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Biology is a natural science concerned with the study of life and living organisms. Modern biology is a vast and eclectic field composed of many specialized disciplines that study the structure, function, growth, distribution, evolution, or other features of living organisms. However, despite the broad scope of biology, there are certain general and unifying concepts that govern all study and research:
the cell is the basic unit of life genes (consisting of DNA or RNA) are the basic unit of heredity evolution accounts for the unity and diversity seen among living organisms all organisms survive by consuming and transforming energy all organisms maintain a stable internal environment
Biological research indicates the first forms of life on Earth were microorganisms that existed for billions of years before the evolution of larger organisms. The mammals, birds, and flowers so familiar to us are all relatively recent, originating within the last 200 million years. Modern-appearing humans, Homo sapiens, are a relatively new species, having inhabited this planet for only the last 200,000 years (approximately).
HISTORY OF BIOLOGICAL SCIENCE
LESSON 1
INTRODUCTION TO BIOLOGY
TOPICS
1. The scientific study of organisms
2. Properties of Life
3. Assumptions, methods, and limitations of science
4. Underlying themes of Biology
5. Evolution as a unifying concept
LEARNING OUTCOMES
At the end of the lesson, you should be able to:
1. Discuss scientific processes and how they are used in studying biology.
2. Distinguish between living organisms and nonliving matter.
3. Identify some limitations of science.
4. Discuss some underlying themes of biology (e.g. hierarchy, homeostasis,
emergent properties)
5. Explain evolution and natural selection
TOPIC 1: The Scientific Study of Organisms
Although modern biology is a relatively recent development, sciences related to and included within it have been studied since ancient times. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, Egypt, the Indian subcontinent, and China. However, the origins of modern biology and its approach to the study of nature are most often traced back to ancient Greece. (Biology is derived from the Greek word “bio” meaning “life” and the suffix “ology” meaning “study of.”)
Advances in microscopy also had a profound impact on biological thinking. In the early 19th century, a number of biologists pointed to the central importance of the cell and in 1838, Schleiden and Schwann began promoting the now universal ideas of the cell theory. Jean-Baptiste Lamarck was the first to present a coherent theory of evolution, although it was the British naturalist Charles Darwin who spread the theory of natural selection throughout the scientific community. In 1953, the discovery of the double helical structure of DNA marked the transition to the era of molecular genetics.
SCIENCE AND PSEUDOSCIENCE
Science is a process for learning about the natural world. Most scientific investigations involve the testing of potential answers to important research questions. For example, oncologists (cancer doctors) are interested in finding out why some cancers respond well to chemotherapy while others are unaffected. Based on their growing knowledge of molecular biology, some doctors suspect a connection between a patient’s genetics and their response to chemotherapy. Many years of research have produced numerous scientific papers documenting the evidence for a connection between cancer, genetics, and treatment response. Once published, scientific information is available for anyone to read, learn from, or even question/dispute. This makes science an iterative, or cumulative, process, where previous research is used as the foundation for new research. Our current understanding of any issue in the sciences is the culmination of all previous work.
Pseudoscience is a belief presented as scientific although it is not a product of scientific investigation. Pseudoscience is often known as fringe or alternative science. It usually lacks the carefully-controlled and thoughtfully-interpreted experiments which provide the foundation of the natural sciences and which contribute to their advancement.
THE PROCESS OF SCIENCE
Science (from the Latin scientia, meaning “knowledge”) can be defined as knowledge that covers general truths or the operation of general laws, especially when acquired and tested by the scientific method. The steps of the scientific method will be examined in detail later, but one of the most important aspects of this method is the testing of hypotheses (testable statements) by means of repeatable experiments. Although using the scientific method is inherent to science, it is inadequate in determining what science is. This is because it is relatively easy to apply the scientific method to disciplines such as physics and chemistry, but when it comes to disciplines like archaeology, paleoanthropology, psychology, and geology, the scientific method becomes less applicable as it becomes more difficult to repeat experiments.
region, then the distribution of plants and animals should change. These predictions have been written and tested, and many such predicted changes have been observed, such as the modification of arable areas for agriculture correlated with changes in the average temperatures.
