Final answer:
A substance that is hydrophilic is 'water-loving' due to its polarity, allowing it to form hydrogen bonds with water and dissolve in it. In contrast, a hydrophobic substance repels water, like oils and fats, and will not dissolve in it. These characteristics affect substance interactions in biological and chemical processes.
Step-by-step explanation:
Being capable of combining with or attracting water (water-loving) is defined as hydrophilic. Substances that are hydrophilic readily interact with water due to their polarity. The molecular structure of hydrophilic compounds allows them to form hydrogen bonds with water molecules. Polar substances like sugars and certain salts, which are able to dissolve in water, are considered hydrophilic. This characteristic is essential in many biological processes where substances need to be dissolved in the body's aqueous environments.
On the other hand, non-polar molecules such as oils and fats exhibit hydrophobic (water-fearing) behavior; they do not form hydrogen bonds with water and tend to separate from it. Knowing whether a substance is hydrophilic or hydrophobic is crucial for understanding how it will interact in different environments, which is particularly important in fields such as chemistry and medicine. For example, cell membranes consist of a phospholipid bilayer that has hydrophilic heads and hydrophobic tails, making the membrane selectively permeable to various substances.