Chapter 1 Biology notes – Biology is the study of life and can be used to both solve societal problems and explain aspects of our daily lives. – Living things share the same 7 characteristics: cellular organization, response to stimuli, homeostasis, metabolism, growth and development, reproduction, and heredity (evolution). Organization and Cells – Organization is the high degree of order within an organism’s internal and external parts and in its interactions with the living world. – A cell is the smallest unit of an organism that can perform all life’s processes. – Multicellular organisms are made up of many cells and show a hierarchy of organization going from the organism to the atom. Response to Stimuli – Organism’s can respond to a stimulus—a physical or chemical change in the internal or external environment. Homeostasis – All living things have mechanisms that allow them to maintain stable internal conditions. Homeostasis is the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. Metabolism – Sum of all the chemical reactions that take in and transform energy and materials from the environment. Growth and Development – The growth of living things results from the division and enlargement of cells. – Development is the process by which an organism becomes a mature adult. Reproduction – Living organisms pass on hereditary information from parents to offspring Heredity/Evolution – Populations of living organisms evolve or change through time. Unity in the Diversity of Life – Life is diverse, or full of variety. – Life is unity, features that all living things have in common. – All living things have descended with modification from a single common ancestor. Think of a branching tree Three Domains of Life – The three domains of life are Bacteria, Archaea, and Eukarya. – The six kingdoms include Archaea, Bacteria, Protista, Fungi, Plantae, and Animalia. Interdependence of Organisms Organisms interact with other organisms and the environment. Evolution – “Descent with modification”, is the process in which the inherited characteristics within populations change over generations. – It explains how species came to exist, have changed over time, and adapt to their environment. Natural selection – Process by which organisms that have certain favorable traits are better able to survive and reproduce successfully than organisms that lack these traits (Survival of the fittest). It can lead to the evolution of populations of species. Section 1-2 Steps of the Scientific Method – Make observations, ask questions, form hypotheses, make predictions, design experiments, analyze data, and draw conclusions. Observation – Act of perceiving a natural occurrence that causes someone to pose a question. The scientific process begins with an observation. Hypothesis – Proposed explanation for the way a particular aspect of the natural world functions. Prediction – Used in testing a hypothesis. A prediction is what is expected to happen if the hypothesis is true. Experimentation – A controlled experiment compares an experimental group and a control group and only has one variable. – The controlled group provides a normal standard against which can be compared to results of the experimental group – The experimental group is identical to the control, except for one factor, the independent variable – The independent variable can be manipulated – Scientists can measure the dependent variable (responding variable) because it is affected by the independent variable. Testing the Experiment – Controlled experiments should be conducted without bias, be able to be repeated, and have enough data to find meaningful results. Analyzing and Comparing Data – Scientists analyze data to draw conclusions about the experiment performed. – Quantitative data can be measured in numbers – An experiment can also be measured by using one of your senses Drawing Conclusions – An inference is a conclusion made on the basis of facts and previous knowledge rather than on direct observations. It is not directly testable – Scientists often apply their findings about the natural world to solve practical problems. – Scientists can also build models to represent or describe things Constructing a Theory – A theory is a set of related hypotheses confirmed to be true many times, and it can explain a great amount of data. Examples include the cell theory or the theory of evolution Publishing a Paper – Scientists submit research papers to scientific journals for publication. – There are 4 sections to a research paper: Introduction, Materials and Methods, Results, and Discussion. Honesty and Bias – Scientific methods and results must be accurate and true in order to improve scientific ideas – A conflict of interest is the threat of a potential scandal based on misleading data or conclusions is a powerful force in science that helps keep scientists honest and fair to an extent. Biogenesis A. States that all living things come from other living things (example Spontaneous generation (17th century) B. Spontaneous generation (17th century): Living things come from nonliving things (example ) C. Disproving Spontaneous Generation 1. Francesco Redi’s Experiment (1650’s) Figure 1-8, page 9 a. Describe the experiment (control, experimental groups) b. Conclusion? 2. 3. Lazzaro Spallanzani’s Experiment (1700’s) Figure 1-10, page 11 a. Describe the experiment (control, experimental groups) b. Conclusion? (“vital force” = weak defense) Louis Pasteur’s Award Winning Experiment (1850’s) Figure 1-11 pg. 12 a. Describe the experiment (control, experimental groups) b. Conclusion? Microorganisms Microscopes as Tools (Upcoming Lab) – A compound light microscope is a microscope that shines light through a specimen and has two lenses to magnify an image. – There are four major parts of a compound light microscope are the ocular lens, objective lens, stage, and light source. – The eyepiece magnifies the image. – The objective lens enlarges the specimen. – The stage is a platform that supports slides with specimens. – The light source is a light bulb that provides light for viewing images. – An electron microscope uses a beam of electrons to produce an enlarged image of a specimen. – Electron microscopes have greater magnification and resolution than light microscopes. – Scanning electron microscopes pass a beam of electrons over the specimen’s surface for better viewing the external surface of a specimen. They can magnify objects up to 100,000X (times). – Transmission electron microscopes transmit a beam of electrons through a thinly sliced specimen for better viewing the internal structures of a specimen. They can magnify objects up to 200,000X (times). Magnification and Resolution (Upcoming Lab) – Magnification is the increase of an object’s apparent size.(10 X 10 = 100X) – Resolution is the power to show details clearly in an image. Units of Measurement – Scientists use a single, standard system of measurement, called the metric system. The official name of the metric system is Système International d’Unités or SI. (Hint, good bonus question!) – The metric system is a decimal system based on the powers of 10. – The metric system has seven base units. (Figure 1-23) – Review this Information! – Derived units are produced by a mathematical relationship between two base units or two derived units. Examples include area and volume (m2) Safety – Lab safety involves safe and common-sense habits. Read page 28.