A. The three most important biological molecules are proteins, nucleic acids, and carbohydrates. Proteins are responsible for signaling receptors and play a key role in DNA production. Nucleic acids, similar to proteins, make up our DNA and make us who we are. Carbohydrates provide us with energy and help our body function.
B. We’ve become so dependent on water that I’d say it’s impossible for humans to live without it. At the most fundamental level, everything we consume — both literally and metaphorically — contains or utilized water. Our favorite foods, drinks, and even buildings contain a percentage of water. Maybe things would be different if we hadn’t allowed it to play such an essential role in practically everything we use, but they aren’t. We need water, which is why going 2 weeks without water could kill us. Sure, there are substitutes for water like milk, but milk is not as good for us as water is. Water balances and purifies our body, while milk fills it up with more waste.