{"id":70,"date":"2019-06-17T17:47:10","date_gmt":"2019-06-17T21:47:10","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/chapter\/2-3-basic-principles-of-biology\/"},"modified":"2022-01-19T15:39:43","modified_gmt":"2022-01-19T20:39:43","slug":"2-3-basic-principles-of-biology","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/chapter\/2-3-basic-principles-of-biology\/","title":{"raw":"2.3\u00a0Basic Principles of Biology","rendered":"2.3\u00a0Basic Principles of Biology"},"content":{"raw":"Created by CK-12\/Adapted by Christine Miller\n<h1 style=\"margin-top: 2.14286em;margin-bottom: 1.42857em;line-height: 1.28571em\">Why Are Humans Such Sweaty\u00a0Animals?<\/h1>\n[caption id=\"attachment_69\" align=\"alignright\" width=\"300\"]<img class=\"wp-image-68 size-medium\" title=\"Photo by Hans Reniers on Unsplash\" src=\"https:\/\/pressbooks.bccampus.ca\/testclone1\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-300x200.jpg\" alt=\"Image shows a close-up view of the upper portion of a person's face. The person's skin shows redness due to heat and beads of sweat on their brow.\" width=\"300\" height=\"200\"> <em>Figure 2.3.1 Humans sweat to lower their body temperature.<\/em>[\/caption]\n\nCombine\u00a0exercise\u00a0and a hot day, and you get sweat \u2014 and lots of it. Sweating is one of the adaptations humans have evolved to maintain\u00a0homeostasis, or a constant internal environment. When sweat evaporates from the skin, it uses up some of the excess\u00a0heat\u00a0energy\u00a0on the skin, thus helping to reduce the body's\u00a0temperature. Humans are among the sweatiest of all\u00a0species, with a fine-tuned ability to maintain a steady internal temperature, even at very high outside temperatures.\n<div>\n<h1>Unifying Principles of Biology<\/h1>\n<\/div>\nAll living things have mechanisms for\u00a0homeostasis. Homeostasis is one of four basic principles or\u00a0theories\u00a0that explain the structure and function of all\u00a0species\u00a0(including our own)<em>.<\/em>\u00a0Whether biologists are interested in ancient life, the life of\u00a0bacteria, or how humans could live on\u00a0Mars, they\u00a0base\u00a0their understanding of biology on these unifying principles:\n<ul>\n \t<li>[pb_glossary id=\"1327\"]<strong>Cell theory<\/strong>[\/pb_glossary]<\/li>\n \t<li>[pb_glossary id=\"1327\"]<strong>Gene theory<\/strong>[\/pb_glossary]<\/li>\n \t<li>[pb_glossary id=\"1346\"]<strong>Homeostasis<\/strong>[\/pb_glossary]<\/li>\n \t<li>[pb_glossary id=\"1935\"]Evolutionary theory[\/pb_glossary]<\/li>\n<\/ul>\n<h2>Cell Theory<\/h2>\nAccording to\u00a0<strong>[pb_glossary id=\"1327\"]cell theory[\/pb_glossary]<\/strong>, all living things are made of\u00a0cells, and living cells come only from\u00a0<em>other<\/em>\u00a0living\u00a0cells. Each living thing begins life as a single cell. Some living things, including\u00a0bacteria, remain single-celled. Other living things, including plants and\u00a0animals, grow and develop into many cells. Your own body is made up of an amazing 100 trillion cells. But even you \u2014 like all other living things \u2014 began life as a single cell.\n\nWatch this TED-Ed video about the origin of cell theory:\n\nhttps:\/\/www.youtube.com\/watch?v=4OpBylwH9DU\n<div class=\"textbox textbox--sidebar textbox--key-takeaways\"><\/div>\n<p style=\"text-align: center\">The Wacky History of Cell Theory - Lauren Royal-Woods, TED-Ed, 2012<\/p>\n\n<h2>Gene Theory<\/h2>\n<strong>[pb_glossary id=\"1347\"]Gene theory[\/pb_glossary]<\/strong>\u00a0is the idea that the characteristics of living things are controlled by genes, which are passed from parents to their offspring. Genes are located on larger structures called\u00a0chromosomes. Chromosomes are found inside every cell, and they consist of molecules of\u00a0DNA\u00a0(deoxyribonucleic acid). Those molecules of DNA are encoded with instructions that \"tell\"\u00a0cells\u00a0how to behave.\n<h2>Homeostasis<\/h2>\n<strong>[pb_glossary id=\"1346\"]Homeostasis[\/pb_glossary]<\/strong>, or the condition in which a system is maintained in a more-or-less steady state, is a characteristic of individual living things, like the human ability to sweat. Homeostasis also applies to the entire biosphere, wherever life is found on Earth. Consider the concentration of oxygen in Earth's atmosphere. Oxygen makes up 21 per cent of the atmosphere, and this concentration is fairly constant. What maintains this homeostasis in the atmosphere? The answer is\u00a0<em>living things<\/em>.