Name 9 weeks exam Study Guide: Nature of Biology

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1 1. I can analyze an experiment and identify the major parts. This means that I know the difference between an independent variable, dependent variable, constant, experimental group, and control group. I can explain the scientific method and apply it. Identify a Problem or Ask a Question: The scientific method starts when you ask a question about something that you observe: How, What, When, Who, Which, Why, or Where?; And, in order for the scientific method to answer the question it must be about something that you can measure, preferably with a number. Do Background Research: look for what is already known about the topic in order to come up with an educated guess as to what is happening; Rather than starting from scratch in putting together a plan for answering your question, you want to be a savvy scientist using library and Internet research to help you find the best way to do things and insure that you don't repeat mistakes from the past. Construct a Hypothesis = A hypothesis is an educated guess about how things work: "If [I do this], then [this] will happen." You must state your hypothesis in a way that you can easily measure, and of course, your hypothesis should be constructed in a way to help you answer your original question. Your hypothesis should identify the independent variable ( if statement) and the dependent variable ( then statement) for the experiment. Conduct an Experiment = test your hypothesis by performing a controlled experiment. Your experiment tests whether your hypothesis is supported or not. It is important for your experiment to be a controlled (fair) test. You conduct a controlled test by making sure that you change only one factor at a time while keeping all other conditions the same. You should also repeat your experiments several times to make sure that the first results weren't just an accident.

2 Collect/Analyze Your Data: During the experiment, you collect your data/measurements so that you can analyze them to see if they support your hypothesis or not. You analyze data by organizing it into charts, graphs, or using statistics to look for patterns. Draw a Conclusion: Scientists often find that their hypothesis was not supported by the data, and in such cases they will construct a new hypothesis based on the information they learned during their experiment. This starts the entire process of the scientific method over again. Even if they find that their hypothesis was supported, they may want to test it again in a new way. A wrong hypothesis is ok because we still learn valuable information. Never change your data to support your hypothesis because communicates false information. Communicate/Publish Your Results = In a classroom experiment, you would communicate your results by presenting your data to the class or completing a lab report. In a science fair project, you would communicate your results to others in a final report and/or a display board. Professional scientists do almost exactly the same thing by publishing their final report in a scientific journal or by presenting their results on a poster or slide-show presentation at a scientific meeting. This is important so that the experiment can be repeated by other scientists to make sure that the results were accurately reported and the conclusions of the experiment were valid. It is also important so that scientists can use the knowledge gained from the experiment in order to make new hypotheses and conduct new research/experiments. Parts of An Experiment: The independent variable is the part of the experiment that is purposefully being changed. There should only be one independent variable in a controlled experiment. If you change more than one variable (factor), then the test is not valid because you cannot tell what caused the change in the results. You manipulate the independent variable (the cause) in order to determine the effect it has on the dependent variable. On a graph, the independent variable should be on the horizontal (X) axis. The dependent variable is what you measure in the experiment. There may be more than one dependent variable that are being measured because they are affected by the independent variable. On a graph, the dependent variable should be on the vertical (Y) axis. All other factors/conditions of the experiment should be kept constant (unchanged). This means that they should be the same for both the experimental group and the control group. The experimental group is the trial(s) that get the changed independent variable. This is sometimes referred to the treatment group because they get the new independent variable (example: a new medicine or drug). The control group is used for comparison so that you can tell if the independent variable had any effect on the dependent variable. You do not change the independent variable for the control group; everything should be under normal conditions. A placebo is often used in drug trials because it looks like the same as the medicine but does not contain the experimental drug. Example Experiment: A researcher wants to determine if Zyrtec is a better allergy medicine than Allegra. She gathers participants who suffer from seasonal allergies. She randomly divides the participants into three groups. Group A receives 1 dose of Allegra in the morning. Group B receives 1 dose of Zyrtec in the morning. Group C takes a pill that has no medication in it called a placebo so that they think they are still taking allergy medicine every day. Over the course of 2 weeks, the participants are exposed to the same types of allergens and are asked to record their symptoms throughout the trial. At the end of 2 weeks, all the data is collected and analyzed in order to determine which medication worked better to treat allergy symptoms. Independent Variable: Type of allergy medicine Dependent Variable: Allergy symptoms Hypothesis: If Zyrtec is a better allergy medicine than Allegra, then patients will report fewer allergy symptoms while taking Zyrtec. Constants: Duration of study (2 weeks); exposure to the same types of allergens; time of day the medicine was taken Experimental Group(s): Groups that received the different types of allergy medicine (Group A = Allegra & Group B = Zyrtec) Control Group: The group that had normal conditions (Group C = placebo)

