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

Biology is the science that studies life. What precisely is life? This might sound like a silly concern with an apparent answer, but it is not straightforward to specify life. For example, a branch of biology dubbed virology researches viruses, which exhibit some of the features of living entities but lack others. It turns out the although viruses can strike living organisms, cause diseases, and also even reproduce, they execute not accomplish the criteria that biologists use to specify life.

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From its earliest beginnings, biology has wrestled with four questions: What room the common properties that make something “alive”? how do those assorted living things function? When confronted with the impressive diversity the life, how do us organize the various kinds of biology so that us can much better understand them? And, finally—what biologists at some point seek come understand—how go this diversity arise and also how is the continuing? As brand-new organisms are discovered every day, biologists continue to look for answers come these and other questions.

Properties of Life

All teams of life organisms re-superstructure multiple key characteristics or functions: order, sensitivity or an answer to stimuli, reproduction, adaptation, growth and also development, regulation, homeostasis, and also energy processing. Once viewed together, these eight qualities serve to define life.


Organisms are extremely organized frameworks that consists one or much more cells. Even really simple, single-celled organisms space remarkably complex. Within each cell, atoms make up molecules. This in turn make up cell components or organelles. Multicell organisms, which might consist of millions of individual cells, have actually an benefit over single-celled organisms in the their cells deserve to be devoted to perform certain functions, and even sacrificed in specific situations for the great of the organism as a whole. Exactly how these dedicated cells come with each other to kind organs such together the heart, lung, or skin in organisms like the toad displayed in number 1. 2 will be debated later.

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

Sensitivity or an answer to Stimuli

Organisms answer to diverse stimuli. For example, plants have the right to bend towards a source of irradiate or respond come touch. Even tiny bacteria deserve to move towards or far from chemistry (a procedure called chemotaxis) or light (phototaxis). Activity toward a stimulus is considered a positive response, while activity away indigenous a stimulus is considered a an unfavorable response.

Figure 1.3 The leaves of this perceptible plant (Mimosa pudica) will certainly instantly droop and also fold once touched. After a few minutes, the plant returns come 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 very first duplicating their DNA, which is the genetic material, and also then separating it equally as the cabinet prepares to divide to form two new cells. Plenty of multicellular organisms (those made up of an ext than one cell) produce committed reproductive cells that will kind new individuals. Once reproduction occurs, DNA containing gene is passed along to one organism’s offspring. These genes are the reason that the offspring will belong come the same types and will have characteristics comparable to the parent, such as hair color and also blood type.


All living organisms exhibit a “fit” to your 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 family tree of reproducing organisms. Instances of adaptations space diverse and unique, native heat-resistant Archaea the live in boiling warm springs come the tongue size of a nectar-feeding moth the matches the dimension of the flower from which the feeds. All adaptations improve the reproductive potential of the individual exhibiting them, including their capability to endure to reproduce. Adaptations are not constant. As an atmosphere changes, natural selection causes the attributes of the people in a populace to track those changes.

Growth and Development

Organisms grow and develop follow to certain instructions coded because that by their genes. This genes carry out instructions that will direct cellular growth and also development, ensuring that a species’ young will prosper up to exhibit many of the same attributes as that is parents.

Figure 1.4 back no two look alike, these kittens have actually inherited genes from both parents and share many of the very same characteristics.


Even the smallest organisms are facility and call for multiple regulation mechanisms to coordinate interior functions, such together the transport of nutrients, an answer to stimuli, and also coping with eco-friendly stresses. Because that example, organ systems such as the digestive or circulatory equipment perform specific functions favor carrying oxygen transparent the body, remove wastes, carrying nutrients come every cell, and also cooling the body.


To function properly, cell require proper conditions such as suitable temperature, pH, and concentrations of varied chemicals. These problems may, however, adjust from one moment to the next. Organisms space able to maintain internal conditions within a narrow selection almost constantly, despite environmental changes, with a procedure called homeostasis or “steady state”—the capacity of an biology to maintain continuous internal conditions. Because that example, plenty of organisms regulate their human body temperature in a procedure known together thermoregulation. Organisms the live in cold climates, such as the polar bear, have body frameworks that help them withstand low temperatures and also conserve human body heat. In warm climates, organisms have methods (such together perspiration in human beings 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 by generating heat and also reducing heat loss through thick fur and also a dense layer of fat under your skin.

Energy Processing

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

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

Living points are very organized and also structured, complying with a pecking order on a range from little to large. The atom is the smallest and also most an essential unit that matter. It consists of a nucleus surrounding by electrons. Atoms form molecules. A molecule is a chemical framework consisting of at least two atoms organized together by a chemical bond. Many molecules that are biologically important are macromolecules, big molecules that are frequently formed by combining smaller sized units called monomers. An instance of a macromolecule is deoxyribonucleic mountain (DNA), which contains the instructions for the work of the biology that includes it.

