1st PUC Biology Question Bank Chapter 12 Mineral Nutrition

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Karnataka 1st PUC Biology Question Bank Chapter 12 Mineral Nutrition

1st PUC Biology Mineral Nutrition NCERT Text Book Questions and Answers

Question 1.
‘All elements that are present in a plant need not be essential to Its survival’. Comment.
Answer:
The criteria for the essentiality of ah element are given below:

• The element must be absolutely necessary for supporting normal growth and reproduction.
• The requirement of the element must be specific, and not replaceable by another element.
• The element must be directly involved in the metabolism of the plant.

All elements that are present in a plant do not fulfill these criteria hence cannot be essential for plant survival.

Question 2.
Why is the purification of water and nutrient salts so important in studies involving mineral nutrition using hydroponics?
Answer:
In I860, Julius von Sachs, a prominent German botanist demonstrated for the first time, that plants could be grown to maturity in a defined nutrient solution in the complete absence of soil. The essence of all these methods involves the culture of plants in a soil-free, defined mineral solution. These methods require purified water and mineral nutrient salts. The presence of pure nutrients will give clear-cut scientific results.

Question 3.
Explain with examples: macronutrients, micronutrients, beneficial nutrients, toxic elements, and essential elements.
Answer:

1. Macronutrients: It must generally be present in plant tissue in the concentration of 1 to 10 mg /gm of dry matter. Examples are carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, potassium, calcium, and magnesium.
2. Micronutrients: There are needed in very small quantity i.e. less than 0.1 mg/gm of dry matter. Examples are iron, manganese, copper, molybdenum, zinc, boron, chlorine, and nickel.
3. Beneficial elements in addition to the 17 essential elements some elements which are needed by some higher plants. Examples sodium, silicon, cobalt, and selenium.
4. Toxic elements: Some micronutrients when moderately increase in the plant body cause toxicity. Example manganese.
5. Essential element: These elements are absolutely necessary for the normal growth and reproduction of plants. They are categorized as micronutrients and macronutrients.

Question 4.
Name at least five different deficiency symptoms in plants. Describe them and correlate them with the concerned mineral deficiency.
Answer:
(i) Iron deficiency: It is a plant disorder also known as lime-induced chlorosis. A deficiency in the soil is rare but iron can be unavailable for absorption if soil P^H is not between 5 and 6.5. A common problem is when the soil is too alkaline. Also, iron deficiency can develop if the soil is too waterlogged or has been overfertilized. Iron is needed to produce chlorophyll, hence its deficiency causes chlorosis.

Symptoms: Leaves turning yellow or brown in the margins between the veins which may remain green, while young leaves may appear to be bleached. Fruit would be of poor quality.

Treatment: By choosing appropriate soil for the growing conditions or by adding well-rooted manure or compost.

(2) Potassium deficiency: Plants require potassium ions for protein synthesis and for the opening and closing of stomata, which is regulated by proton pumps to make surrounding guard cells either turgid or flaccid. A deficiency of potassium ions can impair a plant’s ability to maintain these processes.

Symptoms: Brown scorching and curling of leaf tips and yellowing of leaf veins. Purple spots may appear on the leaf undersides.

Prevention and cure: Feeding with homemade comfrey liquid, adding seaweed meal, composted bracken or other organic potassium-rich fertilizer. Adding plants of well-rotted compost.

(3) Calcium deficiency: Caused by insufficient calcium in the growing medium, but is more frequently a product of a compromised nutrient mobility system in the plant.
Symptoms: Stunted plant growth, necrotic leaf margins on young leaves or curling of the leaves, and eventual death of terminal buds and root tips.

Treatment: Adding agricultural lime to acid soils, aiming at a P^H of 6.5. Adding organic matter to the soil to improve its moisture-retaining capacity.

(4) Nitrogen deficiency: Occurs when woody material such as sawdust is added to the soil. Soil organisms will utilize any nitrogen in order to break this down; thus making it temporarily unavailable to growing plants.

Symptoms: Poor plant growth, leaves are pale green or yellow in case of brassicas. Leaves are said to be etiolated with reduced chlorophyll. Following and fruiting are delayed.

Prevention and control: using grass movings as a mulch, or foliar feeding with manure and building up levels of organic matter in the soil, Leguminous green manures will fix additional nitrogen from the atmosphere.

