To help you learn more efficiently, you can use the Campbell Biology App which organizes these concepts into modular units.

In biology, a is a distinctive aspect or trait of a living organism. Below are three types of features commonly discussed in the Campbell Biology textbook, ranging from molecular structures to evolutionary adaptations.

Every cell is enclosed by a selective plasma membrane that regulates the passage of materials between the cell and its environment. This shared feature is a hallmark of all life, whether prokaryotic (like bacteria) or eukaryotic (like plants and animals).

Organisms possess features that help maintain internal stability, such as thermoregulation (control of body temperature). These physiological mechanisms ensure that an organism’s "internal environment" remains stable despite external changes.