The plant cell cytoplasm is surrounded by both cell wall and cell membrane. The specificity of transport of substances are mostly across the cell membrane, because ........

Explanation

Substances are transported by cell membrane because cell membrane is a semipermeable membrane which has two layered membrane of lipid between protein and carbohydrate. Substances soluble in lipids diffuse through the membrane faster but porins are there for other small sized molecules. Holes are made up of protein. While cell wall does not help molecules to pass through.
Because cell wall is non-living and hard in structure, If gives mechanical strength and protection from bacteria and damage to the cell.