Identify and describe the nature of lifeDescribe the levels of organization among living thingsList examples of various sub techniques in biology

Biology is the scientific research that research studies life. What precisely is life? This might sound prefer a silly question with an noticeable answer, however it is not basic to specify life. For example, a branch of biology dubbed virology studies viruses, i m sorry exhibit several of the features of life entities yet lack others. It turns out the although viruses can assault living organisms, cause diseases, and also even reproduce, they perform not meet the criteria the biologists use to define life.

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From its earliest beginnings, biology has actually wrestled with 4 questions: What are the mutual properties that make other “alive”? just how do those miscellaneous living things function? When challenged with the remarkable diversity of life, how do we organize the various kinds of biology so that we can far better understand them? And, finally—what biologists ultimately seek to understand—how go this diversity arise and also how is it continuing? As new organisms are discovered every day, biologists continue to look for answers to these and other questions.

Properties the Life

All teams of life organisms re-publishing multiple vital characteristics or functions: order, sensitivity or solution to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. Once viewed together, these eight attributes serve to define life.


Organisms are very organized frameworks that consist of one or more cells. Even an extremely simple, single-celled organisms space remarkably complex. Inside each cell, atoms comprise molecules. This in turn consist of cell contents or organelles. Multicellular organisms, which might consist of numerous individual cells, have an advantage over single-celled biology in the their cells can be devoted to perform details functions, and even sacrificed in details situations because that the an excellent of the organism as a whole. Exactly how these specialized cells come together to kind organs such together the heart, lung, or skin in organisms prefer the toad displayed in figure 1. 2 will certainly be debated later.

Figure 1.2 A toad represents a highly organized framework consisting the cells, tissues, organs, and organ systems.

Sensitivity or solution to Stimuli

Organisms respond to varied stimuli. For example, plants have the right to bend toward a resource of light or respond come touch. Also tiny bacteria deserve to move towards or far from chemistry (a process called chemotaxis) or irradiate (phototaxis). Activity toward a economic stimulation is considered a optimistic response, while movement away native a economic stimulation is taken into consideration a an unfavorable response.

Figure 1.3 The leaves of this perceptible plant (Mimosa pudica) will instantly droop and fold once touched. ~ a few minutes, the tree returns to its typical state.

Concept in Action


Watch this video to see how the sensitive plant responds to a touch stimulus.


Single-celled biology reproduce by an initial duplicating their DNA, which is the hereditary material, and also then dividing it equally together the cabinet prepares to divide to kind two new cells. Many multicellular organisms (those made up of an ext than one cell) produce dedicated reproductive cells that will type new individuals. Once reproduction occurs, DNA containing gene is passed along to one organism’s offspring. These genes room the reason that the offspring will belong come the same species and will have characteristics comparable to the parent, such as hair color and blood type.


All living organisms exhibit a “fit” to their environment. Biologists refer to this fit together adaptation and it is a consequence of evolution by natural selection, i m sorry operates in every family tree of reproducing organisms. Examples of adaptations space diverse and also unique, indigenous heat-resistant Archaea that live in boiling hot springs come the tongue size of a nectar-feeding moth that matches the dimension of the flower native which it feeds. Every adaptations enhance the reproductive potential the the individual exhibiting them, including their ability to endure to reproduce. Adaptations room not constant. As an atmosphere changes, natural choice causes the qualities of the people in a populace to track those changes.

Growth and Development

Organisms grow and develop follow to specific instructions coded for by their genes. This genes administer instructions that will direct cellular growth and development, ensuring that a species’ young will thrive up come exhibit plenty of of the same qualities as its parents.

Figure 1.4 although no 2 look alike, these kittens have inherited gene from both parents and share countless of the same characteristics.


Even the the smallest organisms are facility and need multiple regulation mechanisms come coordinate inner functions, such together the carry of nutrients, response to stimuli, and also coping with environmental stresses. Because that example, organ systems such as the digestive or circulatory systems perform details functions like carrying oxygen throughout the body, removing wastes, delivering nutrients to every cell, and cooling the body.


