Some were about available treatment options. While they participated in the also stained by misconduct. One notorious example of unethical study, the men were offered medical exams, transportation to research involving human subjects began in the United States in and from clinics, treatments for other ailments, food, and money and continued until This research was carried out by for their burial expenses if necessary. Investigators wished to study When the study first began, there were few available treat- Biology Matters Historical Focus Connections and Misconceptions What causes meningitis?
Connections and Misconceptions This unique feature presents the types of spontaneous inquiries that you may have as you study the workings of the human body. Questions and answers can be serious or funny, but each will capture your attention. Meningitis is caused by an infection of the meninges by either a virus or a bacterium. Viral meningitis is less severe than bacterial meningitis, which in some cases can result in brain damage and death.
Bacterial meningitis is usually caused by one of three species of bacteria: Haemophilus influenzae type b Hib , Streptococcus pneumoniae, and Neisseria meningitidis. Vaccines are available for Hib bacteria and some forms of S.
The Centers for Disease Control CDC recommend that individuals between the ages of 11 and 18 be vaccinated against bacterial meningitis. Sperm makes its way through the corona radiata.
Control center 5 0 60 70 sperm sends data to thermostat corona radiata 4. Sperm nucleus enters cytoplasm of oocyte. Cortical granules release enzymes; zona pellucida becomes fertilization membrane. Sperm binds to and fuses with oocyte plasma membrane. Acrosomal enzymes digest a portion of zona pellucida. Sperm and egg pronuclei are enclosed in a nuclear envelope. The systems listed here in particular also work with these two systems. Hormones regulate blood glucose and ion levels. Growth factors promote blood cell formation.
Blood vessels transport hormones to target cells. Nervous and Endocrine Systems The nervous and endocrine systems coordinate the activities of the other systems. The brain receives sensory input and controls the activity of muscles and various glands. The endocrine system secretes hormones that influence the metabolism of cells, the growth and development of body parts, and homeostasis.
Respiratory System The respiratory center in the brain regulates the breathing rate. The lungs carry on gas exchange for the benefit of all systems, including the nervous and endocrine systems.
Urinary System Nerves stimulate muscles that permit urination. Hormones ADH and aldosterone help kidneys regulate the water—salt balance and the acid—base balance of the blood. Reproductive System Nerves stimulate contractions that move gametes in ducts, and uterine contraction that occurs during childbirth. Sex hormones influence the development of the secondary sex characteristics. Digestive System Human Systems Work Together Working-together illustrations use brief concise statements to tell you how various other systems help a featured system achieve homeostasis.
The working-together illustrations have been integrated into homeostasis sections making a united whole. The homeostasis sections show how the systems achieve homeostasis despite real-life experiences that could alter the internal environment. For example, see page Nerves stimulate smooth muscle and permit digestive tract movements.
Hormones help regulate digestive juices that break down food to nutrients for neurons and glands. Integumentary System Nerves activate sweat glands and arrector pili muscles. Sensory receptors in skin send information to the brain about the external environment. Skin protects neurons and glands. Muscular System stem Nerves stimulate muscles, whose contractions allow us to move out of danger. Androgens promote growth of skeletal muscles. Sensory receptors in muscles and joints ints send scles protect information to the brain.
Muscles neurons and glands. Bones protect nerves and glands. Blackboard features exciting social learning and teaching tools that foster more logical, visually impactful, and active learning opportunities for students. Gradebooks are now seamless. McGraw-Hill and Blackboard can now offer you easy access to industry leading technology and content, whether your campus hosts it or we do. Be sure to ask your local McGraw-Hill representative for details. As an instructor, you can edit existing questions and author entirely new problems.
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Find the content you need in Create by searching through thousands of leading McGraw-Hill textbooks. Arrange your book to fit your teaching style. Sylvia Mader. Every laboratory has been written to help students learn the fundamental concepts of biology and the specific content of the chapter to which the lab relates, as well as gain a better understanding of the scientific method.
Companion Website www. A new chapter opener on the characteristics of life has been added. Evolutionary trees are now included to indicate the three domains of life.
Part I: Human Organization Chapter 2: Chemistry of Life includes a new illustration of relative pH values to improve student understanding of acid— base relationships and an illustration of the structure of fiber.
The chapter also contains several new applications: a new case study on blood chemistry, a new application reading on the origin of elements, and two new Biology Matters: Health Focus readings on the importance of fiber and omega-3 fatty acids in the diet.
