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

Affiliate ane: Introduction to Biological science

i.1 Themes and Concepts of Biology

By the end of this department, you volition be able to:

• Identify and depict the properties of life
• Describe the levels of organization amidst living things
• List examples of different sub disciplines in biological science

Watch a video well-nigh Evolution by Natural Selection.

Biological science is the science that studies life. What exactly is life? This may sound like a featherbrained question with an obvious answer, merely it is not piece of cake to define life. For example, a branch of biology called virology studies viruses, which exhibit some of the characteristics of living entities but lack others. It turns out that although viruses can attack living organisms, cause diseases, and fifty-fifty reproduce, they practise not meet the criteria that biologists utilize to define life.

From its earliest beginnings, biology has wrestled with four questions: What are the shared properties that make something "alive"? How exercise those various living things role? When faced with the remarkable diversity of life, how do we organize the different kinds of organisms then that we tin can better understand them? And, finally—what biologists ultimately seek to understand—how did this diverseness ascend and how is it continuing? As new organisms are discovered every day, biologists go on to seek answers to these and other questions.

Properties of Life

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

Society

Organisms are highly organized structures that consist of one or more cells. Even very simple, single-celled organisms are remarkably complex. Within each jail cell, atoms brand upwards molecules. These in turn make up prison cell components or organelles. Multicellular organisms, which may consist of millions of individual cells, take an reward over single-celled organisms in that their cells can be specialized to perform specific functions, and fifty-fifty sacrificed in sure situations for the adept of the organism every bit a whole. How these specialized cells come together to form organs such every bit the eye, lung, or skin in organisms like the toad shown in Effigy ane. 2 will exist discussed later.

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

Sensitivity or Response to Stimuli

Organisms reply to various stimuli. For instance, plants tin can bend toward a source of light or reply to bear on. Even tiny leaner can movement toward or away from chemicals (a process called chemotaxis) or light (phototaxis). Movement toward a stimulus is considered a positive response, while movement abroad from a stimulus is considered a negative response.

 

Figure 1.3 The leaves of this sensitive plant (Mimosa pudica) will instantly droop and fold when touched. Afterward a few minutes, the plant returns to its normal country.

Concept in Activeness

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

Reproduction

Unmarried-celled organisms reproduce by first duplicating their DNA, which is the genetic material, and then dividing it equally every bit the cell prepares to dissever to form two new cells. Many multicellular organisms (those made up of more than one prison cell) produce specialized reproductive cells that will course new individuals. When reproduction occurs, Dna containing genes is passed forth to an organism's offspring. These genes are the reason that the offspring will vest to the aforementioned species and will have characteristics similar to the parent, such as fur color and blood type.

Adaptation

All living organisms exhibit a "fit" to their environment. Biologists refer to this fit as adaptation and information technology is a consequence of evolution past natural selection, which operates in every lineage of reproducing organisms. Examples of adaptations are various and unique, from estrus-resistant Archaea that live in boiling hot springs to the tongue length of a nectar-feeding moth that matches the size of the flower from which it feeds. All adaptations enhance the reproductive potential of the private exhibiting them, including their ability to survive to reproduce. Adaptations are not constant. As an environment changes, natural selection causes the characteristics of the individuals in a population to track those changes.

Growth and Development

Organisms grow and develop co-ordinate to specific instructions coded for past their genes. These genes provide instructions that volition direct cellular growth and development, ensuring that a species' young will grow up to showroom many of the aforementioned characteristics equally its parents.

Figure 1.4 Although no 2 look akin, 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 ecology stresses. For case, organ systems such equally the digestive or circulatory systems perform specific functions similar conveying oxygen throughout the body, removing wastes, delivering nutrients to every jail cell, and cooling the body.

Homeostasis

To role properly, cells require appropriate conditions such as proper temperature, pH, and concentrations of diverse chemicals. These weather may, yet, modify from one moment to the next. Organisms are able to maintain internal conditions within a narrow range nigh constantly, despite ecology changes, through a procedure called homeostasis or "steady state"—the ability of an organism to maintain constant internal conditions. For example, many organisms regulate their trunk temperature in a process known as thermoregulation. Organisms that live in common cold climates, such as the polar bear, accept 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 aid them to shed excess body oestrus.