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

Concept in Action


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

Some cell contain aggregates that macromolecules surrounded by membranes; this are dubbed organelles. Organelles are tiny structures the exist within cells and also perform dedicated functions. Every living things are made the cells; the cabinet itself is the smallest basic unit of framework and function in life organisms. (This need is why viruses room not considered living: they room not made of cells. To make new viruses, they have to invade and hijack a living cell; just then deserve to they achieve the materials they should reproduce.) part organisms covers a solitary cell and others space multicellular. Cells room classified as prokaryotic or eukaryotic. Prokaryotes are single-celled biology that lack organelles surrounding by a membrane and also do not have nuclei surrounding by nuclear membranes; in contrast, the cell of standard scale do have membrane-bound organelles and nuclei.

In most multicellular organisms, cells integrate to make tissues, i m sorry are teams of comparable cells transferring out the exact same function. Organs room collections of tissues grouped together based upon a usual function. Offal are existing not just in animals but additionally in plants. An organ system is a higher level of organization that is composed of functionally related organs. For example vertebrate animals have countless organ systems, such together the circulatory device that transports blood transparent the body and also to and also from the lungs; it includes organs such as the heart and blood vessels. Organisms are individual life entities. For example, each tree in a woodland 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 from an atom to the whole Earth, biologic examines all aspects of life.

Which that the complying with statements is false?

Tissues exist within organs i m sorry exist within body organ systems.Communities exist within populaces which exist within 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 types living within a particular area are collectively called a population. For example, a woodland may include many white jaw trees. Every one of these pine trees stand for the population of white pine tree in this forest. Various populations may live in the same certain area. Because that example, the forest with the jaw trees contains populations the flowering plants and also insects and microbial populations. A neighborhood is the set of populaces inhabiting a specific area. For instance, all of the trees, flowers, insects, and other populations in a forest form the forest’s community. The woodland itself is one ecosystem. An ecosystem is composed of every the living points in a particular area in addition to the abiotic, or non-living, components of that atmosphere such together nitrogen in the soil or rainwater. At the highest level of organization, the biosphere is the collection of all ecosystems, and it represents the area of life top top Earth. It contains land, water, and portions that the atmosphere.

The Diversity that Life

The scientific research of biologic is really broad in scope since there is a incredible diversity of life top top Earth. The source of this diversity is evolution, the process of gradual adjust during which brand-new species arise native older species. Evolution biologists study the evolution of living points in everything from the microscopic people to ecosystems.

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

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

The highest possible level, domain, is a relatively new addition come the system due to the fact that the 1990s. Scientists now recognize three domains of life, the Eukarya, the Archaea, and the Bacteria. The domain Eukarya contains organisms that have actually cells through nuclei. It consists of the kingdoms that fungi, plants, animals, and also several kingdoms the protists. The Archaea, space single-celled organisms there is no nuclei and include plenty of extremophiles the live in harsh environments like hot springs. The Bacteria are another quite various group that single-celled organisms without nuclei. Both the Archaea and also the Bacteria room prokaryotes, casual name because that cells without nuclei. The acknowledgment in the 1990s that details “bacteria,” now known 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 into three domains. This dramatic readjust in our knowledge of the tree of life demonstrates the classifications room not permanent and will change when new information becomes available.

In enhancement to the ordered taxonomic system, Linnaeus to be the very first to name organisms utilizing two distinct names, now dubbed the binomial naming system. Before Linnaeus, the usage of typical names to describe organisms led to confusion due to the fact that there were regional differences in these common names. Binomial surname consist the the genus name (which is capitalized) and also the varieties name (all lower-case). Both names are collection in italics as soon as they are printed. Every types is given a distinct binomial i m sorry is well-known the world over, so that a scientist in any location have the right to know which biology is gift referred to. For example, the phibìc American blue jay is recognized uniquely together Cyanocitta cristata. Our own types is Homo sapiens.

Figure 1.10 These photos represent different domains. The scanning electron micrograph shows (a) bacterial cell belong come the domain Bacteria, when the (b) extremophiles, watched all with each other as colored mats 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 also the Phylogenetic Tree

The evolutionary relationships of assorted life forms on earth can be summarized in a phylogenetic tree. A phylogenetic tree is a diagram showing the evolution relationships among biological species based on similarities and also differences in hereditary or physics traits or both. A phylogenetic tree is created of branch points, or nodes, and branches. The interior nodes stand for ancestors and also are point out in advancement when, based on scientific evidence, one ancestor is thought to have actually diverged to form two new species. The length of each branch have the right to be taken into consideration as estimates of family member time.

