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Chapter 1 A View of Life Your skin is an ecosystem There are more individual organisms living on your skin right now than there are people in the world. Most bacteria are not harmful to you ◦ Normal flora/resident bacteria ◦ Actually helpful You and those bacteria actually have a lot in common Image from: http://mercola.com The Characteristics of Life There’s no “official” check-off list I’ve seen lists with as few as 5 characteristics and as many as 8 Some things occupy a gray area ◦ Viruses So, what do a shark and an orchid have in common? Shark: http://britannica.com Orchid: http://www.landscape-and-garden.com Living Things: Are Organized Acquire Materials and Energy Maintain an Internal Environment Respond Reproduce and Develop Have Adaptations See your book for pictures and more examples Evolution: The Core Concept of Biology A shared family history for every living thing on the planet. Evolution explains both the unity and the diversity of life on the planet today ◦ Unity: Cells, DNA, common enzymes ◦ Diversity: Sharks and orchids! An evolutionary tree is a lot like a megafamily tree. ◦ It starts out narrow and small and then branches out. Image from: http://www.cropsforhealth.colostate.edu Organizing Life’s Diversity Humans like to organize things ◦ Lots of reasons why Taxonomy: identifying and naming organisms Systematics: putting those organisms into groups based on evolutionary relationships Categories of Classification Domain Kingdom Phylum Class Order Family Genus Species Scientific Names Modern system invented by Carl Linnaeus ◦ Early to mid 1700’s Name each organism using binomial nomenclature (two-name naming system) Uses Latin (dead language) Genus species or Genus species Homo sapiens, Pisum sativum ◦ H. sapiens, P. sativum Domain This is probably a new one for you. Bigger than kingdoms 3 domains ◦ Bacteria (regular bacteria—prokaryotes) ◦ Archaea (strange prokaryotes—extreme environments) ◦ Eukarya (all eukaryotes) Kingdoms Figuring out kingdoms for archaea and bacteria has turned out to be kind of tricky Eukarya kingdoms ◦ Animalia (multicellular, no photosynthesis) ◦ Plantae (multicellular, photosynthesis) ◦ Fungi (single or multi-celled, no photosynthesis) ◦ Protista (mostly single celled, some photosynthesis) Natural Selection Process by which evolution occurs Darwin and Wallace both figured it out independently in the mid-1800’s Darwin is more famous because he wrote the book On the Origin of Species Important for understanding modern-day problems like antibiotic resistance Descent with Modification Leads to the diversity of life One species can be the common ancestor of many different species Adaptations can be due to differences in: ◦ ◦ ◦ ◦ Where they live How they acquire energy Reproduction strategies Other things too Ecosystems and the Biosphere Ecosystems can be large or small ◦ The Sahara desert vs. the skin in your nose Any ecosystem is made of ◦ Individuals—which belong to ◦ A population—which interact to form a ◦ Community Nutrients and other resources are constantly cycled through and ecosystem due to the law of conservation of matter Energy in Ecosystems Energy is constantly being added to the Earth system from the sun That energy flows from one living thing to the next Energy cannot be destroyed, but it does become more unorganized and less useable So, all (most) living things depend on the constant input from the sun The Impact of People Birds build nests, termites make mounds, pine trees drop needles All organisms have an impact on the environment where they live Humans are unique in the scope and size of the modifications we make to our environment Science: A Way of Knowing There are lots of ways to learn about your world and the things in it It depends on what you want to know and for what purpose Religion, aesthetics, ethics and science all aim to answer different kinds of questions Science attempts to answer questions about how the natural world works through the process of the scientific method The Scientific Method It’s not a check-list, it’s the way you approach a question Observation—it’s how you know there’s a question that needs to be answered ◦ Not just with eyes—other senses ◦ Can be aided by tools/technology Inductive reasoning—using creativity to link separate ideas and “see” connections Hypothesis—a possible, testable explanation Experiments A good experimental design ensures that: ◦ You are testing what you want to test ◦ The results will be meaningful As many variables as possible are kept constant One experimental (independent) variable One responding (dependent) variable Test groups vs. control groups Many repetitions Using models When the real thing is: ◦ ◦ ◦ ◦ Too big/small Too expensive Too complex Too rare Examples ◦ Computer models ◦ Mice instead of humans—drug trials ◦ Terrarium Models aren’t perfect Data Data (pl.), datum (sing.) ◦ “The data are convincing.” Can be qualitative or quantitative Use statistics to analyze ◦ Determine significance Data may suggest a correlation between two variables ◦ Be careful! Correlation does not necessarily equal causation Conclusion Rejecting the hypothesis may turn out to be just as useful as accepting it Leads to different/further investigations Scientists report their findings in peerreviewed journals ◦ Lots of critical reviewing from others in the same field ◦ It can be hard to get published Scientific Theory “It’s just a theory.”—NO Theories in science are unifying concepts ◦ Big, wrap-around ideas that tie a bunch of stuff together Cell theory, Germ theory of disease, Gene theory T.V. shows use it wrong almost all of the time Controlled Study Basics Placebo—a “sugar” pill. It looks like you’re getting the treatment, but you’re not. Blind study—you don’t know if you’re getting the placebo or the real treatment Double blind study—person and researcher don’t know who is getting a placebo Science Publications Peer-reviewed journals ◦ Research findings are submitted by scientists and a panel of other scientists in that field decide if the research was good or not and whether to publish it. Scientific magazines ◦ Can be popular or technical ◦ Report information from the journals to the general public Bioethical Issues Scientific investigations can lead to the development of new technologies What to do with those technologies (whether and how to use them) is an ethical decision What do we do with the information we discover? What laws need to be put in place to regulate different issues? The End! You did it! Let’s look at the Bioethical Issue on pg 18 of your book.
