Write the name and structure of an alcohol with four carbon atoms in its molecule.

A student is observing a permanent slide showing sequentially the different stages of asexual reproduction taking place in yeast. Name this process and draw diagrams of what he observes in a proper sequence.

An object of height 2.5 cm is placed at a distance of 15 cm from the optical centre '0' of a convex lens of focal length 10 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre '0', principal focus F and height of the image on the diagram.

What are those organisms called which bear both the sex organs in the same individual? Give one example of such organism.

Write one negative effect, on the environment, of affluent life style of few persons of a society.