Answer:
Hydrogen bond
Explanation: Pretty much just a type chemical bond
Bacteria in our gut help to protect us by crowding out some of their dangerous relatives that can cause disease. Other good bacteria have been used in medicine to create antibiotics, and others still are used in food production to make fermented foods (think sauerkraut, yogurt, kimchi and kombucha.)
More than likely mutation
We have an internal skeleton and a grasshopper has an external skeleton.