Question

A botanist claims to have discovered a new macronutrient required for plant growth. Most of this scientist's colleagues are skeptical of her claim. Why might they consider it unlikely?

A. It is very difficult to prove that a plant needs a certain nutrient.
B. Plants need thousands of nutrients; a new one is not significant.
C. Plants manufacture their own macronutrients.
D. All the nutrients required for plant growth have already been found.
E.Any nutrient needed in large amounts (macronutrient) has probably been noted already.

Answer 1

Scientists are skeptical about the discovery of a new macronutrient for plant growth because all necessary macronutrients are already known, and the criteria for essentiality are stringent, making new discoveries in this area quite rare.

Step-by-step explanation:

Colleagues may consider it unlikely that a botanist has discovered a new macronutrient required for plant growth primarily because any nutrient needed in large amounts has probably been noted already. Macronutrients such as carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur are well-studied and are known to be essential for various plant functions including growth, energy transfer, and protein synthesis.

Scientists have clearly defined the criteria for an element to be considered essential for plant life; it must meet all three conditions including the inability of a plant to complete its life cycle without it, no other element being able to perform the same function, and the element being directly involved in nutrition. Given the extensive research already conducted in the field of plant nutrition, the discovery of a new macronutrient would be an extraordinary finding.