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

Chapter 1: Introduction to Biological science

one.1 Themes and Concepts of Biological science

By the end of this section, you will be able to:

• Identify and describe the backdrop of life
• Describe the levels of organization among living things
• Listing examples of dissimilar sub disciplines in biological science

Watch a video about Evolution past Natural Selection.

Biology is the science that studies life. What exactly is life? This may audio similar a featherbrained question with an obvious answer, but it is not like shooting fish in a barrel to ascertain life. For example, a branch of biology called virology studies viruses, which exhibit some of the characteristics of living entities but lack others. Information technology turns out that although viruses can assail living organisms, cause diseases, and even reproduce, they practise not encounter the criteria that biologists use to define life.

From its earliest beginnings, biology has wrestled with four questions: What are the shared properties that brand something "alive"? How do those various living things role? When faced with the remarkable diversity of life, how do nosotros organize the different kinds of organisms so that we tin can better empathize them? And, finally—what biologists ultimately seek to empathize—how did this multifariousness arise and how is it continuing? Equally new organisms are discovered every day, biologists proceed to seek answers to these and other questions.

Properties of Life

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

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Organisms are highly organized structures that consist of ane or more cells. Even very simple, single-celled organisms are remarkably complex. Within each jail cell, atoms make up molecules. These in turn make up cell components or organelles. Multicellular organisms, which may consist of millions of individual cells, have an reward over single-celled organisms in that their cells tin 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 every bit the heart, lung, or peel in organisms like the toad shown in Figure 1. 2 will be discussed later on.

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

Sensitivity or Response to Stimuli

Organisms respond to diverse stimuli. For example, plants can bend toward a source of light or reply to touch. Even tiny bacteria tin move toward or away from chemicals (a process called chemotaxis) or light (phototaxis). Movement toward a stimulus is considered a positive response, while movement away 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 institute returns to its normal state.

Concept in Action

Lookout this video to run across how the sensitive plant responds to a bear upon stimulus.

Reproduction

Single-celled organisms reproduce by showtime duplicating their Dna, which is the genetic cloth, so dividing it equally as the cell prepares to divide to class two new cells. Many multicellular organisms (those made up of more than one jail cell) produce specialized reproductive cells that volition class new individuals. When reproduction occurs, DNA containing genes is passed along to an organism'due south offspring. These genes are the reason that the offspring will belong to the same species and will have characteristics like to the parent, such as fur color and claret type.

Adaptation

All living organisms exhibit a "fit" to their environment. Biologists refer to this fit every bit adaptation and it is a effect of evolution past natural pick, which operates in every lineage of reproducing organisms. Examples of adaptations are various and unique, from oestrus-resistant Archaea that live 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 enhance the reproductive potential of the individual exhibiting them, including their ability to survive to reproduce. Adaptations are not abiding. As an surround changes, natural selection causes the characteristics of the individuals in a population to track those changes.

Growth and Development

Organisms grow and develop according to specific instructions coded for past their genes. These genes provide instructions that will directly cellular growth and evolution, ensuring that a species' young will grow up to showroom many of the same characteristics equally its parents.

Figure i.4 Although no 2 look alike, these kittens have inherited genes from both parents and share many of the same characteristics.

Regulation

Fifty-fifty 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 example, organ systems such equally the digestive or circulatory systems perform specific functions similar conveying oxygen throughout the body, removing wastes, delivering nutrients to every prison cell, and cooling the torso.

Homeostasis

To function properly, cells require advisable weather such equally proper temperature, pH, and concentrations of diverse chemicals. These weather condition may, however, change from one moment to the adjacent. Organisms are able to maintain internal weather condition within a narrow range most constantly, despite environmental changes, through a procedure called homeostasis or "steady land"—the ability of an organism to maintain constant internal conditions. For example, many organisms regulate their torso temperature in a process known every bit thermoregulation. Organisms that live in common cold climates, such as the polar comport, have body structures that help them withstand low temperatures and conserve body heat. In hot climates, organisms have methods (such every bit perspiration in humans or panting in dogs) that help them to shed excess trunk heat.

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

Energy Processing

All organisms (such as the California condor shown in Effigy 1.six) use a source of energy for their metabolic activities. Some organisms capture energy from the sun and convert it into chemical free energy in nutrient; others use chemic energy from molecules they take in.

Figure 1.vi A lot of energy is required for a California condor to wing. Chemic 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 nearly primal unit of measurement of matter. It consists of a nucleus surrounded past electrons. Atoms grade molecules. A molecule is a chemic structure consisting of at least ii atoms held together by a chemic bond. Many molecules that are biologically important are macromolecules, large 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 functioning of the organism that contains it.

