Sylvia S. Mader has written several biology texts. She graduated from Harvard University with a degree in Biology and Nova Southeastern University with a degree in Education.

She has taught at a number of colleges and universities over the years. Her books have become models for others who write in the field of biology because of her crisp and entertaining writing style.

He directed a program that enrolls over 4,500 students annually when he was the Introductory Biology Coordinator at Appalachian State University.

He received degrees from Michigan State University and the University of South Florida, and has published papers in areas as diverse as science education, water quality, and the evolution of insecticide resistance. He is interested in the analysis of data from digital learning platforms for the development of personalized microlearning assets. He is a member of several science education associations. He was the keynote speaker for the development of multimedia resources for online and hybrid science classrooms. He won the competition for integrating student data into the textbook revision process.

As an author and editor, Dr. Windelspecht has over 20 reference textbooks. Ricochet Creative productions is a science communication company that develops and assesses new technologies for the science classroom. You can learn more about Dr. Windelspecht by visiting his website.

He teaches biology at Cloud Technical and Community College. He was a middle and high school science teacher with degrees from Bemidji State University and the University of Idaho.

He attended Western Illinois University and Illinois College. Professor Cox teaches introductory biology for nonmajors in the traditional classroom format as well as in a hybrid format. He teaches marine biology and biological field studies as study-abroad courses. He is the co-owner of Howler Publications, a company that sells scientific study abroad courses. He develops educational resources for the industry.

She has been teaching for more than 18 years.

She received her PhD in Plant Sciences from the University of Georgia and was educated in the field of botany at the University of Florida. She is a Visiting Scholar at Duke University. She mentors students interested in teaching careers in the Preparing Future Faculty program.

The process of teaching science is changing quickly. Instructors are being asked to engage their students by making content more relevant, while still providing students with a firm foundation in the core principles of biology. The themes of evolution, biological systems, and nature of science have been integrated into the text.

In addition to the evolution of the introductory biology curriculum, students and instructors are increasingly requesting digital resources to use as learning resources.

Chapter openers and themed readings have been updated to focus on issues and topics important in a nonscience majors classroom 2.

The Vision and Change document clearly shows the need to integrate core concepts in the curriculum. Scientific literacy isn't based on the memorization of a series of facts.

Learning is based on establishing associations and links between different topics.

The nature of science is one of the main themes we have chosen to emphasize. The unit learning outcomes, feature readings, and themes are all integrated into the textbook. The relationship of the chapter's content to each of the themes is introduced at the start of each chapter. "Connecting the Concepts with the Themes" at the end of each chapter reminds the student of the relationships between chapter content and the three core themes, but also acts as a Prelude to topics in the next few chapters of the text. The themes allow the student to see the relationships between the concepts in the text.

The unifying concept of the biological sciences consists of evolutionary change and the mechanism of natural selection. All life is linked by biological evolution. The process of evolution and how scientists study and measure evolutionary change are both shown in feature readings throughout the textbook. By following this theme through the book, students can better understand why evolution is a dynamic process, and one that has shaped and will continue to influence life on this planet.

Scientists study life through the processes of observation, application of the scientific method, and use of both inductive and deductive reasoning. To develop a deeper understanding of the biological sciences, students need to understand that the study of life is a process, and that this process has application in their everyday lives.

All life is connected. Scientists are becoming aware that small changes in the chemical composition of an environment can have a huge impact on the life of that environment.

The theme was chosen to show that all life is connected and that the principles regulating life at the cellular level play a role in the study of the life sciences.

The use of real world examples to demonstrate the importance of biology in the lives of students is an effective teaching strategy for the introductory biology classroom. Students want to know more about the topics they are interested in. The authors of the Mader series of texts are focused on relevancy based resources.

The modules show the connections between biological content and topics that interest society as a whole. Each module has an introductory video, an overview of basic scientific concepts, and a closer look at the application of these concepts to the topic. There are discussion and assessment questions specific to the modules.

The modules can be used in a variety of ways in the classroom, and can be assigned by the instructor.

The BioNow series of videos, narrated and produced by Carlson, provide a relevant, applied approach that allows your students to feel they can actually do and learn biology themselves.

Each video has a story about applying the science of biology to a real problem. Students see the science as something they could do and understand if they use the tools and techniques that the average person has access to.

The PopScience articles on this site give an excellent focus for classroom discussions on topics that are currently being debated in society.

The major topics of the text can be found in the Biology101 project. The site has videos and animations that help students recognize the relevancy of what they are learning in the classroom.

References and links to new BioNow relevancy videos have been added to a number of the chapters in this edition. A lot of the artwork has been changed for the digital environment.

Section 1.1 now contains an explanation of supergroups, as Figure 1.1 now includes species in the levels of biological organization. Section 1.4 now contains a graph about climate change.

Section 6.3.anaerobic energy pathways in athletes has new content added.

There are new figures for spermatogenesis and oogenesis.

Chronic myeloid leukemia is the focus of the content on translocations. The new section focuses on inheritance patterns of human disease. The content on autosomal dominant disorders has been changed to include Huntington disease. The discussion of epistasis now includes human eye color genes. A new figure has been provided with new content on genome editing. New content on genetically-modified plants and the use of green fluorescent protein can be found in the section on biotechnology products. The discussions of gene therapy have been placed with the content on RNA interference. Section 14.4 has a new Evolution feature added.

Section 18.1 has a new Evolution feature called "Possible Extraterrestrial Components ofRNA".

Section 20.1 contains a new Biological Systems feature.

Extracorporeal membrane oxygenation (ECMO) technology is the focus of the Nature of Science feature. Emergency contraception has been added to the section on control of reproduction.

The "Do Animals Have Emotions" feature in the Nature of Science has been reworked to include more recent examples.

The species is now included in 44.1). There are new figures for each cycle.

Some of the early pioneers in the use of student data as a form of review are the authors of this series.

This series of texts and this edition of Biology represent a concerted effort on the part of the authors to give the students a voice in the review process.

The premise is easy to understand. Students don't know what they don't know. We are able to see where the students are having problems by putting the data from all of the probes on the text.

The authors were able to use this information to identify areas of the text that the students were having problems with, as well as areas that needed additional digital resources.

Dr. Sylvia Mader is an icon of science education. Thousands of students have benefited from her clear, concise writing style and her dedication to her students over the past four decades. It is an honor to continue her legacy and bring her message to the next generation of students.

The group of people I worked with on this edition were incredible. I would like to thank the many instructors who have invited me into their classrooms to discuss their needs with their students, as well as the many other instructors who have shared emails with me. You are all dedicated and talented teachers, and your energy and devotion to quality teaching is what drives a textbook revision.

I'm very grateful for the help of so many professionals who helped bring this book to fruition.

Anne Winch, the product developer, kept me focused.

My brand manager reminded me why what I do is important.

My marketing manager, Britney Ross, and market development manager, Beth Theisen, put me in contact with great instructors, on campus and virtually, throughout this process.

