Explain why the hypothalamus can be compared to a thermostat.

Because it plays a major role in regulating body temperature.

Explanation:

The hypothalamus is the heating regulating center of our body which is placed in the hypothalamus. It plays a major role in regulating body temperature, acts as a thermostat and also helps to maintain homeostasis in lots of different ways, for example, by controlling our blood pressure.

When our body cools below the normal temperature it helps to switch up the heat-generating processes and when the body gets overheated it helps to switch off the heat-generating processes.

then that particular organisms become extinct.

sorry, but you do not have posted the diagram.