Both types of logical thinking are related to the two main pathways of scientific study: descriptive science and hypothesis-based science. Descriptive (or discovery) science, which is usually inductive, aims to observe, explore, and discover, while hypothesis-based science, which is usually deductive, begins with a specific question or problem and a potential answer or solution that can be tested. The boundary between these two forms of study is often blurred and most scientific endeavors combine both approaches. The fuzzy boundary becomes apparent when thinking about how easily observation can lead to specific questions. For example, a gentleman in the 1940s observed that the burr seeds that stuck to his clothes and his dog’s fur had a tiny hook structure. Upon closer inspection, he discovered that the burrs’ gripping device was more reliable than a zipper. He eventually developed a company and produced the hook-and- loop fastener popularly known today as Velcro. Descriptive science and hypothesis-based science are in continuous dialogue.
TWO TYPES OF SCIENCE
The scientific community has been debating for the last few decades about the value of different types of science. Is it valuable to pursue science for the sake of simply gaining knowledge, or does scientific knowledge only have worth if we can apply it to solving a specific problem or to bettering our lives? This question focuses on the differences between two types of science: basic science and applied science.
Basic science or “pure” science seeks to expand knowledge regardless of the short-term application of that knowledge. It is not focused on developing a product or a service of immediate public or commercial value. The goal of basic science is knowledge for knowledge’s sake; though this does not mean that, in the end, it may not result in a practical application.
In contrast, applied science or “technology” aims to use science to solve real-world problems such as improving crop yields, finding a cure for a particular disease, or saving animals threatened by a natural disaster. In applied science, the problem is usually defined for the researcher.
REPORTING SCIENTIFIC WORK
Scientists must share their findings in order for other researchers to expand and build upon their discoveries. Collaboration with other scientists—when planning, conducting, and analyzing results—are all important for scientific research. For this reason, a major aspect of a scientist’s work is communicating with peers and disseminating results to peers. Scientists can share results by presenting them at a scientific meeting or conference, but this approach can reach only the select few who are present. Instead, most scientists present their results in peer-reviewed manuscripts that are published in scientific journals. Peer-reviewed manuscripts are scientific papers that are reviewed by a scientist’s colleagues or peers. These colleagues are qualified individuals, often experts in the same research area, who judge whether or not the scientist’s work is suitable for publication. The process of peer review helps to ensure that the research described in a scientific paper or grant proposal is original, significant, logical, and thorough. Grant proposals, which are requests for research funding, are also subject to peer review. Scientists publish their work so other scientists can reproduce their experiments under similar or different conditions to expand on the findings. The experimental results must be consistent with the findings of other scientists.
Figure 2. Properties of Life
Source: (Jane B. Reece, 2014)
BASIC ASSUMPTIONS AND METHODS OF SCIENCE
The process of science builds reliable knowledge about the natural world. To see evidence of this reliability, one can look around at the everyday products of scientific knowledge: from airplanes to antibiotics, from batteries to bridges. These technologies only work because science does.
The process of building scientific knowledge relies on a few basic assumptions that are worth acknowledging. Science operates on the assumptions that:
TOPIC 2: Properties of Life
TOPIC 3: Assumptions, Methods, and Limitations of Science
Fundamentally, the various scientific disciplines are alike in their reliance on evidence, the use of hypothesis and theories, the kinds of logic used, and much more. Nevertheless, scientists differ greatly from one another in what phenomena they investigate and in how they go about their work; in the reliance they place on historical data or on experimental findings and on qualitative or quantitative methods; in their recourse to fundamental principles; and in how much they draw on the findings of other sciences. Still, the exchange of techniques, information, and concepts goes on all the time among scientists, and there are common understandings among them about what constitutes an investigation that is scientifically valid.
Scientific inquiry is not easily described apart from the context of particular investigations. There simply is no fixed set of steps that scientists always follow, no one path that leads them unerringly to scientific knowledge. There are, however, certain features of science that give it a distinctive character as a mode of inquiry. Although those features are especially characteristic of the work of professional scientists, everyone can exercise them in thinking scientifically about many matters of interest in everyday life.
Science Demands Evidence
Sooner or later, the validity of scientific claims is settled by referring to observations of phenomena. Hence, scientists concentrate on getting accurate data. Such evidence is obtained by observations and measurements taken in situations that range from natural settings (such as a forest) to completely contrived ones (such as the laboratory). To make their observations, scientists use their own senses, instruments (such as microscopes) that enhance those senses, and instruments that tap characteristics quite different from what humans can sense (such as magnetic fields). Scientists observe passively (earthquakes, bird migrations), make collections (rocks, shells), and actively probe the world (as by boring into the earth's crust or administering experimental medicines).
