Identify and also describe the nature of lifeDescribe the level of organization amongst living thingsList examples of different sub techniques in biology

Biology is the science that researches life. What exactly is life? This might sound prefer a silly concern with an evident answer, but it is not basic to define life. For example, a branch the biology called virology studies viruses, which exhibit several of the characteristics of living entities but lack others. It transforms out that although viruses can attack living organisms, reason diseases, and also even reproduce, they perform not accomplish the criteria the biologists usage to define life.

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

Properties the Life

All groups of life organisms share multiple key characteristics or functions: order, sensitivity or solution to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. When viewed together, this eight qualities serve to define life.


Organisms are extremely organized structures that consists one or an ext cells. Even very simple, single-celled organisms room remarkably complex. Within each cell, atoms consist of molecules. This in turn make up cell contents or organelles. Multicellular organisms, which might consist of numerous individual cells, have an advantage over single-celled organisms in that their cells can be dedicated to perform particular functions, and even sacrificed in details situations because that the great of the organism as a whole. Just how these specialized cells come with each other to type organs such as the heart, lung, or skin in organisms favor the toad presented in number 1. 2 will be discussed later.

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

Sensitivity or an answer to Stimuli

Organisms answer to varied stimuli. For example, plants have the right to bend toward a source of light or respond come touch. Even tiny bacteria have the right to move toward or far from chemistry (a process called chemotaxis) or irradiate (phototaxis). Movement toward a stimulus is considered a positive response, while movement away from a stimulus is considered a an adverse response.

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

Concept in Action


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


Single-celled biology reproduce by an initial duplicating their DNA, i beg your pardon is the genetic material, and also then dividing it equally together the cell prepares to divide to kind two brand-new cells. Numerous multicellular organisms (those made up of an ext than one cell) produce specialized reproductive cells the will type new individuals. When reproduction occurs, DNA containing genes is passed follow me to an organism’s offspring. This genes space the reason that the offspring will belong come the same varieties and will have characteristics similar to the parent, together as fur color and also blood type.


All life organisms exhibit a “fit” to their environment. Biologists describe this fit as adaptation and also it is a consequence of advancement by organic selection, i m sorry operates in every family tree of reproducing organisms. Examples of adaptations are diverse and unique, native heat-resistant Archaea the live in boiling hot springs to the tongue size of a nectar-feeding moth the matches the dimension of the flower indigenous which the feeds. All adaptations enhance the reproductive potential the the separation, personal, instance exhibiting them, consisting of their ability to endure to reproduce. Adaptations are not constant. Together an environment changes, natural selection causes the attributes of the people in a populace to monitor those changes.

Growth and Development

Organisms grow and develop according to particular instructions coded for by their genes. These genes administer instructions the will direct cellular growth and also development, ensuring the a species’ young will prosper up come exhibit numerous of the same characteristics as that parents.

Figure 1.4 although no 2 look alike, these kittens have inherited genes from both parents and also share numerous of the exact same characteristics.


Even the the smallest organisms are complicated and call for multiple regulatory mechanisms come coordinate interior functions, such as the transport of nutrients, an answer to stimuli, and coping with environmental stresses. Because that example, body organ systems such as the cradle or circulatory systems perform specific functions choose carrying oxygen throughout the body, removed wastes, transferring nutrients come every cell, and also cooling the body.


To role properly, cells require suitable conditions together as ideal temperature, pH, and concentrations of varied chemicals. These problems may, however, adjust from one minute to the next. Organisms are able to keep internal problems within a narrow selection almost constantly, regardless of environmental changes, through a process called homeostasis or “steady state”—the capacity of an biology to maintain consistent internal conditions. For example, many organisms regulate their human body temperature in a process known together thermoregulation. Organisms the live in cold climates, such together the polar bear, have actually body frameworks that aid them withstand low temperatures and conserve human body heat. In hot climates, organisms have actually methods (such together perspiration in people or panting in dogs) that assist them to shed excess human body heat.

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

Energy Processing

All biology (such together the California condor shown in figure 1.6) usage a source of power for your metabolic activities. Some organisms catch energy native the sun and also convert it right into chemical power in food; others use chemical power from molecule they take it in.

Figure 1.6 A many of power is forced for a California condor come fly. Chemical energy derived from food is supplied to power flight. California condors room an threatened species; scientists have strived to ar a soup tag on each bird to help them identify and also locate each individual bird.Levels of company of life Things

Living things are highly organized and also structured, complying with a pecking order on a range from tiny to large. The atom is the smallest and also most fundamental unit of matter. It consists of a nucleus surrounding by electrons. Atoms kind molecules. A molecule is a chemical framework consisting the at the very least two atoms held together through a chemistry bond. Plenty of molecules that are biologically necessary are macromolecules, big molecules that are frequently formed by combining smaller units dubbed monomers. An example of a macromolecule is deoxyribonucleic acid (DNA), which consists of the instructions because that the work of the biology that contains it.

Figure 1.7 A molecule, favor this large DNA molecule, is created of atoms.