To duty properly, cell require suitable conditions together as proper temperature, pH, and also concentrations of varied chemicals. These conditions may, however, adjust from one minute to the next. Organisms space able to preserve internal problems within a narrow range almost constantly, in spite of environmental changes, v a process called homeostasis or “steady state”—the ability of an organism to maintain consistent internal conditions. Because that example, many organisms manage their body temperature in a process known as thermoregulation. Organisms the live in cold climates, such together the polar bear, have actually body structures that assist them stand up to low temperatures and also conserve human body heat. In hot climates, organisms have methods (such as perspiration in humans or panting in dogs) that assist them to shed excess body heat.

Figure 1.5 Polar bears and also other mammals living in ice-covered regions maintain their human body temperature by generating heat and also reducing heat loss through thick fur and a dense layer that fat under their skin.

Energy Processing

All biology (such together the California condor displayed in figure 1.6) usage a source of energy for your metabolic activities. Part organisms capture energy indigenous the sun and also convert it right into chemical power in food; others usage chemical power from molecules they take it in.

Figure 1.6 A lot of power is compelled for a California condor to fly. Chemical energy derived from food is used to strength flight. California condors room an intimidated species; scientists have actually strived to location a soup tag on each bird to aid them identify and also locate each individual bird.Levels of organization of living Things

Living points are highly organized and structured, adhering to a pecking order on a scale from little to large. The atom is the smallest and most an essential unit of matter. It is composed of a nucleus surrounded by electrons. Atoms kind molecules. A molecule is a chemical structure consisting the at the very least two atoms held together by a chemistry bond. Countless molecules that are biologically crucial are macromolecules, big molecules the are typically formed through combining smaller sized units called monomers. An example of a macromolecule is deoxyribonucleic acid (DNA), which contains the instructions for the to work of the biology that consists of it.

Figure 1.7 A molecule, prefer this big DNA molecule, is composed of atoms.

Concept in Action


To see an animation of this DNA molecule, click here.

Some cells contain aggregates the macromolecules surrounding by membranes; this are called organelles. Organelles are tiny structures the exist in ~ cells and perform committed functions. Every living things room made that cells; the cell itself is the smallest basic unit of framework and role in life organisms. (This need is why viruses are not thought about living: they space not do of cells. Come make brand-new viruses, they need to invade and also hijack a life cell; only then can they acquire the materials they have to reproduce.) some organisms consist of a solitary cell and others space multicellular. Cells room classified as prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that absence organelles surrounded by a membrane and do not have nuclei surrounding by atom membranes; in contrast, the cell of eukaryotes do have membrane-bound organelles and also nuclei.

In most multicellular organisms, cells combine to do tissues, which are teams of similar cells delivering out the same function. Organs space collections of organization grouped together based on a typical function. Guts are current not just in animals but likewise in plants. An organ device is a greater level of organization that is composed of functionally connected organs. For example vertebrate pets have numerous organ systems, such as the circulatory mechanism that transports blood transparent the body and also to and also from the lungs; it contains organs such as the heart and also blood vessels. Organisms are individual life entities. Because that example, each tree in a forest is an organism. Single-celled prokaryotes and single-celled standard scale are also considered organisms and also are generally referred to together microorganisms.

Figure 1.8 indigenous an atom come the entire Earth, biologic examines all aspects of life.

Which of the following statements is false?

Tissues exist within organs i m sorry exist within organ systems.Communities exist within populaces which exist in ~ ecosystems.Organelles exist within cell which exist in ~ tissues.Communities exist within ecosystems i m sorry exist in the biosphere.

All the individuals of a species living within a particular area are collectively called a population. Because that example, a woodland may include numerous white pine tree trees. Every one of these pine trees stand for the population of white pine tree in this forest. Various populations might live in the same particular area. Because that example, the forest with the pine trees has populations of flowering tree and likewise insects and also microbial populations. A ar is the collection of populations inhabiting a particular area. For instance, all of the trees, flowers, insects, and also other populaces in a forest form the forest’s community. The woodland itself is one ecosystem. An ecosystem consists of every the living points in a particular area in addition to the abiotic, or non-living, parts of that setting such together nitrogen in the soil or rainwater. At the greatest level of organization, the biosphere is the repertoire of all ecosystems, and it to represent the area of life top top Earth. It consists of land, water, and portions of the atmosphere.

