CBSE Class 11-science Answered

1. Nerve cells lack centriole and hence, they cannot undergo mitosis and divide to form new cells. Once neurons become fully mature, they do not move any further into the cell division cycle.

Plant cells lack centrioles, however, they are still able to form a mitotic spindle from the centrosome region of the cell just outside of the nuclear envelope. As a result, they are able to undergo mitosis and divide to form new cells.

2. The nucleosome complex consists of histones H2A, H2B, H3, and H4 which come together to form a histone octamer.