\n\nMost living things need oxygen to survive, so they remove oxygen from the air. On the other hand, many living things, including plants, give off oxygen when they\u00a0convert carbon dioxide and\u00a0water\u00a0to food in the process of\u00a0photosynthesis.\u00a0These two processes balance out so the air maintains a constant level of oxygen.\n<h2>Evolutionary Theory<\/h2>\n[caption id=\"attachment_69\" align=\"alignleft\" width=\"301\"]<img class=\"wp-image-69 \" src=\"https:\/\/pressbooks.bccampus.ca\/testclone1\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-300x178.jpg\" alt=\"A chameleon on a branch, surrounded by foliage. The chameleon is camouflaged to blend into its surroundings.\" width=\"301\" height=\"179\"> <em>Figure 2.3.2 A chameleon exhibits its colour changing adaptation to match its background.<\/em>[\/caption]\n\n<strong>[pb_glossary id=\"1246\"]Evolution[\/pb_glossary]<\/strong>\u00a0is a change in the characteristics of populations of living things over time. Evolution can occur by a process called\u00a0<strong>[pb_glossary id=\"1547\"]natural selection[\/pb_glossary]<\/strong><strong>,\u00a0<\/strong>which<strong>\u00a0<\/strong>results from random genetic\u00a0mutations\u00a0in a\u00a0population. If these mutations lead to changes that allow\u00a0the living things\u00a0to better survive, then their chances of surviving and reproducing\u00a0in a given environment increase. They will then\u00a0pass more genes to the next generation. Over many generations, this can lead to major changes in the characteristics of those living things. Evolution explains how living things are changing today, as well as how modern living things descended from ancient life forms that no longer exist on Earth.\n\nTraits that help living things survive and reproduce in a given environment are called\u00a0[pb_glossary id=\"1397\"]<strong>adaptation<span style=\"font-size: 1em\">s<\/span><\/strong><span style=\"text-align: initial;font-size: 1em\">[\/pb_glossary]<\/span><span style=\"text-align: initial;font-size: 1em\">. You can see an obvious adaptation in the image below. The chameleon is famous for its ability to change its colour to match its background as camouflage. Using camouflage, the chameleon can hide in plain sight.<\/span>\n<h1><span style=\"font-size: 1.266em;font-style: italic;font-weight: bold\">Feature: Myth vs. Reality<\/span><\/h1>\nMisconceptions about evolution are common. They include the following myths:\n<table class=\"grid\" style=\"border-collapse: collapse;width: 100%;height: 243px\" border=\"0\">\n<tbody>\n<tr style=\"height: 50px\">\n<td style=\"width: 30.058%;height: 50px\">\n<h2><span style=\"color: #ff0000\">Myth<\/span><\/h2>\n<\/td>\n<td style=\"width: 69.942%;height: 50px\">\n<h2><span style=\"color: #339966\">Reality<\/span><\/h2>\n<\/td>\n<\/tr>\n<tr style=\"height: 60px\">\n<td style=\"width: 30.058%;height: 60px\"><em>\"Evolution is \"just\" a theory or educated guess.\"<\/em><\/td>\n<td style=\"width: 69.942%;height: 60px\"><strong>Scientists accept evolutionary theory as the best explanation for the\u00a0diversity of life\u00a0on Earth because of the large body of scientific evidence supporting it. Like any\u00a0scientific theory, evolution is a broad, evidence-supported explanation for multiple phenomena.<\/strong><\/td>\n<\/tr>\n<tr style=\"height: 45px\">\n<td style=\"width: 30.058%;height: 45px\"><em>\"The theory of evolution explains how life on Earth began.\"<\/em><\/td>\n<td style=\"width: 69.942%;height: 45px\"><strong>The\u00a0theory of evolution\u00a0explains how life\u00a0<em>changed<\/em>\u00a0on Earth after it began.<\/strong><\/td>\n<\/tr>\n<tr style=\"height: 60px\">\n<td style=\"width: 30.058%;height: 60px\"><em>\"The theory of evolution means that humans evolved from apes like those in zoos.\"<\/em><\/td>\n<td style=\"width: 69.942%;height: 60px\"><strong>Humans and modern apes both evolved from a common ape-like ancestor millions of years ago.