The Biology I Course was developed through the Ohio Department of Higher Education OER Innovation Grant. The course is part of the Ohio Transfer Assurance Guides and is also named OSC003. This work was completed and the course was posted in October 2019. For more information about credit transfer between Ohio colleges and universities, please visit: www.ohiohighered.org/transfer.Team LeadCathy Sistilli Eastern Gateway Community CollegeContent ContributorsLisa Aschemeier Northwest State Community CollegeShaun Blevins Rhodes State CollegeRachel Detraz Edison State Community College Sara Finch Sinclair Community CollegeWendy Gagliano Clark State Community College AJ Snow University of Akron Wayne CollegeLibrarianAmanda Rinehart Ohio State UniversityReview TeamJessica Hall Ohio Dominican UniversitySanhita Gupta Kent State UniversityErica Mersfelder Sinclair Community College
The theory of evolution is the unifying theory of biology, meaning it is the framework within which biologists ask questions about the living world. Its power is that it provides direction for predictions about living things that are borne out in ongoing experiments. The Ukrainian-born American geneticist Theodosius Dobzhansky famously wrote that “nothing makes sense in biology except in the light of evolution.” He meant that the tenet that all life has evolved and diversified from a common ancestor is the foundation from which we approach all questions in biology.
Animal evolution began in the ocean over 600 million years ago with tiny creatures that probably do not resemble any living organism today. Since then, animals have evolved into a highly diverse kingdom. But what is an animal? While we can easily identify dogs, birds, fish, spiders, and worms as animals, other organisms, such as corals and sponges, are not as easy to classify. Animals vary in complexity—from sea sponges to crickets to chimpanzees—and scientists are faced with the difficult task of classifying them within a unified system. They must identify traits that are common to all animals as well as traits that can be used to distinguish among related groups of animals. The animal classification system characterizes animals based on their anatomy, morphology, evolutionary history, features of embryological development, and genetic makeup. This classification scheme is constantly developing as new information about species arises. Understanding and classifying the great variety of living species help us better understand how to conserve the diversity of life on earth.
In scientific terms, phylogeny is the evolutionary history and relationship of an organism or group of organisms. A phylogeny describes the organism's relationships, such as from which organisms it may have evolved, or to which species it is most closely related. Scientists must collect accurate information that allows them to make evolutionary connections among organisms. It is a highly dynamic field of biology because phylogenetic modeling concepts are constantly changing as new information is collected. Over the last several decades, new research has challenged scientists’ ideas about how organisms are related.
Carl Woese and his colleagues proposed that all life on Earth evolved along three lineages, called domains. Two of the three domains—Bacteria and Archaea—are prokaryotic. Prokaryotes were the first inhabitants on Earth, appearing 3.5 to 3.8 billion years ago. These organisms are abundant and ubiquitous; that is, they are present everywhere. In addition to inhabiting moderate environments, they are found in extreme conditions: from boiling springs to permanently frozen environments in Antarctica; from salty environments like the Dead Sea to environments under tremendous pressure, such as the depths of the ocean; and from areas without oxygen, such as a waste management plant, to radioactively contaminated regions, such as Chernobyl. Prokaryotes reside in the human digestive system and on the skin, are responsible for certain illnesses, and serve an important role in the preparation of many foods.
People did not understand the mechanisms of inheritance, or genetics, at the time Charles Darwin and Alfred Russel Wallace were developing their idea of natural selection. Scholars rediscovered Mendel’s work in the early twentieth century, and over the next few decades scientists integrated genetics and evolution in what became known as the modern synthesis—the coherent understanding of the relationship between natural selection and genetics that took shape by the 1940s. Natural selection can affect a population’s genetic makeup, and, in turn, this can result in the gradual evolution of populations. In the early twentieth century, biologists in the area of population genetics began to study how selective forces change a population through changes in allele and genotypic frequencies. Adaptive evolution is the process by which natural selection increases the frequency of beneficial alleles in the population, while decreasing the frequency of deleterious alleles.
Viewed from space, Earth offers no clues about the diversity of life forms that reside there. Scientists believe that the first forms of life on Earth were microorganisms that existed for billions of years in the ocean before plants and animals appeared. The mammals, birds, and flowers so familiar to us are all relatively recent, originating 130 to 250 million years ago. The earliest representatives of the genus Homo, to which we belong, have inhabited this planet for only the last 2.5 million years, and only in the last 300,000 years have humans started looking like we do today. The study of life is a vast field that delves into the past, present, and future. This module will provide an introduction into the science of Biology as well as a look into its major themes and concepts.
The Biology II Course was developed through the Ohio Department of Higher Education OER Innovation Grant. The course is part of the Ohio Transfer Assurance Guides and is also named OSC004. This work was completed and the course was posted in October 2019. For more information about credit transfer between Ohio colleges and universities, please visit: www.ohiohighered.org/transfer.Team LeadCathy Sistilli Eastern Gateway Community CollegeContent ContributorsLisa Aschemeier Northwest State Community CollegeShaun Blevins Rhodes State CollegeRachel Detraz Edison State Community College Sara Finch Sinclair Community CollegeWendy Gagliano Clark State Community College AJ Snow University of Akron Wayne CollegeLibrarianAmanda Rinehart Ohio State UniversityReview TeamJessica Hall Ohio Dominican UniversitySanhita Gupta Kent State UniversityErica Mersfelder Sinclair Community College
The cellular processes of life require energy. How do living organism obtain energy and how is it used? This Chapter answers these questions by exploring forms of energy and energy transfer within and between living organisms, as well as the role of enzymes and adenosine triphosphate (ATP) in chemical reactions in cells.