Calves can be ready for weaning by 3 to 4 weeks of age; however, in Penn State studies calves weaned at 3 weeks required extra attention. The increased time and labor required to get these calves eating starter suggest that waiting until 4 weeks of age would be prudent.
Plant cell walls are semipermeable and only allow small molecules into the plant cell. This allows nutrients and water to pass through the cell wall, but doesnât allow pathogenic bacteria and viruses into the plant. In this way, cell walls protect plants from disease. Cell walls also help promote cellular communication. Oligosaccharides are parts of cell walls that are responsible for cell-to-cell signaling. These compounds can stimulate plant hormone product, protect plants from bacteria and viruses, and induce enzymatic changes within the plant cells.
The cell wall is a rigid structure that supports the cell membrane and lets nutrients and other minerals pass through. It is extremely important to all cells. The cell wall â¦ is rigid (up to many micrometers in thickness) and gives plant cells a very defined shape.he cell wall is in PLANT CELLS ONLY !   I'm here to improve the answer, like the person said above, the cell wall does protect the â¦ cell membrane and is in plant cells only. Here's a little bit more information:   The cell wall provides supprot for the cell membrane and protects it.