(5) Manganese deficiency: Most common in poorly drained soils also where organic matter levels are high.

Symptoms: yellowing of leaves with smallest leaf veins remaining green to produce a chequered effect. Brown spots appear on leaf surfaces and severely affected leaves turn brown and wither.

Question 5.
If a plant shows a symptom which could develop due to deficiency of more than one nutrient, how would you find out experimentally, the real deficient mineral element?
Answer:
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. Hence, to identify the deficient element, one has to study all the symptoms developed in all the various parts of the plant and compare them with the available standard tables. We must also be aware that different plants also respond differently to the deficiency of some elements.

Question 6.
Why is it that in certain plants deficiency symptoms appear first in younger parts of the plant while in others they do so in mature organs?
Answer:

1. Deficiency symptoms depend on the mobility of the element in plants.
2. Here, elements which are actively mobilised within the plants and exported to young developing tissue, the deficiency symptom tend to first appear in older tissues.
3. For example, deficiency symptoms of nitrogen, potassium, and magnesium.
4. 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. For example, sulphur and calcium.

Question 7.
How are the minerals absorbed by the plants?
Answer:
Much of the studies on the mechanism of absorption of elements by plants have been carried out in isolated cells, tissues, or organs. These studies revealed that the process of absorption can be demarcated into two main phases. In the first phase, the initial rapid uptake of ions into the ‘free space’ or ‘outer space’ of cells- the apoplast, is passive. In the second phase of uptake, the ions are taken in slowly into the inner space – the symplast of the cells. The passive movement of ions into the apoplast usually occurs through ion-channels, the transmembrane proteins that function as selective pores.

On the other hand, the entry or exit of ions to and from the symplast requires the expenditure of metabolic energy, which is an active process. The movement of ions is usually called flux; the inward movement into the cells is influx and the outward movement, efflux.

Mineral salts are translocated through the xylem along with the ascending stream of water, which is pulled up through the plant by the transpirational pull. Analysis of xylem sap shows the presence of mineral salts in it. The use of radioisotopes of mineral elements also substantiates the view that they are transported through the xylem.

Question 8.
What are the conditions necessary for the fixation of atmospheric nitrogen by Rhizobium? What is their role in N₂ -fixation?
Answer:
Conditions for N2 Fixation:

• Presence of enzyme nitrogenase (= dinitrogenase)
• The occurrence of anaerobic conditions in the area of nitrogenase activity,
• ATP
• Source of hydrogen, NADPH, or FMNH2.
• Source of electron donor, ferredoxin.
• The deficient occurrence of nitrate in the soil,
• (Source of organic carbon in the form of ketoacidosis.

Role in Nitrogen Fixation. ATP provides energy to enzyme nitrogenase while ferredoxin supplies electrons from respiratory substrate. Atmospheric nitrogen attaches to the Fe-Mo component of dinitrogenase. Bonds between its two atoms are weakened by this attachment. In the presence of energy and electrons, hydrogen combines with nitrogen atoms to form N2H2 (diamide), N2H4 (hydrazine), and 2NH3 (ammonia). A reducing environment is essential for this. It is provided by leghaemoglobin which stores excess oxygen and sends only small limited quantities of oxygen inside the bunch of bacteroids. NH3 is immediately assimilated with the help of organic acids.

Question 9.
What are the steps involved in the formation of a root nodule?
Answer:
Nodule formation involves a sequence of multiple interactions between Rhizobium and the roots of the host plant. Principle 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 the exchange of nutrients.

Question 10.
Which of the following statements are true? If false, correct them:

1. Boron deficiency leads to the stout axis.
2. Every mineral element that is present in a cell is needed by the cell.
3. Nitrogen as a nutrient element is highly immobile in the plants.
4. It is very easy to establish the essentiality of micronutrients because they are required only in trace quantities.

Answer:

1. False.
   (Correct – All areas of high metabolic activity like stem tips and root tips get killed; stunting of the stem and root growth; chlorosis necrosis and distortion of leaves; reduced flowering and fruiting).
2. True
3. True
4. True

1st PUC Biology Mineral Nutrition Additional Questions and Answers

1st PUC Biology Mineral Nutrition One Mark Questions 

Question 1.
Why is leghaemoglobin called oxygen scavenger?
Answer:
Leghaemoglobin binds with oxygen and creates an anaerobic condition, so it is called an oxygen scavenger.

