Plywood grades are (best to worst) A, B, C and D for face or front face. The back grades are (best to worst) 1, 2, 3, and 4. Plywood grading standards are published by the Hardwood Plywood & Veneer Association.ardwood Plywood Grades Here's a concise explanation of hardwood plywood grades and what they mean.
Cell (biology) The cell (from Latin cella, meaning small room) is the basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life that can replicate independently, and cells are often called the building blocks of life. The study of cells is called cell biology.
A tissue is one of the building blocks of an organism--either animal or plant. An organism is comprised of tissues, which are made up of individual cells. These cells share a similar structure (how they're built) and function (what they do). The study of tissues is a field known as histology.