Concept in Action


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

Some cell contain aggregates of macromolecules surrounding by membranes; these are referred to as organelles. Organelles are little structures the exist in ~ cells and also perform specialized functions. All living things room made that cells; the cell itself is the smallest an essential unit of framework and role in living organisms. (This requirement is why viruses space not considered living: they space not do of cells. Come make new viruses, they need to invade and hijack a life cell; only then have the right to they attain the materials they must reproduce.) part organisms consist of a single cell and also others are multicellular. Cells room classified as prokaryotes or eukaryotic. Prokaryotes room single-celled biology that lack organelles surrounded by a membrane and also do not have nuclei surrounded by nuclear membranes; in contrast, the cell of standard scale do have actually membrane-bound organelles and nuclei.

In most multicellular organisms, cells incorporate to make tissues, which are groups of similar cells moving out the exact same function. Organs room collections of tissues grouped together based upon a typical function. Guts are present not just in animals but additionally in plants. An organ mechanism is a greater level of organization that consists of functionally connected organs. For example vertebrate pets have countless organ systems, such together the circulatory system that transports blood transparent the body and also to and from the lungs; it consists of organs such as the heart and also blood vessels. Organisms room individual life entities. Because that example, every tree in a woodland is an organism. Single-celled prokaryotes and single-celled eukaryotes are likewise considered organisms and also are frequently referred to as microorganisms.

Figure 1.8 native an atom to the entire Earth, biologic examines all facets of life.

Which of the following statements is false?

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

All the individuals of a types living within a particular area are jointly called a population. For example, a woodland may include plenty of white pine tree trees. Every one of these pine tree trees represent the populace of white pine trees in this forest. Various populations might live in the same certain area. Because that example, the woodland with the pine trees contains populations that flowering plants and also insects and also microbial populations. A ar is the collection of populaces inhabiting a particular area. Because that instance, all of the trees, flowers, insects, and also other populations in a forest kind the forest’s community. The woodland itself is one ecosystem. An ecosystem is composed of all the living things in a details area in addition to the abiotic, or non-living, parts of that setting such as nitrogen in the soil or rainwater. In ~ the greatest level the organization, the biosphere is the repertoire of all ecosystems, and also it to represent the zones of life top top Earth. It includes land, water, and portions that the atmosphere.

The Diversity of Life

The science of biology is really broad in scope because there is a incredible diversity of life on Earth. The resource of this diversity is evolution, the procedure of gradual change during which new species arise indigenous older species. Evolution biologists study the development of living points in every little thing from the microscopic world to ecosystems.

In the 18th century, a scientist named Carl Linnaeus very first proposed organizing the known varieties of organisms into a hierarchical taxonomy. In this system, varieties that space most comparable to each other are placed together in ~ a grouping known as a genus. Furthermore, similar genera (the many of genus) are put together in ~ a family. This grouping continues until all organisms are accumulated together into teams at the greatest level. The present taxonomic system now has actually eight level in the hierarchy, from shortest to highest, they are: species, genus, family, order, class, phylum, kingdom, and domain. Thus species are grouped within genera, genera room grouped in ~ families, families are grouped in ~ orders, and so on.

Figure 1.9 This diagram mirrors the level of taxonomic pecking order for a dog, from the broadest category—domain—to the many specific—species.

The greatest level, domain, is a relatively brand-new addition to the system because the 1990s. Scientists now recognize three domains of life, the Eukarya, the Archaea, and also the Bacteria. The domain Eukarya contains organisms that have cells through nuclei. It includes the kingdoms that fungi, plants, animals, and also several kingdoms the protists. The Archaea, are single-celled organisms without nuclei and include countless extremophiles the live in harsh atmospheres like hot springs. The Bacteria are one more quite different group that single-celled organisms there is no nuclei. Both the Archaea and the Bacteria space prokaryotes, an informal name because that cells without nuclei. The acknowledgment in the 1990s that particular “bacteria,” now well-known as the Archaea, were 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 expertise of the tree the life demonstrates that classifications space not permanent and also will readjust when brand-new information i do not care available.

In enhancement to the hierarchical taxonomic system, Linnaeus to be the first to surname organisms using two distinct names, now called the binomial naming system. Prior to Linnaeus, the usage of usual names to describe organisms brought about confusion due to the fact that there were local differences in these usual names. Binomial names consist that the genus surname (which is capitalized) and the varieties name (all lower-case). Both name are collection in italics as soon as they room printed. Every species is offered a distinctive binomial which is known the people over, so the a scientist in any location deserve to know which organism is being referred to. For example, the north American blue jay is well-known uniquely together Cyanocitta cristata. Our own varieties is Homo sapiens.

Figure 1.10 These photos represent various domains. The scanning electron micrograph reflects (a) bacterial cells belong come the domain Bacteria, when the (b) extremophiles, watched all with each other as colored carpet in this hot spring, belong come domain Archaea. Both the (c) sunflower and (d) lion are component of domain Eukarya.

