Introduction to Biology 1 Biology – The Study of Life • • • • Section 1: The World of Biology Section 2: Themes in Biology Section 3: The Study of Biology (Section 4: Tools and Techniques ~ will be covered in separate power point) HUTCHCROFT Introduction to Biology • Biology: The study of life • Life arose more than 3.5 billion years ago in Archean eon of Precambrian period • First organisms (living things) were single celled (unicellular); Only life on Earth for millions of years • First multicellular organisms arose in the Proterozoic eon of Precambrian period between 550 million and 2.5 billion years ago! •Organisms changed over time (evolved) Introduction to Biology • New organisms arose from older kinds ! Today, estimates suggest 10 – 100 million organisms may exist!!!!!!!!! Only 1.5 million of these have been named! • 99% of organisms that EVER existed may already be extinct, having never been identified and named!! • 99% of all animal species are smaller than bumble bees! • Organisms inhabit almost EVERY region of the Earth today! The World of Biology • Biology: The study of life • Characteristics of life • Organization and Cells • Response to Stimuli • Homeostasis • Metabolism • Growth and Development • Reproduction • Change Through Time Organization and Cells • • • • • All living things are composed of one or more cells Cells are the smallest units that can perform all life’s processes In multicellular organisms, many are specialized to perform specific functions Cells are always very small The size of multi-celled organisms depends on the number of cells NOT their size Organization and Cells, cont. • • • Organized at both the molecular and cellular levels Take in substances from the environment and organize them in complex ways Specific cell structures (organelles) carry out particular functions • In multicellular organisms, cells and groups of cells are organized by their function (hierarchy of life) • Atom Biological Molecule Organelle Cell Tissue Organ Organ System Organism I don’t care what you say – that’s funny right there!!! LOL!! Want more? How about the whole hierarchy of Life from the organism on…… 1st Level of Organization • Organism: An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops 2nd Level of Organization • Population: A group of organisms, all of the same species, which interbreed and live in the same place at the same time. 3rd Level of Organization • Biological Community: All the populations of different species that live in the same place at the same time and interact (solely biotic in terms of composition). 4th Level of Organization • Ecosystem: Populations of plants and animals that interact with each other in a given area, along with the abiotic components (physical and chemical) of that area. [terrestrial or aquatic] • Biosphere: 5th Level of Organization •Earth:apple::biosphere:skin of apple Broadest, most inclusive level, i.e., the thin volume of Earth and its atmosphere that supports life (5 to 6 miles above surface to deepest part of the oceans) Response to Stimuli • Organisms can respond to a stimulus, or a physical or chemical change in the internal or external environment Homeostasis • The maintenance of a stable level of internal conditions even though environmental conditions are constantly changing, e.g., body temperature, water content, glucose levels Metabolism • The sum of all the chemical reactions that take in and transform energy and materials from the environment PHOTOSYNTHESIS Metabolism • ALL energy comes from the SUN (directly or indirectly) • Photosynthesis is the process by which some organisms capture the energy from the sun (solar) and transform it into energy (chemical) that can be used by living things PHOTOSYNTHESIS Metabolism • Organisms that make their own food are called autotrophs • Phototrophs – use solar energy (photosynthesis) to get energy • Convert H2O and CO2 into sugar and O2 • Chemotrophs – use different chemical processes to get energy • Organisms that must take in food to meet their energy needs are called heterotrophs Consume autotrophs (herbivores), other heterotrophs (carnivores) or both (omnivores) for their energy needs • Complex chemicals are broken down and reassembled into chemicals and structures needed by organisms Growth and Development • All living things grow and increase in size from the division and enlargement of cells • Development is the process by which an organism becomes a mature adult; involves cell division and c differentiation, or specialization Reproduction • Production of new organisms is essential for the continuation of a species • Hereditary information is transferred to offspring during two kinds of reproduction • Sexual reproduction – hereditary information recombines from two organisms of the same species • Asexual reproduction – hereditary