Looking at the onion root tip under the microscope you can see large, rectangular cells with visible distinct cell walls surrounding it (cells have a more regular shape because of the wall). Inside the cells, you can notice darkly stained nucleus, large vacuoles at the center and sometimes small granules within the cytoplasm. Looking the onion root tip under the microscope is often the way to observe mitosis. Usually, you cannot see organelles such as mitochondria, ribosomes, rough and smooth endoplasmic reticulum, centrioles and Golgi body as they appear translucent and because are too small to be seen under the light microscope (electron microscope required). Also, chloroplasts are not present in an onion cell because it is not a photosynthetic cell.
Question:
how does a tumor form?
Answer:
En general, los tumores ocurren cuando las células se dividen y se multiplican excesivamente en el cuerpo. Normalmente, el cuerpo controla la división y el crecimiento de las células.
English:
In general, tumors occur when cells divide and multiply excessively in the body. Normally, the body controls the division and growth of cells.
There are a few different names for Mitosis: Cell division and cellular division (these are the words that I can think of) I hope this helps.