Macronutrients

Options

A. are so called because they are more essential than micronutrients.
B. include manganese, boron, and zinc, among others.
C. function as catalysts.
D. are required in concentrations of at least 1 gram per kilogram of plant dry matter

Answer

### Step-by-Step Solution

1. **Understanding Macronutrients**:
- Macronutrients are essential nutrients that plants require in larger quantities compared to micronutrients. They are vital for various physiological functions necessary for plant growth and development.

2. **Identifying Macronutrients**:
- Common macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. These nutrients are required in amounts greater than 1 gram per kilogram of plant dry matter.

3. **Analyzing the Options**:
- **Option A**: States that macronutrients are more essential than micronutrients. This is incorrect as both are equally essential for plant survival.
- **Option B**: Mentions manganese, boron, and zinc, which are actually micronutrients, not macronutrients. Hence, this option is also incorrect.
- **Option C**: Claims that macronutrients function as catalysts. This is misleading since it is primarily the role of micronutrients to act as catalysts in various biochemical reactions.
- **Option D**: States that macronutrients are required in concentrations of at least 1 gram per kilogram of plant dry matter. This statement is correct and accurately describes macronutrients.

4. **Conclusion**:
- After analyzing all the options, the correct answer is **Option D**, as it correctly defines the requirement of macronutrients in plants.