) Statement 3 is incorrect
d) All statement are incorrect
2.) _______________is theEssential element plays an important role in the opening and closing of stomata.
a) Potassium
b) Chlorine
c) Sulphur
d) Bromine
3.) What is the basis of categorisation of elements which are essential for plant growth and metabolism?
4.) What amount of macronutrients are generally present in plant tissues?
5) What amount of micronutrients are normally required by plant?
6) Give reason – why micronutrients are called as Trace elements?
Answer key
1.) b
2.) a
3.) Elements which are essential for plant growth and metabolism are divided into two categories based on their quantitative requirements are as, Macronutrients and Micronutrients
4.) Macronutrients are generally present in plant tissues in large amounts in excess of 10 mmole Kg –1 of dry matter.
5.) Micronutrients or trace elements, are needed in very small amounts less than 10 mmole Kg –1 of dry matter.
6.) Micronutrients are also called as Trace elements because they are required in very less quantity but are essential for growth, development and perform various physiological processes.
CASE 2
Essential elements perform several functions. They participate in various metabolic processes in the plant cells such as permeability of cell membrane, maintenance of osmotic concentration of cell sap, electron transport systems, buffering action, enzymatic activity and act as major constituents of macromolecules and co-enzymes.
Nitrogen is the essential nutrient element required by plants in the greatest amount. It is absorbed mainly as NO3 – though some are also taken up as NO2 – or NH4 + . Nitrogen is required by all parts of a plant, particularly the meristematic tissues and the metabolically active cells. Nitrogen is one of the major constituents of proteins, nucleic acids, vitamins and hormones.
Phosphorus is absorbed by the plants from soil in the form of phosphate ions. Phosphorus is a constituent of cell membranes, certain proteins, all nucleic acids and nucleotides, and is required for all phosphorylation reactions.
Potassium is absorbed as potassium ion (K+ ). In plants, this is required in more abundant quantities in the meristematic tissues, buds, leaves and root tips. Potassium helps to maintain an anion-cation balance in cells and is involved in protein synthesis, opening and closing of stomata, activation of enzymes and in the maintenance of the turgidity of cells.
Plant absorbs calcium from the soil in the form of calcium ions (Ca2+). Calcium is required by meristematic and differentiating tissues. During cell division it is used in the synthesis of cell wall, particularly as calcium pectate in the middle lamella. It is also needed during the formation of mitotic spindle. It accumulates in older leaves. It is involved in the normal functioning of the cell membranes. It activates certain enzymes and plays an important role in regulating metabolic activities.
Plants obtain iron in the form of ferric ions (Fe3+). It is required in larger amounts in comparison to other micronutrients. It is an important constituent of proteins involved in the transfer of electrons like ferredoxin and cytochromes. It is reversibly oxidised from Fe2+ to Fe3+ during electron transfer. It activates catalase enzyme, and is essential for the formation of chlorophyll.
1.) Nitrogen is absorbedas
a) NO3 –, NO2 + or NH4 +
b) NO3 –, NO3 – or NH4 +
c) NO3 –, NO2 – or NH4 +
d) NO3 +, NO2 – or NH4 –
3.) Phosphorus is absorbed by the plants from soil in the form of _____________
Phosphorus ions
Phosphate ions
Phosulphate ions
Phosphoric ions
2.) Name the element which required by plant in highest amount.
4.) Name the element which is an important constituent of electron acceptor proteins involved in the transfer of electrons.
5.) Name the element which plays an important role in stomata functioning.
Answer key
1.) c
2.) b
3.) Nitrogen is the essential nutrient element required by plants in the highest amount. Nitrogen is required by all parts of a plant, particularly the meristematic tissues and the metabolically active cells. Nitrogen is one of the major constituents of proteins, nucleic acids, vitamins and hormones.
4.) Iron is an important constituent of proteins involved in the transfer of electrons like ferredoxin and cytochromes.
5.) Potassium is absorbed as potassium ion (K+ ) plays an important role in opening and closing of stomata and activation of enzymes and in the maintenance of the turgidity of cells.