Chapter 3: Cell Structure and Function contains a new case study on Tay—Sachs disease, a Biology Matters: Science Focus reading on the use of green fluorescent proteins in cell biology, and new application readings on cystic fibrosis and induced pluripotent stem cells.
A virtual lab on enzymes is provided at the end of the chapter. Chapter 4: Organization and Regulation of Body Systems includes a new case study on artificial skin and new applications on the safety of tanning beds and the causes of meningitis.
Part II: Maintenance of the Human Body Chapter 5: Cardiovascular System: Heart and Blood Vessels includes a case study on peripheral artery disease and a new application reading on the development of the heart in a fetus. A virtual lab on blood pressure is included at the end of the chapter. Chapter 6: Cardiovascular System: Blood was revised to include a new case study on leukemia and application readings on stem cells, blood doping, Christmas disease, and Bombay syndrome.
Chapter 7: Lymphatic System and Immunity now opens with a case study on lupus. In addition, application readings on the effects of refrigeration on the growth of bacteria and the mode of action of aspirin are now included. Chapter 8: Digestive System and Nutrition opens with a new case study on gastroesophageal reflux disease GERD , and a virtual lab on nutrition has been placed in the end-of-chapter material. In Chapter 9: Respiratory System, the opening material has been enhanced to indicate more of the tests for sleep apnea, and a new application reading on cystic fibrosis has been included.
Chapter Urinary System has been reorganized so that the discussions of homeostasis coincide with the coverage of the regulatory functions of the kidneys. A new case study on polycystic kidney disease PKD starts the chapter, and a new application reading on the causes of a floating kidney is provided. A new application reading investigates the evolutionary reasons why human toes are shorter than fingers.
The Biology Matters: Health Focus on osteoporosis has been updated with new recommendations on calcium and vitamin D intake.
Chapter Muscular System examines the tests used to detect muscular dystrophy in the opening case study. The application readings examine the number of muscles in the body, the interaction of hemoglobin and muscle tissue, the use of Botox to remove wrinkles, and the causes of muscle soreness following exercise.
A virtual lab on muscle stimulation is provided at the end of the chapter. A new application on the mode of action of aspirin is included, as well as new material on the pharmacology of methamphetamines.
Chapter Endocrine System opens with a case study on the tests for diabetes mellitus. Part V: Reproduction in Humans Chapter Reproductive System includes a case study that examines the causes and diagnosis of cervical cancer.
New application readings for this chapter examine polyploidy in liver cells, hormone replacement therapy, and emergency contraceptive pills. Chapter Development and Aging opens with a case study on pregnancy testing.
The chapter also includes information on greenhouse gases, and ecosystems on the floor of the ocean. A virtual lab on modeling ecosystems is provided at the end of the chapter. Chapter Human Population, Planetary Resources, and Conservation includes an updated case study with additional information on overfishing, and application readings on methylmercury and the topic of birthrates and death rates in developed and developing countries.
The discussion of Barr bodies has been moved from Chapter 3 to Chapter The chapter opens with a new case study on cell cycle control and breast cancer, and an additional application reading examines the relationship between the age of a woman and the risk of Down syndrome in her children. A virtual lab on the cell cycle and cancer is included at the end of the chapter.
Chapter Cancer includes new illustrations on the roles of tumor suppressor and proto-oncogenes in the cell. Data on cancer types Figures Chapter 19 opens with a case study on nephroblastoma, and a new application reading explores the potential link between transposons and cancer. Chapter Patterns of Genetic Inheritance begins with a case study on phenylketonuria.
The new application readings in the chapter examine the history of the Punnett square, the relationship between skin color and race, and fragile X syndrome. Virtual labs on the use of Punnett squares and sex-linked traits are included at the end of the chapter. A case study that examines the development of insulin using recombinant DNA technology opens the chapter, and the topics of microRNA, and the universal nature of the genetic code, are included in new application readings.
Two virtual labs, classifying using biotechnology and knocking out genes, are included at the end of the chapter. The chapter also includes new application readings on vestigial organs in humans, intelligent design, and artificial selection. Sylvia Mader represents one of the icons of science education. Her dedication to her students, coupled to her clear, concise, writing style, has benefited the education of thousands of students over the past three decades.
