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 how red and blue light affect plant growth and metabolic activities
Discuss gravitropism
Understand how hormones affect plant growth and development
Describe thigmotropism, thigmonastism, and thigmogenesis
Explain how plants defend themselves from predators and respond to wounds

How do we communicate with the outside world? How are our senses of vision, smell, taste and pain controlled at the cellular and molecular levels? What causes medical conditions like allergies, hypertension, depression, obesity and various central nervous system disorders? G-protein coupled receptors (GPCRs) provide a major part of the answer to all of these questions. GPCRs constitute the largest family of cell-surface receptors and in humans are encoded by more than 1,000 genes. GPCRs convert extracellular messages into intracellular responses and are involved in essentially all physiological processes. GPCR dysfunction results in numerous human disorders, and over 50% of all prescription drugs on the market today directly or indirectly target GPCRs.In this course, we will discuss GPCR signal transduction pathways, GPCR oligomerization and the diseases caused by GPCR dysfunction. We will study the structure and function of rhodopsin, a dim-light photoreceptor and a well-studied GPCR that converts light into electric impulses sent to the brain and leads to vision. We will also discuss how mutations in rhodopsin cause retinal degeneration and congenital night blindness. This course is one of many Advanced Undergraduate Seminars offered by the Biology Department at MIT. These seminars are tailored for students with an interest in using primary research literature to discuss and learn about current biological research in a highly interactive setting. Many instructors of the Advanced Undergraduate Seminars are postdoctoral scientists with a strong interest in teaching.