This 12-minute video lesson looks at how professional antigen presenting cells present parts of engulfed pathogens on MHC II complexes (major histocompatibility complexes). [Biology playlist: Lesson 54 of 71].

This 25-minute video lesson looks at the Punnett square diagram in the study of genetics. It covers dihybrid crosses, independent assortment, incomplete dominance, codominance and multiple alleles. [Biology playlist: Lesson 15 of 71].

This 16-minute video looks at oxygen uptake by hemoglobin in red blood cells. [Biology playlist: Lesson 38 of 71].

This 11-minute video lesson provides a review of B cells, CD4+ T cells and CD8+ T cells. [Biology playlist: Lesson 57 of 71].

This 16-minute video lesson looks at the role of phagocytes in innate or nonspecific immunity. It also discusses neutrophils, macrophages, and dendritic cells. MHC II. [Biology playlist: Lesson 51 of 71].

This 15-minute video lesson looks at the role of the sarcoplasmic reticulum in controlling calcium ion concentrations within the muscle cell. [Biology playlist: Lesson 49 of 71].

This 14-minute video lesson looks at secondary active transport in the Nephron. [Biology playlist: Lesson 60 of 71].

This 14-minute video lesson covers the chromosomal basis for gender and sex-linked traits. [Biology playlist: Lesson 17 of 71].

This 14-minute video lesson looks at how a sodium potassium pump can maintain a voltage gradient across a cell or neuron's membrane. [Biology playlist: Lesson 42 of 71].

This 9-minute video lesson discusses what a species is and isn't. It considers ligers, tiglons, mule, hinnies, and dogs. [Biology playlist: Lesson 61 of 71].

This 13-minute video lesson looks at the science of taxonomy and where humans fit into the tree of life. [Biology playlist: Lesson 62 of 71].

This 19-minute video lesson provides an overview of how the nephrons in the kidney filter blood and reabsorb water and other molecules. [Biology playlist: Lesson 59 of 71].

This 21-minute video lesson looks at the pulmonary system including the lungs, larynx, trachea, bronchi, bronchioles, alveoli and thoracic diaphragm. [Biology playlist: Lesson 37 of 71].

This 9-minute video lesson looks at tropomyosin and troponin and their role in regulating muscle contraction. How calcium ion concentration dictates whether a muscle is contracting or not. [Biology playlist: Lesson 48 of 71].

This 8-minute video lesson presents an overview of types of immune responses. It looks at the difference between innate and adaptive immunity and the differences between humoral adaptive immunity and cell-mediated adaptive immunity. [Biology playlist: Lesson 52 of 71].

This 20-minute video lesson discusses how variation can be introduced into a species. [Biology playlist: Lesson 7 of 71].

This 23-minute video provides an introduction to viruses. [Biology playlist: Lesson 19 of 71].

This series of videos focusing on calculus covers sample questions from the A.P, Calculus AB and AC exams (both multiple choice and free answer).

The Calculus BC AP exam is a super set of the AB exam. It covers everything in AB as well as some of the more advanced topics in integration, sequences and function approximation. This tutorial is great practice for anyone looking to test their calculus mettle!

This series of videos focusing on calculus covers minima, maxima, and critical points, rates of change, optimization, rates of change, L'Hopital's Rule, mean value theorem.