In the past, biologist grouped life organisms into five kingdoms: animals, plants, fungi, protists, and also bacteria. The pioneering work-related of American microbiologist Carl Woese in the at an early stage 1970s has actually shown, however, the life on earth has developed along 3 lineages, now referred to as domains—Bacteria, Archaea, and Eukarya. Woese suggest the domain as a new taxonomic level and also Archaea together a new domain, come reflect the brand-new phylogenetic tree. Many organisms belonging to the Archaea domain live under too much conditions and also are dubbed extremophiles. To construct his tree, Woese used hereditary relationships quite than similarities based upon morphology (shape). Assorted genes were offered in phylogenetic studies. Woese’s tree was constructed from comparative sequencing the the genes that are universally distributed, found in some slightly altered kind in every organism, conserved (meaning the these genes have actually remained just slightly adjusted throughout evolution), and also of an proper length.

Figure 1.11 This phylogenetic tree was created by microbiologist Carl Woese using genetic relationships. The tree mirrors the separation of life organisms into three domains: Bacteria, Archaea, and Eukarya. Bacteria and Archaea space organisms there is no a nucleus or other organelles surrounded by a membrane and, therefore, space prokaryotes.

The border of biological is vast and because of this contains plenty of branches and also sub disciplines. Biologists might pursue one of those below disciplines and also work in a an ext focused field. Because that instance, molecule biology studies organic processes in ~ the molecular level, consisting of interactions among molecules such together DNA, RNA, and also proteins, and also the method they are regulated. Microbiology is the research of the structure and function of microorganisms. It is fairly a vast branch itself, and depending top top the topic of study, over there are also microbial physiologists, ecologists, and also geneticists, among others.

Another ar of biological study, neurobiology, studies the biology of the worried system, and although the is considered a branch of biology, it is also recognized as an interdisciplinary ar of study well-known as neuroscience. Due to the fact that of that is interdisciplinary nature, this sub technique studies different functions that the nervous device using molecular, cellular, developmental, medical, and computational approaches.

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

Paleontology, an additional branch the biology, offers fossils to research life’s history. Zoology and also botany space the study of animals and plants, respectively. Biologist can additionally specialize as biotechnologists, ecologists, or physiologists, to name just a few areas. Biotechnologists use the knowledge of biology to create beneficial products. Ecologists examine the interaction of biology in your environments. Physiologists study the functions of cells, tissues and also organs. This is just a little sample of the plenty of fields the biologists deserve to pursue. From our own bodies to the world we live in, explorations in biologic can influence us in very direct and also important ways. We count on these discoveries for our health, ours food sources, and also the benefits detailed by ours ecosystem. Because of this, knowledge of biological can benefit us in making decision in our day-to-day lives.

The breakthrough of technology in the twenty century that continues today, particularly the an innovation to describe and manipulate the genetic material, DNA, has transformed biology. This transformation will permit biologists to continue to know the history of life in higher detail, just how the human body works, our person origins, and also how humans deserve to survive as a species on this planet in spite of the stresses caused by our boosting numbers. Biologists proceed to decipher huge mysteries around life arguing that we have actually only begun to recognize life on the planet, that history, and also our relationship to it. Because that this and also other reasons, the knowledge of biology obtained through this textbook and also other printed and also electronic media have to be a advantage in whichever field you enter.

Forensic Scientist

Forensic science is the applications of scientific research to answer concerns related come the law. Biologists and chemists and also biochemists can be forensic scientists. Forensic scientists carry out scientific evidence for usage in courts, and also their project involves assessing trace material connected with crimes. Attention in forensic science has increased in the last couple of years, possibly due to the fact that of popular television mirrors that function forensic scientists on the job. Also, the advancement of molecular techniques and the establishment of DNA databases have updated the types of work-related that forensic scientists can do. Their job activities are generally related to crimes versus people such as murder, rape, and assault. Their job-related involves assessing samples such as hair, blood, and also other human body fluids and additionally processing DNA discovered in plenty of different environments and materials. Forensic scientists also analyze other organic evidence left in ~ crime scenes, such as insect components or pollen grains. College student who desire to go after careers in forensic science will most likely be compelled to take chemistry and also biology courses and some extensive math courses.

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

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Section Summary

Biology is the scientific research of life. All living organisms share several vital properties such as order, sensitivity or solution to stimuli, reproduction, adaptation, growth and also development, regulation, homeostasis, and also energy processing. Living things are extremely organized complying with a pecking order that has atoms, molecules, organelles, cells, tissues, organs, and organ systems. Organisms, in turn, room grouped as populations, communities, ecosystems, and the biosphere. Advancement is the resource of the tremendous biological diversity on planet today. A diagram called a phylogenetic tree can be provided to display evolutionary relationships amongst organisms. Biology is very broad and includes countless branches and sub disciplines. Examples encompass molecular biology, microbiology, neurobiology, zoology, and also botany, amongst others.