Eric Weber helped me see the possibilities in the new digital world.

Your contributions are visible on every page of biology.

Dawnelle was my copyeditor for this edition.

Jane Peden works behind the scenes to keep us functioning.

Inkling provided a dynamic authoring platform and Aptara provided all of their technical assistance.

One of my greatest passions is communicating the importance of science. Modern society is based on advances in science and technology. There are many challenges facing humans, and an understanding of how science can help analyze, and offer solutions to, these problems is critical to our species' health and survival.

I want to thank my family for their support. Sandy has never wavered in her support of my projects. I have watched my children's natural curiosity grow over the course of my work with McGraw-Hill. Thanks for making our world a better place.

Understanding biology involves themes of evolution, nature of science and biological systems.

Life can be found anywhere, from the deepest trenches in the ocean to the top of the highest mountains.

Understanding all aspects of living organisms is the focus of biology.

The themes that define these explorations are going to be the focus of this text. The central theme of biology is evolution and how life changes over time. The nature of science is the second theme. Experiments and hypothesis testing are a part of science. The third theme is biological systems. Throughout this text, you will discover that life is connected at many levels, from similarities in our genetic information to the cycling of nutrients in the environment.

As we go through this chapter, consider how we are connected with other species.

Understand the basic characteristics of life.

The study of life is called biology. Life on Earth is often functioning and behaving in strange ways. When they reproduce, some species of puffballs are capable of producing trillions of spores. Sand sharks kill and eat their siblings. There is a small brain in the squid. bristlecone pine trees outlive 10 generations of humans, while somebacteria live their entire life in 15 minutes.

The major groups of living organisms are shown in Figure 1.1. Micro organisms with a very simple structure are widely distributed from left to right.

Protists are more complex thanbacteria. The naked eye can easily see the other organisms in Figure 1.1. They can be seen by how they get their food. A morel digests its food outside. An animal that eats its food is an aquatic animal, while a plant that makes its own food is a sunflower.

The study of life is called biology.

There are many different types of life on planet Earth.

Some of the basic characteristics of life are shared by all organisms. Like non living things, organisms are composed of chemical elements. The laws of chemistry and physics govern everything in the universe. The characteristics of life give insight into the unique nature of life, and help to distinguish living organisms from non living things.

A cell is not made from living cells.

All life is connected by levels of biological organization.

The brain works with the spine and nerves to form the nervous system.

There are levels of biological organization beyond the individual organisms. A group of organisms are capable of interbreeding. A forest may have a population of gray squirrels and white oaks. Animals and plants in the forest make up a community. The basic characteristics of life cannot be carried out when cells are broken down into bits. All levels of biological organization function as biological systems. A change in carbon dioxide concentrations can affect the operation of organs, organisms, and entire ecosystems. Life is connected at a variety of levels.

Without an outside source of energy and nutrition, living organisms can't maintain their organization.

Food can be used as building blocks or for energy.

Cells carry out a sequence of chemical reactions when they make their parts and products. Chemical reactions occur in a cell.

Acquiring energy and nutrition. The bear and fish need energy.

The sun is the most important source of energy on Earth.

Plants and other organisms can take solar energy and convert it into chemical energy through their photosynthesis process. All life on Earth is metabolizing food.

This applies to plants.

The flow of energy and chemical between organisms is what defines how an ecology works. Chemical cycling and energy flow begin when producers, such as grasses, take in solar energy and organic nutrition to produce food. Chemical cycling occurs when chemicals move from one population to another in a food chain, until death and decomposition allow them to be returned to the producers. Plants and other members of the food chain get energy from the sun as they feed on one another. The energy is dissipated and returns to the atmosphere as heat. Without solar energy and the ability of organisms to absorb it, the ecosystems wouldn't stay in existence.

Chemical cycling and energy flow begin when plants use solar energy to produce their own food. In a food chain, chemicals and energy are passed from one population to another. Chemicals are returned to living plants when organisms die.

When it comes to the climate of the environment, energy flow and nutrient cycling are the most important factors. Deserts and forests require a lot of rain. Tropical rain forests and coral reefs are where solar energy is most abundant. The grasslands in North America are home to many animals, including rabbits, hawks, and various types of grasses.

Hawks feed on rabbits and other organisms, while rabbits feed on grasses.

Maintaining a state of biological balance is a must to survive. In order for life to continue, temperature, humidity, acidity, and other factors must be within the tolerance range of the organisms.

Homeostasis is maintained by systems that monitor internal conditions.

Organisms have control mechanisms that do not require conscious activity. The nervous system may be involved in controlling these mechanisms.

Your blood sugar levels are kept within normal limits when you are studying and don't eat lunch. The behavior of organisms regulates their environment. These behaviors are controlled by the nervous system in animals. A lizard can raise its internal temperature by basking in the sun or by moving into the shade.

Living organisms interact with the environment. Single-celled organisms can respond to their environment.

In some cases, the snapping of whiplike tails moves them away from light or chemicals.

More complex responses can be managed by multicellular organisms. A vulture can detect a carcass a kilometer away. A monarch butterfly can sense the approach of fall and begin its flight south.

Animals dart toward safety when the leaves of a land plant turn toward the sun. Appropriate responses allow the organisms to carry on with their daily activities. Organisms show a variety of behaviors as they compete for energy, shelter, and mates. Complex communication, hunting, and defense behaviors are displayed by many organisms.

Life is what comes from life. All forms of life are capable of making another one of their own. The organisms split in two. In most multicellular organisms, the reproductive process begins with the sperm and egg from one partner and the egg from the other partner. The union of sperm and egg results in an immature stage, which progresses through stages of change to become an adult.

Random combinations of sperm and egg ensure that the offspring have different characteristics. An embryo develops into a whale, a yellow daffodil, or a human because of its specific set of genes. The genes are made of long molecule. The instructions for the metabolism and organization of the particular organisms are provided by DNA. All cells in a multicellular organisms have the same set of genes, but only certain genes are turned on in specialized cells.

There are obvious differences between species, and you may notice that not all members of a species are the same. These differences are caused by changes in the genetic information.

There is a source of variation in the genetic information. The observable differences in eye and hair color are examples of mutations.

Even within a group of organisms with the same genes, there is a staggering diversity of life. Some organisms have characteristics that allow them to be more suited to their way of life.

Modifications that make organisms better able to function in a particular environment are called adaptation. penguins are adapted to an aquatic existence A waterproof coat is formed by covering an extra layer of downy feathers with short, thick feathers. Birds are kept warm in cold water by layers of blubber. penguins have long, flattened wings that are suitable for swimming. The flat feet allow them to walk on land, even though their feet and tails serve as rudders in the water.

The penguins use their bellies to slide across the snow in order to conserve energy. The eggs are protected by a pouch of skin when they are carried on their feet. The birds can huddle together for warmth while standing erect.

Living organisms can adapt. The penguins have evolved complex behaviors to adapt to their environment.

