How can a microscopic paramecium and a large giraffe both be described by cell theory? how are they different?

The cell theory by Schleiden and Schwann provided the evidence and suggested that all the living organism on earth are made up of cells and cell is the structural and functional unit of life. Additionally, the cell arises from the pre-existing cells was added by the Virchow to the cell theory.

The cell theory indicates that whether an organism is microscopic or a macroscopic giraffe as discussed in the question are made up the fundamental unit of life called "cell".   The paramecium is unicellular whereas the giraffe is multicellular.

the most common energy conversion is from kinetic energy to potential energy, and then from potential energy to kinetic energy.

later on comes the heat energy, mechanical energy, and other energy conversions.

this energy conversion is so common that we can find it in our day to day lives as well.

- one of the most common energy conversions involves the changing of potential energy to kinetic energy or kinetic energy to potential energy