Identify and also describe the properties of lifeDescribe the level of organization amongst living thingsList examples of various sub disciplines in biology

Biology is the scientific research that studies life. What exactly is life? This might sound like a silly question with an apparent answer, however it is not straightforward to define life. For example, a branch of biology dubbed virology researches viruses, which exhibit some of the attributes of living entities yet lack others. It transforms out the although viruses can assault living organisms, cause diseases, and even reproduce, they carry out not fulfill the criteria the biologists usage to specify life.

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

Properties that Life

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


Organisms are very organized structures that consist of one or an ext cells. Even very simple, single-celled organisms space remarkably complex. Within each cell, atoms make up molecules. This in turn consist of cell components or organelles. Multicell organisms, which might consist of countless individual cells, have actually an benefit over single-celled organisms in the their cells can be devoted to perform specific functions, and even sacrificed in specific situations because that the great of the organism together a whole. Just how these specialized cells come with each other to kind organs such as the heart, lung, or skin in organisms prefer the toad displayed in figure 1. 2 will be questioned later.

Figure 1.2 A toad to represent a extremely organized structure consisting of cells, tissues, organs, and organ systems.

Sensitivity or response to Stimuli

Organisms answer to varied stimuli. For example, plants can bend towards a resource of irradiate or respond to touch. Even tiny bacteria can move toward or far from chemistry (a procedure called chemotaxis) or irradiate (phototaxis). Activity toward a economic stimulation is considered a optimistic response, while motion away indigenous a economic stimulation is taken into consideration a negative response.

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

Concept in Action


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


Single-celled biology reproduce by first duplicating your DNA, i m sorry is the hereditary material, and then dividing it equally as the cell prepares to division to type two new cells. Numerous multicellular biology (those made up of an ext than one cell) produce devoted reproductive cells that will type new individuals. Once reproduction occurs, DNA containing genes is passed along to one organism’s offspring. These genes space the reason that the offspring will belong to the same species and will have actually characteristics comparable to the parent, together as fur color and blood type.


All living organisms exhibition a “fit” to their environment. Biologists describe this fit together adaptation and it is a an effect of development by herbal selection, i beg your pardon operates in every lineage of reproducing organisms. Instances of adaptations are diverse and also unique, native heat-resistant Archaea that live in boiling hot springs come the tongue length of a nectar-feeding moth the matches the size of the flower indigenous which it feeds. Every adaptations enhance the reproductive potential of the individual exhibiting them, including their capability to make it through to reproduce. Adaptations are not constant. As an atmosphere changes, natural an option causes the features of the individuals in a population to track those changes.

Growth and Development

Organisms grow and develop follow to certain instructions coded for by your genes. These genes provide instructions the will direct cellular growth and development, ensuring that a species’ young will grow up to exhibit many of the same features as its parents.

Figure 1.4 although no two look alike, this kittens have actually inherited genes from both parents and share countless of the very same characteristics.


Even the smallest organisms are facility and require multiple regulatory mechanisms to coordinate inner functions, such together the deliver of nutrients, response to stimuli, and coping with ecological stresses. Because that example, organ systems such together the digestive or circulatory systems perform specific functions favor carrying oxygen transparent the body, removing wastes, transferring nutrients to every cell, and also cooling the body.


To role properly, cells require proper conditions together as appropriate temperature, pH, and concentrations of varied chemicals. These problems may, however, readjust from one minute to the next. Organisms room able to keep internal conditions within a narrow variety almost constantly, despite environmental changes, through a process called homeostasis or “steady state”—the ability of an organism to maintain continuous internal conditions. For example, countless organisms regulate their human body temperature in a procedure known as thermoregulation. Organisms the live in cold climates, such as the polar bear, have body frameworks that aid them stand up to low temperatures and also conserve body heat. In hot climates, organisms have actually methods (such as perspiration in human beings or panting in dogs) that assist them to burned excess body heat.

Figure 1.5 Polar bears and other mammals life in ice-covered regions maintain their body temperature by generating heat and reducing warmth loss with thick fur and also a thick layer of fat under your skin.

Energy Processing

All organisms (such together the California condor displayed in figure 1.6) use a resource of energy for their metabolic activities. Some organisms record energy from the sun and convert it into chemical power in food; others use chemical energy from molecules they take in.

Figure 1.6 A lot of energy is forced for a California condor to fly. Chemical energy obtained from food is supplied to strength flight. California condors room an endangered species; scientists have strived to location a soup tag on every bird to help them identify and locate every individual bird.Levels of company of living Things

Living points are highly organized and structured, adhering to a power structure on a scale from small to large. The atom is the smallest and most fundamental unit the matter. It consists of a nucleus surrounding 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. Plenty of molecules that space biologically necessary are macromolecules, big molecules that are generally formed through combining smaller units referred to as monomers. An instance of a macromolecule is deoxyribonucleic acid (DNA), which includes the instructions for the work of the biology that contains it.