Life on Earth is very diverse because organisms respond to changing environments by adapting.

The framework for evolutionary change is provided by Page 6 adaptation. "An unrolling" is the way in which populations of organisms change over the course of many generations to become more suited to their environments.

In the next section, we will take a closer look at this process.

They are all composed of the same cells. Their genes are composed of DNA, and they carry out the same metabolic reactions to acquire energy and maintain their organization. The first cell or cells are thought to be descended from the unity of life.

Charles Darwin came to the conclusion that the process that makes modification is possible.

Some aspect of the environment selects which traits are more likely to be passed on to the next generation during natural selection.

A biotic agent is part of the living environment, such as a deer, while an abiotic agent is part of the physical environment.

Natural selection selects for or against a new trait. Competition, predation, and the physical environment can change the makeup of a population, favoring those more suited to the environment and lifestyle.

Natural selection is influenced by variations among the members of a population. The deer prefer smooth leaves over hairy leaves, so the plant with hairy leaves has an advantage.

The plant with hairy leaves produces more seeds than most of its neighbors. Most plants of this species produce hairy leaves later in life.

Although all individuals within a population have the ability to reproduce, not all do so with the same success, as was shown by this example. When long-necked, but not short-necked, giraffes can reach their food source, or an inability to escape being eaten because long legs, but not short legs, can carry an object, are some of the factors that can prevent reproduction.

It can be seen that organisms with good genes can produce more offspring than those with bad genes.

Living organisms change over time and are passed on from one generation to the next. The introduction of newer, more beneficial traits into a population can change a species.

New species can be created from existing ones. The three domains of life are the diversity of life.

Existing organisms give rise to new ones. The ancestors of all living organisms were a common ancestor about 4 billion years ago. The prokaryotes are included in the domain Archaea and domain Bacteria. Both single-celled and multicellular organisms have a nucleus.

A family tree is an evolutionary tree. An evolutionary tree traces the ancestry of life on Earth to a common ancestor, just as a family tree shows how a group of people have descended from one couple. One couple can have diverse children, and a population can be a common ancestor to several other groups, each adapted to a particular set of environmental conditions. Over time, different life-forms have arisen. Evolution is considered the unifying concept of biology because it explains so many aspects of it.

It's helpful to group organisms into categories because they are so diverse. "usage" is the discipline of grouping organisms according to rules. Taxonomy is meant to give valuable insight into evolution because of the variety of life on Earth. Systematists learn more about living organisms. Systematists use DNA technology to discover previously unknown relationships between organisms.

A group of interbreeding individuals is referred to as a model, kind. There are more types of organisms in each category than in the preceding one. The most closely related species in the same kingdom are the only ones that share general characteristics with one another. The most distantly related species are placed in different domains.

The first common ancestor may have evolved from the domain Archaea. archaea's cell walls and membranes are more similar to eukaryotes than tobacteria. The Page 8 conclusion is that the archaeal line of descent split into two.

Archaea can live in environments that are too salty, hot, or acidic for most other organisms. The environments may be similar to those of the primitive Earth and archaea.

"ancient" are the least evolved forms of life. In the water, soil, and atmosphere, as well as on our skin and in our mouth and large intestine, are variously adapted to living.

The kingdoms were divided by the classification of domain Eukarya. Some people need to acquire their food.

There are currently four kingdoms in the domain.

Plants, fungi, and animals evolved from protists.

Thekingdom Fungi include the familiar molds and mushrooms that help break down dead organisms.

The animals that are representative are aardvarks, jellyfish, and zebras.

The development of improved techniques in analyzing the DNA of organisms suggests that not all of the protists share the same evolutionary path. There are five super groups for Eukarya.

The relationship and structure of these groups is being revised. The structure of the supergroups will be explored in more detail in Section 21.1.

Biologists use a two-part name called a scientific name for living organisms. Biologists use scientific names to avoid confusion. Common names vary depending on locality and the language of the country. Latin is a universally used language that is well known by most scholars.

The scientific method has components.

Determine the hypothesis, experiment, control groups, and conclusions of a scientific experiment.

The multiple stages of biological organization mean that life can be studied at a variety of levels. The study of cells, the study of structure, the study of function, the study of animals, and the study of heredity are some of the biological disciplines.

Humans seek order in the natural world through religion, ethics, and science. The scientific method, a standard series of steps used in gaining new knowledge that is widely accepted among scientists, distinguishes the nature of scientific inquiry from other ways of knowing and learning. The scientific method is a guideline for scientific studies. Scientists modify or adapt the process to suit their field of study.

A scientist makes a hypothesis on the basis of new and previous observations. New data either supports or does not support the hypothesis as it is used to develop predictions to be tested. A scientist often retests the same hypothesis after an experiment. A scientific theory may be developed from the conclusion of many different experiments. The theory of evolution is supported by studies pertaining to development, anatomy, and fossil.

Scientists use all of their senses.

Scientists use instruments to extend their senses, for example, the microscope allows us to see objects that could never be seen by the naked eye. Scientists can take advantage of the knowledge and experiences of other scientists to expand their understanding.

They may look up past studies at the library or on the internet, or they may write or speak to others who are researching similar topics.

A scientist uses logic to come up with a possible explanation for a phenomenon. Chances alone may help a scientist arrive at an idea.

The antibiotic penicillin was discovered in 1928. There was an area that was free ofbacteria. The mold might have been producing an antibacterial compound according to Flemming.

A hypothesis is an informed statement that can be tested in a manner suited to the processes of science.

All of a scientist's past experiences have the potential to influence the formation of a hypothesis. A scientist only considers hypotheses that can be tested. Moral and religious beliefs can be very important in the lives of many people, but may not be scientifically testable.

Deductive reasoning is used to determine how to test a hypothesis.

The control group is not exposed to the experimental variable. The experimenter knows that the hypothesis predicting a difference between the two groups is not supported if the control group and test groups show the same results.

A hypothesis is often tested by scientists. Cell biologists can use mice to model the effects of a new drug. Model systems allow the scientist to control variables in a way that may not be possible in the natural environment.

Ecologists can use computer programs to model how human activities will affect the climate. Models do not always answer the original question completely. Medicine that is effective in mice should be tested in humans, and ecological experiments that are conducted using computer simulations need to be verified by field experiments. Biologists and other scientists constantly revise their experiments to better understand how different factors may affect their original observations.

The relationship between two quantities is shown in a graph. Graphs can be used to summarize data in a simpler way.

The bars represent the standard error in the results. When looking at a graph, first check the two axes to determine what the graph pertains to, as the title and labels can assist you in reading a graph. By looking at the graph, we can see that the cholesterol levels were highest in week 2, and that the values varied over the course of the study.

The variation in the concentration of cholesterol is shown in the line graph. The bars represent the standard error in the results.