Figure 1.5 Polar bears and other mammals living in ice-covered regions maintain their body temperature by generating heat and reducing oestrus loss through thick fur and a dense layer of fatty nether their skin.

Energy Processing

All organisms (such equally the California condor shown in Figure i.half-dozen) use a source of energy for their metabolic activities. Some organisms capture energy from the sun and convert it into chemic energy in food; others use chemical energy from molecules they take in.

Figure 1.half-dozen A lot of free energy is required for a California condor to fly. Chemical energy derived from food is used to power flight. California condors are an endangered species; scientists have strived to place a wing tag on each bird to help them identify and locate each individual bird.

Levels of Organization of Living Things

Living things are highly organized and structured, following a hierarchy on a scale from small to large. The atom is the smallest and virtually fundamental unit of affair. Information technology consists of a nucleus surrounded by electrons. Atoms course molecules. A molecule is a chemical structure consisting of at to the lowest degree 2 atoms held together past a chemical bond. Many molecules that are biologically important are macromolecules, big molecules that are typically formed by combining smaller units called monomers. An example of a macromolecule is deoxyribonucleic acid (Dna), which contains the instructions for the performance of the organism that contains it.

Effigy 1.7 A molecule, like this big DNA molecule, is composed of atoms.

Concept in Action

To run into 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 fabricated of cells; the prison cell itself is the smallest cardinal unit of measurement of structure and office in living organisms. (This requirement is why viruses are non considered living: they are non fabricated of cells. To make new viruses, they have to invade and hijack a living jail cell; only then tin they obtain the materials they need to reproduce.) Some organisms consist of a single jail cell and others are multicellular. Cells are classified equally prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that lack organelles surrounded by a membrane and practise non have nuclei surrounded past nuclear membranes; in dissimilarity, the cells of eukaryotes exercise have membrane-spring organelles and nuclei.

In most multicellular organisms, cells combine to make tissues, which are groups of similar cells carrying out the aforementioned office. Organs are collections of tissues grouped together based on a common office. Organs are nowadays not but 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 equally the circulatory system that transports blood throughout the body and to and from the lungs; it includes organs such as the middle and blood vessels. Organisms are individual living entities. For example, each tree in a wood is an organism. Single-celled prokaryotes and unmarried-celled eukaryotes are also considered organisms and are typically referred to as microorganisms.

Effigy one.8 From an cantlet to the entire World, biological science examines all aspects of life.

Which of the following statements is false?

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

All the individuals of a species living within a specific area are collectively called a population. For case, a forest may include many white pino copse. All of these pine trees represent the population of white pine trees in this forest. Different populations may live in the aforementioned specific area. For example, the woods with the pine trees includes populations of flowering plants and likewise insects and microbial populations. A community is the set of populations inhabiting a particular area. For instance, all of the trees, flowers, insects, and other populations in a forest form the woods's community. The forest itself is an ecosystem. An ecosystem consists of all the living things in a particular area together with the abiotic, or not-living, parts of that environment such as nitrogen in the soil or rainwater. At the highest level of organization, the biosphere is the collection of all ecosystems, and it represents the zones of life on Earth. It includes land, water, and portions of the atmosphere.

The Diversity of Life

The science of biology is very broad in scope because in that location is a tremendous diversity of life on Globe. The source of this variety is evolution, the process of gradual change during which new species ascend from older species. Evolutionary biologists study the evolution of living things in everything from the microscopic globe to ecosystems.

In the 18th century, a scientist named Carl Linnaeus first proposed organizing the known species of organisms into a hierarchical taxonomy. In this system, species that are most similar to each other are put together within a grouping known every bit a genus. Furthermore, similar 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 organization now has eight levels in its hierarchy, from lowest to highest, they are: species, genus, family, 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 1.9 This diagram shows the levels of taxonomic hierarchy for a dog, from the broadest category—domain—to the about specific—species.