CASE 3
The concentration of the essential element below which plant growth is retarded is termed as critical concentration. The element is said to be deficient when present below the critical concentration. Since each element has one or more specific structural or functional role in plants, in the absence of any particular element, plants show certain morphological changes. These morphological changes are indicative of certain element deficiencies and are called deficiency symptoms. The deficiency symptoms vary from element to element and they disappear when the deficient mineral nutrient is provided to the plant. However, if deprivation continues, it may eventually lead to the death of the plant. The deficiency symptoms tend to appear first in the older tissues. For example, the deficiency symptoms of nitrogen, potassium and magnesium are visible first in the senescent leaves.
The deficiency symptoms tend to appear first in the young tissues whenever the elements are relatively immobile and are not transported out of the mature organs. The aspect of mineral nutrition of plants is of a great significance and importance to agriculture and horticulture.
The kind of deficiency symptoms shown in plants include chlorosis, necrosis, stunted plant growth, premature fall of leaves and buds, and inhibition of cell division. Chlorosis is the loss of chlorophyll leading to yellowing in leaves. This symptom is caused by the deficiency of elements N, K, Mg, S, Fe, Mn, Zn and Mo. Likewise, necrosis, or death of tissue, particularly leaf tissue, is due to the deficiency of Ca, Mg, Cu, K. Lack or low level of N, K, S, Mo causes an inhibition of cell division. Some elements like N, S, Mo delay flowering if their concentration in plants is low.
The deficiency of any element can cause multiple symptoms and that the same symptoms may be caused by the deficiency of one of several different elements.
1.) Destruction of chlorophyll pigment molecule results into yellowing in leaves, such condition is termed as
a) Necrosis
b) Wilting of leaves
c) Chlorosis
d) Senescence
2.) When the concentration of the essential element goes down to the low level, which result abnormal and stunted plant growth is referred as ____________
a) Deficiency concentration
b) Critical concentration
Extreme concentration
Ample concentration
3.) What indicate the elemental deficiency?
4.) Name the condition in which tissue of plant became dead due to elemental deficiency?
5.) What if essential elements critical concentration continues for long time?
Answer key
1.) c
2.) b
3.) In the absence of any particular element, plants show certain morphological changes. These morphological changes are indication of certain element deficiencies, these morphological and anatomical changes occurred in plant are called as deficiency symptoms.
4.) Necrosis is a condition in which plant tissue become dead due to elemental deficiency, particularly leaf tissue, is due to the deficiency of Ca, Mg, Cu, and K.
5.) Each essential element has one or more specific structural or functional role in plants, in the absence of any particular element it results certain morphological changes. These morphological changes are indicative of certain element deficiencies and are called deficiency symptoms. The deficiency symptoms vary from element to element. When essential elements deprivation continues for long time, it may eventually lead to the death of the plant.
CASE 4
Very few living organisms can utilise the nitrogen in the form N2, it is available abundantly in the air. Reduction of nitrogen to ammonia by living organisms is called biological nitrogen fixation. The enzyme, nitrogenase which is capable of nitrogen reduction is present exclusively in prokaryotes. Such microbes are called N2 – fixers.
The nitrogen-fixing microbes could be free-living or symbiotic. Examples of free-living nitrogen-fixing aerobic microbes are Azotobacter and Beijerinckia while Rhodospirillum is anaerobic and free-living. In addition, a number of cyanobacteria such as Anabaena and Nostoc are also free living nitrogen-fixers.
Several types of symbiotic biological nitrogen fixing associations are known. The most prominent among them is the legume-bacteria relationship. Species of rod-shaped Rhizobium has such relationship with the roots of several legumes such as alfalfa, sweet clover, sweet pea, lentils, garden pea, broad bean, clover beans, etc. The most common association on roots is as nodules. These nodules are small outgrowths on the roots. The microbe, Frankia, also produces nitrogen-fixing nodules on the roots of non-leguminous plants (e.g., Alnus). Both Rhizobium and Frankia are free living in soil, but as symbionts, can fix atmospheric nitrogen.
Nodule formation involves a sequence of multiple interactions between Rhizobium and roots of the host plant. Principal stages in the nodule formation are summarised as follows: Rhizobia multiply and colonise the surroundings of roots and get attached to epidermal and root hair cells. The root-hairs curl and the bacteria invade the root-hair. An infection thread is produced carrying the bacteria into the cortex of the root, where they initiate the nodule formation in the cortex of the root. Then the bacteria are released from the thread into the cells which leads to the differentiation of specialised nitrogen fixing cells. The nodule thus formed, establishes a direct vascular connection with the host for exchange of nutrients. The nodule contains all the necessary biochemical components, such as the enzyme nitrogenase and leghaemoglobin.
