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Minerals, Practice Problems and FAQs

Minerals, Practice Problems and FAQs

What would happen if you do not eat a balanced diet? Your body will start showing symptoms of nutrient deficiency. You must have seen the cartoon character Popeye becoming super strong after having spinach. Do you know what was the idea behind this? It was to encourage children to eat more spinach because spinach is a rich source of iron. You must be wondering, isn’t iron used to make rods and ships and what not? Why would I need iron? Well, iron is very necessary for the synthesis of the haemoglobin pigment of your blood that helps to transport oxygen throughout your body and makes your blood red. Just like iron, there are many such inorganic elements that our body needs to survive and we call those elements as minerals. But what about plants? Do they need minerals to survive?

You might be thinking, why would plants need extra food when they are capable of preparing their own food by photosynthesis? Right? But the fact is that through photosynthesis, plants are only getting the glucose and oxygen. Plants use glucose as a source of energy and to create other compounds like cellulose and starch. The oxygen is used up for respiration. But, is this enough for them? The answer is no. For their healthy growth and development they need minerals and nutrients. Minerals are essential for a number of different functions in the plant body such as formation of chlorophyll, effective absorption of water, transport of water into and out of the cell etc. 

So where do living beings obtain these minerals from? Animals obtain it from the food that they have whereas plants absorb these minerals from the soil, along with water, with the help of their roots. In this article we will discuss the various minerals that are required for nutrition in plants and humans.



Fig: Plant absorbing water and minerals

 from the soil

Table of contents:

Introduction to Minerals 

In the context of nutrition, minerals refer to the solid inorganic elements that living organisms require for proper growth and development of the body. These are required in various biological processes and may serve as cofactors to various enzymes in the metabolic reactions. These include sodium, potassium , calcium, magnesium, phosphorus, sulphur, chlorine, copper, iron, zinc, cobalt, iodine, fluorine, etc.

Minerals required by plants

Essential and Non-essential elements

Out of 105 elements discovered, more than 60 elements are present in different plants. 



GIF: Periodic table showing essential elements

These elements are categorised as essential and non-essential elements based on certain criteria. Let’s have a look at what determines the essentiality of an element. In order to be classified as an essential element -

  • an element must be absolutely necessary for supporting normal growth and reproduction of the plant.
  • it should be a part of the structural components of the plant cells and tissues.
  • it should be required in specific amounts and should be non-replaceable, that is, its deficiency should not be met by any other element.
  • it must be directly involved in the metabolism of the plant.
  • reduced availability of the element should manifest as deficiency symptoms in the plant,



Fig: Criteria for essentiality

Essential elements

Elements that are absolutely essential for the growth and development of plants are called essential elements. Examples: Mg, C, H, P, K, etc.

Non-essential elements

Those elements that are not required for the growth and development of plants are called non essential elements. Examples: Al, B, Ar, Br, etc.

Classification of essential elements

Based on the source of the essential elements, they can be classified into mineral and non-mineral elements. 

Non-mineral elements

The essential elements that the plants obtain from air and water are considered as non-minerals elements. These include carbon (C), hydrogen (H) and oxygen (O).

Mineral elements

The inorganic essential elements which the plants obtain from the soil are known as mineral elements. Soil contains most of the minerals and these minerals enter the plants through the root system. These include potassium (K), phosphorus (P), sulphur (S), magnesium (Mg), calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn), boron (B), copper (Cu), molybdenum (Mo), chlorine (Cl), and nitrogen (N).

Essential mineral elements are absolutely necessary for plant growth and metabolism. These are further divided into two categories based on their quantitative requirements. These are:

  • Macronutrients
  • Micronutrients
Macronutrients

These are present in plant tissue in large amounts and are required in excess of 10 mmol kg-1 of dry matter. Examples of minerals which are macronutrients are nitrogen, phosphorus, potassium, sulphur, calcium and magnesium. 

Carbon, hydrogen and oxygen are also essential macronutrients but they are non-mineral elements.



Fig: Macronutrients

Role of mineral macronutrients 

Name of element

Functions

Deficiency symptoms

Nitrogen (N)

Constituents of proteins, cytochrome, phytochrome, chlorophyll, auxins, purines, pyrimidines, NAD, NADP, DNA, RNA, promotes vegetative growth, and functions as enzymes.

Early leaf fall, suppressed tillering (production of shoot from the sides) and lateral buds, late flowering, purple coloration on the surface of the shoot axis due to the formation of anthocyanins, wrinkling of cereal grains, chlorosis (loss of chlorophyll) beginning with older leaves, stunted development due to decreased protein synthesis, smaller cells, and reduced yield.