The highest level, domain, is a relatively new addition to the system since the 1990s. Scientists now recognize iii domains of life, the Eukarya, the Archaea, and the Leaner. 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 live in harsh environments like hot springs. The Leaner are some other quite dissimilar group of single-celled organisms without nuclei. Both the Archaea and the Bacteria are prokaryotes, an informal proper noun for cells without nuclei. The recognition in the 1990s that certain "bacteria," at present known equally the Archaea, were as different genetically and biochemically from other bacterial cells as they were from eukaryotes, motivated the recommendation to split up life into three domains. This dramatic change in our knowledge of the tree of life demonstrates that classifications are not permanent and will change when new information becomes bachelor.

In addition to the hierarchical taxonomic system, Linnaeus was the starting time to name organisms using two unique names, now called the binomial naming organization. Before Linnaeus, the employ of common names to refer to organisms caused confusion because in that location were regional differences in these common names. Binomial names consist of the genus proper name (which is capitalized) and the species name (all lower-case). Both names are ready in italics when they are printed. Every species is given a unique binomial which is recognized the world over, and so that a scientist in whatever location tin can know which organism is being referred to. For example, the Due north American blue jay is known uniquely every bit Cyanocitta cristata. Our ain species is Homo sapiens.

Figure i.x These images represent 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 role of domain Eukarya.

Development in Action

Carl Woese and the Phylogenetic Tree

The evolutionary relationships of various life forms on Earth 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 physical traits or both. A phylogenetic tree is composed of branch points, or nodes, and branches. The internal nodes represent ancestors and are points in evolution when, based on scientific prove, an ancestor is idea to have diverged to grade two new species. The length of each branch can be considered as estimates of relative time.

In the past, biologists grouped living organisms into 5 kingdoms: animals, plants, fungi, protists, and leaner. The pioneering work of American microbiologist Carl Woese in the early on 1970s has shown, however, that life on Earth has evolved along three lineages, now called domains—Bacteria, Archaea, and Eukarya. Woese proposed the domain equally a new taxonomic level and Archaea as a new domain, to reflect the new phylogenetic tree. Many organisms belonging to the Archaea domain live under extreme weather 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, establish in some slightly contradistinct form in every organism, conserved (meaning that these genes have remained only slightly changed throughout evolution), and of an appropriate length.

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

Branches of Biological Report

Watch a video about 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 piece of work in a more focused field. For case, molecular biology studies biological processes at the molecular level, including interactions among molecules such as Deoxyribonucleic acid, RNA, and proteins, as well every bit the way they are regulated. Microbiology is the study of the structure and function of microorganisms. Information technology is quite a broad branch itself, and depending on the subject of report, in that location are also microbial physiologists, ecologists, and geneticists, amid others.

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

Effigy 1.12 Researchers work on excavating dinosaur fossils at a site in Castellón, Spain.

Paleontology, another branch of biology, uses fossils to study life'south history. Zoology and botany are the study of animals and plants, respectively. Biologists can likewise specialize equally biotechnologists, ecologists, or physiologists, to name simply a few areas. Biotechnologists utilise the knowledge of biology to create useful products. Ecologists report the interactions of organisms in their environments. Physiologists report the workings of cells, tissues and organs. This is just a small sample of the many fields that biologists can pursue. From our own bodies to the world nosotros live in, discoveries in biological science can affect the states in very directly and important ways. We depend on these discoveries for our health, our food sources, and the benefits provided past our ecosystem. Because of this, knowledge of biological science can benefit us in making decisions in our solar day-to-day lives.

The development of technology in the twentieth century that continues today, particularly the applied science to describe and dispense the genetic textile, Deoxyribonucleic acid, has transformed biological science. This transformation will let biologists to go along 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 go on to decipher huge mysteries near life suggesting that nosotros take simply begun to sympathize life on the planet, its history, and our relationship to information technology. For this and other reasons, the knowledge of biological science gained through this textbook and other printed and electronic media should be a benefit in whichever field you enter.