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

Concept in Action

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

Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are pocket-sized structures that exist within cells and perform specialized functions. All living things are made of cells; the prison cell itself is the smallest cardinal unit of structure and function in living organisms. (This requirement is why viruses are not considered living: they are not fabricated of cells. To make new viruses, they have to invade and hijack a living cell; just then can they obtain the materials they need to reproduce.) Some organisms consist of a unmarried jail cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that lack organelles surrounded past a membrane and do not accept nuclei surrounded by nuclear membranes; in contrast, the cells of eukaryotes do 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 mutual office. Organs are present not only in animals but besides in plants. An organ system is a higher level of system that consists of functionally related organs. For example vertebrate animals have many organ systems, such equally the circulatory arrangement that transports blood throughout the body and to and from the lungs; it includes organs such as the center and claret vessels. Organisms are individual living entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and single-celled eukaryotes are as well considered organisms and are typically referred to as microorganisms.

Figure one.8 From an cantlet to the unabridged Earth, biology examines all aspects of life.

Which of the following statements is false?

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

All the individuals of a species living inside a specific area are collectively chosen a population. For example, a forest may include many white pine trees. All of these pine trees represent the population of white pine trees in this forest. Different populations may live in the same specific expanse. For example, the forest with the pine trees includes populations of flowering plants and also 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 grade the forest's customs. The forest itself is an ecosystem. An ecosystem consists of all the living things in a detail area together with the abiotic, or non-living, parts of that environment such every bit 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 temper.

The Diversity of Life

The science of biology is very wide in scope because there is a tremendous variety of life on Earth. The source of this diverseness is development, the process of gradual change during which new species ascend from older species. Evolutionary biologists report the development of living things in everything from the microscopic earth to ecosystems.

In the 18th century, a scientist named Carl Linnaeus start 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 as a genus. Furthermore, similar genera (the plural of genus) are put together within a family. This grouping continues until all organisms are collected together into groups at the highest level. The current taxonomic organisation now has eight levels in its hierarchy, from lowest to highest, they are: species, genus, family unit, social club, form, phylum, kingdom, and domain. Thus species are grouped within genera, genera are grouped within families, families are grouped within orders, and so on.

Effigy 1.nine 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 system since the 1990s. Scientists at present recognize 3 domains of life, the Eukarya, the Archaea, and the Bacteria. The domain Eukarya contains organisms that have cells with nuclei. It includes the kingdoms of fungi, plants, animals, and several kingdoms of protists. The Archaea, are single-celled organisms without nuclei and include many extremophiles that live 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 as the Archaea, were as unlike genetically and biochemically from other bacterial cells as they were from eukaryotes, motivated the recommendation to split life into three domains. This dramatic change in our knowledge of the tree of life demonstrates that classifications are not permanent and will alter when new data becomes available.

In improver to the hierarchical taxonomic organization, Linnaeus was the outset to proper noun organisms using 2 unique names, now called the binomial naming system. Earlier Linnaeus, the use of common names to refer to organisms acquired defoliation because at that place 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 gear up in italics when they are printed. Every species is given a unique binomial which is recognized the world over, so that a scientist in whatsoever location can know which organism is existence referred to. For example, the North American blue jay is known uniquely equally Cyanocitta cristata. Our own species is Homo sapiens.

Figure one.10 These images correspond different domains. The scanning electron micrograph shows (a) bacterial cells belong to the domain Bacteria, while the (b) extremophiles, seen all together every bit colored mats in this hot spring, belong to domain Archaea. Both the (c) sunflower and (d) lion are function of domain Eukarya.

Evolution in Activeness

Carl Woese and the Phylogenetic Tree

The evolutionary relationships of diverse life forms on Earth can exist summarized in a phylogenetic tree. A phylogenetic tree is a diagram showing the evolutionary relationships amid 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 development when, based on scientific evidence, an ancestor is thought to have diverged to form two new species. The length of each branch can be considered equally estimates of relative time.

In the past, biologists grouped living organisms into five kingdoms: animals, plants, fungi, protists, and bacteria. 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 every bit 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 conditions and are called extremophiles. To construct his tree, Woese used genetic relationships rather than similarities based on morphology (shape). Diverse genes were used in phylogenetic studies. Woese'due south tree was constructed from comparative sequencing of the genes that are universally distributed, institute in some slightly altered form in every organism, conserved (meaning that these genes take remained only slightly changed throughout evolution), and of an appropriate length.

Figure 1.11 This phylogenetic tree was constructed by microbiologist Carl Woese using genetic relationships. The tree shows the separation of living organisms into three domains: Bacteria, 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 Study

Spotter a video virtually Scientific discipline and Medicine

The scope 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 than focused field. For instance, molecular biology studies biological processes at the molecular level, including interactions amid molecules such as DNA, RNA, and proteins, besides as the style they are regulated. Microbiology is the written report of the construction and function of microorganisms. Information technology is quite a broad branch itself, and depending on the subject area of study, 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 it is considered a branch of biology, it is also recognized equally an interdisciplinary bailiwick known equally neuroscience. Because of its interdisciplinary nature, this sub subject area studies different functions of the nervous arrangement using molecular, cellular, developmental, medical, and computational approaches.