Statistics are used by most authors who publish research articles. The standard deviation tells us how uncertain a particular value is. Predicting how many hurricanes Florida will have next year is possible by calculating the average number over the past 10 years. The standard error will be larger if the number of hurricanes varies widely. The standard error tells you how far off the average is. If the average number of hurricanes is four and the standard error is +- 2, then your prediction is between two and six hurricanes. This shows the statistical analysis of the data.

It is possible that the results of an experiment are due to chance or another factor. When calculating the probability value, investigators take into account a number of factors. Researchers describe the results as statistically significant if the probability value is low. The lower the p value, the less likely it is that the results are due to chance. The lower the p value, the more confidence the investigators have in the results. Most scientists like to have a p value of 0.05, but p values of 0.001 are common in many studies.

Before information is published in scientific journals, it is reviewed by experts who make sure the research is credible, accurate, unbiased, and well executed. A scientist should be able to read about an experiment in a scientific journal, repeat the experiment in a different location, and get the same results. When reviewers think there is something questionable about the design of an experiment or the manner in which it was conducted, some articles are rejected for publication. The process of rejection in science causes researchers to critically review their hypotheses, predictions, and experimental designs so that their next attempt will more adequately address their hypothesis. It can take several rounds of revision before a research is accepted for publication.

The information in these articles comes from previously published articles.

The ultimate goal of science is to understand the natural world in terms of scientific theories, which are concepts that join together well-supported and related hypotheses.

The theory of evolution is the unifying concept of biology because it deals with many different aspects of life. The theory of evolution allows scientists to understand the history of life and the development of organisms. Behavior can be described through evolution, as we will see in a study later in this chapter.

The theory of evolution has helped scientists come up with new ideas. The term evolution is sometimes used for theories that are generally accepted by an overwhelming number of scientists, because this theory has been supported by so many observations and experiments for over 100 years. Some prefer the term instead of principle. In the next chapter, we will look at the laws of thermodynamics.

Let's say investigators want to know which antibiotics are best for the treatment of an ulcer.

In this case, the medications being tested, clinicians try to vary just the Page 12 experimental variables. One or more test groups receive the medications, but a control group isn't given them. If the control group shows the same results as the test group, the investigators immediately know that the results of their study are invalid because the medications may have had nothing to do with them.

A controlled study example. There were three groups of people in this study. The placebo was given to the control group. One of the test groups received medication A, while the other received medication B. A graph shows that medication B was more effective than medication A for the treatment of ulcers.

The investigators might use one control group and two test groups. Reducing the number of possible variables, such as sex, weight, and other illnesses, among the groups is important. The investigators randomly divide a large group of volunteers into three groups. The hope is that the differences will be distributed evenly. If the investigators have a lot of volunteers, this is possible.

The investigators will want the subjects to believe they are getting the same treatment after they have been proven to have ulcers. The results are protected from any influence other than the medication. The control group can receive a placebo, a treatment that appears to be the same as that given to the other two groups, but actually contains no medication. The use of a placebo would help ensure the same dedication by all subjects.

After two weeks of administering the same amount of medication in the same way, the stomach and intestinal linings of each subject are examined to determine if they still have ulcers. A small, flexible tube with a camera on the end is inserted into the throat, stomach, and upper part of the small intestine. The doctor can see the lining of the organs.

The examiner's prejudice may affect the examination. A double-blind study is when neither the patient nor the technician are aware of the treatment.

The effectiveness of the medication may be determined by the percentage of people who no longer have ulcers. The medication is 80% effective if 20 people still have ulcers.

On the basis of their data, the investigators conclude that their hypothesis has been substantiated.

Discuss the major challenges facing society.

Science is a systematic way of acquiring knowledge about the natural world. Science is not the same as technology. The majority of technological advances are the result of scientific investigations. A new technology, such as your cell phone or a new drug, is based on years of scientific investigations. There are many challenges facing society despite our technological advances. Some of the critical challenges that scientists are investigating will be explored in this section.

The total number and relative abundance of species, the variability of their genes, and the different ecosystems in which they live are all known as "biodiversity".

Approximately 2.3 million species have been identified and named so far, and the planet has an estimated 8.7 million species. It is estimated that we are losing hundreds of species every year due to human activities and that as much as 38% of all species may be in danger of extinction before the end of the century. Climate change is associated with many extinctions. Many biologists are alarmed about the current rate of extinction and believe it may eventually rival the rates of the five mass extinctions that occurred during our planet's history.

It is believed to be the first mammal species to go extinct as a result of climate change.

Tropical rain forests and coral reefs are home to many organisms. Human activities are threatening these ecosystems. Orchids, insects, and monkeys can be found in the canopy of the tropical rain forest.

Coral reefs, which are found just offshore of the continents and islands near the equator, are built up from calcium carbonate skeletons of sea animals. Some of the world's most colorful fishes can be found in the coral reef. Coral reefs are in danger as the human population increases. 25% of all coral reefs have been destroyed by human activities in a few decades, and another 30% have been degraded. Almost three-quarters could be destroyed in 40 years. Statistics are available for tropical rain forests.

There are many consequences of the destruction of healthy ecosystems.

We depend on them for food, medicines, and raw materials. The construction of levees and the draining of the natural wetlands of the Mississippi and Ohio rivers have made farmland undesirable. The destruction of South American rain forests has killed many species that may have yielded the next miracle drug and has decreased the availability of many types of lumber. We are starting to realize that we need more services from the ecosystems.

The environment of the biosphere is suitable for the continued existence of humans. Several studies show that ecosystems can't function properly if they aren't biologically diverse. The concept of biodiversity will be explored in greater detail in Chapters 44 through 47.

Over the past decade, swine flu, Severe Acute Respiratory Syndrome, and Middle East respiratory syndrome have all been in the news. Emerging diseases are new to humans. Increased exposure to animals or insect populations may result in some of them. Changes in human behavior and use of technology can cause diseases. The consumption of civets, a type of exotic cat, is thought to have caused the emergence of the disease.

The civets may have been exposed to horseshoe bats. A large air-conditioning system in a hotel caused the emergence of Legionnaires' disease in 1976. The cooling tower was the water source for the airconditioning system. The transport of diseases all over the world was previously restricted to isolated communities. The first cases of the disease were reported in southern China. By the end of February 2003 there were nine countries/provinces that had been affected by the disease.

Birds are jumping from one host to another, for example. Birds were thought to be unaffected by the flu before 1997. The 1997 outbreak was caused by a strain that jumped to humans. 1.5 million chickens were killed to remove the source of the virus. Every few years new forms of bird flu are discovered.

Reemerging diseases are a concern. Unlike an emerging disease, a reemerging disease has been known to cause disease in humans for some time, but has not been considered a health risk due to a relatively low level of incidence in human populations. Reemerging diseases can cause problems. The outbreak of the disease in West Africa was an excellent example.

Small groups of humans have been affected. There was a much larger outbreak. Over 11,000 people were killed by the disease, but the exact numbers may never be known. The societies of several West African nations have been disrupted by the outbreak.

