You can Download Chapter 12 Mineral Nutrition Questions and Answers, 1st PUC Biology Question Bank with Answers, Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.
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 essentiality of an element are given below:
- The element must be absolutely necessary for supporting normal growth and reproduction. In the absence of the element the plants do not complete their life cycle or set the seeds.
- The requirement of the element must be specific and not replaceable by another element. In other words, deficiency of any one element cannot be met by supplying some other element.
- The element must be directly involved in, the metabolism of the plant.
Question 2.
Why is 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 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:
Macronutrients: Generally present in plant tissues in large amounts. The macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, 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: Also called Trace elements are needed in very small amounts. These include iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel.
Beneficial nutrients: Include sodium, silicon, cobalt and selenium. They are required by higher plants.
Toxic elements: Any mineral ion concentration in tissues that reduces the dry weight of tissues by about 10 percent is considered toxic. The toxicity symptoms are difficult to identify. Micronutrients in excess causes toxicity.
Essential elements: 4 categories on the basis of their diverse functions.
(a) As components of biomolecules and hence structural elements of cells.
e.g. carbon, hydrogen, oxygen and nitrogen.
(b) As components of energy related chemical compounds in plants.
e.g. magnesium in chlorophyll
(c) Elements that activate or inhibit enzymes, e.g. Mg2+ is an activator for both ribulose bisphosphate carboxylase oxygenase and phosphoenol pyruvate carboxylase.
(d) Elements that alter the osmotic potential of a cell.
e.g. Potassium in opening and closing of stomata.
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 PH 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 overfertilised. 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 PH 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 utilise 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:
Since each elements 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 subsequently lead to the death of the plant. This way by administering different nutrients and observing the symptoms disappear we can find out experimentally the real deficient mineral element.
Question 6.
Why is that in certain plants deficiency symptoms appear first in younger parts of the plant while in others they do so in mature organs?
Answer:
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, elements like sulphur and calcium are a part of the structural component of the cell and hence are not easily released.
Question 7.
How are the minerals absorbed by the plants?
Answer:
Plants uptake essential elements from the soil through their roots and from the air through leaves. Nutrient uptake in the soil is achieved by cation exchange, wherein root hairs pump hydrogen ions into the soil through proton pumps. These hydrogen ions displace cations attached to negatively charged soil particles so that the cations are available for uptake by the root. In the leaves, stomata open to take in carbon dioxide and expel oxygen. The carbon dioxide molecules are used as the carbon source in photosynthesis.
Question 8.
What are the conditions necessary for fixation of atmospheric nitrogen by Rhizoblum. What is their role in N2 -fixation?
Answer:
Rhizobia are unique because they live in a symbiotic relationship with legumes. Necessary conditions:
- Requires a strong reducing agent and energy in the form of ATP.
- The enzyme nitrogenase which is very sensitive to oxygen is required.
- The processes take place in anaerobic environment
- The energy is provided by the respiration of host cells.
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. Several types of symbiotic biological nitrogen fixing associations are known. The most common association on roots is as nodules. Their role in N2– fixation is to supply the plants with nitrogenase that converts nitrogen to amino acids.
Question 9.
What are the steps involved in formation of a root nodule?
Answer:
Nodule formation involves a sequence of multiple interactions between Rhizobium and 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 exchange of nutrients.
Question 10.
Which of the following statements are true? If false, correct them:
(a) Boron deficiency leads to stout axis.
Answer:
True
(b) Every mineral element that is present in a cell is needed by the cell.
Answer:
False. All the mineral elements present in a cell are not needed by the cell, e.g. plants growing near radioactive mining sites tend to accumulate large amounts of radioactive compounds which are not essential.
(c) Nitrogen as a nutrient element, is highly immobile in the plants.
Answer:
False. Nitrogen as a nutrient element is highly mobile in plants. It can be mobilised from the old and mature parts of a plant to its younger parts.
(d) It is very easy to establish the essentiality of micronutrients because they are required only in trace quantities.
Answer:
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 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.
Name the enzyme that can reduce nitrogen to ammonia.
Answer:
Nitrogenase.
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.
Name the group of enzymes activated by zinc.
Answer:
Carboxylases.
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.
Name two symbiotic nitrogen-fixing bacteria.
Answer:
Rhizobium, Frankia.
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.
How are amides transported In plants?
Answer:
Amides are transported along with water through xylem.
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 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:
- Nitrification is the process by which ammonia is converted first into nitrites and then into nitrates.
- Nitrosococcus and Nitrosomonas convert ammonia into nitrite
- Nitrobacter converts nitrite into nitrate proteins that function as selective pores for movement of ions.
Question 3.
Name the organism that fixes nitrogen in symbiotic association with a legume. Where does it live in such plants?
Answer:
Rhizobium. It lives in the root nodules of leguminous plants.
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 PO4- 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.
In what form is boron absorbed by plants from the soil? Mention its two uses in plants and give two deficiency symptoms of boron in them.
Answer:
Boron is absorbed as \({ H }_{ 2 }{ Po }_{ 4- }\quad and\quad { HPo }_{ 4 }^{ 2- }\)
- Translocation of carbohydrates
- Pollen germination
Deficiency symptoms
- Death of root and shoot tips
- Abscission of flowers
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 porphyrins 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 loss of chlorophyll. Deficiency of nitrogen, sulphur, magnesium and iron can cause this.
Question 5.
Why does excess of 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 movement of ions into the cells.
- Efflux refers to 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 turgidity of cells
- It maintains anion cation balance of cells
Question 2.
Name at least five different deficiency symptoms in plants. Describe them and correlate them with concerned mineral deficiency.
Answer:
- Chlorosis – yellowing of leaves due to loss of chlorophyll caused by the deficiency of N, S, mg, Fe.
- Necrosis – Death of tissues, especially in leaves caused by the deficiency of Ca, Mg, Ca & K.
- Delay in flowering caused by the deficiency of molybdenum, nitrogen, and sulphur.
- Dieback of roots caused by a deficiency of copper.
- Inhibition of cell division caused by a deficiency of potassium, calcium and nitrogen.
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.