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

Concept in Action


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

Some cell contain aggregates of macromolecules surrounding by membranes; this are dubbed organelles. Oribel are small structures that exist in ~ cells and perform dedicated functions. Every living things space made the cells; the cabinet itself is the smallest an essential unit of framework and function in living organisms. (This need is why viruses room not taken into consideration living: they room not make of cells. To make new viruses, they have to invade and also hijack a life cell; only then deserve to they acquire the materials they have to reproduce.) some organisms covers a single cell and others room multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that lack organelles surrounding by a membrane and do not have actually nuclei surrounded by nuclear membranes; in contrast, the cells of eukaryotes do have actually membrane-bound organelles and nuclei.

In many multicellular organisms, cells incorporate to do tissues, i m sorry are groups of comparable cells moving out the exact same function. Organs are collections of organization grouped together based on a usual function. Offal are current not just in animals but likewise in plants. One organ device is a higher level of organization that is composed of functionally connected organs. For example vertebrate animals have many organ systems, such as the circulatory mechanism that transports blood throughout the body and also to and also from the lungs; it includes organs such together the heart and blood vessels. Organisms room individual life entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and also single-celled eukaryotes are additionally considered organisms and are commonly referred to together microorganisms.

Figure 1.8 indigenous an atom to the whole Earth, biologic examines all aspects of life.

Which of the complying with statements is false?

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

All the individuals of a species living in ~ a certain area are jointly called a population. For example, a woodland may include many white pine trees. All of these pine tree trees represent the population of white pine trees in this forest. Different populations may live in the same certain area. Because that example, the woodland with the jaw trees includes populations that flowering plants and also insects and also microbial populations. A ar is the collection of populaces inhabiting a certain area. For instance, every one of the trees, flowers, insects, and also other populations in a forest form the forest’s community. The forest itself is an ecosystem. One ecosystem consists of all the living things in a specific area along with the abiotic, or non-living, parts of that environment such together nitrogen in the floor or rainwater. In ~ the highest level the organization, the biosphere is the repertoire of every ecosystems, and it represents the area of life ~ above Earth. It has land, water, and portions the the atmosphere.

The Diversity the Life

The scientific research of biological is really broad in scope because there is a incredible diversity that life on Earth. The resource of this diversity is evolution, the process of gradual readjust during which brand-new species arise indigenous older species. Evolutionary biologists examine the advancement of living things in everything from the microscopic civilization to ecosystems.

In the 18th century, a scientist called Carl Linnaeus an initial proposed organizing the known species of organisms into a ordered taxonomy. In this system, species that are most similar to each other are put together in ~ a grouping recognized as a genus. Furthermore, similar genera (the many of genus) are placed together in ~ a family. This grouping proceeds until all organisms are gathered together into teams at the greatest level. The present taxonomic device now has eight level in that hierarchy, from shortest to highest, castle are: species, genus, family, order, class, phylum, kingdom, and domain. Thus species are grouped in ~ genera, genera are grouped within families, family members 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 many specific—species.

The greatest level, domain, is a relatively brand-new addition to the system due to the fact that the 1990s. Scientists currently recognize three domain names of life, the Eukarya, the Archaea, and also the Bacteria. The domain Eukarya contains organisms that have actually cells v nuclei. It has the kingdoms of fungi, plants, animals, and several kingdoms the protists. The Archaea, room single-celled organisms without nuclei and also include many extremophiles that live in harsh settings like warm springs. The Bacteria are an additional quite various group that single-celled organisms there is no nuclei. Both the Archaea and the Bacteria room prokaryotes, casual name because that cells without nuclei. The recognition in the 1990s that details “bacteria,” now recognized as the Archaea, to be as various genetically and also biochemically from other bacterial cells as they were from eukaryotes, encouraged the referral to division life right into three domains. This dramatic readjust in our knowledge of the tree of life demonstrates the classifications room not permanent and also will change when brand-new information becomes available.

In addition to the ordered taxonomic system, Linnaeus to be the an initial to name organisms utilizing two distinctive names, now called the binomial specify name system. Before Linnaeus, the use of common names to refer to organisms caused confusion due to the fact that there were regional differences in these typical names. Binomial surname consist of the genus name (which is capitalized) and also the varieties name (all lower-case). Both surname are set in italics once they are printed. Every types is given a distinctive binomial i beg your pardon is well-known the people over, so the a scientist in any kind of location can know which biology is gift referred to. Because that example, the north American blue jay is known uniquely as Cyanocitta cristata. Ours own species is Homo sapiens.