Fig:Chlorosis of leaves

Phosphorus (P)

Constituents of RNA, DNA, NADP, ATP, ADP, ANP, GTP, GDP, phospholipids etc. Important in energy transfer reactions in cell metabolism. It is also present in nucleoproteins and phospholipids.

Stunted growth, leaves are dull green or have purple and red anthocyanin patches, older leaves will first experience necrosis (tissue death) or premature abscission (detachment of plant parts), delayed flowering, premature fall of flower bud, weak vascular tissues, and delayed seed germination.

Sulphur (S)

Constituents of amino acids like cysteine and methionine, vitamins like biotin, thiamine and Coenzyme A. It is also a part of ferredoxin. 

Young leaves are most frequently affected by chlorosis initially; deficiency can also cause anthocyanin accumulation, stunted growth, leaf curling, decreased juice content in citrus fruits, decreased nodulation in legumes, and defoliation (loss of leaves) in tea.

Potassium (K)

Essential for enzyme function. Other functions are regulation of stomatal opening and closing, electroosmotic movement of sucrose across sieve plates (common in cell sap), the synthesis of proteins from amino acids and conversion of sugar to starch.

Older leaves show the earliest signs of mottled interveinal chlorosis, as well as apical or marginal yellowing or scorching and curling. Other symptoms of deficiency include dieback (death of a plant starting from the tip and proceeding backwards), bushy habit, shorter internodes, loss of apical dominance, lodging (bending of stems close to the ground) in cereals, loss of cambial activity, plastid disintegration, and an increase in respiration rate.

Calcium (Ca)

Constituents of the cell wall, middle lamella, activator of amylase, ATPase and phospholipase. It is utilised during cell division in the mitotic spindle.

Growth is slowed down, meristem degeneration; particularly at the root apex. Chlorosis, necrosis, and curling first appear in immature leaves as deficiency symptoms. 



Fig: Curling of leaves

 

Premature flower abscission, and blossom end rot can also happen in tomatoes.



Fig: Blossom end rot in tomatoes

Magnesium (Mg)

It is a part of chlorophyll and the cofactor for several enzymes involved in photosynthesis and respiration. It aids in the production of DNA and RNA and maintains ribosome structure.

Reduced growth, underdeveloped phloem and pith, interveinal chlorosis with purple anthocyanin pigmentation first emerging in older leaves, green veins, chlorotic patches that may turn necrotic and cause premature leaf abscission.



Fig: Interveinal chlorosis

Micronutrients

These are also known as trace elements. These are present in very small amounts in plant tissues and are required in less than 10 mmol kg-1 of dry matter. Examples are: iron, manganese, copper, molybdenum, zinc, boron, chlorine, and nickel.



Fig: Micronutrients

Role of micronutrients 

Name of element

Functions

Deficiency symptoms

Iron (Fe)

Components of cytochromes, ferredoxin, catalase, nitrogenase etc. Important for the production of chlorophyll and for the ETS of respiration and the light reaction in photosynthesis.

Younger leaves with localised or widespread interveinal chlorosis.

Copper (Cu)

In the respiratory chain it is the terminal electron carrier. It acts as the activator of various enzymes, including oxidases. It is a part of plastocyanin, which is a component that functions as an electron carrier in the light reaction of photosynthesis in plants. It also participates in redox processes and is reversibly oxidised from Cu+ to Cu2+.

Young leaves develop necrosis at their tips, which extends down the edges toward the leaf bases. It is also known as reclamation disease or leaf tip disease. Shoot dieback occurs in fruit trees, where leaves wilt and drop. The bark turns tough and begins to exude gummy substances. It also causes the potato tubers to turn black.

Molybdenum(Mo)

It is a component of enzymes nitrogenase which participates in nitrogen fixation and nitrate reductase which helps in nitrogen metabolism. It plays a role in the synthesis of ascorbic acid and is required by some hydrogenase enzymes.

Leaves develop mottled chlorosis, marginal necrosis and infolding. Members of the family Brassicaceae develop whiptail disease which causes mottling, curling and scorching of young leaves. The leaf lamina withers and falls off. In oats, the lamina undergoes necrosis breadthwise in the middle such that the upper half folds over the lower half. Legumes develop symptoms of nitrogen deficiency as nitrogen fixation is hampered by the deficiency of molybdenum. Fruits and flowers fall prematurely.