It is an honor to continue her legacy, and to bring her message to the next generation of students. Throughout each chapter, I have striven to ensure that the material was written and illustrated in the familiar Mader style. A project such as this could never be completed without the work of a coordinated group. As always, the McGraw-Hill professionals guided this revision, assisting in all aspects.
From beginning brainstorming sessions to completed text, this team supplied creativity, advice, and support whenever it was needed. Their dedication to providing a quality educational product is evident throughout this text.
I would also like to thank the Publisher, Michael Hackett, for the opportunity to contribute to the scientific literacy of our students. Fresh, appealing new photos are a feature of this book, which students and professors alike will enjoy. Jo Johnson and Lori Hancock did a superb job of finding just the right photographs and micrographs. The design of the book is the result of the creative talents of Laurie Janssen and many others who assisted in deciding the appearance of each element in the text.
Marketing Manager Tamara Maury directed the marketing team whose work is second to none. Eric Weber, the Digital Product Manager, played an integral role in developing the ConnectPlus resources for this text. I am extremely grateful to my contributing author for this edition, Lynn Preston of Tarrant County College. Lynn assisted me with this project from beginning to end. Together with the editorial team, she supplied ideas and content for the many updates, new features, and new illustrations that enrich this twelfth edition of Human Biology.
Finally, this edition of Human Biology would not be of the same excellent quality without the suggested changes from the many reviewers listed in the following sections. Who I am, as an educator and an author, is a direct reflection of what I have learned from my students.
Education is a two-way street, and it is my honest opinion that both my professional life and my personal life have been enriched by interactions with my students. They have encouraged me to learn more, teach better, and never stop questioning the world around me.
Sylvia Mader, and especially my wife Sandra for the opportunity to make this dream a reality. Michael Windelspecht, Ph. It is dedicated to continual large-scale and incremental improvement driven by multiple customer feedback loops and checkpoints.
This is initiated during the early planning stages of our new products, and intensifies during the development and production stages, then begins again upon publication in anticipation of the next edition. This process is designed to provide a broad, comprehensive spectrum of feedback for refinement and innovation of our learning tools, for both student and instructor.
We appreciate the expertise of the many individuals involved in this process. Heick, St. Ambrose University Jonathan P. Dunbar, Cabrini College William E.
Hayes, Marshall University Mark F. Hull, Lincoln University Laurie A. Kevin Langford, Stephen F. Austin State University Lee H. Martin, Kishwaukee College Deborah J.
Europa is one of the larger moons of Jupiter, and it has had held a special fascination for astronomers since Galileo first described it in Today, Europa is one of the prime candidates to harbor life outside of Earth. Having analyzed past comet impact sites on the surface of Europa, geologists also believe that this ocean contains the basic ingredients for life, including carbon and possibly even free oxygen. Titan is the second-largest satellite in the solar system, larger than even our moon.
Although it is in orbit around Saturn, and thus located some distance from the influence of the sun, Titan has become a focal point for the study of extraterrestrial life since the NASA space probe Cassini—Huygens first arrived at Saturn in Cassini has detected the presence of the building blocks of life on Titan, including lakes of methane and ammonia, and vast deposits of hydrogen and carbon compounds called hydrocarbons.
On Earth, scientists are exploring the extreme environments near volcanoes and deep-sea thermal vents to get a better picture of what life may have looked like under the inhospitable conditions that dominated at the time we now know life first began on our planet.
Already, in the past few years, marine biologists have discovered new forms of life that cannot only live off of hydrogen sulfide, a deadly gas to most life, but also thrive under extreme pressure and temperatures. The process of evolution accounts for the diversity of living things and why living things share the same basic characteristics of life.
We differ from other mammals, including apes, by our highly developed brain, upright stance, creative language, and the ability to use a wide variety of tools. A hypothesis is formulated and tested to arrive at a conclusion. Theories explain how the natural world is organized. Everyone has a responsibility to ensure that science and technology are used for the good of all. What are the basic characteristics that define life?
What evidence would you look for on Europa or Titan that would tell you that life may have existed on these moons in the past? What does it tell us if we discover life on Europa or Titan and it has similar characteristics to life on Earth? What if it is very different? Explain the basic characteristics that are common to all living things.
Describe the levels of organization of life. Summarize how the terms homeostasis, metabolism, development, and adaptation all relate to living organisms. Recognize the special relationship between life and evolution. The science of biology is the study of living organisms and their environments.