<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">2.3 Summary<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n \t<li>Four basic principles or theories unify all fields of biology: cell theory, gene theory, homeostasis, and evolutionary theory.<\/li>\n \t<li>According to cell theory, all living things are made of cells and come from other living cells.<\/li>\n \t<li>Gene theory states that the characteristics of living things are controlled by genes that pass from parents to offspring.<\/li>\n \t<li>All living things strive to maintain internal balance, or [pb_glossary id=\"1346\"]<strong>homeostasis<\/strong>[\/pb_glossary].<\/li>\n \t<li>The characteristics of populations of living things change over time through the process of micro-evolution as organisms acquire adaptations, or traits that better suit them to a given environment.<\/li>\n<\/ul>\nUse the flashcards below to review the four principles:\n\n[h5p id=\"9\"]\n\n<\/div>\n<\/div>\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">2.3 Review Questions<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ol>\n \t<li>[h5p id=\"10\"]<\/li>\n \t<li>How does sweating help the human body maintain homeostasis?<\/li>\n \t<li>Explain\u00a0cell theory and gene theory.<\/li>\n \t<li>Describe an example of homeostasis in the atmosphere.<\/li>\n \t<li>Describe how you can apply the concepts of evolution,natural selection, adaptation, and homeostasis to the human ability to sweat.<\/li>\n \t<li>Which of the four unifying principles of biology is primarily concerned with:\n<ul>\n \t<li>how DNA is passed down to offspring?<\/li>\n \t<li>how internal balance is maintained?<\/li>\n<\/ul>\n<\/li>\n \t<li>_____________ are located on ______________.\n<ul>\n \t<li>chromosomes; genes<\/li>\n \t<li>genes;chromosomes<\/li>\n \t<li>genes; traits<\/li>\n \t<li>none of the above<\/li>\n<\/ul>\n<\/li>\n \t<li>Define an adaptation and give one example.<\/li>\n \t<li>Explain how gene theory and evolutionary theory relate to each other.<\/li>\n \t<li>Does evolution by\u00a0natural selection occur within one generation? Why or why not?<\/li>\n \t<li>Explain why you think chameleons evolved the ability to change their colour to match their background, as well as how natural selection may have acted on the ancestors of chameleons to produce this adaptation.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">2.3 Explore More<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n\nhttps:\/\/www.youtube.com\/watch?v=Wg5DBH6uMCw&amp;amp;amp;feature=emb_logo\n<p style=\"text-align: center\">Myths and misconceptions about evolution - Alex Gendler, TEDEd, 2013<\/p>\n\n<\/div>\n<\/div>\n<h2>Attributions<\/h2>\n<strong>Figure 2.3.1<\/strong>\n\n<a href=\"https:\/\/unsplash.com\/photos\/mE6e5-5jLu8\">Photo<\/a><a href=\"https:\/\/unsplash.com\/photos\/mE6e5-5jLu8\">(perspiration)<\/a>, by <a href=\"https:\/\/unsplash.com\/@hansreniers\">Hans Reniers<\/a> on <a href=\"https:\/\/unsplash.com\/\">Unsplash<\/a>. is used under the <a href=\"https:\/\/unsplash.com\/license\">Unsplash license<\/a> (https:\/\/unsplash.com\/license).\n\n<strong>Figure 2.3.2<\/strong>\n\n<a href=\"https:\/\/pixabay.com\/photos\/chameleon-mediterranean-chameleon-1240928\/\">Mediterranean Chameleon Reptile Lizard<\/a>, by <a href=\"https:\/\/pixabay.com\/users\/1588877-1588877\/\">user:1588877<\/a> on <a href=\"https:\/\/www.maxpixel.net\/\">Pixabay<\/a>, is used under the <a href=\"https:\/\/pixabay.com\/service\/license\/\">Pixabay\u00a0license<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).\n<h2><strong>References<\/strong><\/h2>\n<p class=\"hanging-indent\">TED-Ed. (2012, June 4). The wacky history of cell theory - Lauren Royal-Woods. YouTube. https:\/\/www.youtube.com\/watch?v=4OpBylwH9DU&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED-Ed. (2013, July 8). Myths and misconceptions about evolution - Alex Gendler. YouTube. https:\/\/www.youtube.com\/watch?v=mZt1Gn0R22Q&amp;t=10s<\/p>\n&nbsp;","rendered":"<p>Created by CK-12\/Adapted by Christine Miller<\/p>\n<h1 style=\"margin-top: 2.14286em;margin-bottom: 1.42857em;line-height: 1.28571em\">Why Are Humans Such Sweaty\u00a0Animals?