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This collection is being developed for the revised MCAT® exam that will first be administered in spring 2015. Videos will be added to the collection through fall 2014. All content in this collection has been created under the direction of the Khan Academy and has been reviewed under the direction of the Association of American Medical Colleges (AAMC). All materials are categorized according to the pre-health competencies tested by the MCAT²⁰¹⁵ exam; however, the content in this collection is not intended to prescribe a program of study for the MCAT²⁰¹⁵ exam. The content is also included in the Pre-health Collection within MedEdPORTAL’s iCollaborative sponsored by the AAMC: www.mededportal.org/pre-health *MCAT® is a program of the AAMC and related trademarks owned by the Association include Medical College Admission Test, MCAT, and MCAT²⁰¹⁵. For more information about the MCAT exam visit : www.aamc.org/mcat2015
Community Questions


Foundational Concept 1: Biomolecules have unique properties that determine how they contribute to the structure and function of cells, and how they participate in the processes necessary to maintain life.


Foundational Concept 2: Highly-organized assemblies of molecules, cells, and organs interact to carry out the functions of living organisms

Organ systems

Foundational Concept 3: Complex systems of tissues and organs sense the internal and external environments of multicellular organisms, and through integrated functioning, maintain a stable internal environment within an ever-changing external environment.

Physical processes

Foundational Concept 4: Complex living organisms transport materials, sense their environment, process signals, and respond to changes using processes that can be understood in terms of physical principles.

Chemical processes

Foundational Concept 5: The principles that govern chemical interactions and reactions form the basis for a broader understanding of the molecular dynamics of living systems.

Processing the environment

Foundational Concept 6: Biological, psychological, and socio-cultural factors influence the ways that individuals perceive, think about, and react to the world.


Foundational Concept 7: Biological, psychological, and socio-cultural factors influence behavior and behavior change.

Individuals and society

Foundational Concept 8: Psychological, socio-cultural, and biological factors influence the way we think about ourselves and others.

Society and culture

Foundational Concept 9: Cultural and social differences influence well-being.

Social inequality

Foundational concept 10: Social stratification and access to resources influence well-being.

Biological sciences practice passage questions

Go ahead and practice some biological science passages!

Physical sciences practice passage questions

Go ahead and practice some physical science passages!

Social sciences practice passage questions

Go ahead and practice some social science passages!
Foundational Concept 2: Highly-organized assemblies of molecules, cells, and organs interact to carry out the functions of living organisms
All content in “Cells”

Cell membrane overview

2A: Not all shall pass! Yards have fences, and cells have membranes. You don’t want just anybody waltzing into your backyard. Similarly, a healthy cell doesn’t just let in any random molecule - this is the concept of selective permeability. Some molecules (e.g. steroids) more easily cross the barrier whereas others (e.g. charged ions) have a more difficult time getting inside the cell without a little help from transporters in the membrane.

Cell-cell Interactions

2A: The human body is composed of about 100 trillion cells (this is not counting your bacterial buddies, who actually outnumber your cells 10 to 1!) Your cells must speak to each other to coordinate this massive symphony of life. In this tutorial, you will learn about the molecular basis of cellular signaling that makes this vast network speedy and efficient.

Transport across a cell membrane

2A: Each cell in your body has a “membrane potential.” Think of it like rolling a ball to the top of a hill - once the ball is at the top, it is smooth sailing down. Similarly, this electric membrane potential allows ions to flow down a gradient of electrical energy (the inside of the cell is negative relative to the outside). We will discuss this concept as well as other mechanisms for movement of ions, water, and other molecules across cellular membranes.