Chapter 39, Problem 1TYK

Summary Introduction

Introduction:

An essential nutrient is an element or compound that is required by plant to exhibit normal physiological functions like growth and reproduction and plant is not able to finish its life cycle without this nutrient. Essential nutrients are further divided into macronutrients and micronutrients. Macronutrients are elements required by plants in moderately large quantities. For example, macronutrients form main components of nucleic acids, proteins, and phospholipids. Micronutrients are elements required by plants in small quantities. For example, molybdenum is a micronutrient act as a cofactor for many enzymes involved in nitrogen processing.

Answer to Problem 1TYK

Correct answer:

If essential nutrient is missing, a plant cannot grow or reproduce normally.

Explanation of Solution

Justification for the correct answer:

Option (b) is given as if essential nutrient is missing, a plant cannot grow or reproduce normally. An essential nutrient is crucial for growth and reproduction of plants. The key macronutrients are nitrogen (N), phosphorus (P), and potassium (K) which plays significant role in growth of a plant as they form major elements in building blocks like proteins, nucleic acids, lipids, carbohydrates, and energy molecules like ATP. These elements N, P, and/or K are also involved in synthesis of soil fertilizer for increasing plant growth. The deficiency or shortage of essential nutrient causes yellowing of leaves, stunted growth, dead spots, delayed maturity, poor seed and fruit formation. Hence, option (b) is correct.

Justification for the incorrect answers:

Option (a) is given as if essential nutrient has to be added as fertilizer to achieve maximum seed production. The primary function of fertilizer is to increase plant growth, crop production, and crop quality. Hence, option (a) is an incorrect answer.

Option (c) is given as if essential nutrient is present at high concentration, plant growth increases. It is not necessary that high concentration of essential nutrient increases plant growth. High concentrations of essential nutrient in the soil can hamper plant growth and decrease crop yields. Hence, option (c) is an incorrect answer.

Option (d) is given as if essential nutrient is absent, other nutrients may be substituted for it. It is not necessary that other nutrients substitute for essential nutrient. Many essential nutrients have specific role like micronutrient molybdenum, as it acts as a cofactor for several enzymes involved in nitrogen processing. Its deficiency can hamper nitrogen metabolism in plants. Hence, option (d) is an incorrect answer.

Conclusion

The precise definition of essential nutrient is its requirement for plant growth and reproduction.