What Are the Themes of Biology That Come Up Again and Again

Affiliate ane: Introduction to Biology

i.i Themes and Concepts of Biology

Past the end of this section, you lot will exist able to:

• Identify and depict the properties of life
• Describe the levels of organization among living things
• List examples of different sub disciplines in biology

Watch a video about Evolution past Natural Selection.

Biology is the science that studies life. What exactly is life? This may sound like a lightheaded question with an obvious answer, but it is non piece of cake to define life. For example, a branch of biology chosen virology studies viruses, which exhibit some of the characteristics of living entities only lack others. Information technology turns out that although viruses can attack living organisms, cause diseases, and even reproduce, they practise not run across the criteria that biologists use to define life.

From its primeval beginnings, biology has wrestled with four questions: What are the shared properties that make something "alive"? How exercise those various living things function? When faced with the remarkable diversity of life, how do we organize the different kinds of organisms so that we tin can amend sympathize them? And, finally—what biologists ultimately seek to understand—how did this diversity arise and how is information technology continuing? As new organisms are discovered every day, biologists continue to seek answers to these and other questions.

Backdrop of Life

All groups of living organisms share multiple key characteristics or functions: guild, sensitivity or response to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. When viewed together, these 8 characteristics serve to define life.

Gild

Organisms are highly organized structures that consist of i or more cells. Even very simple, single-celled organisms are remarkably circuitous. Inside each cell, atoms brand upwardly molecules. These in plow make up prison cell components or organelles. Multicellular organisms, which may consist of millions of individual cells, have an advantage over single-celled organisms in that their cells can be specialized to perform specific functions, and fifty-fifty sacrificed in certain situations for the good of the organism as a whole. How these specialized cells come together to form organs such as the center, lung, or skin in organisms like the toad shown in Figure i. 2 will exist discussed later.

Figure one.2 A toad represents a highly organized structure consisting of cells, tissues, organs, and organ systems.

Sensitivity or Response to Stimuli

Organisms answer to various stimuli. For instance, plants can bend toward a source of lite or respond to touch on. Even tiny leaner can move toward or away from chemicals (a procedure called chemotaxis) or light (phototaxis). Movement toward a stimulus is considered a positive response, while motion abroad from a stimulus is considered a negative response.

 

Effigy one.3 The leaves of this sensitive plant (Mimosa pudica) will instantly droop and fold when touched. Subsequently a few minutes, the plant returns to its normal state.

Concept in Activity

Watch this video to see how the sensitive constitute responds to a bear upon stimulus.

Reproduction

Unmarried-celled organisms reproduce by first duplicating their DNA, which is the genetic material, and and so dividing information technology equally every bit the cell prepares to divide to form two new cells. Many multicellular organisms (those fabricated upwardly of more than than one cell) produce specialized reproductive cells that will course new individuals. When reproduction occurs, DNA containing genes is passed forth to an organism'due south offspring. These genes are the reason that the offspring will belong to the aforementioned species and will have characteristics similar to the parent, such every bit fur color and blood blazon.

Adaptation

All living organisms exhibit a "fit" to their surroundings. Biologists refer to this fit as adaptation and it is a issue of evolution by natural option, which operates in every lineage of reproducing organisms. Examples of adaptations are various and unique, from heat-resistant Archaea that alive in humid hot springs to the tongue length of a nectar-feeding moth that matches the size of the flower from which it feeds. All adaptations raise the reproductive potential of the individual exhibiting them, including their ability to survive to reproduce. Adaptations are non abiding. As an environment changes, natural selection causes the characteristics of the individuals in a population to rails those changes.

Growth and Development

Organisms grow and develop according to specific instructions coded for by their genes. These genes provide instructions that will straight cellular growth and evolution, ensuring that a species' young will grow upwards to exhibit many of the same characteristics every bit its parents.

Effigy i.four Although no two wait alike, these kittens have inherited genes from both parents and share many of the same characteristics.