Both emerging and reemerging diseases can cause health problems for humans. Scientists investigate not only the causes of these diseases, but also their effects on our bodies and the mechanisms by which they are transmitted.

We will look at the viruses in Chapter 20.

The term climate change refers to changes in the normal cycles of the Earth's climate that may be attributed to human activity. Climate change is caused by the chemical cycling of the element carbon. Normally, carbon is removed from the environment. More carbon dioxide is being released into the atmosphere because of human activities. In 1850, atmospheric CO2 was around 280 parts per million. The increase is due to the burning of fossil fuels and the destruction of forests. The amount of carbon dioxide released into the atmosphere is twice what remains in the atmosphere. It is believed that most of this is dissolved in the ocean.

Climate change and global warming are caused by the global average carbon dioxide concentration.

Climate change and global warming are causing significant changes in many of the Earth's ecosystems and are one of the greatest challenges of our time.

Some living organisms have the same characteristics.

An example of a metabolism is photosynthesis.

The stimuli help the organisms react to changes in their environment.

The theory of evolution explains how all living organisms evolved from a common ancestor. There are changes within a population that create new characteristics. Natural selection can shape species over time and create new ones from existing ones.

The study of evolutionary relationships between species is called systematics.

There are three domains of life.

Tables or graphs are often used to present the results.

The conclusion is whether the results support the hypothesis or not.

The results can be submitted to a scientific publication.

The theory of evolution is related to biology.

Pick the best answer for the question.

A population is the level of organization that includes organisms of the same species.

Natural selection is the process of passing on genetic information.

A species is the least inclusive level of classification.

Natural selection is the process by which evolution occurs.

A hypothesis is published in a scientific journal.

Experiments look at the contribution to the observation.

Two extinct species are H5N1 and MERS.

The video is called BioNow.

An investigator spills dye on a culture plate and notices that thebacteria live despite their exposure to sunlight. He wants to know if the dye protects against UV light. There are two groups of culture plates, one with onlybacteria exposed to UV light and the other withbacteria and dye. The plates have deadbacteria on them.

When you want to grow large tomatoes, you notice that a name-brandfertilizer claims to produce larger plants than a generic brand.

Some of the planets and moons of our solar system may have life on them.

The basic unit of life is the cell. We need to understand what cells are made of to explore the various functions of the cell. We are going to take a quick look at chemistry.

Understanding basic chemistry and the nature of water will be the first thing we do. The structure of the organic molecule that is used to perform the functions of the cell can be found once we have established this chemical foundation of life.

Cells have to acquire energy and materials in order to survive. The majority of the chapters in this unit help us understand how cells accomplish their goals. We will look at how the cell's structure relates to its function, either as a single-celled organisms or as part of a multicellular tissue. The process of cellular reproduction and response to stimuli will be discussed in later units.

Since the cell forms the foundation for all life, your understanding of these concepts will serve you well as you move into the later parts of the text.

Take a few moments to review the discussions before you start this chapter.

One of Jupiter's moons is Enceladus.

Scientists believe that both of these moons have water. Beneath the frozen surface of Enceladus and Europa are oceans of liquid water, because of the pull of their parent planets. Water has an important relationship with life.

Scientists are looking for evidence of the chemicals that act as the building blocks of life at other locations in our solar system.

The hypothesis that comets may contain organic building blocks of life is supported by some of the early data from this mission. The search for signs of life in our solar system will continue with NASA's missions to Mars and Europa. There are many searches that focus on the presence of water. The information obtained from these missions will help us understand how life began.

The importance of water to life as we know it will be explored in this chapter.

The periodic table can be used to evaluate the relationship between atomic number and mass number.

Everything we touch, from the water we drink to the air we breathe, is composed of matter.

Anything that takes up space and has mass is referred to as matter. Matter has many different forms, but it is only in four different states.

All matter, both living and non living, is composed of basic substances called An element, which cannot be broken down by ordinary chemical means. The elements have their own unique properties, such as density, solubility, melting point, and reactivity.

In the known universe, there are only 92 naturally occurring elements that serve as the building blocks of matter. Physicists have created elements that are not biologically important.

The Earth's crust and organisms are composed of elements, but they are not the same. About 85% of the body weight of organisms are made up of only six elements. The human and the tree are examples of cells and organisms that are unique to them. Other elements, such as calcium, iron, magnesium, and zinc, are important to life.

The elements that make up the Earth's crust are compared.

Oxygen, nitrogen, carbon, and hydrogen are the elements found in living organisms. The elements sulfur and P are found in biological molecules.

An atom is the smallest part of an element. There are one or two letters that stand for this name. The symbol H is a hydrogen atom, the symbol Rn is for radon, and the symbol Na is for L.

There are a number of particles that make up atoms.

The nucleus has electrons moving about it. shading is used to indicate the probable positions of the electrons. The average location of the electrons is indicated when we use a model of an atom to predict a chemical reaction.

The particles are located as shown in the 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 There are particles and electrons outside of the nucleus.

The probable location of the electrons is shown in the shading. An electron shell can be used to represent the average location of an electron. The electric charge and atomic mass units of the particles are different.

The concept of an atom has changed over time.

Physicists are using high-energy supercolliders to explore the structure of the atom.

The majority of an atom is empty space.

The nucleus of an atom would be like a gumball in the center of the field, and the electrons would be tiny specks in the upper stands.

There is an atomic symbol, an atomic number, and a mass number. The nucleus has the same number of protons as the atoms.

One atomic mass unit is assigned to each of the particles. The AMU of electrons is considered to be zero in most calculations. When an atom is alone, the atomic number is written as a subscript to the lower left of the atomic symbol.

The number of neutrons may be different than the atomic number. "Equal" are atoms of the same element that have different numbers of neutrons.

The mass of substances on the moon has not changed despite the fact that the Earth's gravity is greater.

The atomic mass of carbon is closer to 12 than to 13 or 14. Take the closest whole number and subtract the number of protons from the atomic mass to determine the number of neutrons.

Even though each element has a different atom, certain chemical and physical characteristics recur after being discovered by chemists.

Figure 2.3 shows a portion of the periodic table. The periodic table has periods in the horizontal rows and groups in the vertical columns. If you read from left to right, the number of atoms increases by one. All the atoms in a group have the same type of chemical bonds. The noble gases in group VIII are inert and rarely react with one another. noble gases include Helium, neon, argon, and krypton.

The periodic table has elements listed in the order of their atomic numbers, but they are arranged so that each element is placed in a group. All the atoms in a particular group have the same number of electrons. The number of electron shells for an element is shown each period. The complete periodic table is in Appendix A and contains the elements most important in biology.

Some elements are unstable or radioactive.

As carbon 14 decays, it releases various types of energy. There are a number of ways in which the radiation can be detected. The Geiger counter is used to detect radiation. In 1896, the French physicist AntoineHenri Becquerel discovered that a sample of uranium would produce a bright image on a photographic plate even in the dark, and a similar method of detecting radiation is still in use today. Biologists use radiation to date objects from our distant past, to create images, and to trace the movement of substances in the body.