Forensic Scientist

Forensic science is the application of science to answer questions related to the law. Biologists too as chemists and biochemists can be forensic scientists. Forensic scientists provide scientific evidence for employ in courts, and their chore involves examining trace material associated with crimes. Interest in forensic science has increased in the last few years, possibly because of popular television set shows that feature forensic scientists on the job. Too, the development of molecular techniques and the establishment of DNA databases have updated the types of work that forensic scientists can practise. Their job activities are primarily related to crimes confronting people such as murder, rape, and set on. Their work involves analyzing samples such as hair, blood, and other body fluids and likewise processing DNA plant in many dissimilar environments and materials. Forensic scientists as well analyze other biological testify left at crime scenes, such as insect parts or pollen grains. Students who want to pursue careers in forensic science volition nearly probable be required to have chemistry and biology courses as well as some intensive math courses.

Effigy i.thirteen This forensic scientist works in a Dna extraction room at the U.Southward. 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 hierarchy that includes atoms, molecules, organelles, cells, tissues, organs, and organ systems. Organisms, in turn, are grouped equally populations, communities, ecosystems, and the biosphere. Development is the source of the tremendous biological diverseness on Globe today. A diagram called a phylogenetic tree can be used to bear witness evolutionary relationships amid organisms. Biology is very broad and includes many branches and sub disciplines. Examples include molecular biology, microbiology, neurobiology, zoology, and botany, amid others.

cantlet: a bones unit of matter that cannot be cleaved downward past normal chemical reactions

biology: the study of living organisms and their interactions with 1 another and their environments

biosphere: a collection of all ecosystems on Earth

cell: the smallest fundamental unit of construction and office in living things

community: a set of populations inhabiting a item area

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

eukaryote: an organism with cells that have nuclei and membrane-spring organelles

development: the process of gradual change in a population that can besides atomic number 82 to new species arising from older species

homeostasis: the ability of an organism to maintain constant internal conditions

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

molecule: a chemical construction consisting of at to the lowest degree two atoms held together by a chemical bail

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

organ system: the higher level of organization 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 among biological species based on similarities and differences in genetic or concrete traits or both

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

prokaryote: a unicellular organism that lacks a nucleus or any other membrane-bound organelle

tissue: a grouping of similar cells carrying out the aforementioned function

Media Attribution

• Effigy one.2 by Ivengo(RUS) © Public Domain
• Figure 1.3 by Alex Lomas © CC BY (Attribution)
• Figure 1.4 by Pieter & Renée Lanser © CC BY (Attribution)
• Figure one.5 past David © CC BY (Attribution)
• Figure 1.6 by Pacific Southwest Region USFWS © CC BY (Attribution)
• Figure i.7 by Brian0918 © Public Domain
• Figure 1.eight
  • "molecule": modification of work past Jane Whitney;
  • "organelles": modification of work by Louisa Howard;
  • "cells": modification of work by Bruce Wetzel, Harry Schaefer, National Cancer Institute;
  • "tissue": modification of work by "Kilbad" © Public Domain
  • "organs": modification of work past Mariana Ruiz Villareal, Joaquim Alves Gaspar;
  • "organisms": modification of work by Peter Dutton;
  • "ecosystem": modification of work by "gigi4791″ © CC Past (Attribution)
  • "biosphere": modification of work by NASA © Public Domain
• Effigy 1.ten
  • EscherichiaColi NIAID: modification of piece of work by Rocky Mountain Laboratories, NIAID, NIH © Public Domain
  • Extremophiles modification of work by Steve Jurvetson © CC By (Attribution)
  • Sunflower modification of work by Michael Arrighi
  • King of beasts modification of work by Frank Vassen  © CC Past (Attribution)
• Figure 1.12 past Mario Modesto © Public Domain
• Effigy 1.13 by U.South. Regular army CID Command Public Affairs