1.) ____________________ are the aerobic microbes which are capable innitrogen-fixing.
a) Azotobacter
b) Beijerinckia
c) Rhodospirillum
d) Both a & b
2) _____________________ is free-living nitrogen-fixing anaerobic microbe.
a) Azotobacter
b) Rhodospirillum
c) Beijerinckia
d) Cyanobacteria
3.) Name the organism that fixes nitrogen in symbiotic association with a legume plants. Where does it occurs in such plants?
4.) Name the enzymes which occurs in nodule.
5.) Explain how nodule formation takes place?
Answer key
1.) d
2.) b
3.) Rhizobiumfixes nitrogen in symbiotic association with a legume plant. It occurs in the root nodules which developed in leguminous plants.
4.) Nodules have all the necessary biochemical components, such as the enzyme nitrogenase and leghaemoglobin.
5.) Nodule formation takes place are as follows:
- Rhizobia multiply and colonise the surroundings of roots and get attached to epidermal and root hair cells.
- The root-hairs curl and the bacteria invade the root-hair.
- An infection thread is produced carrying the bacteria into the cortex of the root, where they initiate the nodule formation in the cortex of the root.
- Then the bacteria are released from the thread into the cells which leads to the differentiation of specialised nitrogen fixing cells.
- Once nodule is formed, it establishes a direct vascular connection with the host for exchange of nutrients.
CASE 5
Apart from carbon, hydrogen and oxygen, nitrogen is the most prevalent element in living organisms. Nitrogen is a constituent of amino acids, proteins, hormones, chlorophylls and many of the vitamins. Plants compete with microbes for the limited nitrogen that is available in soil. Thus, nitrogen is a limiting nutrient for both natural and agricultural eco-systems. Nitrogen exists as two nitrogen atoms joined by a very strong triple covalent bond (N ≡ N). The process of conversion of nitrogen (N2) to ammonia is termed as nitrogen fixation. In nature, lightning and ultraviolet radiation provide enough energy to convert nitrogen to nitrogen oxides (NO, NO2 , N2O). Industrial combustions, forest fires, automobile exhausts and power -generating stations are also sources of atmospheric nitrogen oxides. Decomposition of organic nitrogen of dead plants and animals into ammonia is called ammonification. Some of this ammonia volatilises and re-enters the atmosphere but most of it is converted into nitrate by soil bacteria.
Ammonia is first oxidised to nitrite by the bacteria Nitrosomonas and/or Nitrococcus. The nitrite is further oxidised to nitrate with the help of the bacterium Nitrobacter. These steps are called nitrification. These nitrifying bacteria are chemoautotrophs. The nitrate thus formed is absorbed by plants and is transported to the leaves. In leaves, it is reduced to form ammonia that finally forms the amine group of amino acids. Nitrate present in the soil is also reduced to nitrogen by the process of denitrification. Denitrification is carried by bacteria Pseudomonas and Thiobacillus.
1.) __________________the process that converts nitrate to nitrogen.
a) Denitrification
b) Nitrification
c) Ammonification
d) Nitratefixation
2.) Nitrogen atoms are joined by __________________
a) Triple ionic bond
b) Triple covalent bond
c) Triple metallic bond
d) None of the above
3.) Name the bacteria which carried out denitrification?
4) Name the bacteria which converts ammonia into nitrite?
5) Why nitrogen is considered as limiting nutrient?
Answer key
1.) a
2.) b
3.) Denitrification is carried by bacteria Pseudomonas and Thiobacillus.
4.) Nitrosomonas and Nitrococcus are the bacteria. These bacteria convert ammonia into nitrite by oxidation.
5.) In addition to carbon, hydrogen and oxygen, nitrogen is the most prevalent element required in living organisms. Nitrogen is a constituent of various amino acids, proteins, hormones, chlorophylls, pigments and many of the vitamins. Plants compete with microbes for the limited nitrogen that is available in soil. Hence, nitrogen is considered as limiting nutrient.