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

Biology is the scientific research that studies life. What exactly is life? This may sound favor a silly inquiry with an obvious answer, but it is not easy to define life. For example, a branch that biology called virology researches viruses, which exhibit few of the qualities of life entities but lack others. It transforms out that although viruses can strike living organisms, reason diseases, and even reproduce, they perform not accomplish the criteria the biologists usage to define life.

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From its earliest beginnings, biology has actually wrestled with four questions: What space the shared properties that make miscellaneous “alive”? how do those miscellaneous living points function? When faced with the exceptional diversity the life, exactly how do us organize the various kinds of organisms so that we can far better understand them? And, finally—what biologists at some point seek to understand—how go this diversity arise and also how is that continuing? As new organisms are discovered every day, biologists continue to look for answers to these and other questions.

Properties that Life

All teams of life organisms re-superstructure multiple an essential characteristics or functions: order, sensitivity or an answer to stimuli, reproduction, adaptation, growth and also development, regulation, homeostasis, and energy processing. As soon as viewed together, this eight attributes serve to define life.


Organisms are extremely organized structures that covers one or much more cells. Even very simple, single-celled organisms room remarkably complex. Inside each cell, atoms comprise molecules. These in turn comprise cell materials or organelles. Multicell organisms, which may consist of countless individual cells, have an benefit over single-celled biology in that their cells can be committed to perform particular functions, and even sacrificed in certain situations because that the good of the organism as a whole. How these dedicated cells come together to kind organs such as the heart, lung, or skin in organisms like the toad displayed in figure 1. 2 will be debated later.

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

Sensitivity or response to Stimuli

Organisms respond to diverse stimuli. Because that example, plants have the right to bend toward a resource of light or respond come touch. Even tiny bacteria deserve to move towards or away from chemistry (a process called chemotaxis) or light (phototaxis). Movement toward a stimulus is considered a positive response, while movement away indigenous a stimulus is thought about a an adverse response.

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

Concept in Action


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


Single-celled organisms reproduce by an initial duplicating their DNA, i beg your pardon is the genetic material, and also then dividing it equally together the cabinet prepares to division to form two brand-new cells. Numerous multicellular biology (those consisted of of an ext than one cell) produce committed reproductive cells that will type new individuals. Once reproduction occurs, DNA containing genes is passed follow me to one organism’s offspring. This genes are the reason that the offspring will belong come the same species and will have characteristics similar to the parent, such as hair color and also blood type.


All life organisms exhibit a “fit” to their environment. Biologists refer to this fit together adaptation and it is a consequence of development by organic selection, i m sorry operates in every family tree of reproducing organisms. Examples of adaptations room diverse and unique, indigenous heat-resistant Archaea that live in boiling warm springs come the tongue length of a nectar-feeding moth the matches the dimension of the flower from which it feeds. Every adaptations improve the reproductive potential that the individual exhibiting them, consisting of their ability to survive to reproduce. Adaptations space not constant. As an setting changes, natural selection causes the features of the individuals in a population to monitor those changes.

Growth and Development

Organisms grow and develop according to specific instructions coded for by your genes. This genes administer instructions that will straight cellular growth and also development, ensuring that a species’ young will flourish up come exhibit countless of the same characteristics as that is parents.

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


Even the smallest organisms are complicated and require multiple regulation mechanisms come coordinate internal functions, such as the deliver of nutrients, response to stimuli, and also coping with ecological stresses. For example, organ systems such together the cradle or circulatory systems perform particular functions favor carrying oxygen throughout the body, removing wastes, transporting nutrients come every cell, and also cooling the body.


To function properly, cells require ideal conditions such as appropriate temperature, pH, and also concentrations of varied chemicals. These conditions may, however, readjust from one minute to the next. Organisms room able to preserve internal conditions within a narrow range almost constantly, regardless of environmental changes, with a procedure called homeostasis or “steady state”—the capability of an biology to maintain constant internal conditions. For example, numerous organisms control their human body temperature in a procedure known together thermoregulation. Organisms the live in cold climates, such together the polar bear, have actually body structures that aid them stand up to low temperatures and conserve body heat. In hot climates, organisms have actually methods (such as perspiration in people or panting in dogs) that help them to shed excess body heat.

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

Energy Processing

All organisms (such together the California condor presented in number 1.6) usage a resource of energy for their metabolic activities. Part organisms record energy from the sun and also convert it into chemical power in food; others usage chemical power from molecules they take it in.

