This annotated slideshow adapted from KET's Electronic Field Trip to the Forest illustrates how blight decimated the American chestnut tree and the methods scientists use to identify and pollinate the remaining trees to create blight-resistant trees.

The homeobox genes that define the basic body plan of mice and fruit flies are illustrated in this graphic from The Human Evolution Coloring Book by Adrienne Zihlman. The accompanying article describes how these genes act as "molecular architects" in all animal species.

An introductory lesson on the basics of heredity, and the inheritance of genetic traits. [7:57]

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:

Explain the relationship between genotypes and phenotypes in dominant and recessive gene systems
Develop a Punnett square to calculate the expected proportions of genotypes and phenotypes in a monohybrid cross
Explain the purpose and methods of a test cross
Identify non-Mendelian inheritance patterns such as incomplete dominance, codominance, recessive lethals, multiple alleles, and sex linkage

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

Explain Mendel’s law of segregation and independent assortment in terms of genetics and the events of meiosis
Use the forked-line method and the probability rules to calculate the probability of genotypes and phenotypes from multiple gene crosses
Explain the effect of linkage and recombination on gamete genotypes
Explain the phenotypic outcomes of epistatic effects between genes

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

Describe the scientific reasons for the success of Mendel’s experimental work
Describe the expected outcomes of monohybrid crosses involving dominant and recessive alleles
Apply the sum and product rules to calculate probabilities

This 17-minute video lesson provides an introduction to heredity and classical genetics. It looks at dominant and recessive traits as well as heterozygous and homozygous genotypes. [Biology playlist: Lesson 14 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.

An overview of Mendel's pea plant experiments.

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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].

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.

This is a group of Mendelian Genetics exercises that are designed to show the evolution of a trait within a population. The site covers instruction in calculating genotypic and allelic frequencies, determining dominance, the Hardy-Weinberg equilibrium, neutral genetic drift, and natural selection.

Paul Nurse describes his research that showed that humans share some genes with organisms as different from us as simple brewer's yeast. Footage from Secret of Life: "Immortal Thread."

Explore how populations change over time in a NetLogo model of sheep and grass. Experiment with the initial number of sheep, the sheep birthrate, the amount of energy sheep gain from the grass, and the rate at which the grass re-grows. Remove sheep that have a particular trait (better teeth) from the population, then watch what happens to the sheep teeth trait in the population as a whole. Consider conflicting selection pressures to make predictions about other instances of natural selection.

This Dinosaur Train video will help children foster the understanding of heredity: inheritance and variation of traits. Buddy and Daphne compare how they are similar and different. Included are printable dinosaur fact cards. [0:54]

Dr. Stephen O'Brien of the National Cancer Institute discovers a 700-year-old mutation that makes a person resistant to HIV infection. From Evolution: "Evolutionary Arms Race."

This pathway provides an introduction to genetic disorders including examining the different ways genetic information may be changed and specific examples of genetic disease. For a deeper look at this topic, we recommend the pathway Modern Understandings of Inheritance from the OpenStax textbook Biology for AP® Courses.

Get it all straight! The "Tour of the Basics" will help clarify the basic principals of genetics science from DNA, genes, chromosomes, proteins, heredity, and traits.

The Geniverse software is being developed as part of a five-year research project funded by the National Science Foundation. Still in its early stages, a Beta version of the software is currently being piloted in six schools throughout New England. We invite you to try the current Beta version, keeping in mind that you may encounter errors or pages that are not fully functional. If you encounter any problem, it may help to refresh or reload the web page.