<\/h1>\n<figure id=\"attachment_69\" aria-describedby=\"caption-attachment-69\" style=\"width: 300px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-68 size-medium\" title=\"Photo by Hans Reniers on Unsplash\" src=\"https:\/\/pressbooks.bccampus.ca\/testclone1\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-300x200.jpg\" alt=\"Image shows a close-up view of the upper portion of a person's face. The person's skin shows redness due to heat and beads of sweat on their brow.\" width=\"300\" height=\"200\" srcset=\"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-300x200.jpg 300w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-1024x683.jpg 1024w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-768x512.jpg 768w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-65x43.jpg 65w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-225x150.jpg 225w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty-350x233.jpg 350w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2019\/06\/sweaty.jpg 1350w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-69\" class=\"wp-caption-text\"><em>Figure 2.3.1 Humans sweat to lower their body temperature.<\/em><\/figcaption><\/figure>\n<p>Combine\u00a0exercise\u00a0and a hot day, and you get sweat \u2014 and lots of it. Sweating is one of the adaptations humans have evolved to maintain\u00a0homeostasis, or a constant internal environment. When sweat evaporates from the skin, it uses up some of the excess\u00a0heat\u00a0energy\u00a0on the skin, thus helping to reduce the body&#8217;s\u00a0temperature. Humans are among the sweatiest of all\u00a0species, with a fine-tuned ability to maintain a steady internal temperature, even at very high outside temperatures.<\/p>\n<div>\n<h1>Unifying Principles of Biology<\/h1>\n<\/div>\n<p>All living things have mechanisms for\u00a0homeostasis. Homeostasis is one of four basic principles or\u00a0theories\u00a0that explain the structure and function of all\u00a0species\u00a0(including our own)<em>.<\/em>\u00a0Whether biologists are interested in ancient life, the life of\u00a0bacteria, or how humans could live on\u00a0Mars, they\u00a0base\u00a0their understanding of biology on these unifying principles:<\/p>\n<ul>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1327\"><strong>Cell theory<\/strong><\/a><\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1327\"><strong>Gene theory<\/strong><\/a><\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1346\"><strong>Homeostasis<\/strong><\/a><\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1935\">Evolutionary theory<\/a><\/li>\n<\/ul>\n<h2>Cell Theory<\/h2>\n<p>According to\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1327\">cell theory<\/a><\/strong>, all living things are made of\u00a0cells, and living cells come only from\u00a0<em>other<\/em>\u00a0living\u00a0cells. Each living thing begins life as a single cell. Some living things, including\u00a0bacteria, remain single-celled. Other living things, including plants and\u00a0animals, grow and develop into many cells. Your own body is made up of an amazing 100 trillion cells. But even you \u2014 like all other living things \u2014 began life as a single cell.<\/p>\n<p>Watch this TED-Ed video about the origin of cell theory:<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"The wacky history of cell theory - Lauren Royal-Woods\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/4OpBylwH9DU?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<div class=\"textbox textbox--sidebar textbox--key-takeaways\"><\/div>\n<p style=\"text-align: center\">The Wacky History of Cell Theory &#8211; Lauren Royal-Woods, TED-Ed, 2012<\/p>\n<h2>Gene Theory<\/h2>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1347\">Gene theory<\/a><\/strong>\u00a0is the idea that the characteristics of living things are controlled by genes, which are passed from parents to their offspring. Genes are located on larger structures called\u00a0chromosomes. Chromosomes are found inside every cell, and they consist of molecules of\u00a0DNA\u00a0(deoxyribonucleic acid). Those molecules of DNA are encoded with instructions that &#8220;tell&#8221;\u00a0cells\u00a0how to behave.