Regulation

Even the smallest organisms are complex and require multiple regulatory mechanisms to coordinate internal functions, such as the transport of nutrients, response to stimuli, and coping with environmental stresses. For case, organ systems such equally the digestive or circulatory systems perform specific functions like carrying oxygen throughout the body, removing wastes, delivering nutrients to every cell, and cooling the torso.

Homeostasis

To office properly, cells require appropriate weather condition such as proper temperature, pH, and concentrations of diverse chemicals. These weather condition may, yet, change from one moment to the next. Organisms are able to maintain internal atmospheric condition within a narrow range almost constantly, despite environmental changes, through a procedure called homeostasis or "steady land"—the ability of an organism to maintain constant internal conditions. For instance, many organisms regulate their torso temperature in a process known equally thermoregulation. Organisms that live in cold climates, such as the polar deport, have body structures that help them withstand depression temperatures and conserve body estrus. In hot climates, organisms have methods (such as perspiration in humans or panting in dogs) that assistance them to shed excess body heat.

Figure one.five Polar bears and other mammals living in water ice-covered regions maintain their body temperature by generating rut and reducing heat loss through thick fur and a dumbo layer of fat under their skin.

Energy Processing

All organisms (such as the California condor shown in Figure 1.half-dozen) utilize a source of energy for their metabolic activities. Some organisms capture energy from the sun and convert information technology into chemical energy in food; others employ chemical energy from molecules they take in.

Figure i.6 A lot of energy is required for a California condor to wing. Chemical energy derived from nutrient is used to ability flight. California condors are an endangered species; scientists have strived to place a wing tag on each bird to help them place and locate each individual bird.

Levels of Arrangement of Living Things

Living things are highly organized and structured, following a hierarchy on a scale from small-scale to big. The atom is the smallest and nigh fundamental unit of matter. It consists of a nucleus surrounded by electrons. Atoms form molecules. A molecule is a chemical structure consisting of at least ii atoms held together by a chemical bond. Many molecules that are biologically important are macromolecules, large molecules that are typically formed by combining smaller units called monomers. An instance of a macromolecule is deoxyribonucleic acid (DNA), which contains the instructions for the performance of the organism that contains it.

Figure 1.vii A molecule, like this large DNA molecule, is equanimous of atoms.

Concept in Action

To see an blitheness of this Dna molecule, click here.

Some cells comprise aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are small structures that exist inside cells and perform specialized functions. All living things are made of cells; the cell itself is the smallest fundamental unit of structure and part in living organisms. (This requirement is why viruses are not considered living: they are not made of cells. To brand new viruses, they accept to invade and hijack a living cell; just then can they obtain the materials they need to reproduce.) Some organisms consist of a single jail cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that lack organelles surrounded by a membrane and do non have nuclei surrounded by nuclear membranes; in contrast, the cells of eukaryotes practice have membrane-bound organelles and nuclei.

In most multicellular organisms, cells combine to make tissues, which are groups of like cells carrying out the same function. Organs are collections of tissues grouped together based on a common function. Organs are present not simply in animals but also in plants. An organ system is a higher level of organization that consists of functionally related organs. For example vertebrate animals have many organ systems, such as the circulatory system that transports blood throughout the body and to and from the lungs; it includes organs such as the heart and blood vessels. Organisms are individual living entities. For case, each tree in a forest is an organism. Unmarried-celled prokaryotes and single-celled eukaryotes are likewise considered organisms and are typically referred to as microorganisms.

Figure ane.8 From an atom to the entire World, biology examines all aspects of life.

Which of the following statements is false?

1. Tissues exist within organs which be within organ systems.
2. Communities exist within populations which be within ecosystems.
3. Organelles exist within cells which be inside tissues.
4. Communities exist within ecosystems which be in the biosphere.

