an ester created from glycerol and three fatty acids
The concentration of glucose outside the cell is higher than the concentration of glucose inside the cell, thus there is a concentration gradient. The molecules of glucose move randomly and there is a net movement from outside to the inside, down the concentration gradient.
Using little tweezers you can pull each strand
The answer to this question would be: limbic system
Limbic system is part of the brain that responsible for emotion. One of this part is the olfactory bulb where the smells are processed. That is why a smell of something might make someone remember some memories that were related to the emotion.
In some organism, smells is important for survivability. Smelling a predator might cause the organism to feel fear and run away from them before they got close.