<\/p>\n<h2>Homeostasis<\/h2>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1346\">Homeostasis<\/a><\/strong>, or the condition in which a system is maintained in a more-or-less steady state, is a characteristic of individual living things, like the human ability to sweat. Homeostasis also applies to the entire biosphere, wherever life is found on Earth. Consider the concentration of oxygen in Earth&#8217;s atmosphere. Oxygen makes up 21 per cent of the atmosphere, and this concentration is fairly constant. What maintains this homeostasis in the atmosphere? The answer is\u00a0<em>living things<\/em>.<\/p>\n<p>Most living things need oxygen to survive, so they remove oxygen from the air. On the other hand, many living things, including plants, give off oxygen when they\u00a0convert carbon dioxide and\u00a0water\u00a0to food in the process of\u00a0photosynthesis.\u00a0These two processes balance out so the air maintains a constant level of oxygen.<\/p>\n<h2>Evolutionary Theory<\/h2>\n<figure id=\"attachment_69\" aria-describedby=\"caption-attachment-69\" style=\"width: 301px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-69\" src=\"https:\/\/pressbooks.bccampus.ca\/testclone1\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-300x178.jpg\" alt=\"A chameleon on a branch, surrounded by foliage. The chameleon is camouflaged to blend into its surroundings.\" width=\"301\" height=\"179\" srcset=\"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-300x178.jpg 300w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-1024x609.jpg 1024w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-768x457.jpg 768w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-1536x914.jpg 1536w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-65x39.jpg 65w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-225x134.jpg 225w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch-350x208.jpg 350w, https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-content\/uploads\/sites\/1601\/2022\/01\/chameleon-on-branch.jpg 1920w\" sizes=\"auto, (max-width: 301px) 100vw, 301px\" \/><figcaption id=\"caption-attachment-69\" class=\"wp-caption-text\"><em>Figure 2.3.2 A chameleon exhibits its colour changing adaptation to match its background.<\/em><\/figcaption><\/figure>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1246\">Evolution<\/a><\/strong>\u00a0is a change in the characteristics of populations of living things over time. Evolution can occur by a process called\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1547\">natural selection<\/a><\/strong><strong>,\u00a0<\/strong>which<strong>\u00a0<\/strong>results from random genetic\u00a0mutations\u00a0in a\u00a0population. If these mutations lead to changes that allow\u00a0the living things\u00a0to better survive, then their chances of surviving and reproducing\u00a0in a given environment increase. They will then\u00a0pass more genes to the next generation. Over many generations, this can lead to major changes in the characteristics of those living things. Evolution explains how living things are changing today, as well as how modern living things descended from ancient life forms that no longer exist on Earth.<\/p>\n<p>Traits that help living things survive and reproduce in a given environment are called\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1397\"><strong>adaptation<span style=\"font-size: 1em\">s<\/span><\/strong><span style=\"text-align: initial;font-size: 1em\"><\/a><\/span><span style=\"text-align: initial;font-size: 1em\">. You can see an obvious adaptation in the image below. The chameleon is famous for its ability to change its colour to match its background as camouflage. Using camouflage, the chameleon can hide in plain sight.<\/span><\/p>\n<h1><span style=\"font-size: 1.266em;font-style: italic;font-weight: bold\">Feature: Myth vs. Reality<\/span><\/h1>\n<p>Misconceptions about evolution are common. They include the following myths:<\/p>\n<table class=\"grid\" style=\"border-collapse: collapse;width: 100%;height: 243px\">\n<tbody>\n<tr style=\"height: 50px\">\n<td style=\"width: 30.058%;height: 50px\">\n<h2><span style=\"color: #ff0000\">Myth<\/span><\/h2>\n<\/td>\n<td style=\"width: 69.942%;height: 50px\">\n<h2><span style=\"color: #339966\">Reality<\/span><\/h2>\n<\/td>\n<\/tr>\n<tr style=\"height: 60px\">\n<td style=\"width: 30.058%;height: 60px\"><em>&#8220;Evolution is &#8220;just&#8221; a theory or educated guess.