All the individuals of a species living within a specific surface area are collectively called a population. For example, a woods may include many white pine trees. All of these pine trees represent the population of white pino trees in this forest. Dissimilar populations may live in the same specific area. For example, the wood with the pine trees includes populations of flowering plants and likewise insects and microbial populations. A community is the set up of populations inhabiting a detail area. For instance, all of the copse, flowers, insects, and other populations in a wood form the forest's community. The forest itself is an ecosystem. An ecosystem consists of all the living things in a particular expanse together with the abiotic, or non-living, parts of that surroundings such as nitrogen in the soil or rainwater. At the highest level of arrangement, the biosphere is the drove of all ecosystems, and it represents the zones of life on Globe. Information technology includes land, water, and portions of the atmosphere.

The Diverseness of Life

The scientific discipline of biological science is very wide in scope considering there is a tremendous diversity of life on Earth. The source of this multifariousness is development, the procedure of gradual change during which new species ascend from older species. Evolutionary biologists study the evolution of living things in everything from the microscopic world to ecosystems.

In the 18th century, a scientist named Carl Linnaeus outset proposed organizing the known species of organisms into a hierarchical taxonomy. In this system, species that are nearly like to each other are put together within a grouping known as a genus. Furthermore, like genera (the plural of genus) are put together within a family unit. This grouping continues until all organisms are collected together into groups at the highest level. The current taxonomic organisation now has 8 levels in its hierarchy, from everyman to highest, they are: species, genus, family unit, order, class, phylum, kingdom, and domain. Thus species are grouped within genera, genera are grouped within families, families are grouped within orders, and so on.

Figure i.9 This diagram shows the levels of taxonomic hierarchy for a canis familiaris, from the broadest category—domain—to the most specific—species.

The highest level, domain, is a relatively new addition to the arrangement since the 1990s. Scientists now recognize three domains of life, the Eukarya, the Archaea, and the Bacteria. The domain Eukarya contains organisms that have cells with nuclei. Information technology includes the kingdoms of fungi, plants, animals, and several kingdoms of protists. The Archaea, are single-celled organisms without nuclei and include many extremophiles that alive in harsh environments like hot springs. The Bacteria are another quite different group of single-celled organisms without nuclei. Both the Archaea and the Bacteria are prokaryotes, an informal name for cells without nuclei. The recognition in the 1990s that certain "bacteria," now known equally the Archaea, were as different genetically and biochemically from other bacterial cells as they were from eukaryotes, motivated the recommendation to divide life into three domains. This dramatic change in our knowledge of the tree of life demonstrates that classifications are not permanent and volition modify when new data becomes available.

In addition to the hierarchical taxonomic system, Linnaeus was the first to name organisms using 2 unique names, at present called the binomial naming organisation. Before Linnaeus, the use of common names to refer to organisms caused confusion considering there were regional differences in these mutual names. Binomial names consist of the genus proper noun (which is capitalized) and the species proper name (all lower-case). Both names are set in italics when they are printed. Every species is given a unique binomial which is recognized the world over, so that a scientist in any location tin can know which organism is being referred to. For example, the Northward American blue jay is known uniquely as Cyanocitta cristata. Our own species is Homo sapiens.

Figure 1.x These images stand for different domains. The scanning electron micrograph shows (a) bacterial cells belong to the domain Bacteria, while the (b) extremophiles, seen all together as colored mats in this hot spring, belong to domain Archaea. Both the (c) sunflower and (d) lion are function of domain Eukarya.

Evolution in Action

Carl Woese and the Phylogenetic Tree

The evolutionary relationships of various life forms on World can be summarized in a phylogenetic tree. A phylogenetic tree is a diagram showing the evolutionary relationships among biological species based on similarities and differences in genetic or concrete traits or both. A phylogenetic tree is composed of co-operative points, or nodes, and branches. The internal nodes represent ancestors and are points in evolution when, based on scientific evidence, an ancestor is idea to have diverged to grade two new species. The length of each branch tin exist considered equally estimates of relative time.

