This collection is being developed for the revised MCAT® exam that will first be administered in April 2015. The collection contains more than 900 videos and 2000 practice questions. Content will be added to the collection through 2015. All content in this collection has been created under the direction of the Khan Academy and has been reviewed under the direction of the AAMC (Association of American Medical Colleges). All materials are categorized according to the pre-health competencies tested by the new MCAT exam; however, the content in this collection is not intended to prescribe a program of study for the new MCAT exam. The content is also included in the Pre-health Collection within MedEdPORTAL’s iCollaborative sponsored by the AAMC: *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
Community Questions

Biological and Biochemical Foundations of Living Systems Passages

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Chemical and Physical Foundations of Biological Systems Passages

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Psychological, Social, and Biological Foundations of Behaviors Passages

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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.


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.
Community Questions
All content in “Biomolecules”

Enzyme structure and function

1A: The multitude of reactions within our cells are sped up by enzymes. Without these biomolecules, these biochemical pathways would be as slow as a turtle. For instance, without enzymes, your body may never be able to break down and absorb the hamburger you just had for lunch. The hamburger would simply sit there, a lump in your stomach, until reactions slowly started to happen on their own - enzymes speed that up!

Gene control

1B: Cells have many intricate mechanisms which regulate expression of genetic material - from transcription of RNA to translation of protein. At every point in this process, enzymes in your body can step in to modulate how much or how little RNA, or protein is produced from the genome. Sometimes, these genetic controls go awry, and so cells grow without inhibition - this is often how tumors develop, a pathogenic process we will also explore.

Genetic mutations

1C: Mutations are not always a bad thing - they give rise to much of the spice and flavor of life. But sometimes they are a result of environmental injury and can give rise to malignant disease processes like cancer. We will look at the causes and types of genetics mutations in this series as we also examine their effect on biological systems.

Mendelian genetics

1C: Why do some people have blue eyes and others brown? What determines your blood type? You will be able to answer questions like these as you have some fun with Punnett squares and discover the mechanisms of inheritance (and what all this has to do with a 19th-century German monk).

Chromosomal inheritance

Between 1856 and 1863, Gregor Mendel did a series of experiments with pea plants that established much of our fundamental understanding of heredity. In this section you will learn how traits are passed down from parents to their offspring and how genetic recombination can produce organisms with new gene combinations.

Evolution and population dynamics

1C: Charles Darwin inaugurated the field of evolutionary biology 150 years ago with the publication of “On the Origin of Species.” You will learn about the driving forces of evolution beyond natural selection and the relationship between populations and their environments. The story of Darwin’s finches will make a lot more sense.

Principles of bioenergetics

1D: When you light a candle, energy in the form of heat is dissipated into the surroundings. Without energy transfer, frogs wouldn’t jump, and cheetahs wouldn’t run. We will discuss Gibbs free energy, enthalpy, and Le Chatelier’s principles, thermodynamic concepts governing energy transfer as we examine their relationship to metabolism. After this tutorial, you will understand what it really means to “burn calories” during exercise.

Overview of metabolism

1D: You are breathing, your heart is beating, and you are reading this sentence. All these processes would be impossible were it not for the chemical energy produce within our cells. In this tutorial, we will integrate the biology and chemistry of metabolism as we walk you through the electron transport chain and the production of ATP, the ultimate energy currency in our bodies.

Carbohydrate Metabolism

1D: The glucose in the bread of the ham and cheese sandwich you just had for lunch goes on a productive journey within your cells after it is absorbed - the glucose in the bread is involved in several interlinked pathways. Your body has a decision to make - it can either break down the glucose for energy or store it for later. We will delve into the metabolic pathways of glucose - glycolysis, gluconeogenesis, and the pentose phosphate shunt.

Fat and protein metabolism

1D: The ham and cheese sandwich you just enjoyed need to be processed by the cells of your body. In addition to the sweet glucose we happily consume, we also take in fat (great for storing energy compactly) and proteins (which can be metabolized to produce energy or used as building blocks for innumerable parts of your body). These tutorials will shed light on the key metabolic pathways governing the metabolism of fats and proteins.

Endocrine system

1D: Glands are special organs that secrete chemical messages called hormones, which seep into the blood - it’s like putting a tea bag in hot water. As the heart pumps, this blood carries these chemical messages throughout the body, allowing the hormones to interact with specific target cells and organs. Endocrine glands help us to maintain our appetites, grow up, metabolize molecules, concentrate urine,- and oh, so much more! We will examine how these variegated hormones play a role in homeostasis as the body responds to a changing environment.