All living things Fig. Living things 1 are organized, 2 acquire materials and energy, 3 reproduce, 4 grow and develop, 5 are homeostatic, 6 respond to stimuli, and 7 have an evolutionary history. Living Things Are Organized Figure 1. A cell is the small- medicinal leech mushrooms est structural and functional unit of an organism. Some organisms are single cells. Humans are multicellular because they are composed of many different types of cells. A nerve cell is one of the types of cells in the human body.
It has a structure suitable to conducting a nerve impulse. A tissue is a group of similar cells that perform a particular function. Nervous tissue is composed of millions of nerve cells that transmit signals to all parts of the body. Several types of tissues make up an organ, and each organ belongs to an organ system.
The organs of an organ system work together to accomplish a common purpose. The brain works with the spinal cord to send commands to body parts by way of nerves. Organisms, such as trees and humans, are a collection of organ systems. The levels of biological organization extend beyond the individual. All the members of one species group of interbreeding organisms in a particular area belong to a population.
A tropical grassland may have a population of zebras, acacia trees, and humans, for example. The interacting populations of the grasslands make up a community. The community of populations interacts with the physical environment to form an ecosystem. From the simplest one-celled organisms to complex plants and animals, all life shares seven basic characteristics.
Living organisms are organized. The smallest unit of living organisms is the cell. The sum of all living things—and the locations that they inhabit—is called the biosphere. Humans and other animals acquire materials and energy when they eat food Fig. Food provides nutrient molecules, which are used as building blocks or for energy. It takes energy work to main- Connections and Misconceptions How many cells are in your body? The number of cells in a human body varies depending on the size of the person and whether cells have been damaged or lost.
However, most estimates suggest that there are well over trillion cells in a human body. Some nutrient molecules are broken down completely to provide the necessary energy to convert other nutrient molecules into the parts and products of cells.
The term metabolism describes all of the chemical reactions that occur within a cell. The ultimate source of energy for the majority of life on Earth is the sun. Plants, algae, and some bacteria are able to harvest the energy of the sun and convert it to chemical energy by a process called photosynthesis. Photosynthesis produces organic molecules, such as sugars, that serve as the basis of the food chain for many other organisms, including humans and all other animals.
Life Is Homeostatic b. For the metabolic pathways within a cell to function correctly, the environmental conditions of the cell must be kept within strict operating limits. The ability of a cell or an organism to maintain an internal environment that operates under specific conditions is called homeostasis. In humans, many of our organ systems work to maintain homeostasis. For example, human body temperature normally fluctuates slightly between In general, the lowest temperature usually occurs between 2 a.
However, activity can cause the body temperature to rise, and inactivity can cause it to decline. The cardiovascular system and the nervous system work together to maintain a constant temperature. Even though we can shiver when we are cold and perspire when we are hot, we will die if the external temperature becomes overly cold or hot.
This text emphasizes how all the systems of the human body help maintain homeostasis. The digestive system takes in nutrients, and the respiratory system exchanges gases with the environment.
The cardiovascular system distributes nutrients and oxygen to the cells and picks up their wastes. The metabolic waste products of cells are excreted by the urinary system. The work of the nervous and endocrine systems is critical because these systems coordinate the functions of the other systems. Throughout the text, the Connecting the Concepts sections will provide you with links to more information on homeostasis. Figure 1. Humans eat plants and animals they raise for food.
A red-tailed hawk captures prey to feed its young. Some animals feed only on plants, such as these grazing sheep. Certain sensory receptors also detect a change in the internal environment, and then the central nervous system brings about an appropriate response.
When you are startled by a loud noise, your heartbeat increases, which causes your blood pressure to increase. If blood pressure rises too high, the brain directs blood vessels to dilate, helping to restore normal blood pressure. Living things respond to external stimuli, often by moving toward or away from a stimulus, such as the sight of food.
Living things use a variety of mechanisms to move, but movement in humans and other animals is dependent upon their nervous and musculoskeletal systems. The leaves of plants track the passage of the sun during the day; when a houseplant is placed near a window, its stems bend to face the sun.
The movement of an animal, whether self-directed or in response to a stimulus, constitutes a large part of its behavior. Some behaviors help us acquire food and reproduce. Living Things Reproduce and Develop Reproduction is a fundamental characteristic of life. Cells come into being only from pre-existing cells, and all living things have parents. When living things reproduce, they create a copy of themselves and ensure the continuance of their own kind.