Evolution in Action

Carl Woese and also the Phylogenetic Tree

The evolutionary relationships of assorted life creates on planet can be summary in a phylogenetic tree. A phylogenetic tree is a diagram reflecting the evolution relationships amongst biological types based top top similarities and differences in hereditary or physical traits or both. A phylogenetic tree is created of branch points, or nodes, and branches. The inner nodes represent ancestors and also are point out in advancement when, based on scientific evidence, one ancestor is thought to have actually diverged to type two new species. The length of each branch have the right to be considered as estimates of relative time.

In the past, biologist grouped living organisms into five kingdoms: animals, plants, fungi, protists, and also bacteria. The pioneering job-related of American microbiologist Carl Woese in the early 1970s has shown, however, the life on earth has advanced along 3 lineages, now called domains—Bacteria, Archaea, and Eukarya. Woese propose the domain together a new taxonomic level and also Archaea as a new domain, come reflect the brand-new phylogenetic tree. Plenty of organisms belonging come the Archaea domain live under extreme conditions and are called extremophiles. To build his tree, Woese used genetic relationships quite than similarities based on morphology (shape). Various genes were supplied in phylogenetic studies. Woese’s tree was created from compare sequencing the the gene that are universally distributed, uncovered in part slightly altered type in every organism, conserved (meaning that these genes have actually remained just slightly readjusted throughout evolution), and of an appropriate length.

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

The border of biological is wide and therefore contains plenty of branches and sub disciplines. Biologists might pursue one of those sub disciplines and also work in a an ext focused field. For instance, molecule biology studies organic processes in ~ the molecular level, including interactions among molecules such together DNA, RNA, and also proteins, and the way they room regulated. Microbiology is the study of the framework and function of microorganisms. The is quite a large branch itself, and depending top top the subject of study, there are additionally microbial physiologists, ecologists, and geneticists, among others.

Another field of biological study, neurobiology, studies the biological of the concerned system, and although that is thought about a branch of biology, the is likewise recognized as an interdisciplinary ar of study known as neuroscience. Due to the fact that of that interdisciplinary nature, this sub technique studies different functions of the nervous system using molecular, cellular, developmental, medical, and computational approaches.

Figure 1.12 Researchers occupational on excavating dinosaur fossils in ~ a website in Castellón, Spain.

Paleontology, an additional branch the biology, provides fossils to study life’s history. Zoology and also botany space the research of animals and plants, respectively. Biologist can also specialize as biotechnologists, ecologists, or physiologists, to name simply a couple of areas. Biotechnologists apply the knowledge of biology to create useful products. Ecologists research the interactions of biology in your environments. Physiologists research the operations of cells, tissues and organs. This is simply a tiny sample that the many fields that biologists can pursue. Indigenous our own bodies come the world we live in, explorations in biology can impact us in an extremely direct and also important ways. We depend on these explorations for ours health, our food sources, and also the benefits listed by our ecosystem. Since of this, knowledge of biologic can benefit us in making decision in our day-to-day lives.

The advance of an innovation in the twentieth century that continues today, an especially the an innovation to describe and manipulate the genetic material, DNA, has transformed biology. This revolution will enable biologists to proceed to know the background of life in better detail, just how the person body works, our human origins, and also how humans can survive as a types on this planet in spite of the stresses resulted in by our boosting numbers. Biologists continue to decipher huge mysteries about life saying that we have actually only begun to understand life on the planet, that history, and our relationship to it. For this and other reasons, the expertise of biology obtained through this textbook and other printed and also electronic media need to be a advantage in whichever field you enter.

Forensic Scientist

Forensic scientific research is the applications of scientific research to answer questions related to the law. Biologists as well as chemists and biochemists deserve to be forensic scientists. Forensic scientists administer scientific proof for usage in courts, and their job involves analyzing trace material associated with crimes. Attention in forensic science has increased in the last couple of years, possibly due to the fact that of famous television shows that function forensic scientists on the job. Also, the advance of molecule techniques and also the establishment of DNA databases have updated the types of occupational that forensic scientists deserve to do. Your job activities are generally related come crimes versus people such as murder, rape, and assault. Their work-related involves analyzing samples such as hair, blood, and other human body fluids and additionally processing DNA uncovered in countless different environments and also materials. Forensic scientists likewise analyze other organic evidence left in ~ crime scenes, such together insect parts or pollen grains. Students who want to go after careers in forensic science will most likely be compelled to take chemistry and biology courses and also some intensive math courses.

Figure 1.13 This forensic scientist functions in a DNA extraction room at the U.S. Army Criminal examination Laboratory.

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Section Summary

Biology is the science of life. Every living biology share several crucial properties such together order, sensitivity or solution to stimuli, reproduction, adaptation, growth and also development, regulation, homeostasis, and also energy processing. Living points are extremely organized following a hierarchy that has atoms, molecules, organelles, cells, tissues, organs, and also organ systems. Organisms, in turn, space grouped together populations, communities, ecosystems, and also the biosphere. Advancement is the resource of the tremendous biological diversity on planet today. A diagram referred to as a phylogenetic tree deserve to be used to display evolutionary relationships among organisms. Biological is an extremely broad and includes countless branches and sub disciplines. Examples encompass molecular biology, microbiology, neurobiology, zoology, and botany, among others.