Exam 1 Study Guide - Biology 118 Study Guide Chapters 1-3...

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Biology 118 Study Guide: Chapters 1-3, 6-7 Homeostasis: 1. What is homeostasis? What does it accomplish and how does it work? Homeostasis is the maintenance of a relatively constant internal environment. It keeps the body at a constant temperature etc. There is a receptor that receives the stimulus, a control center that processes information from the receptor and then finally an effector which responds to the commands of the control center who either opposes (negative feedback) or reinforces the stimulus (positive feedback) 2. What is a negative feedback loop? Give an example. Negative feedback is when the outside opposes changes in the input (outside changing to protect the homeostasis on the inside). An example of negative feedback loop would be when gland X releases hormone X, this stimulates target cells to release hormone Y. When there is an excess of hormone Y, gland X "senses" this and inhibits its release of hormone X. 3. What is a positive feedback loop? Give an example. In positive feedback, the initial stimulus produces a response that reinforces that stimulus. Positive feedback loop is when it continues to reinforce it. Positive feedback loops is involved when regulation of a potentially dangerous or stressful process must be completed quickly. An example is blood clotting. 4. What are the levels of biological organization? The levels of biological organization is: Atoms Molecules Cells Tissue Organs Organ System Organism Atoms and inorganic chemistry: 5. What are the four most abundant elements in the human body, and why are they the most abundant? Oxygen, Carbon, Hydrogen and Nitrogen make up 96% of the Body. This is so because they are readily available, and they can join together-> forming various bonds. 6. Name the particles that make up an atom. Protons (+ Charge), Electrons (- Charge), Neutrons (No charge). Protons + Neutrons is in the nucleus, while the electrons are floating around in an orbital in the outer shell. 7. What is an electron shell, and how does this contribute an atom’s reactivity? (i.e., why is carbon reactive, while neon is inert?) In the Electron shell there is a limited number of spaces for electrons. Atoms want the outer most shell to be completely filled. Carbon is reactive because it is not stable because its electron shells is not full. However Neon’s electron shell is completely full so it cannot give or take any electrons. 8. What is covalent bonding? Name two molecules that are held together by covalent bonding. Covalent bonding is when atoms fill their outer electron shells by sharing electrons with other atoms.
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H20 is held together by covalent bonds. 9. What is an ion? An ion is an atom or molecule bearing a positive or negative charge due to the gain or loss of an electron. 10.
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This note was uploaded on 10/27/2011 for the course BIOLOGY 118 taught by Professor Tolgabilgen during the Spring '09 term at University of Washington.

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Exam 1 Study Guide - Biology 118 Study Guide Chapters 1-3...

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