Mineral Nutrition

What is Mineral Nutrition?

Mineral nutrients are the inorganic natural substances absorbed by plants from soil, water, and air. These nutrients are essential for plant growth and development. They play a major role in physiological functions within the plant, like enzyme activation, energy transfer, and cell structure formation.

• Minerals are an inorganic element.

• Nutrient is a substance that provides nourishment essential for the maintenance of life and for growth

Classification of Plant Nutrients

The plants need both non-mineral and mineral nutrients to grow. Non-mineral elements like carbon, hydrogen, and oxygen come from air and water. Mineral nutrients are absorbed from the soil and are classified as macronutrients and micronutrients. Both are essential for plant health and development.

Criteria For Essentiality Of Elements

The criteria for essentiality of elements are:

1. Necessary for normal growth: The element must be absolutely necessary for the plant to grow and complete its life cycle properly.

2. Cannot be replaced by other elements: The element’s requirement must be specific and cannot be covered by any other element's function.

3. Direct role in metabolism: The element should directly participate in the plant’s metabolic processes.

Example: Magnesium (Mg) is an essential mineral element that cannot be replaced by any other element, as it is a basic component of chlorophyll essential for photosynthesis and necessary as a cofactor for multiple enzymes participating in cellular respiration and various metabolic pathways.

Functions Of Mineral Nutrients

The functions of mineral nutrients are:

Mineral Uptake And Absorption

Mineral uptake involves both passive (apoplast) and active processes (symplast).

• In the initial phase, ions move passively from soil into spaces outside root cells as an apoplast pathway. This rapid uptake requires no energy.

• In the metabolic phase, ions enter root cell cytoplasm and vacuoles as symplast pathways via active transport. This phase requires metabolic energy.

• After absorption, minerals and water move through the xylem vessels.

• The xylem acts as a tube for transporting nutrients and water to all plant parts.

Nutrient Deficiency Symptoms

The deficiency symptoms of essential elements can be visible in plants, such as direct results of a lack of essential minerals, such as magnesium and iron, in the form of the following symptoms:

1. Chlorosis - yellowing of leaves due to lack of chlorophyll (seen in magnesium or iron deficiency)

2. Necrosis - dead patches or spots on leaves (caused by lack of calcium, potassium, etc.)

3. Stunted growth - the plant becomes smaller and weaker

4. Delayed flowering - flowers take longer to form or may not form at all

5. Poor root and fruit development - due to a lack of phosphorus or potassium

6. Falling of leaves or buds - often due to a deficiency of nutrients like zinc or boron

Nitrogen Fixation

The plants need nitrogen to grow, but they can't use it directly from the air. The nitrogen cycle helps convert nitrogen into an absorbable form through a process called nitrogen fixation. There are two main ways this happens:

Symbiotic Nitrogen Fixation

Some plants, like legumes (peas, beans) have a relationship with bacteria called Rhizobium. These bacteria live in small swellings on the roots called nodules. They take nitrogen from the air and convert it into ammonia, which the plant can use. In return, the plant gives the bacteria food and shelter.

Non-Symbiotic Nitrogen Fixation

Some free-living bacteria in the soil, like Azotobacter and Clostridium, undergo nitrogen metabolism on their own, without needing a plant partner.

Mineral Nutrition NEET MCQs (With Answers & Explanations)

The key concepts to be covered under this topic for different exams are:

• Macronutrients and Micronutrients

• Symptoms of nutrient deficiencies

• Nitrogen fixation

Practice Questions for NEET

Q1. Minerals are absorbed by plants in

1. Colloidal form

2. Ionic form

3. Precipitated form

4. None of these

Correct answer: 2) Ionic form

Explanation:

Minerals in the plant are taken up as ions from the soil into the roots. This is a result of both passive absorption when ions move through concentration gradients without utilizing energy, and active absorption, which requires using energy to force ions against their gradients. Ions of special importance are K⁺ (potassium), Ca²⁺ (calcium), and NO₃⁻ (nitrate). Root hairs increase the absorption efficiency, whereas mycorrhizal fungi also increase mineral absorption, which facilitates essential physiological processes and the neural well-being of plants.

Hence, the correct answer is option 2) Ionic form.

Q2. Which of the following is not a criteria of essentiality of mineral nutrients?

1. Which of the following is not a criteria of essentiality of mineral nutrients?

2. The element must be directly involved in the metabolism

3. In the absence of element, no disorder or malformation in plant should occur

4. The requirement of element must be specific

Correct answer: 3) In the absence of element, no disorder or malformation in plant should occur

Explanation:

The criteria of essentiality are as follows.

1. The element must be 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.

2. 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.

3. The element must be directly involved in the metabolism of the plant.

4. In the absence of an element a disorder or malformation in plants occur

Hence, the correct answer is option 3) In the absence of an element, no disorder or malformation in the plant should occur.

Q3. The technique of growing plants in a liquid nutrient solution is called

1. Mineral nutrition

2. Hydroponics

3. Aeroponics

4. Both a and b

Correct answer: 2) Hydroponics

Explanation:

Hydroponics is a method of growing plants without soil, using a nutrient-rich water solution to supply the essential nutrients required for plant growth. The roots of the plants are submerged in this nutrient solution, allowing them to absorb water and nutrients directly. Hydroponics can be used to grow a wide variety of plants, including vegetables, herbs, and even fruits, in environments where soil may not be available or suitable for traditional farming. This method offers several benefits, such as faster plant growth, efficient use of water, and the ability to grow in controlled environments like greenhouses or indoors.

Hence, the correct answer is option 2) Hydroponics.

Also Read:

• MCQs on Essential Mineral Nutrients in Plants

• Uptake and Transport of Mineral Nutrients

• Difference between Macronutrients And Micronutrients

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