The Diversity that Life

The scientific research of biologic is an extremely broad in scope since there is a tremendous diversity the life on Earth. The resource of this diversity is evolution, the process of gradual adjust during which new species arise indigenous older species. Evolutionary biologists research the development of living things in whatever from the microscopic civilization to ecosystems.

In the 18th century, a scientist called Carl Linnaeus an initial proposed organizing the known types of organisms into a ordered taxonomy. In this system, varieties that are most similar to each various other are placed together within a grouping well-known as a genus. Furthermore, comparable genera (the many of genus) are placed together in ~ a family. This grouping continues until every organisms are built up together into groups at the greatest level. The existing taxonomic system now has eight level in that is hierarchy, from lowest to highest, they are: species, genus, family, order, class, phylum, kingdom, and domain. Thus species are grouped within genera, genera are grouped in ~ families, family members are grouped in ~ orders, and so on.

Figure 1.9 This diagram shows the levels of taxonomic pecking order for a dog, native the broadest category—domain—to the most specific—species.

The greatest level, domain, is a relatively new addition to the system since the 1990s. Scientists now recognize three domains of life, the Eukarya, the Archaea, and the Bacteria. The domain Eukarya has organisms that have cells with nuclei. It consists of the kingdoms the fungi, plants, animals, and several kingdoms of protists. The Archaea, are single-celled organisms there is no nuclei and also include numerous extremophiles the live in harsh atmospheres like warm springs. The Bacteria are one more quite various group that single-celled organisms there is no nuclei. Both the Archaea and the Bacteria room prokaryotes, an informal name for cells there is no nuclei. The acknowledgment in the 1990s that details “bacteria,” now recognized as the Archaea, to be as different genetically and biochemically from various other bacterial cells as they to be from eukaryotes, urged the recommendation to division life right into three domains. This dramatic adjust in our knowledge of the tree that life demonstrates the classifications are not permanent and also will change when new information i do not care available.

In enhancement to the ordered taxonomic system, Linnaeus to be the very first to name organisms using two unique names, now dubbed the binomial naming system. Before Linnaeus, the use of usual names to refer to organisms caused confusion since there were regional differences in these usual names. Binomial surname consist that the genus name (which is capitalized) and the species name (all lower-case). Both name are collection in italics when they space printed. Every varieties is given a distinctive binomial i m sorry is recognized the world over, so the a scientist in any type of location can know which organism is being referred to. Because that example, the north American blue jay is recognized uniquely together Cyanocitta cristata. Ours own varieties is Homo sapiens.

Figure 1.10 These pictures represent different domains. The scanning electron micrograph mirrors (a) bacterial cells belong to the domain Bacteria, if the (b) extremophiles, seen all with each other as colored mats in this hot spring, belong come domain Archaea. Both the (c) sunflower and (d) lion are part of domain Eukarya.

Evolution in Action

Carl Woese and the Phylogenetic Tree

The evolutionary relationships of assorted life forms on planet can be summarized in a phylogenetic tree. A phylogenetic tree is a diagram reflecting the evolutionary relationships among biological varieties based top top similarities and differences in hereditary or physical traits or both. A phylogenetic tree is composed of branch points, or nodes, and branches. The internal nodes stand for ancestors and are points in evolution when, based upon scientific evidence, an ancestor is assumed to have actually diverged to type two brand-new species. The length of every branch have the right to be taken into consideration as estimates of family member time.

In the past, biologists grouped life organisms into 5 kingdoms: animals, plants, fungi, protists, and bacteria. The pioneering job-related of American microbiologist Carl Woese in the at an early stage 1970s has actually shown, however, that life on earth has progressed along three lineages, now dubbed domains—Bacteria, Archaea, and also Eukarya. Woese proposed the domain together a brand-new taxonomic level and also Archaea as a brand-new domain, to reflect the new phylogenetic tree. Many organisms belonging to the Archaea domain live under excessive conditions and also are called extremophiles. To construct his tree, Woese used hereditary relationships quite than similarities based on morphology (shape). Miscellaneous genes were provided in phylogenetic studies. Woese’s tree was created from to compare sequencing that the gene that room universally distributed, uncovered in part slightly altered kind in every organism, conserved (meaning the these genes have remained only slightly adjusted throughout evolution), and of an suitable length.