Figure 1.6 A lot of of energy is compelled for a California condor come fly. Chemistry energy acquired from food is used to strength flight. California condors room an endangered species; scientists have actually strived to place a soup tag on every bird to help them identify and also locate each individual bird.Levels of company of life Things

Living points are very organized and also structured, following a pecking order on a range from small to large. The atom is the smallest and most an essential unit of matter. It consists of a nucleus surrounded by electrons. Atoms type molecules. A molecule is a chemical framework consisting that at the very least two atoms organized together by a chemical bond. Plenty of molecules that are biologically crucial are macromolecules, big molecules that are commonly formed by combining smaller sized units dubbed monomers. An example of a macromolecule is deoxyribonucleic mountain (DNA), which includes the instructions because that the functioning of the biology that consists of it.

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

Concept in Action


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

Some cell contain aggregates that macromolecules surrounded by membranes; this are called organelles. Oribel are small structures that exist in ~ cells and perform devoted functions. All living things room made of cells; the cell itself is the smallest an essential unit of framework and duty in life organisms. (This need is why viruses are not thought about living: they space not made of cells. Come make new viruses, they need to invade and also hijack a life cell; just then can they obtain the products they have to reproduce.) part organisms consist of a single cell and others room multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes space single-celled biology that lack organelles surrounding by a membrane and do not have nuclei surrounding by atom membranes; in contrast, the cells of standard scale do have actually membrane-bound organelles and also nuclei.

In most multicellular organisms, cells integrate to do tissues, i m sorry are teams of similar cells delivering out the same function. Organs are collections of organization grouped together based upon a usual function. Guts are present not only in pets but additionally in plants. One organ system is a greater level of organization that consists of functionally related organs. For instance vertebrate animals have countless organ systems, such as the circulatory device that transports blood throughout the body and to and also from the lungs; it has organs such as the heart and blood vessels. Organisms space individual living entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and also single-celled standard scale are also considered organisms and also are typically referred to as microorganisms.

Figure 1.8 from an atom come the whole Earth, biological examines all facets of life.

Which the the complying with statements is false?

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

All the people of a varieties living within a particular area are collectively called a population. Because that example, a woodland may include many white jaw trees. Every one of these pine tree trees represent the population of white pine tree in this forest. Various populations might live in the same particular area. For example, the woodland with the jaw trees has populations the flowering plants and additionally insects and microbial populations. A neighborhood is the collection of populaces inhabiting a certain area. Because that instance, every one of the trees, flowers, insects, and also other populations in a forest form the forest’s community. The woodland itself is one ecosystem. One ecosystem consists of all the living things in a certain area along with the abiotic, or non-living, components of that environment such as nitrogen in the floor or rainwater. In ~ the highest level that organization, the biosphere is the arsenal of all ecosystems, and it to represent the zones of life on Earth. It has land, water, and portions the the atmosphere.

The Diversity the Life

The science of biologic is very broad in scope due to the fact that there is a incredible diversity the life top top Earth. The source of this diversity is evolution, the process of gradual readjust during which new species arise indigenous older species. Evolutionary biologists examine the development of living points in every little thing from the microscopic people to ecosystems.

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

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

The greatest level, domain, is a relatively brand-new addition come the system since the 1990s. Scientists now recognize three domain names of life, the Eukarya, the Archaea, and the Bacteria. The domain Eukarya includes organisms that have cells with nuclei. It includes the kingdoms of fungi, plants, animals, and several kingdoms of protists. The Archaea, are single-celled organisms without nuclei and also include countless extremophiles the live in harsh environments like hot springs. The Bacteria are one more quite various group the single-celled organisms there is no nuclei. Both the Archaea and the Bacteria are prokaryotes, an informal name for cells without nuclei. The recognition in the 1990s that specific “bacteria,” now known as the Archaea, to be as various genetically and also biochemically from other bacterial cells together they to be from eukaryotes, motivated the referral to division life right into three domains. This dramatic readjust in our understanding of the tree of life demonstrates that classifications room not permanent and will adjust when new information i do not care available.

In addition to the hierarchical taxonomic system, Linnaeus to be the an initial to name organisms making use of two distinct names, now called the binomial naming system. Prior to Linnaeus, the usage of common names to refer to organisms led to confusion because there were regional differences in these typical names. Binomial surname consist of the genus surname (which is capitalized) and also the types name (all lower-case). Both name are set in italics when they space printed. Every types is provided a distinct binomial i beg your pardon is well-known the civilization over, so the a scientist in any location have the right to know which biology is gift referred to. Because that example, the phibìc American blue jay is well-known uniquely together Cyanocitta cristata. Ours own types is Homo sapiens.

Figure 1.10 These pictures represent different domains. The scanning electron micrograph shows (a) bacterial cells belong come the domain Bacteria, while the (b) extremophiles, seen all together as colored carpet in this warm 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 various life develops on earth can be summarized in a phylogenetic tree. A phylogenetic tree is a diagram reflecting the evolutionary relationships among biological species based top top similarities and differences in hereditary or physics traits or both. A phylogenetic tree is created of branch points, or nodes, and branches. The inner nodes represent ancestors and are clues in advancement when, based on scientific evidence, one ancestor is believed to have diverged to kind two brand-new species. The length of every branch have the right to be considered as approximates of relative time.