The chemical behavior of a radioactive isotope is the same as that of a stable element. The various reactions that occur during the process of photosynthesis were detected by using carbon 14.

The importance of chemistry to medicine can be seen in the many uses of radioactive isotopes. The body's organs and tissues can be imaged with specific tracers. After a patient drinks a solution containing a minute amount of iodine 131, the only organ to take it up is the thyroid. An image of the thyroid shows whether it is healthy in structure and function.

Comparative activity of tissues can be determined using Positron-emission tomography. A particle known as a positron is injected into the body. The radiation is analyzed by a computer. The result is a color image that shows which tissues have taken up the sugar. The areas of the brain that are most active are in the red areas. Patients with memory disorders, suspected brain tumors, or seizure disorders that might benefit from surgery, can be evaluated with a PET Scan of the brain. Low blood flow to the heart can be detected with the use of radioactive thallium.

The colored image shows the presence of a tumor that does not take up radioactive iodine. The green and red colors indicate which parts of the brain are active.

Radioactive substances can harm cells and cause cancer. Marie Curie and many of her co-workers developed cancer because they were not aware of the harmful effects of radiation. The release of radioactive particles following a nuclear power plant accident can have long-term effects on human health. Good use of the harmful effects of radiation can be found in Figure 2.5. Medical and dental products have been used to sterilize for many years. The U.S. mail and other packages can now be free of potential pathogens with the use of radiation. Radiation can be used to kill cancer cells.

On March 11, 2011, a magnitude 8.9 earthquake struck the coast of Japan, causing the shutdown of 11 of Japan's nuclear power reactor, including reactor 1, 2, and 3. After the shutdown, the pressure within reactor 1 was twice that of normal levels. Radiation was released from the reactor in an attempt to relieve pressure. The levels of radiation in the surrounding areas continued to rise as the plant continued to have problems. Over the course of the next few days, Japanese officials increased the size of the evacuated area from 10 km to 20 km, resulting in the relocation of close to 390,000 people.

A number of radioactive particles were released into the atmosphere and ocean. They included the radioactive elements of iodine, cesium, and xenon. Nuclear fission reactions occur within a nuclear power plant. The energy and particles from the breaking down of the uranium in these plants are released. This is called radioactive decay, and the loss of particles transforms the original atom into something else.

Three of the more common isotopes were released by the disaster. The types of radiation that they release, their half-lives, and their potential adverse effects on living organisms are different.

The release of radioactive cesium was the biggest concern after the disaster.

cesium is a metal with an atomic number of 55 and an atomic mass of 132.9.

There are two isotopes of cesium in a nuclear reactor. Two years and 30 years are the half-lives of Cesium-134 and Cesium-137. Both of these isotopes release particles as they decay. Both particles have the ability to penetrate tissues and damage cells.

Exposure to radiation can cause burns and increase the chance of cancer.

There were concerns about 137Cs entering the atmosphere and the Pacific Ocean after the disaster. The winds caused most of the 137Cs to be carried back over Japan, forcing the relocation of up to 22 miles inland. The large areas of the zone are still not safe due to the soil being contaminated by 137Cs. There were small amounts of atmospheric 137Cs detected on the west coast of the United States, but they were not considered to be hazardous to humans.

131I was also released by the reactor. Iodine has an atomic number of 53 and an atomic mass of 126.9. 131I is formed mainly from nuclear fission reactions. Like 137Cs, 131I emits particles that can damage tissues. It releases small amounts of radiation.

The long-term effect on the environment is minimal because of the half-life of radioactive iui. In our bodies, the production of the hormones associated with metabolism, including overall metabolism, is done by the use of iodine. Exposure to 131I may cause health problems. The medical profession uses low doses of the radioactive substance, called IoI, to diagnose and treat some forms of cancer.

An explosion of the plant was caused by the earthquake and a 15 meter wave that triggered a radioactive release into the atmosphere and surrounding water.

A noble gas with an atomic number of 54 and an atomic weight of 131.2 is called Xe. The half-life of 133Xe is only 5 days. The short half-life of 133Xe makes it less likely that it will cause serious problems. As a noble gas, xenon does not react with other elements and thus is not easily introduced into the chemical compounds within cells.

The medical profession uses 133Xe to diagnose disease. It is often used in the diagnosis of lung disorders.

Studies are underway to use 133Xe as a form of treatment for certain types of lung cancer, since it easily enters the lungs and can help destroy lung cancer cells.

Radiation therapy is used to kill cancer cells.

Various models can be used to show the structure of a single atom.

It is not possible to determine the exact location of an individual electron at any given moment since they are located in the nucleus. One of the more common models is the Bohr model.

The average energy levels of an electron are represented by the electron shells about the nucleus. It takes energy to push the negatively charged electrons away from the positively charged nucleus. The more distant the shell is, the more energy it takes. It is more accurate to say that electrons are at particular energy levels in relation to the nucleus. Electrons can move between levels of energy. When we explore the processes of photosynthesis, we will learn that when atoms absorb the energy of the sun, electrons are boosted to a higher energy level. As the electrons return to their original energy level, energy is released and transformed into chemical energy. Our existence is dependent on the energy of electrons, because this chemical energy supports all life on Earth.

The lower shells of the atoms are filled with electrons.

The nucleus has particular energy levels. Each shell is most stable when it has eight electrons in it. There may be more electrons in the outer shells of atoms with an atomic number above 20. The atom's chemical properties and how many other elements it can interact with are determined by the shell.

The sulfur atom has two electrons in the first shell, eight electrons in the second shell, and six electrons in the third shell. The period tells you how many shells an atom has. Sulfur is in group VI. The group tells you the number of electrons in the atom.

The chemical properties of an atom are determined by the valence shell. The valence shell is complete when there are two electrons in the atom. The valence shell is the most stable in atoms with more than one shell. Each atom in a group has the same number of electrons. The atoms in group VIII of the periodic table have eight electrons in their valence shell. The noble gases are elements that do not normally react.

Each atom has a stable outer shell after it reacts with other atoms. The number of electrons in an atom's valence shell determines whether the atom gives up, accepts, or shares electrons to the outer shell.

There are different types of bonds between elements.

A molecule has at least two different elements. In practice, these two terms are used the same way, but in biology they are usually used in different ways. H2O is a molecule of hydrogen and oxygen.

The bonds between atoms have energy as well. Organisms rely on chemical-bond energy to survive. The organisms break down the sugar to get energy. When a chemical reaction occurs, electrons shift in their relationship to one another, and energy is released. Spontaneous reactions always release energy.

Na has one electron in its valence shell and is an electron donor. The second shell, with its stable configuration of eight electrons, becomes the outer shell when it gives up an electron.

Chlorine is an electron acceptor. If it only acquires one electron, it has a stable outer shell. An electron is transferred from the sodium atom to the chlorine atom when there is a chlorine atom. Both atoms have electrons in their outer shells.