In some circumstances, scientists can control conditions deliberately and precisely to obtain their evidence. They may, for example, control the temperature, change the concentration of chemicals, or choose which organisms mate with which others. By varying just one condition at a time, they can hope to identify its exclusive effects on what happens, uncomplicated by changes in other conditions. Often, however, control of conditions may be impractical (as in studying stars), or unethical (as in studying people), or likely to distort the natural phenomena (as in studying wild animals in captivity). In such cases, observations have to be made over a sufficiently wide range of naturally occurring conditions to infer what the influence of various factors might be. Because of this reliance on evidence, great value is placed on the development of better instruments and techniques of observation, and the findings of any one investigator or group are usually checked by others.
Science Is a Blend of Logic and Imagination
Although all sorts of imagination and thought may be used in coming up with hypotheses and theories, sooner or later scientific arguments must conform to the principles of logical reasoning—that is, to testing the validity of arguments by applying certain criteria of inference, demonstration, and common sense. Scientists may often disagree about the value of a particular piece of evidence, or about the appropriateness of particular assumptions that are made—and therefore disagree about what conclusions are justified. But they tend to agree about the principles of logical reasoning that connect evidence and assumptions with conclusions.
Scientists do not work only with data and well-developed theories. Often, they have only tentative hypotheses about the way things may be. Such hypotheses are widely used in science for choosing what data to pay attention to and what additional data to seek, and for guiding the interpretation of data. In fact, the process of formulating and testing hypotheses is one of the core activities of scientists. To be useful, a hypothesis should suggest what evidence would support it and what evidence would refute it. A hypothesis that cannot in principle be put to the test of evidence may be interesting, but it is not likely to be scientifically useful.
The use of logic and the close examination of evidence are necessary but not usually sufficient for the advancement of science. Scientific concepts do not emerge automatically from data or from any amount of analysis alone. Inventing hypotheses or theories to imagine how the world works and then figuring out how they can be put to the test of reality is as creative as writing poetry, composing music, or designing skyscrapers. Sometimes discoveries in science are made unexpectedly, even by accident. But knowledge and creative insight are usually required to recognize the meaning of the unexpected. Aspects of data that have been ignored by one scientist may lead to new discoveries by another.
Science Explains and Predicts
Scientists strive to make sense of observations of phenomena by constructing explanations for them that use, or are consistent with, currently accepted scientific principles. Such explanations—theories—may be either sweeping or restricted, but they must be logically sound and incorporate a significant body of scientifically valid observations. The credibility of scientific theories often comes from their ability to show relationships among phenomena that previously seemed unrelated. The theory of moving continents, for example, has grown in credibility as it has shown relationships among such diverse phenomena as earthquakes, volcanoes, the match between types of fossils on different continents, the shapes of continents, and the contours of the ocean floors.
The essence of science is validation by observation. But it is not enough for scientific theories to fit only the observations that are already known. Theories should also fit additional observations that were not used in formulating the theories in the first place; that is, theories should have predictive power. Demonstrating the predictive power of a theory does not necessarily require the prediction of events in the future. The predictions may be about evidence from the past that has not yet been found or studied. A theory about the origins of human beings, for example, can be tested by new discoveries of human-like fossil remains. This approach is clearly necessary for reconstructing the events in the history of the earth or of the life forms on it. It is also necessary for the study of processes that usually occur very slowly, such as the building of mountains or the aging of stars. Stars, for example, evolve more slowly than we can usually observe. Theories of the evolution of stars, however, may predict unsuspected relationships between features of starlight that can then be sought in existing collections of data about stars.