Following the fertilization of the egg by a sperm cell, the resulting zygote undergoes a rapid period of growth and development. This is common in almost all living organisms. In humans, growth occurs as the 5 fertilized egg develops into a fetus Fig. Growth, recognized by an increase in size and often the number of cells, is a part of development. In humans, development includes all the changes that occur from the time the egg is fertilized until death; therefore, it includes all the changes that occur during childhood, adolescence, and adulthood.
Development also includes the repair that takes place following an injury. The purpose of reproduction is to pass on a copy of the genetic information to the offspring. DNA contains the hereditary information that directs not only the structure of each cell but also its function. The information in the DNA is contained within genes, short sequences of hereditary material that specify the instructions for a specific trait.
Before reproduction occurs, DNA is replicated so that an exact copy of each gene may be passed on to the offspring. When humans reproduce, a sperm carries genes contributed by a male into the egg, which contains genes contributed by a female. The genes direct both growth and development so that the organism will eventually resemble the parents. Sometimes, minor variations in these genes, called mutations, may result in an organism making it better suited for its environment.
These mutations are the basis of evolutionary change. Living Things Adapt and Evolve Evolution is the process by which a species changes through time.
When a new variation arises that allows certain members of the species to capture more resources, these members tend to survive and have more offspring than the other, unchanged members. Therefore, each successive generation will include b. A small acorn becomes a tree, and b following fertilization, an embryo becomes a fetus by the process of growth and development.
Consider, for example, a redtailed hawk, which catches and eats rabbits. A hawk can fly, in part, because it has hollow bones to reduce its weight and flight muscles to depress and elevate its wings.
When a hawk dives, its strong feet take the first shock of the landing and its long, sharp claws reach out and hold onto the prey. Evolution, which has been going on since the origin of life and which will continue as long as life exists, explains both the unity and the diversity of life. All organisms share the same characteristics of life because their ancestry can be traced to the first cell or cells. Organisms are diverse because they are adapted to different ways of life.
Check Your Progress 1. Summarize how each characteristic of life contributes to homeostasis. Explain why living things are organized. Summarize the place of humans in the overall classification of living organisms. Describe the relationship between humans and the biosphere, and the role of culture in shaping that relationship. Both homeostasis and evolution are central themes in the study of biology. For more examples of homeostasis and evolution, refer to the following discussions.
Section 9. Biologists classify living things as belonging to one of three domains. The evolutionary relationships of these domains are presented in Figure 1. Two of these domains, domain Bacteria and domain Archaea, contain prokaryotes, Figure 1. Living organisms are classified into three domains: Bacteria, Archaea, and Eukarya. A geologic time scale is provided on the bottom for reference.
This figure provides some of the characteristics of the organisms of each of the major domains and kingdoms of life. Humans belong to the domain Eukarya and kingdom Animalia. Organisms in the third domain, Eukarya, are classified as being members of one of four kingdoms Fig. Most organisms in kingdom Animalia are invertebrates, such as the earthworm, insects, and mollusks. Vertebrates are animals that have a nerve cord protected by a vertebral column, which gives them their name.
Fish, reptiles, amphibians, and birds are all vertebrates. Vertebrates with hair or fur and mammary glands are classified as mammals. Humans, raccoons, seals, and meerkats are examples of mammals. Human beings are most closely related to apes. We are distinguished from apes by our 1 highly developed brains, 2 completely upright stance, 3 creative language, and 4 ability to use a wide variety of tools.
Humans did not evolve from apes; apes and humans share a common, apelike ancestor. Our relationship to apes is analogous to you and your first cousin being descended from your grandparents. We could not have evolved from our cousins because we are contemporaries— living on Earth at the same time. Humans Have a Cultural Heritage Human beings have a cultural heritage in addition to a biological heritage. Culture encompasses human activities and products passed on from one generation to the next outside of direct biological inheritance.
Among animals, only humans have a language that allows us to communicate information and experiences symbolically. We are born without knowledge of an accepted way to behave, but we gradually acquire this knowledge by adult instruction and imitation of role models. Many of the skills involve tool use, which can vary from how to hunt in the wild to how to use a computer.
Human skills have also produced a rich heritage in the arts and sciences. However, a society highly dependent on science and technology has its drawbacks as well. Unfortunately, this cultural development may mislead us into believing that humans are somehow not part of the natural world surrounding us.
