CBSE Class 11 Biology Notes Chapter 12 Mineral Nutrition

CBSE Class 11 Biology Notes Chapter 12: CBSE Class 11 Biology Notes Chapter 12 covers the topic of mineral nutrition. In the CBSE class 11 biology notes chapter 12 notes, we will look at the many minerals essential for life and what their specific functions are. The roles and functions of all essential minerals are very important for the board exam and entrance exam and students find it very difficult to remember them. This is why we have provided CBSE Class 11 Biology Notes Chapter 12. Students can use these notes as a study guide which can be quite beneficial.

CBSE Class 11 Biology Notes

CBSE Class 11 Biology Notes Chapter 12 Overview

Minerals Definition

What are Essential Mineral Elements?

Criteria for Essentiality

• The element must be important for normal growth and reproduction. If the element is absent, plants cannot complete their life cycle or produce seeds.
• The need for the element must be specific and cannot be substituted by another element.
• The element must play a direct role in the plant's metabolism.

Classification of Minerals Based on Quantitative Requirements

Classification of Minerals Based on Functions

• Those elements which are fundamental components of biomolecules serve as structural elements within cells. Examples include carbon, hydrogen, oxygen, and nitrogen.
• Those elements which are the main parts of energy-related chemical compounds within plants. For example, magnesium is a component of chlorophyll, while phosphorus is found in ATP (adenosine triphosphate).
• Those elements which play roles in enzyme activation or inhibition. For example, magnesium ions (Mg^2+) activate key enzymes involved in photosynthetic carbon fixation, while zinc ions (Zn^2+) activate alcohol dehydrogenase.
• Some essential elements can influence the osmotic potential of cells. Potassium, for instance, is essential for regulating the opening and closing of stomata, thereby affecting the plant's water balance.

Roles of Macronutrients and Micronutrients

• Plants require nitrogen in the largest quantity.
• It is absorbed primarily as nitrate (NO3-) but also as nitrite (NO2-) or ammonium (NH4+).
• Nitrogen is essential for all plant parts, especially meristematic tissues and metabolically active cells.
• It is a major component of proteins, nucleic acids, vitamins, and hormones.

• Plants absorb phosphorus as phosphate ions (H2PO4- or HPO4^2-).
• It is required for cell membranes, certain proteins, nucleic acids, and phosphorylation reactions.

• Absorbed as potassium ions (K+)
• Potassium is needed in higher quantities in meristematic tissues, buds, leaves, and root tips.
• It helps maintain cell ion balance, protein synthesis, stomata regulation, enzyme activation, and cell turgidity.

• Plants take up calcium as calcium ions (Ca2+).
• Required for meristematic and differentiating tissues
• Calcium helps in cell wall synthesis, mitotic spindle formation, membrane function, enzyme activation, and metabolic regulation.

• Absorbed as divalent Mg2+ ions, magnesium activates enzymes for respiration, photosynthesis, DNA, and RNA synthesis.
• It is a component of chlorophyll and maintains ribosome structure.

• Plants obtain sulfur as sulfate ions (SO4^2-).
• It is present in amino acids, coenzymes, vitamins, and ferredoxin.

• Absorbed as ferric ions (Fe3+), iron is crucial for electron transfer proteins, catalase activation, and chlorophyll formation.

• Absorbed as manganese ions (Mn2+), manganese activates enzymes for photosynthesis, respiration, and nitrogen metabolism, particularly in water-splitting during photosynthesis.

• Plants absorb zinc as Zn2+ ions, which activate various enzymes, especially carboxylases, and aid in auxin synthesis.

• Absorbed as cupric ions (Cu2+), copper is essential for overall plant metabolism, involved in redox reactions and enzyme activation.

• Plants take up boron as borate ions (BO3^3- or BO4^2-), necessary for Ca2+ uptake, membrane function, pollen germination, cell elongation, differentiation, and carbohydrate transport.

• Absorbed as molybdate ions (MoO4^2-), molybdenum is a component of enzymes like nitrogenase and nitrate reductase crucial for nitrogen metabolism.

• Absorbed as chloride ions (Cl-), chlorine along with Na+ and K+
• Calcium helps regulate solute concentration and anion-cation balance in cells.
• It is essential for water-splitting in photosynthesis.

What is Nutrient Deficiency?

Deficiency Symptoms

• Deficiency symptoms vary depending on the element and disappear when the lacking nutrient is supplied, but prolonged deprivation can lead to plant death.
• Elements actively mobilized and exported to young tissues show symptoms first in older tissues. For example, nitrogen, potassium, and magnesium deficiencies manifest in senescent leaves first.
• Elements relatively immobile within mature organs exhibit symptoms first in young tissues. Examples include sulfur and calcium, which are structural components of cells.

Types of Deficiency Symptoms

CBSE Class 11 Biology Notes Chapter 12 Benefits

• The notes help clarify important concepts such as the classification of minerals, their functions in plant and human nutrition, and the consequences of deficiencies.
• These notes categorize minerals into macronutrients and micronutrients, and further subdivide them based on their functions and sources.
• Students can use these notes as a quick reference to refresh their memory on important concepts and facts.