Reviewing Key Concepts Major Animal Phyla Mastering Biology

Affiliate 1: Introduction to Biology

1.1 Themes and Concepts of Biology

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

• Place and draw the properties of life
• Describe the levels of organisation among living things
• Listing examples of dissimilar sub disciplines in biology

Watch a video about Development by Natural Selection.

Biology is the science that studies life. What exactly is life? This may sound similar a light-headed question with an obvious answer, but it is non easy 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 tin can attack living organisms, cause diseases, and even reproduce, they do not encounter the criteria that biologists employ to define life.

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

Properties of Life

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

Lodge

Organisms are highly organized structures that consist of one or more than cells. Fifty-fifty very elementary, unmarried-celled organisms are remarkably complex. Inside each cell, atoms brand up molecules. These in turn make upwards jail 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 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 every bit the heart, lung, or skin in organisms like the toad shown in Figure i. 2 will be discussed subsequently.

Figure 1.two A toad represents a highly organized structure consisting of cells, tissues, organs, and organ systems.

Sensitivity or Response to Stimuli

Organisms respond to various stimuli. For example, plants can bend toward a source of light or answer to touch on. Even tiny bacteria tin move toward or away from chemicals (a process chosen chemotaxis) or light (phototaxis). Motion toward a stimulus is considered a positive response, while move away from a stimulus is considered a negative response.

 

Figure 1.three The leaves of this sensitive institute (Mimosa pudica) will instantly droop and fold when touched. After a few minutes, the plant returns to its normal state.

Concept in Action

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

Reproduction

Unmarried-celled organisms reproduce past first duplicating their DNA, which is the genetic fabric, and then dividing information technology as as the prison cell prepares to dissever to grade two new cells. Many multicellular organisms (those made up of more one jail cell) produce specialized reproductive cells that volition class new individuals. When reproduction occurs, DNA containing genes is passed forth to an organism'south offspring. These genes are the reason that the offspring will belong to the same species and will accept characteristics like to the parent, such as fur color and blood type.

Accommodation

All living organisms exhibit a "fit" to their surround. Biologists refer to this fit as adaptation and it is a issue of evolution by natural selection, which operates in every lineage of reproducing organisms. Examples of adaptations are various and unique, from heat-resistant Archaea that live in humid hot springs to the natural language 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 power to survive to reproduce. Adaptations are not constant. Equally an environs changes, natural pick causes the characteristics of the individuals in a population to rails those changes.

Growth and Development

Organisms abound and develop according to specific instructions coded for past their genes. These genes provide instructions that will direct cellular growth and development, ensuring that a species' young volition abound up to exhibit many of the same characteristics as its parents.

Figure 1.4 Although no two await alike, these kittens accept 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 as the digestive or circulatory systems perform specific functions like carrying oxygen throughout the body, removing wastes, delivering nutrients to every jail cell, and cooling the torso.

Homeostasis

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

Figure 1.5 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.

Free energy Processing

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

Figure 1.6 A lot of free energy is required for a California condor to fly. Chemical free 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 assistance them identify and locate each private bird.

Levels of Arrangement of Living Things

Living things are highly organized and structured, following a hierarchy on a calibration from small to large. The atom is the smallest and most fundamental unit of matter. It consists of a nucleus surrounded past electrons. Atoms course molecules. A molecule is a chemical construction consisting of at least two atoms held together by a chemical bail. 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 animation of this Deoxyribonucleic acid molecule, click here.

Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are pocket-size structures that exist within cells and perform specialized functions. All living things are made of cells; the cell itself is the smallest cardinal unit of structure and function in living organisms. (This requirement is why viruses are non considered living: they are not made of cells. To make new viruses, they have to invade and hijack a living 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 every bit prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that lack organelles surrounded by a membrane and do not have nuclei surrounded by nuclear membranes; in contrast, the cells of eukaryotes do take membrane-bound organelles and nuclei.

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

Figure 1.8 From an atom to the unabridged Earth, biological science examines all aspects of life.

