What does the term 'hydrophilic' indicate about a substance?

The term 'hydrophilic' indicates that a substance is attracted to water and typically contains polar bonds. Hydrophilic substances are those that can form hydrogen bonds with water molecules, allowing them to interact favorably with the aqueous environment. This interaction often leads to the solubility of hydrophilic substances in water, making them essential in biological systems where water is a key solvent. For instance, many biological molecules such as sugars and amino acids are hydrophilic, allowing them to function effectively in cellular environments.

In contrast, substances that are hydrophobic are characterized by their lack of affinity for water and often possess non-polar bonds, which leads to them being repelled by water. Therefore, the understanding of hydrophilic substances is crucial for appreciating how molecules behave in biological systems, particularly in relation to membranes, solubility, and biochemical reactions.