The chlorine atom has an electron transferred from the sodium atom. Each atom has eight electrons in the outer shell, but it also carries a charge. In a sodium chloride crystal, ionic bonding between Na+ and Cl- causes the atoms to assume a three-dimensional lattice in which each sodium ion is surrounded by six chloride ions. The result is crystals of salt. The sodium atom has a net charge of + after giving up an electron. The chlorine atom has a net charge of -1 because it has one more electron than it has protons. The charged particles are called ion. There are other biologically important ion, such as Na+) and chloride. Some are formed by the transfer of a single electron to another atom, while others are formed by the transfer of two electrons.

NaCl results when chlorine reacts with sodium.

There is a salt. Table salt is used to season food.

A result is when two atoms share electrons in a way that each atom has an octet of electrons in the outer shell. When there are two electrons in a hydrogen atom, the outer shell is complete. If hydrogen is in the presence of a strong electron acceptor, it becomes a hydrogen ion.

If this is not possible, hydrogen can share with another atom and have a finished outer shell. The electrons are shared between the two electron shells. Each atom has an outer shell because they form a bond and share an electron pair.

There are covalently bonding molecules. Each atom can have a completed outer shell in a covalent bond. Two hydrogen atoms share a pair of electrons in a molecule of hydrogen. There are three ways in which this bond can be shown. There are two pairs of electrons in a molecule of oxygen. A molecule of methane has one carbon atom and four hydrogen atoms.

Drawing a line between the two atoms is a more common way to symbolize that atoms are sharing electrons.

Just as a handshake requires two hands, one from each person, a covalent bond between two atoms requires two electrons, one from each atom.

Some atoms share more than one pair of electrons. A double covalent bond is formed when two atoms share electrons. The molecule can be written as OO to show that it has a double bond. Nitrogen gas (N2), which can be written as N[?]N, is possible for atoms to form triple covalent bonds. Double and triple bonds are even stronger than single bonds.

One atom is able to attract more electrons than the other.

The shape of a molecule can affect whether it is polar or non polar. While carbon is larger and has more protons than a hydrogen atom, the symmetrical nature of a methane molecule cancels out any polarities.

Water is polar because the oxygen atom is more negative than the Page 27 hydrogen atoms.

Water is a polar molecule because of its nonsymmetrical shape. The more positive end of the molecule is designated slightly positive.

There are other polar molecule in living organisms.

The polarity of the molecule affects how they interact with each other.

An ionic bond and a covalent bond can be compared.

Water's solid, liquid, and vapor states allow life to exist on Earth.

The top formula shows that when water forms, an oxygen atom is sharing electrons with two hydrogen atoms. The ball-and-stick model shows that the bonds between oxygen and hydrogen are at an angle. The three-dimensional shape of the molecule is given by the space-filling model.

The shape of the molecule is not indicated by the electron model. The ball-and-stick model shows that there are two bonds in a water molecule. The V shape of a water molecule is shown in the space-filling model. Water has hydrogen bonding between it. Each water molecule has the ability to bond with up to four other molecule. Water forms and breaks hydrogen bonds when it is in a liquid state.

In biology, structure relates to function. This is true at many levels, including water.

Different shapes of hormones allow them to be seen by the cells in the body. The way a key fits a lock and the shapes of disease-causing agents can only be removed with the help of antibodies.

Because carbon dioxide is symmetrical, the opposing charges cancel one another and hydrogen bonding does not occur.

The dotted lines show that the hydrogen atoms in one water molecule are attracted to the oxygen atoms in other water molecule.

The hydrogen bonds are weaker than the ionic or covalent bonds.

The dotted lines show that hydrogen bonds are more difficult to break.

Water has hydrogen bonding. Other biologicalmolecules, such as DNA, have polar covalent bonds involving hydrogen and oxygen. There can be a hydrogen bond between the same molecule and nearby ones.

A single hydrogen bond is more difficult to break than a single covalent bond.

Cells have hydrogen bonds that help maintain their structure and function. The two strands of DNA are held together by hydrogen bonds. When a copy of itself is made, hydrogen bonds can easily break. The hydrogen bonds add stability to the molecule. The shape of a molecule is maintained by hydrogen bonding between different parts. Many of the important properties of water are the result of hydrogen bonding.

All living organisms are 70% water. Water has unique chemical properties because of hydrogen bonding. Without hydrogen bonding between molecule, water would freeze at -100degC and boil at -91degC, making most of the water on Earth steam, and life unlikely.

Water is a liquid at temperatures found on the Earth's surface. It is cold at 0degC and hot at 100degC.

The chapter opener states that the search for life on other planets often begins with the search for water.

The amount of heat energy needed to raise the temperature of 1 g of water is called A. In comparison, other covalently bonding liquids only need half the amount of energy to rise.

Water is able to absorb heat without the temperature changing. The loss of 80 calories of heat energy is required to convert 1 g of liquid water to ice. The temperature of water falls more slowly than that of other liquids. The property of water is important for all life.

At naturally occurring environmental temperatures, water can be a solid, liquid, or gas. Water is a liquid at room temperature and pressure. When water becomes ice, it gives off heat, which can help keep the temperature higher than expected. When water is evaporates, it takes up a lot of heat as it changes from a liquid to a gas. splashing water on the body will keep the temperature within a normal range.

When water is boiled, it becomes liquid, meaning that it goes into the environment. 540 calories of energy is required to convert 1 g of the hottest water to a gas. Water has a high temperature because hydrogen bonds must be broken before it can boil.

Animals in a hot environment can release excess body heat by using water's high heat of vaporization. Body heat is used to cool the animal when it sweats or gets splashed.

During the summer and winter, the ocean absorbs and stores solar heat.

Water facilitates chemical reactions both outside and inside living systems. It is a great solvent because of the number of polar substances it is capable of dissolving. solutes are dissolved substances. When ionic salts are put into water, the negative ends of the water molecule are attracted to the sodium ion, and the positive ends of the water molecule are attracted to the chloride ion. The attraction causes the sodium and the chloride to separate.

Water is a solvent for ammonia.

At any moment in time, a water molecule can form hydrogen bonds with other water molecule. Water flows freely, yet water does not separate from each other.

The water's polarity is the reason for this. Multicellular animals have internal vessels in which water helps the transport of vitamins and minerals because they have the same chemistry as the cardiovascular system. The liquid portion of our blood, which transports dissolved and suspended substances about the body, is only 10% water.

The transport of water in plants is aided by cohesion and adhesion. Plants have roots in the soil that absorb water, but the leaves are exposed to solar energy. Water from transport vessels that extend from the roots to the leaves is replaced with water from the leaves.

A tension is created that pulls the water column up from the roots. Adhesion of water to the walls of the transport vessels helps keep the water column from breaking apart.

Section 25.3 will discuss capillary action as essential to plant life.

Water is cohesive and strong. The movement of water in a plant is dependent on cohesion and adhesion.

Plants need this capillary action to function.

