How many chromosomes do drones of honeybee possess? Name the type of cell division involved in the production of sperms by them.

How many chromosomes are present in the nucleus of the human cell?

How many types of elements together make xylem tissue? Name them.

What do you mean by negative interactions between species? Name the type of interactions involved in following examples. Control of mosquito larvae by Gambusia fish.

In how many groups bryophytes are classified? Name them.

How many pairs of adjacent sides are there in a triangle? Name them

What do you mean by negative interactions between species? Name the type of interactions involved in following examples. Algae and fungus association in lichens.