Students compare and contrast passive and active transport by playing a game to model this phenomenon. Movement through cell membranes is also modeled, as well as the structure and movement typical of the fluid mosaic model of the cell membrane. Concentration gradient, sizes, shapes and polarity of molecules determine the method of movement through cell membranes. This activity is associated with the Test your Mettle phase of the legacy cycle.

Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Describe the various types of body plans that occur in animals
Describe limits on animal size and shape
Relate bioenergetics to body size, levels of activity, and the environment

By the end of this section, you will be able to do the following:

Name and describe lung volumes and capacities
Understand how gas pressure influences how gases move into and out of the body

By the end of this section, you will be able to do the following:

Describe the passage of air from the outside environment to the lungs
Explain how the lungs are protected from particulate matter

By the end of this section, you will be able to do the following:

Explain why and how passive transport occurs
Understand the osmosis and diffusion processes
Define tonicity and its relevance to passive transport

This 19-minute video lesson looks at diffusion and osmosis. [Biology playlist: Lesson 36 of 71].

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Great overview of cell membranes. The site presents the information as a tutorial with multiple choice questions to guide the learner. Very well designed site on cell membranes.

Paul Andersen details the first 7 of 13 labs in the AP Biology Curriculum. The following topics are all covered: Artificial Selection, Hardy-Weinberg Equilibrium, Comparing DNA using BLAST, Diffusion and Osmosis, Photosynthesis, Respiration, Mitosis and Meiosis. [13:26]

In the following video Paul Andersen explains how light that is perfectly reflected creates specular reflection. The angle of the incident ray is equal to the angle of the reflected ray. Specular reflection is also known as mirror-like reflection. If the reflecting surface is irregular it will create diffuse, rather than specular reflection. [4:33]

Students learn about the different structures that comprise cell membranes, fulfilling part of the Research and Revise stages of the legacy cycle. They view online animations of cell membrane dynamics (links provided). Then they observe three teacher demonstrations that illustrate diffusion and osmosis concepts, as well as the effect of movement through a semi-permeable membrane using Lugol's solution.

A narrated, video tutorial illustrating how diffusion works. It shows the concentration gradient that diffusion follows, explains the difference between diffusion and facilitated diffusion, and presents real life examples. [7:46]

This pathway introduces the structure of cell membranes and how they function in cellular transport.

This pathway provides an introduction to cellular mechanisms of transport, including a comparison of passive and active mechanisms. For a deeper look at this topic, we recommend the pathway Structure and Function of Plasma Membranes from the OpenStax textbook Biology for AP® Courses.

Diffusion is the net movement of particles from areas of high concentration (number of particles per unit area) to low concentration. In this activity, students use a molecular dynamics model to view the behavior of diffusion in gases and liquids.