What the light microscope shows

Now to name the parts the two activities showed. A light microscope reveals only five of them — three present in both kinds of cell, and two belonging to the plant cell alone.

Figure to be added

Figure 6.4 — the animal cell as seen under the light microscope, with the cell membrane, nucleus and cytoplasm labelled.

Figure to be added

Figure 6.5 — the plant cell as seen under the light microscope, with the cell wall, cytoplasm, nucleus and vacuole labelled.

In the animal cell

Every animal cell is covered by the plasma membrane, also called the cell membrane. It is a living membrane, both semi-permeable and selectively permeable. In animal cells the nucleus sits centrally within the cytoplasm, and the cytoplasm is a jelly-like material.

In the plant cell

The outer covering of a plant cell is the cell wall, which is made of cellulose. Inside the cell wall lies the plasma membrane. In the middle of a plant cell there is a large vacuole; vacuoles that large are not normally to be seen in animal cells.

Why was the onion nucleus off to one side?

The large central vacuole pushes the cytoplasm out to the periphery of the cell. Since the nucleus sits within that cytoplasm, it is pushed aside along with it. That answers the observation from Activity 02 directly.

This is where the light microscope stops

Both plant and animal cells hold many more parts within the cytoplasm, each carrying out a function of its own. Most of them, though, are too small to be observed with a light microscope at all.