In the by, biologists grouped living organisms into five kingdoms: animals, plants, fungi, protists, and leaner. The pioneering work of American microbiologist Carl Woese in the early 1970s has shown, however, that life on Earth has evolved along three lineages, now called domains—Bacteria, Archaea, and Eukarya. Woese proposed the domain as a new taxonomic level and Archaea equally a new domain, to reflect the new phylogenetic tree. Many organisms belonging to the Archaea domain live under extreme weather condition and are called extremophiles. To construct his tree, Woese used genetic relationships rather than similarities based on morphology (shape). Various genes were used in phylogenetic studies. Woese's tree was constructed from comparative sequencing of the genes that are universally distributed, found in some slightly contradistinct course in every organism, conserved (meaning that these genes take remained simply slightly inverse throughout evolution), and of an appropriate length.

Figure 1.xi This phylogenetic tree was constructed by microbiologist Carl Woese using genetic relationships. The tree shows the separation of living organisms into iii domains: Bacteria, Archaea, and Eukarya. Bacteria and Archaea are organisms without a nucleus or other organelles surrounded by a membrane and, therefore, are prokaryotes.

Branches of Biological Study

Watch a video most Science and Medicine

The telescopic of biology is broad and therefore contains many branches and sub disciplines. Biologists may pursue one of those sub disciplines and work in a more focused field. For instance, molecular biology studies biological processes at the molecular level, including interactions among molecules such as Dna, RNA, and proteins, likewise as the way they are regulated. Microbiology is the report of the construction and function of microorganisms. It is quite a broad branch itself, and depending on the subject of written report, there are also microbial physiologists, ecologists, and geneticists, among others.

Another field of biological study, neurobiology, studies the biology of the nervous system, and although information technology is considered a co-operative of biology, it is also recognized as an interdisciplinary field of study known every bit neuroscience. Because of its interdisciplinary nature, this sub subject studies different functions of the nervous system using molecular, cellular, developmental, medical, and computational approaches.

Figure one.12 Researchers work on excavating dinosaur fossils at a site in Castellón, Kingdom of spain.

Paleontology, some other branch of biology, uses fossils to report life's history. Zoology and botany are the study of animals and plants, respectively. Biologists tin can also specialize equally biotechnologists, ecologists, or physiologists, to proper name just a few areas. Biotechnologists employ the knowledge of biology to create useful products. Ecologists study the interactions of organisms in their environments. Physiologists study the workings of cells, tissues and organs. This is simply a small sample of the many fields that biologists can pursue. From our own bodies to the globe we live in, discoveries in biology can affect us in very direct and of import ways. Nosotros depend on these discoveries for our health, our nutrient sources, and the benefits provided past our ecosystem. Because of this, cognition of biology can benefit us in making decisions in our day-to-day lives.

The development of technology in the twentieth century that continues today, particularly the technology to describe and dispense the genetic textile, DNA, has transformed biology. This transformation will allow biologists to continue to understand the history of life in greater detail, how the human body works, our human origins, and how humans can survive as a species on this planet despite the stresses caused by our increasing numbers. Biologists continue to decipher huge mysteries virtually life suggesting that we accept but begun to understand life on the planet, its history, and our human relationship to it. For this and other reasons, the noesis of biology gained through this textbook and other printed and electronic media should be a benefit in whichever field y'all enter.

Forensic Scientist

Forensic science is the awarding of scientific discipline to answer questions related to the police force. Biologists as well equally chemists and biochemists can exist forensic scientists. Forensic scientists provide scientific show for employ in courts, and their job involves examining trace material associated with crimes. Interest in forensic science has increased in the last few years, mayhap considering of popular television shows that feature forensic scientists on the job. As well, the development of molecular techniques and the establishment of DNA databases have updated the types of work that forensic scientists can do. Their job activities are primarily related to crimes against people such as murder, rape, and assault. Their work involves analyzing samples such equally hair, blood, and other trunk fluids and likewise processing DNA found in many different environments and materials. Forensic scientists besides analyze other biological testify left at offense scenes, such equally insect parts or pollen grains. Students who want to pursue careers in forensic science will most likely be required to take chemical science and biology courses too equally some intensive math courses.