&#8221;<\/em><\/td>\n<td style=\"width: 69.942%;height: 60px\"><strong>Scientists accept evolutionary theory as the best explanation for the\u00a0diversity of life\u00a0on Earth because of the large body of scientific evidence supporting it. Like any\u00a0scientific theory, evolution is a broad, evidence-supported explanation for multiple phenomena.<\/strong><\/td>\n<\/tr>\n<tr style=\"height: 45px\">\n<td style=\"width: 30.058%;height: 45px\"><em>&#8220;The theory of evolution explains how life on Earth began.&#8221;<\/em><\/td>\n<td style=\"width: 69.942%;height: 45px\"><strong>The\u00a0theory of evolution\u00a0explains how life\u00a0<em>changed<\/em>\u00a0on Earth after it began.<\/strong><\/td>\n<\/tr>\n<tr style=\"height: 60px\">\n<td style=\"width: 30.058%;height: 60px\"><em>&#8220;The theory of evolution means that humans evolved from apes like those in zoos.&#8221;<\/em><\/td>\n<td style=\"width: 69.942%;height: 60px\"><strong>Humans and modern apes both evolved from a common ape-like ancestor millions of years ago.<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">2.3 Summary<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li>Four basic principles or theories unify all fields of biology: cell theory, gene theory, homeostasis, and evolutionary theory.<\/li>\n<li>According to cell theory, all living things are made of cells and come from other living cells.<\/li>\n<li>Gene theory states that the characteristics of living things are controlled by genes that pass from parents to offspring.<\/li>\n<li>All living things strive to maintain internal balance, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_70_1346\"><strong>homeostasis<\/strong><\/a>.<\/li>\n<li>The characteristics of populations of living things change over time through the process of micro-evolution as organisms acquire adaptations, or traits that better suit them to a given environment.<\/li>\n<\/ul>\n<p>Use the flashcards below to review the four principles:<\/p>\n<div id=\"h5p-9\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-9\" class=\"h5p-iframe\" data-content-id=\"9\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Unifying Principles of Biology - Flashcards\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">2.3 Review Questions<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ol>\n<li>\n<div id=\"h5p-10\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-10\" class=\"h5p-iframe\" data-content-id=\"10\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Basic Principles of Biology\"><\/iframe><\/div>\n<\/div>\n<\/li>\n<li>How does sweating help the human body maintain homeostasis?<\/li>\n<li>Explain\u00a0cell theory and gene theory.<\/li>\n<li>Describe an example of homeostasis in the atmosphere.<\/li>\n<li>Describe how you can apply the concepts of evolution,natural selection, adaptation, and homeostasis to the human ability to sweat.<\/li>\n<li>Which of the four unifying principles of biology is primarily concerned with:\n<ul>\n<li>how DNA is passed down to offspring?<\/li>\n<li>how internal balance is maintained?<\/li>\n<\/ul>\n<\/li>\n<li>_____________ are located on ______________.\n<ul>\n<li>chromosomes; genes<\/li>\n<li>genes;chromosomes<\/li>\n<li>genes; traits<\/li>\n<li>none of the above<\/li>\n<\/ul>\n<\/li>\n<li>Define an adaptation and give one example.<\/li>\n<li>Explain how gene theory and evolutionary theory relate to each other.<\/li>\n<li>Does evolution by\u00a0natural selection occur within one generation? Why or why not?<\/li>\n<li>Explain why you think chameleons evolved the ability to change their colour to match their background, as well as how natural selection may have acted on the ancestors of chameleons to produce this adaptation.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">2.3 Explore More<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"Myths and misconceptions about evolution - Alex Gendler (TEDEducation)\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/Wg5DBH6uMCw?