NAS 2 Challenge Exam Study Guide Already Graded A+

NAS 2 Challenge Exam Study Guide Already Graded A+ Levels of Organization: chemical, cellular, tissue, organ, organ system, organismal Survival Needs nutrients, oxygen, water, appropriate temperature, atmospheric pressure Requirements for Life maintaining boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth Homeostasis ability to maintain relatively stable internal conditions even though the outside world changes continuously Basic Mechanisms receptor, control center, effector Negative Feedback Mechanisms most common homeostasis control mechanism; the net effect is that the original output of the system shuts off the original stimulus or reduces the intensity Positive Feedback Mechanisms cause the level of a variable to change in the same direction as the an initial change Ionic bond chemical bond between atoms formed by the transfer of electrons Covalent bond shared electrons between atoms Hydrogen bond hydrogen shares a pair of electrons with another atom Nonpolar electrically balanced molecules Polar non symmetrical molecules that contain electrically unbalanced atoms (water) Decomposition molecule is broken down Synthesis a chemical reaction in which larger, more complex molecule are formed from smaller ones Exchange bonds are made and broken Organic Compounds contain carbon Polymer chainlike molecules consisting of many repeated units Carbohydrates easily used energy source for the body Lipids insulate body organs, build cell membranes, and provide stored energy Substrate reactant on which an enzyme acts to cause a chemical action to proceed Enzymes creates catalytic activity with substrate at active site Cell Theory - basic unit of living organisms - activity of an organism depends on both the individual and the combined activities of its cells - the biochemical activities of cells are dictated by their shapes, and by the relative number of the sub cellular structures they contain - cells can only arise from other cells Cell Cycle Interphase (G1, S, G2), the mitotic phase (prophase, metaphase, anaphase, telophase), cytokinesis Mitosis prophase: cooling of the chromosomes accompanied by migration of the two daughter centrioles toward the poles of the cell, and nuclear membrane breakdown