Page 30 cling together when the liquid surface is exposed to air because they are attracted to each other. Humans can skip rocks on water because of its high surface tension. Water striders can walk on the surface of a pond without breaking it.

The molecule come closer together as liquid water cools. The water is dense at 4degC. hydrogen bonding becomes more rigid but also more open at temperatures below 4 degrees. Cans of soda burst when placed in a freezer, or frost heaves make northern roads bumpy in the winter, because water expands as it reaches 0degC. It also means that ice floats on liquid water.

Water is denser than ice. The water is denser at 4degC. Water expands when it freezes because the hydrogen bonds in water are farther apart than in liquid water. The property of water allows ice to flow, providing habitats for some aquatic species and protecting other species that live beneath the ice.

If ice did not float on the water, it would sink to the bottom, making life impossible in the water and on land. The ice on the water acts as an insulation to keep the water below it from freezing. The winter allows aquatic organisms to survive. It helps prevent a sudden change in temperature by drawing heat from the environment.

Analyze how buffers prevent large pH changes.

acidic solutions include lemon juice, coffee, and tomatoes. Acids release hydrogen ion (H+) in water. The acidity of a substance depends on how much water it has in it.

Adding hydrochloric acid to a beaker of water will increase the number of hydrogen ion.

Milk of magnesia and ammonia are familiar to most people.

The number of hydrogen ion decreases if the water is added with sodium hydroxide.

The is used to indicate the basicity of a solution. The hydrogen ion and hydroxide ion concentrations are equal in a neutral state. The hydrogen ion concentration is greater than the hydroxide concentration in acidic solutions. The [OH-] is greater than the [H+]. Each unit is 10 times more acidic than the previous unit as we move down the scale. Each unit is 10 times more basic as we move up the scale. The pH 5 is 100 times more acidic than the other two.

0 is the most acidic and 14 is the most basic on the pH scale. A basic pH has more OH- than H+.

The use of numbers was eliminated with the creation of the pH scale.

Consider the following question to understand the relationship between hydrogen ion concentration and pH. A number with a smaller negative is indicative of a bigger quantity of hydrogen ion. The solution is acidic.

The impact of acid deposition on the environment is described in the Biological Systems feature. There are health consequences if the pH is maintained in a narrow range.

The carbon dioxide in the air and water combine to give a weak solution of carbonic acid, which is why the rain has a pH of about 5.6. Acid deposition includes rain or snow that has a pH of less than 5, as well as dry acidic particles that fall to Earth from the atmosphere.

When fossil fuels such as coal, oil, and gasoline are burned, sulfur dioxide and nitrogen oxides combine with water to produce sulfuric and nitric acids. The pollutants are found in the east because of wind patterns. The tall smokestacks cause them to be carried hundreds of miles away.

Acid rain can affect biological systems. In areas where the soil is thin and lacks limestone as a buffer, aluminum may come from the soil.

Toxic mercury may be converted into toxic methyl mercury by acid rain.

There are serious sensory and muscular health problems that can be caused by the build up of mercury in body tissues over time. Hundreds of lakes in Canada and New England have been devoid of fish due to acid rain.

Plants that have been damaged by acid rain are no longer able to use photosynthesis. Plants are vulnerable to diseases and pests when they are stressed. Acid rain affects forests on mountaintops more than those at lower levels. Toxic chemicals such as aluminum can damage forests. These kill soil fungi that help the roots get the vitamins they need. Millions of acres of highelevation forests have been destroyed in New England.

Acid deposition and destruction of the environment are caused by SO2 and NOx. Over the past several decades, clean air legislation and stricter emission standards have resulted in decreases in SO2 and NOx, chemicals that lead to acid rain.

Humans may be affected by acid rain. Respiratory illnesses, such as asthma, are more likely to be caused by inhaling dry sulfate and nitrate particles.

Limestone and marble buildings break down when exposed to acid rain. The paint on cars is degraded.

If we reduce chemicals that contribute to acid rain, the damage to natural systems and human structures will decrease.

A combination of chemicals keeps the pH within normal limits. There is an added incentive for us to buy commercial products.

In living organisms, the pH of body fluids has to be maintained within a narrow range.

acidosis results if the blood pH drops to about 7. Alkalosis results if the blood pH goes up to 7.8.

The body has mechanisms to prevent pH changes. One of the important mechanisms is the buffer.

Buffers help keep the pH within normal limits because they are chemicals or combinations of chemicals that take up excess hydrogen ion.

There is a combination of carbonic acid and bicarbonate in the blood.

Any change in blood pH is prevented by these reactions.

Determine if a pH of 2.0 is more acidic than a pH of 4.0.

Discuss the role of buffers in living organisms.

Carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur are some of the elements found in living organisms.

Radioactive isotopes can be used in biological experiments and medical procedures.

The electron shells are at a distance from the nucleus. When there are two electrons in the first shell, it's complete. Every shell beyond the first is stable when eight electrons are present. The octet rule states that most atoms do not have filled outer shells.

There are three types of bonds.

Water is essential for life. The hydrogen bonds between water molecule are formed by the polarity of the water molecule.

Cells have the structure and function of hydrogen bonds.

Water's unique properties allow life to exist and carry on cellular activities.

There is a high heat capacity in water.

The water has a high temperature. A large amount of heat is needed to cause liquid water to change to gas.

Water is a liquid. Water is strong.

Liquid water is denser than frozen water. Ice floats on liquid water.

Solutions with equal numbers of H+ and OH are neutral.

Cells can be sensitive to pH changes.

Pick the best answer for the question.

There is a number of protons.

An atom with two electrons in the valence shell is most likely a share.

A negatively charged ion is formed when an atom gains electrons.

A/an a. ionic bond has an equal sharing of electrons.

The temperature inside and outside the cell can be stable with water.

Water is cohesive.

Match the statements with the property of water in the key.

The water flows because it is cohesive.

The water holds the heat.

Water and cells make up the majority of our blood.

Our blood is acidic.

A normal body temperature is maintained by us.

The buffer system in the body is called H2CO3/NaHCO3.

The pH will go up.

The pH will go down.

The solution is 100 times more acidic.

The solution is 100 times simpler.

Natural phenomena need an explanation. Section 2.3 explains why the oceans don't freeze.

Calvin used radioactive carbon to find a group of molecule that form during photosynthesis.

On a hot summer day, you decide to dive into a swimming pool. The surface of the water is smooth before you dive. Your skin temperature feels cooler after the dive because some water droplets are clinging to your skin.

Water has been found in the soil of Mars, suggesting that life once existed on the planet.

An over-the-counter remedy for heartburn is antacids.

One electron and one protons are contained in a hydrogen atom. A hydrogen ion has a single protons.

A mole is defined as 6.02 x 1023 of any atom, molecule, or ion. 6.02 x 1023 atoms of 12C have a mass of 12 g.

The negative log of the hydrogen ion concentration is called 3pH. The power to which 10 must be raised is called a log.