Boron(B)

It is essential for maintaining the structural integrity of the cell wall. Aids in pollen germination, cell division, flowering, and fruiting. Additionally, it is necessary for the uptake and utilisation of Ca2+ and membrane operation.

The deficiency results in the deformation and death of root and shoot tips, as well as the loss of apical dominance. Other signs include abscission of flowers, small fruit size, lack of root nodules in leguminous plants, and stunted growth. Brown hearts in turnips, internal corks in apples, heart rot in sugar beets, browning of cauliflower, and diminished nodulation in legumes will also occur. The stem will be brittle but sturdy.

Zinc (Zn)

It is an enzyme activator, particularly for alcoholic dehydrogenase, lactic dehydrogenase, carbonic anhydrase, carboxypeptidase, alkaline phosphatase, glutamic dehydrogenase, superoxide dismutase. Helps in auxin biosynthesis and protein synthesis.

Little leaves, leaf rosettes, interveinal chlorosis, stunted growth, white buds, and interveinal necrosis in citrus leaves are some of the deficiency symptoms.

Manganese (Mn)

It is an activator of multiple enzymes such as reductases, oxidases, peroxidases, decarboxylases, kinases, dehydrogenases, etc. As an activator of decarboxylases and dehydrogenases, manganese is important for the Krebs cycle. It is also needed for the evolution of oxygen during photolysis of water.

Interveinal chlorosis, which is followed by necrosis of old leaves is one symptom of deficiency. Veins are still green but there will be spots or stripes of grey on the leaves. Cotyledons of legume plants with brown spots, known as marsh spot disease, and sterile flowers are another deficiency symptom. 



Fig: Marsh spot disease

Chlorine (Cl)

Aids in the transport of electrons from H2O to PSII during photosynthesis. Along with Na+ and K+, it  aids in determining the anion-cation balance and solute concentration in cells, which are necessary for cell division in both leaves and roots.

Bronze colour and wilting of the leaves, thick, club-shaped roots that are stunted, flower abscission, and decreased fruiting are the symptoms.



Fig: Wilting of leaves

Minerals required by humans

Minerals are the inorganic elements that are essential for our growth and development. They constitute 4% of our body weight and are required by our body for various enzymatic functions. Being small molecules, they do not need to be digested and are directly absorbed from the gut into the blood. Based on their requirements, minerals needed by animals are also distinguished as macro minerals and microminerals or trace minerals. 

Macro minerals are needed in larger quantities while trace minerals are needed in much smaller amounts. In humans macronutrients are required only at the amount of 0.1 g per day while micronutrients are needed as low as 0.01g per day.

Role of macrominerals

Name of element

Source

Role

Deficiency symptoms

Calcium (Ca)

Dairy food, eggs, green leafy vegetables, whole grains, legumes, nuts, etc.

Required for the formation of bones and teeth, essential for the cascade reactions that lead to blood clotting, help in conduction of nerve impulses and muscle contraction, and acts as an activator for multiple enzymes.

Weak bones and teeth, osteomalacia or rickets (softening of bones).

Phosphorus (P)

Vegetables, dairy products, cereals, egg, fish, liver, etc.

Essential for the synthesis of nucleic acids, ATP and phospholipids, which are integral cell membrane components. Phosphorus also helps in bone formation and strengthening as it is an essential component of bone matrix. It acts as a buffer in blood and plays an important role in sugar metabolism.

Poor development of bones and osteomalacia/rickets in children. Adults can suffer from loss of appetite, bone pain, fragile bones, stiff joints, fatigue, weakness, etc.

Sulphur (S)

Meat, eggs, dairy products, fruits, legumes, etc

It is a major constituent of proteins and coenzymes. It is required for the detoxification of harmful substances in the body.

Deficiency can lead to acne, itchy scalp and skin, eczema, arthritis, brittle bones and nails, rashes, slow wound healing, gastrointestinal issues, headaches, memory loss, etc.

Potassium (K)

Banana, mushrooms, meat, whole grains, vegetables, legumes, etc.

Required for conduction of nerve impulses, muscle contraction, protein synthesis. Crucial in maintaining membrane potential.

Nausea, anorexia, muscle weakness, irregular heart beat, confusion, constipation, tingling or numbness due to neural disturbance, etc.

Chlorine (Cl)

Table salt

Helps in water balance in the body, required for HCl synthesis in order to aid in digestion, principal negative ion in extracellular fluid and helps to maintain the membrane potential of cells.

Loss of body fluid due to diarrhoea and vomiting, dehydration, fatigue, difficulty of breathing, etc.