Which of the following statements is simulated?

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

All the individuals of a species living within a specific area are collectively called a population. For instance, a wood may include many white pine copse. All of these pine trees represent the population of white pine trees in this forest. Dissimilar populations may alive in the aforementioned specific area. For case, the woods with the pine copse 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 form the forest's community. The wood itself is an ecosystem. An ecosystem consists of all the living things in a detail surface area together with the abiotic, or non-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 World. It includes land, water, and portions of the atmosphere.

The Diversity of Life

The science of biological science is very broad in telescopic because there is a tremendous diversity of life on Earth. The source of this diversity is evolution, the process of gradual change during which new species arise from older species. Evolutionary biologists report the development of living things in everything from the microscopic world 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 arrangement, species that are most like to each other are put together inside a group known as 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 electric current taxonomic system now has eight levels in its hierarchy, from lowest to highest, they are: species, genus, family, guild, class, phylum, kingdom, and domain. Thus species are grouped within genera, genera are grouped inside families, families are grouped within orders, and and then on.

Figure 1.9 This diagram shows the levels of taxonomic hierarchy for a dog, 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 now recognize three 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 Leaner are some other quite different group of unmarried-celled organisms without nuclei. Both the Archaea and the Bacteria are prokaryotes, an breezy 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 separate life into 3 domains. This dramatic alter in our cognition of the tree of life demonstrates that classifications are not permanent and will alter when new data becomes available.

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

Figure ane.ten 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 leap, vest to domain Archaea. Both the (c) sunflower and (d) panthera leo are part of domain Eukarya.

Evolution in Activity

Carl Woese and the Phylogenetic Tree

The evolutionary relationships of various life forms on Globe tin 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 equanimous of branch points, or nodes, and branches. The internal nodes correspond 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 co-operative can be considered as 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 1970s has shown, nevertheless, that life on Earth has evolved forth iii lineages, at present called domains—Bacteria, Archaea, and Eukarya. Woese proposed the domain as a new taxonomic level and Archaea equally a new domain, to reverberate 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). Various genes were used in phylogenetic studies. Woese's tree was synthetic from comparative sequencing of the genes that are universally distributed, found in some slightly altered class in every organism, conserved (meaning that these genes take remained only slightly changed throughout development), and of an advisable length.

Figure ane.11 This phylogenetic tree was synthetic past 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 by a membrane and, therefore, are prokaryotes.

Branches of Biological Report

Watch a video most Scientific discipline and Medicine

The scope of biology is wide 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, too as the way they are regulated. Microbiology is the study of the structure and function of microorganisms. It is quite a broad branch itself, and depending on the subject of study, at that place are besides microbial physiologists, ecologists, and geneticists, amongst others.

Another field of biological written report, neurobiology, studies the biological science of the nervous arrangement, and although it is considered a branch of biology, it is also recognized every bit an interdisciplinary field of study known as neuroscience. Because of its interdisciplinary nature, this sub discipline studies different functions of the nervous system using molecular, cellular, developmental, medical, and computational approaches.

Figure ane.12 Researchers piece of work on excavating dinosaur fossils at a site in Castellón, Spain.

Paleontology, another co-operative of biology, uses fossils to study life'southward history. Zoology and phytology are the study of animals and plants, respectively. Biologists tin can also specialize as biotechnologists, ecologists, or physiologists, to name just a few areas. Biotechnologists employ the knowledge of biology to create useful products. Ecologists report the interactions of organisms in their environments. Physiologists written report the workings of cells, tissues and organs. This is just a small-scale sample of the many fields that biologists tin can pursue. From our own bodies to the globe nosotros live in, discoveries in biology can impact usa in very directly and important ways. We depend on these discoveries for our wellness, our food sources, and the benefits provided past our ecosystem. Because of this, knowledge of biological science can benefit u.s.a. in making decisions in our day-to-day lives.