3 2. I can identify the level of organization given examples or characteristics. I can put the levels of organization in the correct order from atom to organism. The levels of biological organization from smallest to largest are: atom molecule organelle cell tissue organ organ system organism An Atom is the smallest unit of matter. They are made of protons, neutrons, and electrons. Molecules are made of more than one atom. These could be atoms of the same element or different elements. These are sometimes referred to as compounds. Organelles are cell structures. They are made of organic molecules. Cells are the smallest unit of life. Nothing smaller than a cell is considered living. A unicellular organism performs all of the functions of life in one cell. Cells are made of organelles and a fluid called cytoplasm. Tissues are made of cells that work together to perform the same function. Organs are made of tissues that work together to perform the same function. Organ Systems are made of organs that work together to perform the same function. A complex, multicellular Organism is made of organ systems that work together to perform the functions of life. 3. I can tell if something is living based upon the scientific criteria for life. Characteristics of Life Things must meet ALL of the following criteria in order to be considered LIVING: 1) All living things are made of CELLS. 2) All living things REPRODUCE. 3) All living things EVOLVE. 4) All living things have a genetic code called DNA. 5) All living things need MATERIALS and ENERGY. 6) All living things MAINTAIN HOMEOSTASIS (stable internal conditions). 7) All living things RESPOND to changes in their environment. 8) All living things GROW and DEVELOP. While many organisms move or breathe, not ALL living things move and/or breathe. Movement and breathing are not characteristics of ALL living things. You cannot use those to determine if something is living. It must meet all 8 of the characteristics of life. 4. I can list the major organs and jobs of each human body system. I can explain how the organ systems work together to maintain homeostasis. Nervous System Function = control and coordinate body responses, receive stimuli, communication between body parts Organs = Brain & spinal cord Cardiovascular (Circulatory) System Function = transporting substances throughout the body (examples: oxygen from the lungs to other tissues; carbon dioxide from other tissues to the lungs; nutrients from the digestive system; waste to the urinary system); also helps maintain body temperature Organs = heart, blood, veins, & arteries Respiratory System Function = inhale oxygen and exhale carbon dioxide; interact with the cardiovascular system to exchange oxygen and carbon dioxide Organs = mouth, nose, pharynx, larynx, trachea, & lungs Urinary System Function = filter waste out of the blood; produce and excrete urine Organs = kidneys, ureters, bladder, & urethra Digestive System

