How does tempture change affect water cohesion

The hotter the farther apart water molecules become, creating steam
the colder makes the molecules become more dense making ice.
 

Cohesion is basically the attraction between molecules within a substance. The case of water, the cohesion will definitely decrease with the increase in temperature. With the increase in temperature, the molecules will start vibrating more and the attraction among them, will decrease. Hope this helps :)

Because people are wasting it

They are both used to view parts of the cell