information from different organisms is not combined ~ original and new organisms are genetically the same Evolution or Change Through Time • Populations of living organisms evolve or change through time to better adapt to changing conditions • Charles Darwin’s SURVIVAL OF THE FITTEST through the process of natural selection THEMES IN BIOLOGY • Diversity and Unity • Unity in the Diversity of Life • Three Domains of Life • Interdependence of Organisms • Evolution of Life • Natural Selection Unity in the Diversity of Life • Genetic code: rules that govern how cells use the hereditary information in DNA (deoxyribonucleic acid – makes up our genes or instructions for life) • Presence of organelles: carry out all cellular activities • “Tree of Life” – suggests all living things have descended with modification from a single common ancestor; thus, all of life is connected Three Domains of Life • Bacteria • Kingdom • Archaea • Kingdom • Eukarya • Kingdom • Kingdom • Kingdom • Kingdom Bacteria (Eubacteria) Archaea (Archaebacteria) Animalia Plantae Fungi Protists Interdependence of Organisms • Ecology: branch of biology that studies organisms interacting with each other and with the environment • Ecosystems: communities of living species and their physical environments; e.g., minerals, nutrients, water, gases, heat, etc. Evolution of Life • Descent with modification: process in which the inherited characteristics within populations change over generations, such that genetically distinct populations and new species can develop • Natural Selection: organisms that have certain favorable traits are better able to survive and reproduce successfully than organisms that lack these traits • Adaptations: traits that improve an individual’s ability to survive and reproduce Scientific Method Scientific Processes and Methods • 1. Observations/Questioning • 2. Measuring, Organizing Data, and Classifying • 3. Hypothesizing -- a testable explanation based on experience, reading, and/or previous experiments. (NOT A GUESS) • Inductive Reasoning • 4. Predicting -- stating in advance the result that will be obtained from testing • Deductive Reasoning (If…then…statement) Scientific Method, cont. • 5. Experimenting -- A controlled procedure for testing a hypothesis • Control Group -- all conditions remain constant • Experimental Group -- same as control, except for ONE factor • Variable • Independent Variable - condition that changes • Dependent Variable - response to changed condition • Data • Qualitative ~ descriptive • Quantitative ~ numbers Scientific Method, cont. Scientific Method, cont. • 6. Organizing and Analyzing Data Scientific Method, cont. • 7. Inferring Conclusions (concluding from evidence collected during experimentation using facts and previous knowledge rather than direct observtions) • 8. Modeling and Communicating • 9. Test and Re-test ~ law or theory formed Scientific Method, cont. • LAW -- general statement that describes a wide variety of phenomena • If a hypothesis describes HOW things happen and continues to be supported by evidence, it becomes a law. • THEORY -- most probable explanation for a set of data based on best available evidence • If a hypothesis describes WHY things happen and continues to be supported by evidence, it becomes a theory. Scientific Method -- Example • Observations: • Fish populations in Twin Lakes are declining. • The pH (acidity) of the water in the lakes is dropping to 4.2. • One hundred miles west of Twin Lakes is a power plant that is burning tons of coal every year, releasing sulfur dioxide into the air. Problem • Twin Lakes -- Acid Rain Problem 100 miles Power Plant West Branch East Branch Questioning/Hypothesizing (Inductive Reasoning) • Question: Is there a link between the power plant, the pH of the lake, and the fish decline? • Hypothesis: If acid rain falling on Twin Lakes is related to fish reproduction, then increasing acid rain amounts will cause the fish to have poor reproduction. Experiment • Experiment • Twin Lakes is a lake in the mountains that can be divided by a barrier. • A complete inventory will gather baseline data. • One arm of the lake, on the east side of the barrier, will be treated with sulfuric acid to reduce the pH to 4.0. • The west arm of the lake will be left alone, other than monitoring. Experiment • Twin Lakes -- Acid Rain Problem 100 miles East Branch West Branch Barrier Power Plant No Acid Added Acid Rain Added Results • East Branch: • Fish stop reproducing. • West Branch: • No change in fish reproduction. Conclusion • The power plant emits sulfur dioxide into the air which combines with rain to produce acid rain. The addition of this acidic rain to the lakes lowers the pH and causes the fish to stop reproducing. This results in declining fish populations and jeopardizes the survival of the fish.