pH is a measurement of the concentration of in solution.

Correct Answer: C

Rationale: pH measures H+ ion concentration (-log[H+]).

Correct Answer: D

Rationale: Proteins don't directly create energy; they facilitate processes (e.g., enzymes, muscle movement).

Correct Answer: D

Rationale: Nucleotides (DNA/RNA) lack amino acids, which are in proteins.

Correct Answer: D

Rationale: Simple squamous epithelium is a single layer of flat cells, ideal for diffusion.

Correct Answer: C

Rationale: Connective tissue has cells dispersed in a fibrous extracellular matrix, unlike tightly packed epithelium.