The evolution of technology in the twentieth century that continues today, especially the technology to depict and manipulate the genetic material, Deoxyribonucleic acid, has transformed biology. This transformation will permit biologists to go along to sympathize the history of life in greater item, how the human trunk 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 about life suggesting that nosotros have simply begun to understand life on the planet, its history, and our relationship to information technology. For this and other reasons, the cognition of biology gained through this textbook and other printed and electronic media should be a do good in whichever field you enter.

Forensic Scientist

Forensic science is the application of science to respond questions related to the law. Biologists equally well as chemists and biochemists can be forensic scientists. Forensic scientists provide scientific evidence for employ in courts, and their job involves examining trace cloth associated with crimes. Involvement in forensic science has increased in the last few years, possibly considering of popular tv set shows that feature forensic scientists on the task. As well, the evolution of molecular techniques and the establishment of DNA databases have updated the types of work that forensic scientists tin do. Their task activities are primarily related to crimes against people such as murder, rape, and set on. Their piece of work involves analyzing samples such as hair, blood, and other body fluids and besides processing Dna plant in many different environments and materials. Forensic scientists also clarify other biological show left at criminal offense scenes, such equally insect parts or pollen grains. Students who want to pursue careers in forensic scientific discipline will about probable be required to accept chemical science and biological science courses equally well as some intensive math courses.

Figure 1.13 This forensic scientist works in a DNA extraction room at the U.Southward. Army Criminal Investigation Laboratory.

Section Summary

Biology is the science of life. All living organisms share several primal backdrop such equally order, sensitivity or response to stimuli, reproduction, adaptation, growth and development, regulation, homeostasis, and energy processing. Living things are highly organized post-obit 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 diversity on Earth today. A diagram called a phylogenetic tree can exist used to bear witness evolutionary relationships among organisms. Biological science is very broad and includes many branches and sub disciplines. Examples include molecular biology, microbiology, neurobiology, zoology, and botany, amid others.

atom: a bones unit of affair that cannot exist broken down by normal chemical reactions

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

biosphere: a drove of all ecosystems on Earth

cell: the smallest primal unit of structure and role in living things

customs: a set of populations inhabiting a particular surface area

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

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

evolution: the procedure of gradual alter in a population that tin also lead to new species arising from older species

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

macromolecule: a large 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 mutual part

organ organization: the higher level of organization that consists of functionally related organs

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

organism: an individual living entity

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

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

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

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

Media Attribution

• Figure 1.2 by Ivengo(RUS) © Public Domain
• Figure 1.3 by Alex Lomas © CC BY (Attribution)
• Figure 1.4 by Pieter & Renée Lanser © CC By (Attribution)
• Effigy one.v by David © CC BY (Attribution)
• Figure 1.half-dozen by Pacific Southwest Region USFWS © CC Past (Attribution)
• Figure 1.7 by Brian0918 © Public Domain
• Figure 1.8
  • "molecule": modification of work by Jane Whitney;
  • "organelles": modification of work past Louisa Howard;
  • "cells": modification of work by Bruce Wetzel, Harry Schaefer, National Cancer Constitute;
  • "tissue": modification of piece of work past "Kilbad" © Public Domain
  • "organs": modification of work past Mariana Ruiz Villareal, Joaquim Alves Gaspar;
  • "organisms": modification of piece of work by Peter Dutton;
  • "ecosystem": modification of work by "gigi4791″ © CC Past (Attribution)
  • "biosphere": modification of work by NASA © Public Domain
• Figure ane.ten
  • EscherichiaColi NIAID: modification of piece of work past Rocky Mountain Laboratories, NIAID, NIH © Public Domain
  • Extremophiles modification of work by Steve Jurvetson © CC Past (Attribution)
  • Sunflower modification of work by Michael Arrighi
  • Lion modification of work by Frank Vassen  © CC BY (Attribution)
• Figure 1.12 by Mario Modesto © Public Domain
• Effigy 1.xiii by U.S. Army CID Command Public Affairs

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