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

Evolution in Action

Carl Woese and the Phylogenetic Tree

The evolutionary relationships of assorted life develops on planet can be summarized in a phylogenetic tree. A phylogenetic tree is a diagram mirroring the evolution relationships among biological types based ~ above similarities and also differences in hereditary or physics traits or both. A phylogenetic tree is composed of branch points, or nodes, and also branches. The interior nodes represent ancestors and are points in advancement when, based on scientific evidence, one ancestor is believed to have actually diverged to type two brand-new species. The size of each branch have the right to be thought about as estimates of relative time.

In the past, biologist grouped living organisms into 5 kingdoms: animals, plants, fungi, protists, and bacteria. The pioneering work of American microbiologist Carl Woese in the at an early stage 1970s has shown, however, that life on planet has advanced along 3 lineages, now dubbed domains—Bacteria, Archaea, and Eukarya. Woese proposed the domain as a new taxonomic level and also Archaea as a brand-new domain, come reflect the brand-new phylogenetic tree. Countless organisms belonging come the Archaea domain live under excessive conditions and also are dubbed extremophiles. To build his tree, Woese used hereditary relationships fairly than similarities based on morphology (shape). Various genes were supplied in phylogenetic studies. Woese’s tree was constructed from comparative sequencing the the genes that room universally distributed, discovered in part slightly altered type in every organism, conserved (meaning that these genes have actually remained just slightly adjusted throughout evolution), and also of an ideal length.

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

The border of biological is vast and thus contains countless branches and sub disciplines. Biologists might pursue one of those below disciplines and 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 examine of the structure and duty of microorganisms. It is rather a wide branch itself, and depending on the topic of study, over there are likewise microbial physiologists, ecologists, and also geneticists, amongst others.

Another ar of organic study, neurobiology, studies the biological of the worried system, and although that is thought about a branch the biology, the is additionally recognized as an interdisciplinary ar of study well-known as neuroscience. Because of that interdisciplinary nature, this sub self-control studies various functions of the nervous device using molecular, cellular, developmental, medical, and computational approaches.

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

Paleontology, an additional branch that biology, offers fossils to study life’s history. Zoology and also botany space the study of animals and plants, respectively. Biologists can likewise specialize together biotechnologists, ecologists, or physiologists, come name just a couple of areas. Biotechnologists apply the expertise of biology to create advantageous products. Ecologists research the interactions of organisms in your environments. Physiologists study the operations of cells, tissues and also organs. This is simply a small sample the the many fields that biologists deserve to pursue. Indigenous our very own bodies come the people we live in, explorations in biological can influence us in an extremely direct and also important ways. We depend on these explorations for our health, our food sources, and also the benefits noted by our ecosystem. Due to the fact that of this, understanding of biologic can advantage us in making decisions in our day-to-day lives.

The development of modern technology in the twenty century that continues today, specifically the technology to describe and manipulate the genetic material, DNA, has actually transformed biology. This revolution will allow biologists to proceed to know the background of life in greater detail, exactly how the person body works, our human origins, and also how humans deserve to survive as a varieties on this planet despite the stresses led to by our increasing numbers. Biologists continue to decipher substantial mysteries around life suggesting that we have only started to recognize life on the planet, that history, and also our partnership to it. Because that this and other reasons, the knowledge of biology acquired through this textbook and also other printed and also electronic media should be a benefit in whichever field you enter.

Forensic Scientist

Forensic scientific research is the application of science to answer questions related come the law. Biologists and also chemists and also biochemists deserve to be forensic scientists. Forensic scientists administer scientific evidence for usage in courts, and also their job involves evaluating trace material linked with crimes. Attention in forensic science has actually increased in the last couple of years, possibly since of renowned television mirrors that attribute forensic researchers on the job. Also, the development of molecule techniques and also the facility of DNA databases have actually updated the species of work that forensic scientists have the right to do. Their job tasks are mostly related to crimes versus people such as murder, rape, and also assault. Their work-related involves evaluating samples such as hair, blood, and other human body fluids and also processing DNA discovered in numerous different environments and also materials. Forensic scientists likewise analyze other biological evidence left at crime scenes, such together insect parts or pollen grains. Student who want to go after careers in forensic scientific research will most likely be compelled to take chemistry and biology courses and also some extensive math courses.

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

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Section Summary

Biology is the scientific research of life. Every living organisms share several an essential properties such together order, sensitivity or response to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and also energy processing. Living things are very organized following a pecking order that includes atoms, molecules, organelles, cells, tissues, organs, and organ systems. Organisms, in turn, room grouped as populations, communities, ecosystems, and also the biosphere. Evolution is the source of the tremendous biological diversity on earth today. A diagram referred to as a phylogenetic tree have the right to be offered to show evolutionary relationships amongst organisms. Biological is really broad and includes countless branches and also sub disciplines. Examples encompass molecular biology, microbiology, neurobiology, zoology, and botany, amongst others.