In the past, biologists grouped life organisms into 5 kingdoms: animals, plants, fungi, protists, and also bacteria. The pioneering work-related of American microbiologist Carl Woese in the early 1970s has shown, however, the life on planet has advanced along three lineages, now called domains—Bacteria, Archaea, and also Eukarya. Woese proposed the domain as a new taxonomic level and also Archaea together a brand-new domain, come reflect the new phylogenetic tree. Countless organisms belonging to the Archaea domain live under extreme conditions and are referred to as extremophiles. To construct his tree, Woese used genetic relationships rather than similarities based upon morphology (shape). Assorted genes were supplied in phylogenetic studies. Woese’s tree was built from to compare sequencing that the gene that room universally distributed, uncovered in some slightly altered form in every organism, conserved (meaning the these genes have remained just slightly adjusted throughout evolution), and also of an suitable length.

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

The scope of biology is broad and as such contains countless branches and also sub disciplines. Biologists might pursue among those sub disciplines and also work in a much more focused field. Because that instance, molecule biology studies organic processes at the molecule level, including interactions among molecules such together DNA, RNA, and also proteins, as well as the method they room regulated. Microbiology is the examine of the structure and role of microorganisms. The is fairly a large branch itself, and depending ~ above the topic of study, over there are likewise microbial physiologists, ecologists, and also geneticists, among others.

Another field of biological study, neurobiology, research studies the biology of the concerned system, and also although that is thought about a branch of biology, that is likewise recognized together an interdisciplinary field of study well-known as neuroscience. Since of that is interdisciplinary nature, this sub technique studies various functions the the nervous system using molecular, cellular, developmental, medical, and also computational approaches.

Figure 1.12 Researchers work-related on excavating dinosaur fossils at a site in Castellón, Spain.

Paleontology, another branch that biology, offers fossils to examine life’s history. Zoology and botany are the examine of animals and also plants, respectively. Biologists can also specialize as biotechnologists, ecologists, or physiologists, come name just a couple of areas. Biotechnologists use the understanding of biology to create valuable products. Ecologists study the interactions of biology in their environments. Physiologists research the workings of cells, tissues and also organs. This is simply a tiny sample that the many fields the biologists have the right to pursue. Indigenous our very own bodies come the human being we live in, explorations in biological can impact us in an extremely direct and also important ways. We count on these explorations for our health, our food sources, and the benefits provided by ours ecosystem. Because of this, expertise of biological can advantage us in making decisions in our day-to-day lives.

The breakthrough of technology in the twentieth century that continues today, an especially the modern technology to describe and also manipulate the genetic material, DNA, has actually transformed biology. This change will enable biologists to continue to recognize the history of life in greater detail, exactly how the human being body works, our person origins, and also how humans can survive as a species on this planet despite the stresses caused by our raising numbers. Biologists proceed to decipher huge mysteries around life suggesting that we have only started to recognize life on the planet, that history, and also our connection to it. Because that this and also other reasons, the expertise of biology got through this textbook and other printed and electronic media should be a advantage in whichever field you enter.

Forensic Scientist

Forensic science is the application of science to answer concerns related come the law. Biologists and also chemists and also biochemists deserve to be forensic scientists. Forensic scientists provide scientific proof for use in courts, and their task involves assessing trace material associated with crimes. Attention in forensic science has actually increased in the last few years, possibly because of popular television mirrors that feature forensic researchers on the job. Also, the advance of molecular techniques and the facility of DNA databases have updated the types of occupational that forensic scientists deserve to do. Your job tasks are mostly related to crimes versus people such together murder, rape, and assault. Their work-related involves evaluating samples such as hair, blood, and also other human body fluids and also processing DNA found in numerous different environments and materials. Forensic scientists also analyze other organic evidence left at crime scenes, such together insect components or pollen grains. Students who desire to pursue careers in forensic science will most likely be required to take it chemistry and biology courses and some intensive math courses.

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

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Section Summary

Biology is the science of life. All living biology share several crucial properties such together order, sensitivity or an answer to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. Living things are extremely organized following a hierarchy that includes atoms, molecules, organelles, cells, tissues, organs, and organ systems. Organisms, in turn, room grouped as populations, communities, ecosystems, and the biosphere. Development is the resource of the tremendous biological diversity on earth today. A diagram dubbed a phylogenetic tree can be provided to present evolutionary relationships among organisms. Biologic is an extremely broad and includes numerous branches and sub disciplines. Examples encompass molecular biology, microbiology, neurobiology, zoology, and also botany, amongst others.