In the following simplified diagram of at plant cell, five parts / organelles are marked from 1 to 5:

Which one of the following correctly represents the above parts / organelles? 

The correct answer is 1 - cell wall; 2 - cell membrane; 3 - endoplasmic reticulum; 4 - nucleus; 5 - vacuole.

Key Points

• Cell membrane
  • Cell membrane is also called the plasma membrane.
  • It can be observed only through an electron microscope.
  • The plasma membrane is the outermost covering of the cell that separates the contents of the cell from its external environment.
• Cell wall
  • Plant cells, in addition to the plasma membrane, have another rigid outer covering called the cell wall. The cell wall lies outside the plasma membrane.
  • The plant cell wall is mainly composed of cellulose. Cellulose is a complex substance and provides structural strength to plants.
• Vacuoles
  • Empty structure in the cytoplasm is called vacuole. 
  • Large vacuoles are common in plant cells. Vacuoles in animal cells are much smaller.
  • Vacuoles are storage sacs for solid or liquid contents.
• Endoplasmic reticulum
  • The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or long bags (vesicles).
  • There are two types of ER ––
    • rough endoplasmic reticulum (RER) and
    • smooth endoplasmic reticulum (SER).
• Nucleus
  • It is an important component of the living cell.
  • Nucleus is separated from the cytoplasm by a double layered membrane called the nuclear membrane.