🌱 Mineral Nutrition – NEET 2025 Complete Notes by Botany Sir Himansu

🌿 Introduction: Why Do Plants Need Minerals?

Just like humans need vitamins and minerals to stay healthy, plants also require specific nutrients from the soil to grow, reproduce, and carry out life processes. These nutrients influence everything from chlorophyll formation to enzyme activation, protein synthesis, and flower development.

For NEET aspirants, Mineral Nutrition is a scoring chapter because the questions are direct:

✅ Deficiency symptoms

✅ Essential elements

✅ Nitrogen cycle

✅ Hydroponics

✅ Transport & toxicity

Let’s understand this chapter in the most simple and NEET-focused way.

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🌾 Section 1: Essential Mineral Elements

✅ What Makes an Element “Essential”?

An element is considered essential if:

1️⃣ Without it, plants cannot complete the life cycle.

2️⃣ It cannot be replaced by any other element.

3️⃣ It plays a direct role in plant metabolism.

Classification of Essential Elements

1. Macro-nutrients (Required in large amounts)

Nitrogen (N)

Phosphorus (P)

Potassium (K)

Calcium (Ca)

Magnesium (Mg)

Sulfur (S)

Carbon (C)

Hydrogen (H)

Oxygen (O)

2. Micro-nutrients (Required in small amounts)

Iron (Fe)

Zinc (Zn)

Copper (Cu)

Chlorine (Cl)

Boron (B)

Molybdenum (Mo)

Manganese (Mn)

Nickel (Ni)

NEET Tip:

"Mo" (Molybdenum) is needed for nitrogen fixation enzymes (very important MCQ).

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🌿 Section 2: Functions of Essential Elements

✅ Macronutrients Functions

1. Nitrogen (N)

Component of amino acids, proteins, nucleic acids, chlorophyll.

Promotes vegetative growth.

Deficiency: Yellow leaves (chlorosis) starting from older leaves.

2. Phosphorus (P)

Component of ATP, DNA, RNA.

Important for energy transfer.

Deficiency: Purple-red coloration in older leaves.

3. Potassium (K)

Activation of enzymes.

Regulates stomatal opening.

Deficiency: Scorched leaf margins.

4. Calcium (Ca)

Needed for cell wall formation (middle lamella – calcium pectate).

Required in meristematic tissues (growing regions).

Deficiency: Death of shoot and root tips.

5. Magnesium (Mg)

Central atom of chlorophyll.

Activates enzymes of photosynthesis.

Deficiency: Interveinal chlorosis in older leaves.

6. Sulfur (S)

Component of amino acids (cysteine, methionine).

Deficiency: Young leaves turn yellow.

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✅ Micronutrient Functions

1. Iron (Fe)

Required for chlorophyll synthesis (although not a part of chlorophyll).

Deficiency: Interveinal chlorosis in young leaves.

2. Boron (B)

Helps in pollen tube formation.

Deficiency: Poor seed and fruit formation.

3. Zinc (Zn)

Important for auxin synthesis.

Deficiency: Little leaf disease.

4. Copper (Cu)

Component of redox enzymes.

Deficiency: Dieback of shoots.

5. Manganese (Mn)

Required in photolysis of water (Hill reaction).

Deficiency: Interveinal chlorosis + brown spots.

6. Molybdenum (Mo)

Important for nitrogenase enzyme.

Deficiency: Whiptail disease in cauliflower.

7. Chlorine (Cl)

Required for oxygen evolution in photosynthesis.

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🌱 Section 3: Deficiency Symptoms (NEET Favourite)

✅ Highly Predictable NEET Questions:

Nitrogen deficiency → Yellowing of older leaves

Phosphorus deficiency → Purpling of leaves

Potassium deficiency → Leaf tip scorching

Calcium deficiency → Death of meristems

Iron deficiency → Chlorosis in young leaves

Boron deficiency → Cracking of fruits

Molybdenum deficiency → Whiptail in cauliflower

Why do deficiency symptoms vary?

Because minerals differ in mobility.

✅ Mobile nutrients (N, P, K, Mg) — deficiency appears in older leaves first.

✅ Immobile nutrients (Ca, B, Fe) — deficiency appears in younger leaves.

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🌾 Section 4: Toxicity of Mineral Elements

“Too much of anything is bad” — even nutrients!

Excess Manganese (Mn) is most harmful:

Induces iron deficiency

Induces magnesium deficiency

Induces calcium deficiency

Mnemonic: “Mn kills Fe, Mg & Ca”

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🌱 Section 5: Hydroponics (Soilless Culture)

Discovered by Julius von Sachs.

✅ Uses:

Identifying essentiality of minerals

Growing plants where soil fertility is poor

Commercial tomato, lettuce, flower production

NEET Point: Hydroponics uses nutrient solutions, not soil.

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🌿 Section 6: Nitrogen Cycle (Very Important for NEET)

✅ 1. Nitrogen Fixation

Converting atmospheric N₂ → NH₃

Done by:

Rhizobium (symbiotic)

Azotobacter (free-living)

Cyanobacteria (Nostoc, Anabaena)

Enzyme: Nitrogenase

Requires: Anaerobic conditions + Molybdenum

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✅ 2. Nitrification

NH₃ → NO₂⁻ (Nitrosomonas)

NO₂⁻ → NO₃⁻ (Nitrobacter)

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✅ 3. Assimilation

Plants absorb nitrate NO₃⁻ and convert it into amino acids.

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✅ 4. Ammonification

Decomposition → organic N → NH₃

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✅ 5. Denitrification

NO₃⁻ → N₂

Done by: Pseudomonas, Thiobacillus

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🌳 Section 7: Symbiotic Nitrogen Fixation (Root Nodules)

Occurs in legumes.

✅ Key Components:

Rhizobium bacteria

Leghaemoglobin (pink colour)

Maintains low O₂ for nitrogenase activity

Nodules formed by plant–bacteria interaction

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🌸 Section 8: Summary Table (Perfect for Revision)

Element Function Deficiency

N Proteins, chlorophyll Chlorosis

P ATP, DNA Purpling

K Stomata, enzymes Scorching

Ca Cell wall Meristem death

Mg Chlorophyll Interveinal chlorosis

Fe Chlorophyll synthesis Young leaf chlorosis

Mo Nitrogenase Whiptail (Cauliflower)

B Pollen tube Poor fruiting

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🧠 Section 9: NEET PYQs – Mineral Nutrition

✅ NEET 2023

Which element is essential for nitrogen fixation?

✅ Mo (Molybdenum)

✅ NEET 2021

Whiptail disease is caused by deficiency of:

✅ Molybdenum

✅ NEET 2020

Little leaf disease is due to deficiency of:

✅ Zinc

✅ NEET 2019

Chlorosis occurs due to deficiency of:

✅ N, K, Mg, Fe

✅ NEET 2018

Leghaemoglobin helps in:

✅ Maintaining low O₂ for nitrogenase

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🌱 Conclusion

Mineral nutrition builds the foundation of plant health. As a NEET aspirant, mastering:

Functions of elements

Deficiency symptoms

Nitrogen cycle

Nodulation process

…will help you easily score multiple questions in the exam.

This chapter is factual, predictable, and extremely scoring — revise the summary table every day!