Which of the following is NOT a major element found in microbial cells?

• A. Oxygen (O)
• B. Carbon (C)
• C. Nitrogen (N)
• D. Calcium (Ca)

Answer: (D)

Verified step by step guidance

1. Step 1: Understand what major elements in microbial cells are. These are elements that are essential and found in large amounts, such as Oxygen (O), Carbon (C), and Nitrogen (N), which are fundamental to biomolecules like proteins, nucleic acids, carbohydrates, and lipids.
2. Step 2: Review the list of elements provided: Oxygen (O), Carbon (C), Nitrogen (N), and Calcium (Ca). Consider the biological roles and abundance of each element in microbial cells.
3. Step 3: Recognize that Oxygen, Carbon, and Nitrogen are key components of organic molecules and are universally abundant in all living cells, including microbes.
4. Step 4: Understand that Calcium (Ca), while important in some cellular processes such as signaling or structural roles in certain organisms, is not considered a major element because it is present in much smaller amounts and is not a fundamental building block of microbial cell structure.
5. Step 5: Conclude that Calcium (Ca) is the element that is NOT a major element found in microbial cells, distinguishing it from the essential major elements Oxygen, Carbon, and Nitrogen.