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 cell is the basic unit of life, and all organisms are made up of one or many cells. One of the things that all cells have in common is a cell membrane. It is a barrier that separates a cell from its surrounding environment. This outer boundary of the cell is also called the plasma membrane.