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#essential elements

4 public questions tagged with this topic.

Plant tissue culture 1

Micronutrients in plant tissue culture are required:

Micronutrients, also called trace elements, are required in quantities less than 0.5 millimolar, typically micromolar to nanomolar range, yet indispensable for viability and morphogenesis in vitro. Group includes iron 0.1 mM as Fe-EDTA for chlorophyll synthesis, cytochromes and Fe-S proteins of electron transport; manganese activating oxygen evolving complex of photosystem II and Mn superoxide dismutase; zinc structural component of zinc-finger transcription factors carbonic anhydrase alcohol dehydrogenase; boron crosslinking rhamnogalacturonan II in pectin maintaining wall integrity and membrane stability; copper in plastocyanin for photosynthesis and cytochrome oxidase for respiration; molybdenum essential for nitrate reductase and aldehyde oxidase cofactor; nickel for urease; chlorine for PSII water splitting; iodine and cobalt in minute amounts improving growth in some species. They function mainly as enzyme cofactors or prosthetic groups not as bulk structural mass. Despite low requirement, omission causes severe abnormalities stunted growth chlorosis and failure of embryo maturation, while excess induces toxicity, hence careful chelation and balanced formulation are critical for successful culture performance.

Ref: Taiz & Zeiger Chap. 5 mineral nutrition; Epstein & Bloom mineral nutrition.

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Atoms and Molecules

Which of the following elements is not essential for life?

Arsenic is the correct choice because it does not accurately describe or belong to the category addressed in this question. In the context of Atoms and Molecules, the other options (Carbon, Nitrogen, and Oxygen) are all valid and well-established concepts. Arsenic is either unrelated to the topic, describes a different biological process, or represents a common misconception. Questions framed as 'which is NOT' require students to identify the exception among otherwise correct statements, demanding comprehensive knowledge of the topic rather than recognition of a single fact.

Ref: Campbell Biology, Urry et al., 12th Ed.

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Atoms and Molecules

The most abundant elements in living organisms are:

C, H, O, N is the correct answer as it accurately identifies the biological location, composition, or distribution described in this question. In Atoms and Molecules, the spatial organization and localization of molecules are critical to their function. C, H, O, N is specifically associated with the structure or compartment mentioned because of its unique biochemical properties and physiological role. The other options (Na, K, Cl, Mg, Fe, Cu, Zn, Mn, and P, S, Ca, K) are primarily associated with different cellular compartments, tissues, or structural contexts.

Ref: Campbell Biology, Urry et al., 12th Ed.

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