Figure 1.11 This phylogenetic tree was created by microbiologist Carl Woese using genetic relationships. The tree shows the separation of life organisms right into three domains: Bacteria, Archaea, and Eukarya. Bacteria and Archaea are organisms without a cell core or various other organelles surrounded by a membrane and, therefore, space prokaryotes.

The scope of biologic is broad and thus contains numerous branches and also sub disciplines. Biologists might pursue among those sub disciplines and work in a an ext focused field. Because that instance, molecular biology studies biological processes in ~ the molecule level, consisting of interactions among molecules such as DNA, RNA, and also proteins, and the way they are regulated. Microbiology is the research of the framework and duty of microorganisms. The is rather a broad branch itself, and also depending on the topic of study, over there are additionally microbial physiologists, ecologists, and geneticists, amongst others.

Another ar of organic study, neurobiology, researches the biologic of the nervous system, and although it is taken into consideration a branch that biology, it is also recognized as an interdisciplinary ar of study known as neuroscience. Since of that interdisciplinary nature, this sub technique studies different functions the the nervous system using molecular, cellular, developmental, medical, and computational approaches.

Figure 1.12 Researchers work on excavating dinosaur fossils at a website in Castellón, Spain.

Paleontology, one more branch of biology, uses fossils to study life’s history. Zoology and botany space the study of animals and also plants, respectively. Biologist can additionally specialize as biotechnologists, ecologists, or physiologists, come name just a few areas. Biotechnologists apply the understanding of biology come create helpful products. Ecologists examine the interactions of organisms in your environments. Physiologists study the operations of cells, tissues and also organs. This is simply a tiny sample the the many fields the biologists deserve to pursue. From our very own bodies to the human being we live in, discoveries in biological can influence us in very direct and also important ways. We count on these explorations for ours health, our food sources, and also the benefits listed by our ecosystem. Due to the fact that of this, knowledge of biological can advantage us in making decision in our day-to-day lives.

The development of modern technology in the twenty century that proceeds today, specifically the technology to describe and also manipulate the hereditary material, DNA, has actually transformed biology. This transformation will permit biologists to continue to understand the background of life in better detail, how the human body works, our human origins, and also how humans can survive as a types on this planet regardless of the stresses brought about by our raising numbers. Biologists continue to decipher large mysteries around life suggesting that we have only begun to know life top top the planet, its history, and our partnership to it. Because that this and also other reasons, the knowledge of biology obtained through this textbook and other printed and also electronic media have to be a advantage in whichever ar you enter.

Forensic Scientist

Forensic science is the application of science to answer inquiries related come the law. Biologists and also chemists and also biochemists deserve to be forensic scientists. Forensic scientists provide scientific proof for usage in courts, and also their job involves evaluating trace material associated with crimes. Interest in forensic science has increased in the last few years, possibly because of famous television reflects that feature forensic scientists on the job. Also, the advance of molecular techniques and also the establishment of DNA databases have updated the types of occupational that forensic scientists have the right to do. Your job activities are mainly related come crimes versus people such as murder, rape, and assault. Their work-related involves evaluating samples such as hair, blood, and also other human body fluids and likewise processing DNA discovered in countless different environments and also materials. Forensic scientists also analyze other organic evidence left in ~ crime scenes, such as insect parts or pollen grains. Students who desire to seek careers in forensic scientific research will most most likely be compelled to take chemistry and also biology courses as well as some extensive math courses.

Figure 1.13 This forensic scientist functions in a DNA exploit room at the U.S. Military Criminal investigation Laboratory.

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Section Summary

Biology is the scientific research of life. All living organisms share several crucial properties such together order, sensitivity or response to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. Living things are highly organized following a power structure that includes atoms, molecules, organelles, cells, tissues, organs, and organ systems. Organisms, in turn, are grouped together populations, communities, ecosystems, and the biosphere. Development is the resource of the tremendous organic diversity on earth today. A diagram referred to as a phylogenetic tree have the right to be used to show evolutionary relationships among organisms. Biology is very broad and includes plenty of branches and also sub disciplines. Examples encompass molecular biology, microbiology, neurobiology, zoology, and also botany, among others.