Figure one.thirteen This forensic scientist works in a DNA extraction room at the U.S. Army Criminal Investigation Laboratory.

Section Summary

Biological science is the science of life. All living organisms share several key properties such as order, sensitivity or response to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. Living things are highly organized following a bureaucracy that includes atoms, molecules, organelles, cells, tissues, organs, and organ systems. Organisms, in turn, are grouped as populations, communities, ecosystems, and the biosphere. Evolution is the source of the tremendous biological multifariousness on Earth today. A diagram chosen a phylogenetic tree can be used to show evolutionary relationships among organisms. Biology is very broad and includes many branches and sub disciplines. Examples include molecular biology, microbiology, neurobiology, zoology, and phytology, amid others.

atom: a basic unit of measurement of matter that cannot be broken down past normal chemical reactions

biology: the report of living organisms and their interactions with one another and their environments

biosphere: a collection of all ecosystems on Earth

prison cell: the smallest fundamental unit of structure and function in living things

community: a fix of populations inhabiting a particular area

ecosystem: all living things in a particular area together with the abiotic, nonliving parts of that environment

eukaryote: an organism with cells that accept nuclei and membrane-jump organelles

evolution: the process of gradual modify in a population that can likewise lead to new species arising from older species

homeostasis: the power of an organism to maintain constant internal weather

macromolecule: a big molecule typically formed by the joining of smaller molecules

molecule: a chemical structure consisting of at least two atoms held together by a chemical bond

organ: a structure formed of tissues operating together to perform a common function

organ system: the higher level of organisation that consists of functionally related organs

organelle: a membrane-bound compartment or sac within a cell

organism: an individual living entity

phylogenetic tree: a diagram showing the evolutionary relationships amidst biological species based on similarities and differences in genetic or physical traits or both

population: all individuals inside a species living within a specific area

prokaryote: a unicellular organism that lacks a nucleus or whatsoever other membrane-spring organelle

tissue: a group of similar cells carrying out the same role

Media Attribution

• Figure 1.two past Ivengo(RUS) © Public Domain
• Figure one.3 past Alex Lomas © CC BY (Attribution)
• Figure i.4 by Pieter & Renée Lanser © CC BY (Attribution)
• Figure one.v past David © CC BY (Attribution)
• Effigy ane.6 past Pacific Southwest Region USFWS © CC Past (Attribution)
• Figure 1.7 by Brian0918 © Public Domain
• Figure one.8
  • "molecule": modification of piece of work by Jane Whitney;
  • "organelles": modification of work by Louisa Howard;
  • "cells": modification of work by Bruce Wetzel, Harry Schaefer, National Cancer Institute;
  • "tissue": modification of piece of work past "Kilbad" © Public Domain
  • "organs": modification of piece of work past Mariana Ruiz Villareal, Joaquim Alves Gaspar;
  • "organisms": modification of work by Peter Dutton;
  • "ecosystem": modification of work by "gigi4791″ © CC By (Attribution)
  • "biosphere": modification of work by NASA © Public Domain
• Figure 1.10
  • EscherichiaColi NIAID: modification of work by Rocky Mountain Laboratories, NIAID, NIH © Public Domain
  • Extremophiles modification of work past Steve Jurvetson © CC BY (Attribution)
  • Sunflower modification of work by Michael Arrighi
  • King of beasts modification of work by Frank Vassen  © CC By (Attribution)
• Effigy 1.12 by Mario Modesto © Public Domain
• Figure one.13 by U.Southward. Ground forces CID Command Public Diplomacy

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