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

Paleontology, another branch of biology, uses fossils to study life's history. Zoology and botany are the written report of animals and plants, respectively. Biologists can also specialize as biotechnologists, ecologists, or physiologists, to name just a few areas. Biotechnologists apply the cognition of biological science to create useful products. Ecologists study the interactions of organisms in their environments. Physiologists study the workings of cells, tissues and organs. This is just a pocket-sized sample of the many fields that biologists tin pursue. From our own bodies to the world nosotros live in, discoveries in biology tin can affect usa in very direct and important ways. We depend on these discoveries for our health, our food sources, and the benefits provided by our ecosystem. Considering of this, noesis of biology tin benefit us in making decisions in our day-to-day lives.

The development of applied science in the twentieth century that continues today, particularly the engineering to describe and manipulate the genetic cloth, Dna, has transformed biology. This transformation will allow biologists to keep to understand the history of life in greater item, how the homo body works, our human origins, and how humans can survive as a species on this planet despite the stresses acquired by our increasing numbers. Biologists continue to decipher huge mysteries about life suggesting that we have just begun to understand life on the planet, its history, and our human relationship to it. For this and other reasons, the knowledge of biology gained through this textbook and other printed and electronic media should exist a benefit in whichever field you enter.

Forensic Scientist

Forensic science is the application of science to answer questions related to the police force. Biologists as well as chemists and biochemists can exist forensic scientists. Forensic scientists provide scientific show for apply in courts, and their job involves examining trace material associated with crimes. Involvement in forensic scientific discipline has increased in the last few years, possibly because of popular goggle box shows that feature forensic scientists on the task. Too, the evolution of molecular techniques and the establishment of DNA databases have updated the types of work that forensic scientists can exercise. Their job activities are primarily related to crimes confronting people such as murder, rape, and assault. Their work involves analyzing samples such as hair, claret, and other body fluids and also processing DNA found in many different environments and materials. Forensic scientists likewise clarify other biological evidence left at crime scenes, such as insect parts or pollen grains. Students who want to pursue careers in forensic science will almost likely be required to take chemistry and biological science courses besides as some intensive math courses.

Effigy 1.13 This forensic scientist works in a Deoxyribonucleic acid extraction room at the U.S. Army Criminal Investigation Laboratory.

Section Summary

Biology is the scientific discipline of life. All living organisms share several key backdrop 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 as populations, communities, ecosystems, and the biosphere. Development is the source of the tremendous biological variety on Earth today. A diagram called a phylogenetic tree tin can be used to show evolutionary relationships amidst organisms. Biology is very broad and includes many branches and sub disciplines. Examples include molecular biology, microbiology, neurobiology, zoology, and phytology, among others.

atom: a basic unit of matter that cannot be cleaved down by normal chemic reactions

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

biosphere: a collection of all ecosystems on Earth

cell: the smallest central unit of measurement of structure and function in living things

community: a gear up of populations inhabiting a detail area

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

eukaryote: an organism with cells that take nuclei and membrane-bound organelles

development: the procedure of gradual modify in a population that can besides lead to new species arising from older species

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

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

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

organ: a structure formed of tissues operating together to perform a mutual office

organ arrangement: 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 amidst biological species based on similarities and differences in genetic or physical traits or both

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

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

tissue: a grouping of similar cells conveying out the same function

Media Attribution

• Figure 1.two past Ivengo(RUS) © Public Domain
• Figure one.3 past Alex Lomas © CC BY (Attribution)
• Effigy 1.iv by Pieter & Renée Lanser © CC By (Attribution)
• Figure 1.five by David © CC Past (Attribution)
• Figure 1.6 by Pacific Southwest Region USFWS © CC By (Attribution)
• Effigy 1.7 by Brian0918 © Public Domain
• Effigy 1.8
  • "molecule": modification 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 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 BY (Attribution)
  • "biosphere": modification of work by NASA © Public Domain
• Figure 1.ten
  • EscherichiaColi NIAID: modification of work by Rocky Mountain Laboratories, NIAID, NIH © Public Domain
  • Extremophiles modification of work by Steve Jurvetson © CC Past (Attribution)
  • Sunflower modification of piece of work by Michael Arrighi
  • Lion modification of piece of work by Frank Vassen  © CC BY (Attribution)
• Figure one.12 by Mario Modesto © Public Domain
• Figure one.13 by U.South. Army CID Command Public Affairs

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