Which of the following is NOT classified as a plant micro-nutrient (trace element) for growth and metabolism?
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AChlorine
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BIron
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CBoron
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DCarbon
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EMolybdenum
Answer
Correct Answer: Carbon
Explanation
Introduction / Context:Plant nutrients are grouped into macronutrients (required in large amounts) and micronutrients (required in trace quantities). Clear classification aids fertiliser formulation and diagnosis of deficiency symptoms in crops.
Given Data / Assumptions:
- Typical micronutrients: B, Cl, Cu, Fe, Mn, Mo, Zn, Ni.
- Macronutrients: N, P, K, Ca, Mg, S, plus C, H, O from air/water.
Concept / Approach:Carbon is a fundamental macronutrient obtained primarily from atmospheric CO2 through photosynthesis, not a trace element supplied as a micro-nutrient in fertilisers. In contrast, chlorine, iron, boron, and molybdenum are classic micro-nutrients supplied in small amounts through soil amendments or foliar feeds.
Step-by-Step Solution:
List canonical micronutrients and compare with the options.Recognise that carbon is a bulk element acquired from CO2 and organic matter, not a trace mineral fertiliser component.Therefore, select “Carbon.”Other listed elements (Cl, Fe, B, Mo) are established micro-nutrients.Verification / Alternative check:Agronomic texts and extension guides consistently classify C as a macronutrient, while B, Cl, Fe, and Mo are trace elements with defined deficiency/toxicity ranges in soils and plant tissues.
Why Other Options Are Wrong:
- Chlorine, Iron, Boron, Molybdenum: all are required in small amounts and classed as micro-nutrients.
Common Pitfalls:Confusing the term “micro-nutrient” with “minor importance”; micro-nutrients are critical despite low required quantities.
Final Answer:Carbon