Magnesium (Mg)

Green vegetables, meat, whole grains, nuts, milk, legumes, etc. 

Needed as a cofactor for many enzymes and is important for many metabolic reactions involved in respiration. It is also a structural component of bones and teeth. Helps in nerve and muscle function, maintenance of a healthy immune system, helps to keep the heart beat steady.

Poor development of skeleton, nervousness, muscle spasms, pins and needles in fingers and feet, fatigue, weakness, nausea, vomiting, irregular heartbeat, etc.

Sodium (Na)

Green leafy vegetables, table salt, dairy products, pulses, legumes, carrots, beetroot, shellfish, dried meat, etc.

Required for nerve and muscle action, water balance, maintaining the membrane potential, etc. It is the principal positive ion in extracellular fluids.

Nervous debility or weakness, fatigue, nausea, muscle cramps, headache, confusion, seizures, etc.

Role of trace minerals

Name of element

Source

Role

Deficiency symptoms

Chromium (Cr)

Meat, dairy products, whole grains, dried beans, peanuts, etc.

Involved in carbohydrate and fat metabolism, stimulates fatty acid and cholesterol synthesis, glucose breakdown, etc

Loss of weight, impaired coordination, reduced response to sugar in blood, etc.

Cobalt (Co)

Meat, tap water, etc.

Required for formation of Vitamin B12, production of erythrocytes, etc.

Pernicious anaemia due to Vitamin B12 deficiency, fatigue, tingling in hands and feet, etc.

Copper (Cu)

Liver, meat, fish, shellfish, legumes, whole grains, nuts, etc.

Present in the active site of many redox enzymes and electron carriers and hence plays an important role in metabolic processes such as respiration. It helps in bone formation and the production of haemoglobin.

Anaemia, low body temperature, osteoporosis (brittle bones), loss of skin pigment, irregular heartbeat, low WBC count, etc.

Fluorine (F)

Most water supplies

Helps to maintain healthy and strong teeth.

Weak bones, tooth cavities

Iodine (I)

Fish, shellfish, iodised salt, etc.

Crucial for the synthesis of thyroxine hormone.

Goitre, myxoedema, cretinism in children, fatigue, low heart rate, weight gain, low body temperature, etc.

Iron (Fe)

Liver, meat, green vegetables, eggs, whole grains, legumes, nuts, etc.

Important constituent of haemoglobin and required for its synthesis.

Anaemia (lack of haemoglobin), extreme fatigue, weakness, brittle nails, pale skin, headache, dizziness, shortness of breath, increased heart rate, chest pain, etc.

Molybdenum (Mo)

Meat, dairy products, whole grains, legumes, green vegetables, etc.

It is an important cofactor for enzymes needed for the metabolism of sulphur containing amino acids, purines and pyrimidines. Also helps to break down drugs and other toxic substances entering the body. 

Decreased libido (sexual drive), sterility in men, delayed puberty, high concentration of methionine in blood, low uric acid in blood and urine, dislocated lens, seizures, etc.

Selenium (Se)

Sea food, meat, whole grains, eggs, chicken, milk, garlic.

It is an important component of proteins that help in synthesis of DNA and metabolism of thyroid hormones. It also plays a major role in enhancing immunity and lowering oxidative stress in the body.

Weak immunity, muscle weakness, anxiety, confusion, infertility, fatigue, hair loss, etc.

Zinc (Zn)

Dairy products, peanuts, legumes, whole wheat, liver, poultry, beef, shellfish, etc.

It is an important cofactor for 100 different enzymes and is thus required for various biochemical reactions. It plays a major role in synthesis of DNA, proteins, cell growth, strengthening the immune system, healing damaged tissue, etc.

Weak immunity, diarrhoea, hair loss, loss of appetite, impotence, discolouration of nails, etc.

Practice Problems

Q1. From the following, pick the false statement.

A. Deficiency of calcium cannot be met by replacing it with some other element.
B. Macronutrients are required in excess of 10 mmol kg-1 of dry matter.
C. Carbon, oxygen and hydrogen are mineral elements.
D. Micronutrients are also known as trace elements. 

a. I
b. II
c. III
d. IV

Solution: The elements that are absolutely necessary for the growth, development, reproduction and survival of plants are known as essential elements. These elements are either structural components of the plant cell or are absolutely essential for metabolic reactions. These elements are non-replaceable and hence their role cannot be fulfilled by other elements. Their deficiency in the plant body would thereby manifest in the form of some deficiency symptom. Calcium is one such essential element which is a part of the plant cell wall. Being an essential element its deficiency in the plant body reflects as stunted growth, chlorosis, necrosis and curling of leaves, premature abscission, etc. It cannot be replaced by other elements.