Question 2.
What are Chemotrophs?
Answer:
Chemotrophs are organisms that synthesize their own organic food by deriving energy from the oxidation of simple inorganic compounds.

Question 3.
What are bacteroids?
Answer:
Mineral elements are molybdenum and iron. Some of the bacteria affecting the root hair of leguminous plants enlarge to become rod-shaped bacteroids.

Question 4.
Who demonstrated that plants could be grown to maturity in a defined nutrient solution without soil?
Answer:
Julius Von Sachs.

Question 5.
Name two crops that are commonly produced by hydroponics.
Answer:
Tomato, Lettuce.

Question 6.
Mention the two ways in which Ca++ is involved in cell division in plants.
Answer:
Importance of calcium in cell division:

• It is used for the synthesis of the middle lamella.
• It is used for the formation of the mitotic spindle.

Question 7.
Name two elements Involved in the redox reactions.
Answer:
Copper, Iron.

Question 8.
What are Ion-channels?
Answer:
on channels are transmembrane

Question 9.
What is meant by nitrogen fixation?
Answer:
Nitrogen fixation is the process by which atmospheric free nitrogen is converted into ammonia and other nitrogen compounds that can be used by plants.

Question 10.
Which kind of plants harbour nitrogen-fixing bacteria in their root nodules?
Answer:
Leguminous plants.

Question 11.
Name the pigment found in the root nodules of legumes.
Answer:
Leghaemoglobin.

Question 12.
Give the scientific name of an organism which lives as a chemotroph.
Answer:
Nitrobacter.

Question 13.
Name the cells of the root that divide to form root nodules.
Answer:
Cortical cells.

Question 14.
in which form does a soya bean plant transport nitrogen?
Answer:
Ureides

Question 15.
Which are the two macronutrients that usually play the most important role in limiting plant growth globally?
Answer:
Nitrogen and calcium are the two macronutrients that usually play the most important role in limiting plant growth.

1st PUC Biology Mineral Nutrition Two Marks Questions

Question 1.
What Is hydroponics? Give one application of this technique.
Answer:
Hydroponics is the technique of growing plants with their roots immersed in a nutrient solution without soil.
Application:
It is used to grow many crops under artificial conditions for economic purposes.

Question 2.
What is nitrification? Name two nitrifying bacteria in the soil.
Answer:

1. Nitrification is the process by which ammonia is converted first into nitrites and then into nitrates.
2. Nitrosococcus and Nitrosomonas convert ammonia into nitrite
3. Nitrobacter converts nitrite into nitrate proteins that function as selective pores for the movement of ions.

Question 3.
Name the nitrifying bacteria of the soil. Why are they called chemoautotrophs?
Answer:
The nitrifying bacteria of soil are Nitrosomonas and Nitrobacter. They are called chemoautotrophs because they obtain energy liberated during nitrification or chemical reaction.

Question 4.
Why is leghaemoglobin so called? What is its function?
Answer:
Leghaemoglobin resembles the haemoglobin of vertebrates. Since it is present in the leguminous plants it is called as leghaemoglobin. It binds with oxygen and creates an anaerobic condition.

Question 5.
Name four macronutrients?
Answer:
Sulphur, Nitrogen, Phosphorous, Potassium.

Question 6.
Name the structural elements of plants.
Answer:
Carbon, hydrogen, oxygen and nitrogen.

Question 7.
Give four examples of micronutrients.
Answer:
Iron – Boron, Manganese, Molybdenum.

Question 8.
Write the formula of the form in which phosphorous is absorbed. Mention two important roles of it in plants.
Answer:
H₂ PO_4- and \({ HPo }_{ 4 }^{ 2- }\)

• It is necessary for the formation of middle lamella during cell division.
• It is also needed for the formation of spindle fibres.

Question 9.
Name the elements that forms the central core of chlorophyll. Mention any 3 function of this element in plants.
Answer:
Magnesium

• It helps to maintain ribosome structure
• It activates enzymes of phosphate metabolism in respiration and photosynthesis
• It is also involved in the synthesis of DNA and RNA.

