Answer:
B. Warming air expands, becomes less dense, and rises. As the air rises, it pushes cooler, more dense air down.
Explanation:
The options D and A can be eliminated because when a gas expands without gaining additional mass, it will become less dense; when a gas contracts without losing mass, it becomes more dense. Therefore, these two options conflict with the idea of density and cannot be true.
Option B is superior to Option C because convection currents are typically portrayed as beginning with the rise of warm air, which displaces/is replaced by cooler, dense air from the upper atmosphere. While Option C is similar, it describes the opposite series of events.
Yy x Yy yields 25%YY 50% Yy and 25% yy which is 1:2:1 (YY:Yy:yy)
DNA has three billion letters.
Viruses need a host because a host is just like the owner of the virus "business". think of it as a company. the company has a boss- aka the person who made the company (this is the host) and the boss also tells the employees (bacteria etc) what to do and how to do it. without the host, the virus will die. :)