Essential elements that are required in excess of 10 mmol kg-1 of dry matter are called macronutrients. Examples are: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulphur, calcium and magnesium. In this carbon, oxygen and hydrogen are non mineral elements and the rest are mineral elements. Micronutrients are also known as trace elements. They are required in less than 10 mmol kg-1 of dry matter. Examples are: iron, manganese, copper, molybdenum, zinc, boron, chlorine, and nickel.

Hence the correct option is c.

Q2. Match the following:

Element 

Deficiency symptom 

A) Molybdenum

i) Interveinal chlorosis

B) Potassium

ii) Wilted leaves

C) Chlorine 

iii) Whiptail disease of leaves

D) Iron 

iv) Scorched leaf tips

A. A-i, B-ii, C-iii, D-iv
B. A-iii, B-iv, C-ii, D-i
C. A-i, B-iii, C-ii, D-iv
D. A-iii, B-iv, C-ii, D-i

Solution: Molybdenum deficiency in soil is the primary cause of whiptail disease. Whiptail disease appears in young plants as chlorosis of the leaf margins (the entire leaf may turn white), as well as improper growth of the leaf blades. Only the midribs develop when the deficit is severe. 

Chlorosis (yellowing) between leaf veins and brown scorching and curling of leaf tips are typical signs of potassium shortage in plants. 

The wilting of leaves, particularly at the edges, is the Cl deficiency symptom that is most frequently mentioned. Curling, bronzing, chlorosis, and necrosis are symptoms of the deficit as it worsens and spreads. 

The newest, youngest leaves display the signs of iron insufficiency. The vein gap between the leaves turns a pale yellow or white colour (this is called interveinal chlorosis). In most cases, there is no obvious physical deformity, but in extreme cases, the youngest leaves may be completely white and stunted.

Hence the correct option is b.

Q3. What are the functions of the element Copper in a plant?
Answer: In the respiratory chain it is the terminal electron carrier. Activator of various enzymes, including oxidase. It is a part of plastocyanin, which is a component that functions as an electron carrier in the light reaction. It also participates in redox processes and is reversibly oxidised from Cu+ to Cu2+.

Q4. Pernicious anaemia is caused due to the deficiency of which of the following minerals in our body?

A. Iron
B. Cobalt
C. Selenium
D. Zinc

Answer: Pernicious anaemia is actually a Vitamin B12  deficiency disease that is caused due to reduced production of erythrocytes. This is because vitamin B12 is necessary for the synthesis of red blood cells. As cobalt is an integral component of vitamin B12, its deficiency leads to deficiency of vitamin B12 and therefore results in pernicious anaemia.

Thus the correct option is b.

FAQs

Q1. How do plants store minerals?
Answer: Utilising plasma-membrane transporter proteins, nutrients are taken up from the soil, and any excess is either stored in the cell vacuole or transformed into polymerized storage forms. To get the highest yield, it is crucial for crops to balance nutrient supply and demand throughout the growing season.

Q2. Which soil is mineral-rich?
Answer: The minerals in the alluvial soil are abundant. It is incredibly fertile and excellent for farming. Sand, silt, and gravel are frequently present in it. Surface water deposition is the source of alluvial soils. They can be found by rivers, in stream terraces, alluvial fans, floodplains, and deltas.

Q3. What happens if you consume too many minerals?
Answer: Taking too many vitamins and minerals on a regular basis might be harmful. Constipation, diarrhoea, and stomach cramps may result from taking too much zinc or vitamin C. Hair loss, gastrointestinal distress, weariness, and slight nerve damage could all result from consuming too much selenium.

Q4. Which element provides secondary nutrition to plants?
Answer: Sulphur, calcium, and magnesium are essential nutrients for plants. They are referred to as secondary nutrients because plants need less of them than the primary nutrients, which are nitrogen, phosphorus, and potassium.

YOUTUBE VIDEO:

Related Topics

Methods to study the mineral requirements of plants, Practice Problems and FAQs 

Macronutrients, Practice Problems and FAQs

Micronutrients: Introduction, Iron, Copper, Manganese, Molybdenum, Nickel, Boron, Zinc, Chlorine, Practice Problems, FAQs 

Nitrogen Cycle: Overview, Nitrogen fixation (Atmospheric, Industrial, Biological), Nitrification, Assimilation, Denitrification, Ammonification, Practice Problems and FAQs 

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