Humans Are Members of the Biosphere All living things on Earth are part of the biosphere, a living network that spans the surface of the Earth into the atmosphere and down into the soil and seas. Although humans can raise animals and crops for food, we depend on the environment for many services.
Some species of bacteria can clean up pollutants like heavy metals and pesticides. Freshwater ecosystems, such as rivers and lakes, provide fish to eat, drinking water, and water to irrigate crops. The water-holding capacity of forests prevents flooding, and the ability of forests and other ecosystems to retain soil prevents soil erosion. Many of our crops and prescription drugs were originally derived from plants that grew naturally in an ecosystem.
Some human populations around the globe still depend on wild animals as a food source. And we must not forget that almost everyone prefers to vacation in the natural beauty of an ecosystem. Humans Threaten the Biosphere The human population tends to modify existing ecosystems for its own purposes Fig.
Humans clear forests and grasslands to grow crops. Later, houses are built on what was once farmland. Clusters of houses become small towns that often grow into cities. The overuse of water supplies by large human populations can result in desertification, or the expansion of desert regions Fig. Human activities have altered almost all ecosystems and reduced biodiversity the number of different species present.
The present biodiversity of our planet has been estimated to be as high as 15 million species. So far, under 2 million have been identified and named.
It is estimated that we are now losing as many as species per day due to human activities. Many biologists are alarmed about the present rate of extinction death of a species. The dinosaurs became extinct during the last mass extinction 65 million years ago. One of the major bioethical issues of our time is preservation of the biosphere and biodiversity.
If we adopt a conservation ethic that preserves the biosphere and biodiversity, we will ensure the continued existence of our species.
Connections and Misconceptions How many humans are there? As of the end of , it was estimated that there were over 6. Each of those humans needs food, shelter, clean water and air, and materials to maintain a healthy lifestyle.
We add an additional 75 million people per year—that is like adding ten New York Cities per year! This makes human population growth one of the greatest threats to the biosphere. Connecting the Concepts To learn more about the preceding material, refer to the following discussions.
Chapter 22 examines recent developments in the study of human evoution. Chapter 23 provides a more detailed look at ecosystems. Chapter 24 details some of the emerging threats that humans pose to the biosphere. Humans negatively influence many ecosystems. When humans build cities, diversity is lost. An overuse of water resources can lead to desertification. Explain why it is important to know the evolutionary relationships between organisms.
Summarize how the increase in the human population affects our biosphere. Describe the general process of the scientific method. Distinguish between a control group and an experimental group in a scientific test. Recognize the importance of scientific journals in the reporting of scientific information. Science is a way of knowing about the natural world. When scientists study the natural world, they aim to be objective, rather than subjective. Objective observations are supported by factual information, whereas subjective observations involve personal judgment.
For example, the fat content of a particular food would be an objective observation of a nutritional study. Reporting about the good or bad taste of the food would be a subjective observation. It is difficult to make objective observations and conclusions because we are often influenced by our prejudices.
Scientists must keep in mind that scientific conclusions can change because of new findings. New findings are often made because of recent advances in techniques or equipment. This term is the preferred terminology for theories generally accepted as valid by an overwhelming number of scientists. The Scientific Method Has Steps Unlike other types of information available to us, scientific information is acquired by a process known as the scientific method.
The approach of individual scientists to their work is as varied as the scientists. For the sake of discussion, it is possible to speak of the scientific method as consisting of certain steps Fig. After making initial observations, a scientist will, most likely, study any previous data, results and conclusions reported by previous research. Imagination and creative thinking also help a scientist formulate a hypothesis. The new data help a scientist come Observation New observations are made, and previous data are studied.
Importance of Scientific Theories in Biology Science is not just a pile of facts. The ultimate goal of science is to understand the natural world in terms of scientific theories. Scientific theories are concepts that tell us about the order and the patterns within the natural world—in other words, how the natural world is organized.
For example, following are some of the basic theories of biology. Theory Concept Cell All organisms are composed of cells, and new cells only come from pre-existing cells. Homeostasis The internal environment of an organism stays relatively constant. Genes Organisms contain coded information that dictates their form, function, and behavior.
Ecosystem Populations of organisms interact with each other and the physical environment. Evolution All organisms have a common ancestor, but each is adapted to a particular way of life. Evolution is the unifying concept of biology because it makes sense of what we know about living things.
