Explain how the b

A strip of secondary meristem replaces the epidermis of the stem. Cells on the outside are cut off from this layer. This forms the several-layer thick cork or the bark of the tree. Cells of cork are dead and compactly arranged without intercellular spaces and have a chemical called suberin in their walls which makes them impervious to gases and water.

OR

Amoeba obtains food using temporary finger-like extensions on the cell surface which fuse over the food particle forming a food-vacuole. Complex substances are broken down into simpler ones inside the food vacuole which then diffuse into the cytoplasm. The remaining undigested material is moved to the surface of the cell and thrown out resulting in excretion.