Answer:
Disease spread can affect air travel really badly because it can be so easy for anyone to get infected with how crowded airports can be. This usually results in extra safety steps taken up to cancelled flights due to closed borders. A popular example of this is the current pandemic crisis.
Explanation:
They help neutralize the acids produced by the stomach.
Answer:
genetic modification competitors increase
Explanation:
The fish developed the gills because of <em>genetic modification</em>. Because the fish are now able to swim in deep water, their <em>competitors</em> in shallower water will have less food. Likewise, competition for food among deep-water fish that eat the same types of food will <em>increase</em>.