Scientists Try to Identify and Avoid Bias
When faced with a claim that something is true, scientists respond by asking what evidence supports it. But scientific evidence can be biased in how the data are interpreted, in the recording or reporting of the data, or even in the choice of what data to consider in the first place. Scientists' nationality, sex, ethnic origin, age, political convictions, and so on may incline them to look for or emphasize one or another kind of evidence or interpretation. For example, for many years the study of primates—by male scientists—
Structure and Function of Cells
All life-forms consist of at least one cell. In the 17th century, scientists Robert Hooke and Anton von Leeuwenhoek observed cells and noted their characteristics under microscopes. These and subsequent observations led to the formation of the cell theory, stating that cells make up all life, carry out all biological processes and can only come from other cells. All cells contain genetic material and other structures floating in a jelly-like matrix, acquire energy from their surroundings, and are enveloped in protection from the external environment.
Interactions Between Organisms
Organisms don't exist in vacuums. Each living thing has uniquely adapted to a particular habitat and developed specific relationships with other organisms in the same area.
In ecosystems, plants use light energy from the sun to make their own food, which becomes a source of energy for other organisms that consume the plants. Other creatures eat these plant-eating organisms and receive the energy. When plants and animals die, their energy flow doesn't stop; instead, the energy transfers to the soil and back into the environment, thanks to scavengers and decomposers that break down dead organisms.
There are various connections between life-forms. Predators eat prey, parasites find nutrients and shelter at the expense of others, and some organisms form mutually beneficial relationships with one another. As a result, changes affecting one species influence the survival of others within the ecosystem.
Reproduction and Genetics
All organisms reproduce and pass on characteristics to their offspring. In asexual reproduction, offspring are exact replicas of their parents. More complex life-forms lean toward sexual reproduction, which involves two individuals producing offspring together. In this case, the offspring show characteristics of each parent.
In the mid 1800s, an Austrian monk named Gregor Mendel conducted a series of famous experiments exploring the relationship between sexual reproduction and heredity. Mendel realized that units called genes determined heredity and could be passed from parent to offspring.
Evolution and Natural Selection
In the early 1800s, French biologist Jean Baptiste de Lamarck hypothesized that the use of certain features would strengthen their existence, and nonuse would cause them to eventually disappear in subsequent generations. This would explain how snakes evolved from lizards when their legs weren't being used, and how giraffe necks grew longer with stretching, according to Lamarck.
Charles Darwin constructed his own theory of evolution called natural selection. Following his stint as a naturalist on the ship HMS Beagle, Darwin formulated a theory that claimed all individuals possess differences that allow them to survive in a particular environment, reproduce, and pass on their genes to their descendants. Individuals that adapt poorly to their environments would have fewer opportunities to mate and pass on their genes. Eventually, the genes of the stronger individuals would become more prominent in subsequent populations. Darwin’s theory has become the most accepted theory for evolution.
Evolution is the change in living things over time. More specifically, evolution is a change in the genetic makeup of a subgroup, or population, of a species. The concept of evolution links observations from all levels of biology, from cells to the biosphere. A wide range of scientific evidence, including the fossil record and genetic comparisons of species, show that evolution is continuing today.
Adaptation
One way evolution occurs is through natural selection of adaptations. In natural selection, a genetic, or inherited, trait helps some individuals of a species survive and reproduce more successfully than other individuals in a particular environment. An inherited trait that gives an advantage to individual organisms and is passed on to future generations is an adaptation. Over time, the makeup of a population changes because more individuals have the adaptation. Two different populations of the same species might have different adaptations in different environments. The two populations may continue to evolve to the point at which they are different species
Consider the orchid and the thorn bug in the figure below. Both organisms have adapted in ways that make them resemble other organisms. The orchid that looks like an insect lures other insects to it. The insects that are attracted to the orchid can pollinate the flower, helping the orchid to reproduce. The thorn bug’s appearance is an adaptation that makes predators less likely to see and eat it
Figure 4. Different appearance of Thorn bugs
This adaptation allows the thorn bug to survive and reproduce. In different environments, however, you would find other orchid and insect species that have different adaptations.
Adaptation in evolution is different from the common meaning of adaptation. For example, if you say that you are adapting to a new classroom or to a new town, you are not talking about evolution. Instead, you are talking about consciously getting used to something new. Evolutionary adaptations are changes in a species that occur over many generations due to environmental pressures, not through choices made by organisms. Evolution is simply a longterm response to the environment. The process does not necessarily lead to more complex organisms, and it does not have any special end point. Evolution continues today, and it will continue as long as life exists on Earth.
Unity and Diversity
TOPIC 5: Evolution as a Unifying Concept