Question 10.
What is denitrification? Name two organisms that carry out denitrification.
Answer:
Denitrification is the process by which nitrate is converted into free nitrogen gas. The organisms involved are bacteria like pseudomonas and Thiobacillus.

1st PUC Biology Mineral Nutrition Three Marks Questions

Question 1.
List the macronutrients and mention three major functions. (any three)
Answer:
Macronutrients and their function:
1. Carbon, hydrogen, and oxygen – They constitute the essential parts of carbohydrates and are found in fats and proteins also.
2. Nitrogen – Essential constituent of proteins, nucleic acids, vitamins, and many other organic molecules as chlorophyll. Also present in some hormones, coenzymes, and ATP, etc.
3. Phosphorous-Essential constituent of the plasma membrane, nucleic acid, nucleotides, many coenzymes, and organic molecules on ATP.

Question 2.
In what form is magnesium absorbed by plants from the soil? Give two functions of magnesium in plants and is two deficiency symptoms.
Answer:
Magnesium is absorbed as Mg²⁺ ions
Functions

• It forms the central atom of the porphyrin ring of chlorophyll.
• It maintains the ribosome structure Deficiency symptoms:
• Chlorosis and necrosis Premature leaf fall.

Question 3.
Give any three functions of potassium in plants.
Answer:

• It determines the anion – cation balance in plant cells
• It is involved in the opening and closing of stomata
• It maintains the osmotic balance and turgidity of cells.

Question 4.
What is meant by chlorosis? Name four elements whose deficiency causes chlorosis.
Answer:
Chlorosis refers to the yellowing of leaves due to the loss of chlorophyll. The deficiency of nitrogen, sulphur, magnesium, and iron can cause this.

Question 5.
Why does excess manganese cause the appearance of deficiency symptoms of iron, magnesium, and calcium?
Answer:
Manganese competes with iron and magnesium for uptake.

• It also competes with magnesium for binding with enzymes.
• It inhibits the translocation of calcium to shoot apex.

Question 6.
What is meant by flux? Describe its two kinds.
Answer:

• Flux refers to the movement of ions.
• Influx means the movement of ions into the cells.
• Efflux refers to the movement of ions out of the cells.

1st PUC Biology Mineral Nutrition Five Marks Questions

Question 1.
Name the form in which potassium is absorbed from the soil. Name four parts of plant in which this mineral is abundant. Mention five functions of potassium in plants.
Answer:
Potassium is absorbed as K⁺ ions. It is abundant in meristems, buds, leaves and root tips.
Functions:

• It is involved in the opening and closing of stomata. It activates a number of enzymes.
• It is involved in protein synthesis
• It maintains the turgidity of cells
• It maintains anion cation balance of cells

Question 2.
Describe the process of symbiotic biological nitrogen fixation.
Answer:

• Symbiotic biological nitrogen fixation is the fixing of atmospheric nitrogen into usable form by living organisms e.g. Nos toe, Anabaena, Rhizobium, Clostridium, Cyanobacteria, etc.
• During this process atmosphere N2 (dinitrogen); is reduced by the addition of hydrogen atom to ammonia.
  N2 + 8e- + 8H++16ATP → 2NH3 + H2 + 16ADP +16 Pi
• The reaction is catalyzed by the enzyme 1 nitrogenase. The process requires energy in the
  form of ATP, which is provided by photosynthesis or respiration and a strong reducing agent to transfer the hydrogen to nitrogen.
• Ammonium ions are absorbed by the plants and used for f the synthesis of amino acids and proteins. Ammonia presents in the soil is converted to nitrite and then to nitrate which is then absorbed by plants.

Question 3.
Represent schematically the nitrogen cycle. Name the organisms involved in this cycle.
Answer:

Organisms involved:
(i) Nitrogen fixation

• Free-living cyanobacteria-Nostoc
• Free lining aerobic bacteria – Azotobacter,
  Beidernickia
• Free-living anaerobic bacteria – Clostridium, Rhodospririllum
• Symbiotic bacteria – Rhizobium, Frankia

(ii) Ammonification Pseudomonas
(iii) Nitrification
Nitrobacter, Nitrosomonas, Nitrosococcus
(iv) Denitrification Thiobacillus, Pseudomonas.