4 Function = break down food into smaller particles that can be used by cells; absorption of nutrients; elimination of solid waste Organs = mouth, esophagus, stomach, liver, gall bladder, intestines, rectum Skeletal System Function = provide support and a framework for muscle attachment; protection of vital organs; production of blood cells; mineral storage Organs = bones & cartilage; axial vs. appendicular skeleton Muscular System Function = movement including the skeleton, internal organs, and blood; contract &relax Organs = muscles & tendons; cardiac, smooth, & skeletal muscle Integumentary System Function = provides coverings & protection; barrier against infection; maintains body temperature Organs = skin, hair, & nails Endocrine System Function = production of hormones Organs = glands (including pituitary, hypothalamus, pineal, adrenals, thymus, thyroid, parathyroids, pancreas, ovaries, & testes) Lymphatic/Immune System Function = fighting infections and producing allergic response; returning lost fluid to circulatory system Organs = white blood cells, lymph nodes, antibodies, thymus, spleen How do organ systems work together to maintain homeostasis? The circulatory system is critical to the internal environment in that tissue fluid is nourished and purified by the movement of small molecules across capillary walls. The digestive system contributes nutrients to the blood, while the excretory system removes wastes. The respiratory system takes in oxygen and excretes carbon dioxide. Oxygen is used during cellular respiration and carbon dioxide is a waste product of cellular respiration. The nervous and endocrine systems exert the ultimate control over homeostasis because they coordinate the functions of the body's systems. Regulation of body temperature, blood pressure, ph, and glucose concentration are four examples of how the body maintains homeostasis. The hypothalamus is involved to a degree in each of these regulations. The hypothalamus contains a regulatory center for body temperature but is also involved in regulation of blood pressure and breathing rate through its control over the medulla oblongata. Through the production of hypothalamic-releasing factors and release-inhibiting factors, the hypothalamus directly controls the pituitary gland and indirectly controls the secretions of other glands, such as the thyroid and the adrenal cortex. The body has both short-term and long-term measures to control bodily conditions. In regard to temperature control, the short-term measures include shivering and constriction of arteries to conserve body heat, and dilation of arteries along with sweating to lose body heat. A significant long-term measure to increase body temperature is an increase in thyroxin. Thyroxin raises the metabolic rate. A rapid elevation in blood pressure occurs when the vasomotor center stimulates the constriction of abdominal blood vessels and increases the heartbeat. A longer lasting effect occurs when the kidneys secrete renin leading to a reabsorption of sodium and water. The resulting increase in blood volume increases blood pressure. The ph of the body is immediately regulated by chemical buffers, while the excretion of carbon dioxide must wait until blood moves through the lungs. The kidneys are also involved in regulating blood ph, but the effect may not noticed for up to twenty hours. The blood glucose level is usually regulated by insulin and glucagon. But other hormones can also have an effect since thyroxin and glucocorticoids promote gluconeogenesis. A feedback mechanism is often involved in maintaining homeostasis. The temperature-regulating center is activated when the body temperature rises above or falls below a certain level. Once the temperature is within a normal range, the center stops sending out stimulatory nerve impulses. The vasomotor center promotes a rise in blood pressure, but once this has been attained the center is no longer active. If the ph becomes too acidic, the chemoreceptors in the aortic and carotid arteries signal the respiratory center and the breathing rate increases. Once the ph is within a normal range, these bodies no longer signal the respiratory center and breathing rate returns to normal. When glucose concentration is high, insulin is secreted; but once the glucose level falls, insulin is not secreted. These examples make it clear that feedback is a self-regulating mechanism.

5 5. I can identify the differences and between prokaryotes and eukaryotes. I can label a diagram of a prokaryotic cell. Prokaryotes are MUCH smaller and simpler than eukaryotes. Prokaryotes are bacteria. The genetic material (DNA) is found in the cytoplasm of a prokaryote. The DNA is arranged in one circular loop called a plasmid. Prokaryotes reproduce asexually through binary fission. Prokaryotes only have a cell wall, cell membrane, cytoplasm, ribosomes, and DNA. They may also have flagella or cilia. Prokaryotes do NOT have a nucleus (nuclear membrane, nuclear lamina, or nucleolus). Prokaryotes also do NOT have organelles surrounded by membranes such as the endoplasmic reticulum (rough or smooth), lysosomes, centrioles, vacuoles, chloroplasts, mitochondria, or Golgi apparatus. Eukaryotes include protists, fungi, plants, & animals. The genetic material (DNA) is found in the nucleus of a eukaryote. The DNA is arranged in chromosome pairs. Eukaryotes can reproduce asexually through mitosis or sexually through meiosis. Eukaryotes have a nucleus and membrane-bound organelles such as the endoplasmic reticulum (rough or smooth), lysosomes, centrioles, vacuoles, chloroplasts, mitochondria, and Golgi apparatus.

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