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p style=\"text-align: center\">Myths and misconceptions about evolution &#8211; Alex Gendler, TEDEd, 2013<\/p>\n<\/div>\n<\/div>\n<h2>Attributions<\/h2>\n<p><strong>Figure 2.3.1<\/strong><\/p>\n<p><a href=\"https:\/\/unsplash.com\/photos\/mE6e5-5jLu8\">Photo<\/a><a href=\"https:\/\/unsplash.com\/photos\/mE6e5-5jLu8\">(perspiration)<\/a>, by <a href=\"https:\/\/unsplash.com\/@hansreniers\">Hans Reniers<\/a> on <a href=\"https:\/\/unsplash.com\/\">Unsplash<\/a>. is used under the <a href=\"https:\/\/unsplash.com\/license\">Unsplash license<\/a> (https:\/\/unsplash.com\/license).<\/p>\n<p><strong>Figure 2.3.2<\/strong><\/p>\n<p><a href=\"https:\/\/pixabay.com\/photos\/chameleon-mediterranean-chameleon-1240928\/\">Mediterranean Chameleon Reptile Lizard<\/a>, by <a href=\"https:\/\/pixabay.com\/users\/1588877-1588877\/\">user:1588877<\/a> on <a href=\"https:\/\/www.maxpixel.net\/\">Pixabay<\/a>, is used under the <a href=\"https:\/\/pixabay.com\/service\/license\/\">Pixabay\u00a0license<\/a> (https:\/\/pixabay.com\/de\/service\/license\/).<\/p>\n<h2><strong>References<\/strong><\/h2>\n<p class=\"hanging-indent\">TED-Ed. (2012, June 4). The wacky history of cell theory &#8211; Lauren Royal-Woods. YouTube. https:\/\/www.youtube.com\/watch?v=4OpBylwH9DU&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED-Ed. (2013, July 8). Myths and misconceptions about evolution &#8211; Alex Gendler. YouTube. https:\/\/www.youtube.com\/watch?v=mZt1Gn0R22Q&amp;t=10s<\/p>\n<p>&nbsp;<\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_70_1327\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_70_1327\"><div tabindex=\"-1\"><p>A historic scientific theory consisting of 3 statements: all living organisms of made of one or more cells, the cell is the basic unit of all living things, and all cells arise from pre-existing cells.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_70_1346\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_70_1346\"><div tabindex=\"-1\"><p>The ability of an organism to maintain constant internal conditions despite external changes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_70_1935\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_70_1935\"><div tabindex=\"-1\"><p>A theory of evolution by natural selection, first formulated in Darwin's book \"On the Origin of Species\" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_70_1347\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_70_1347\"><div tabindex=\"-1\"><p>A theory which states that the characteristics of living things are controlled by genes that pass from parents to offspring.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_70_1246\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_70_1246\"><div tabindex=\"-1\"><p>The change in characteristics of a population over several generations.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_70_1547\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_70_1547\"><div tabindex=\"-1\"><p>The differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_70_1397\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_70_1397\"><div tabindex=\"-1\"><p>A genetically-based trait that has evolved because it helps living things survive and reproduce in a given environment.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":103,"menu_order":4,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-70","chapter","type-chapter","status-publish","hentry"],"part":56,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/pressbooks\/v2\/chapters\/70","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/wp\/v2\/users\/103"}],"version-history":[{"count":3,"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/pressbooks\/v2\/chapters\/70\/revisions"}],"predecessor-version":[{"id":2522,"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/pressbooks\/v2\/chapters\/70\/revisions\/2522"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/pressbooks\/v2\/parts\/56"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/pressbooks\/v2\/chapters\/70\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/wp\/v2\/media?parent=70"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/pressbooks\/v2\/chapter-type?post=70"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/wp\/v2\/contributor?post=70"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/wp-json\/wp\/v2\/license?post=70"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}