What does a plant cell have as its innermost boundary?

The cell envelope is a chemically complex structure consisting of a tightly bound three-layered structure. Which layer is semi-permeable in nature?

Who proposed the concept of the unit membrane for the tripartite structure?

Who proposed the concept of the unit membrane?

Cut pieces of beetroot do not leave the colour in cold water but do so in hot water. Explain.

The diagram given below represents a fluid mosaic model of the plasma membrane. Match the components marked as $A, B, C, D$ and $E$ in the diagram below from the list $(i)$ to $(vii)$.
$(i)$ Sugar $(ii)$ Protein $(iii)$ Lipid bilayer $(iv)$ Integral protein $(v)$ Cytoplasm $(vi)$ Cell wall $(vii)$ External protein