Questions

Gene is a hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism.

In short it is a piece or segment of chromosome.

Genes undergo mutation when their DNA sequence changes. 

We know that, peninsula is a piece of land that surrounded by water on three sides.  Hence, it is what A piece of land almost surrounded by water i.e, three sides water and one side land.

A postage stamp on the letters, parcels, ... for post will be on the corner of the post but it travels around the world to any address we want send that.

According to Gandhiji, A sound body means one which bends itself to the spirit and is always a ready instrument at its service. Such bodies are not made, in my opinion, on the football field. They are made on cornfields and farms.

Configuration Management is a support for software in managing the different items in the product, and changes in them.

Ctrl+Shift+F Opens the Font dialog box with the focus at the Font combo box.

Here ‘passed each other’ means crossed each other’s path. No preposition is required by ‘passed’.