Q. Into which periods is mitosis has divided?
Mitosis is divided into four periods: metaphase, prophase, telophase and anaphase.
Q. What are the centrioles and in which type of cell are they present?
Centrioles are tiny cylindrical structures made of nine microtubule triplets they appear in pairs in the cell. Centrioles participate in the making of cytoskeleton and of flagella and cilia. In cell division they play a vital role in the formation of the aster fibers.
Centrioles are structures present in the animal cells, in some primitive and in most protists fungi. There are no centrioles in cells of superior plants and generally it is considered that plant cells do not have centrioles although this is not completely correct since some plants have centriole-containing cells.
The region where the centrioles are located is term as the centrosome of the cell.