For example, the theory of evolution enables scientists to understand the variety of living things and their relationships. It explains common structural features, physiology, patterns of development, and behaviors. The results are analyzed, and the hypothesis is supported or rejected. Scientific Theory Many experiments and observations support a theory.
The return arrow indicates that a scientist often chooses to retest the same hypothesis or to test a related hypothesis. Conclusions from many different but related experiments may lead to the development of a scientific theory. For example, studies pertaining to development, anatomy, and fossil remains all support the theory of evolution. Hypotheses are always subject to modification, so they can never be proven true; however, they can be proven untrue.
When the hypothesis is not supported by the data, it must be rejected; therefore, some think of the body of science as what is left after alternative hypotheses have been rejected.
Science is different from other ways of knowing by its use of the scientific method to examine a phenomenon. Any suggestions about the natural world not based on data gathered by employing the scientific method cannot be accepted as within the realm of science. Scientific theories are concepts based on a wide range of observations and experiments.
There he saw many patients who had bleeding stomach ulcers. A pathologist at the hospital, Dr. Robin Warren, told him about finding a particular bacterium, now called Helicobacter pylori, near the site of peptic ulcers open sores in the stomach.
Using the computer networks available at that time, Marshall compiled much data showing a possible correlation between the presence of Helicobacter pylori and the occurrence of both gastritis inflammation of the stomach and stomach ulcers. On the basis of these data, Marshall formulated a hypothesis: Helicobacter pylori is the cause of gastritis and ulcers. He was able to isolate Helicobacter pylori from ulcer patients and grow it in the laboratory.
Success was achieved only after a petri dish was inadvertently left in the incubator for six, instead of two, days. Further, he had determined that bismuth, the active ingredient in Pepto-Bismol, could destroy the bacteria in a petri dish. Despite presentation of these findings to the scientific community, most physicians continued to believe that stomach acidity and stress were the causes of stomach ulcers.
Koch was a scientist who studied anthrax, a type of soil-living bacterium that causes disease in animals and humans. Anthrax was used as a biological weapon in the United States by unknown persons following the terrorist attacks in His procedures are still widely used by scientists and medical professionals. Koch is credited not only with his work on the germ theory but also with the development of several important scientific instruments. He was one of the first to use an incubator, an instrument that maintains a steady temperature for growing bacteria outside of an organism.
He also was the first to use gelatin as a medium for growing bacteria in dishes. Many scientists believed that no bacterium would be able to survive the normal acidity of the stomach.
He had been unable to infect guinea pigs and rats with the bacteria because the bacteria just did not flourish in the intestinal tract of those animals.
Marshall was not able to use human subjects because our society does not condone the use of humans as experimental subjects in dangerous or lifethreatening research. Marshall was so determined to support his hypothesis that, in , he decided to perform the experiment on himself! To the disbelief of those in the lab that day, he and another volunteer swallowed a foul-smelling and -tasting solution of Helicobacter pylori.
Within the week, they felt lousy and were vomiting up their stomach contents. Examination by endoscopy showed that their stomachs were now inflamed, and biopsies of the stomach lining contained the suspected bacterium Fig. Their symptoms abated without need of medication, and they never developed an ulcer. Many tried, but ultimately the investigators supported his findings. The Conclusion In science, many experiments that involve a considerable number of subjects are required before a conclusion can be reached.
Barry Marshall and the cause of stomach ulcers. The inset shows the presence of the bacterium in the stomach. Marshall received all sorts of prizes and awards, but he and Dr. Warren were especially gratified to receive a Nobel Prize in Medicine in Often, scientists perform an experiment, a series of procedures to test a hypothesis. When scientists do an experiment, they try to vary just the experimental variables, in this case, the medications being tested.
Posted on. Page Count. Instructors consistently ask for a human biology textbook that helps students develop an understanding of the main themes of biology while placing the material in the context of the human body.
Mader Human Biology was developed to fill this void. Organized around the main themes of biology, Human Biology guides students to think conceptually about biology and the world around them. Just as the levels of biological organization flow from one level to the next, themes and topics of Biology are tied to one another throughout the chapter, and between the chapters and parts through the concept of homeostasis.
Combined with Dr. Multimedia Integration: Michael Windelspecht represents the new generation of digital authors. Through the integration of multimedia resources, such as videos, animations and MP3 files, and in the design of a new series of interactive animations, Dr Windelspecht has worked to bring Dr. A veteran of the online, hybrid, and traditional teaching environments, Dr.
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