1 BSCI105 Exam Study Guide22 multiple-choice questionsExam I (Ch. 1-5)● Themes of Life○ Theme: New properties emerge at each level in the biological hierarchy■ Biosphere → Ecosystems → Communities → Populations → Organisms● Organisms: Organs/Organ systems → Tissues → Cells → Organelles → Molecules○ Biology - The chemistry of life■ Life has order, evolutionary adaptation, response to the environment, reproduction, growth and development, energy processing, and regulation○ Themes that connect the concepts of biology■ Biology consists of more than memorizing facts■ Themes help to organize biological information■ Organisms interact with other organisms and the physical environment■ Life requires energy transfer and transformation■ Structure and function are correlated at all levels of biological organization■ The cell is an organism’s basic unit of structure and function■ The continuity of life is based on heritable information in the other form of DNA■ Feedback mechanisms regulate biological systems○ The Core Theme: Evolution accounts for the unity and diversity of life■ Evolution, the Overarching theme of biology● Evolution makes sense of everything○ Theme: Organisms Interact with Other Organisms and the Physical Environment○ Theme: Life Requires Energy Transfer and Transformation■ All living organisms use energy to do life’s activities■ Energy in an ecosystem enters as light and exits as heat○ Theme: Structure and Function Are Correlated at All Levels of Biological Organization■ Example: A bird’s wing shape is adapted for flight○ Theme: The Cell Is an Organism’s Basic Unit of Structure and Function■ Cell=lowest level of organization that can perform all activities required for life■ All cells are enclosed by a membrane and use DNA for genetic information2● Eukaryotic Cell: multicellular, contain various membrane-bound organelles, nucleus (with DNA)● Prokaryotic Cell (bacteria, archaea): simple, single-celled, no membrane-bound organelles, no nucleus, contains unbound DNA○ Theme: The Continuity of Life Is Based on Heritable Information in the Form of DNA■ Chromosomes contain a cell’s genetic material (DNA)● Genes: units of inheritance from parents to offspring■ Cells divide for reproduction, growth and repair○ Theme: Feedback Mechanisms Regulate Biological Systems■ Feedback mechanisms allow biological processes to self-regulate (+ & -)● Negative feedback: As more product accumulates, the process slows down and less is produced● Positive Feedback: As more product accumulates, the process speeds up and more is produced● Chemistry○ Elements cannot be broken down chemically to other substances■ Trace elements- required in small quantities (SiMgFeAlCa) ○ A compound contains two or more elements.○ O, C, H, N cover 96% of living matter○ An atom is the smallest unit of an element, has the following components (subatomic particles):■ Protons (+)■ Neutrons■ Electrons (-)● Electrons that are closer to the nucleus have less energy■ Nucleus- contains protons and neutrons○ Spontaneous reactions■ Exothermic- releases heat■ Endothermic- gains heat ○ Atomic # = # of Protons○ Mass number= # of protons + neutrons○ Isotopes- two atoms of an element that differ in neutron number■ Will form the same chemical bonds, have same number of protons, but different number of neutrons○ Isomers- same molecular formula, but different carbon skeletons, different double bond positions, have different chemical properties and different biological activity○ Know electron shells, orbitals, 3D3■ Valence shell- outermost shell; Number of unpaired electrons here determines bonding and the number of covalent bonds○ Know hydrogen bonds, Van der Waals interactions■ Covalent bonds- share a pair of electrons; two nonmetals■ Ionic bonds- attraction of oppositely charged atoms; metal and a nonmetal; weak bond● ex: transfer from sodium to chlorine■ Hydrogen bond- H bonded to 2 electronegative atoms (usually O orN); weak bond● When they break, heat is absorbed● When they form, heat is released■ Van der Waals interactions- between two nonpolar molecules that are close together; weaker than hydrogen bonds● Water○ The solvent of life.○ Properties of water:■ Cohesive behavior- holds molecules together, helps transport wateragainst gravity in plants (ex: water traveling up a tree)● Related to surface tension (how hard it is to break the surface of a liquid)■ Ability to moderate temperature■ Expansion upon freezing■ Versatility as a solvent b/c it can hydrogen bonds and form hydration shells around ions○ Dissociation- transfer of Hydrogen atom from one water molecule to another■ H2O-H2O → H30+ + OH-○ Hydrophobic- substance that does not have an affinity for water■ Has nonpolar side chains (CH groups or rings on the ends)○ Hydrophilic- substance that has an affinity for water■ Has polar side chains (have OH- groups)○ pH= -log[H+]■ Acid pH < 7 (increases H+ concentration)■ Base pH >7 (increases OH- concentration)■ Water pH= 7■ Buffers- minimizes changes in the concentration of H+ and OH- ● H2CO3 - carbonic acid is a buffer in human blood■ Ocean Acidification - CO2 dissolves in seawater it reacts with waterand forms carbonic acid and lowers the oceans pH.4● Reduces carbonate concentration which is required for calcification (in coral reefs etc which are habitats for marine life). ■ Acid Precipitation - rain/snow/fog with a pH lower than 5.2● Biological Molecules: Carbohydrates and Lipids○ 4 classes of biological molecules:■ (1) Carbohydrates - sugars and polymers of sugars (long molecule of monomers); has chemical formula with multiples of CH2O● Sugars○ Monosaccharides (ex. Glucose)- simplest carbs; single sugars; classified by spatial arrangement of atoms (carbonyl and hydroxyl groups)■ Serve as fuel ○ Disaccharides■ Joined by Glycosidic linkage○ Polysaccharides- polymers of sugars; 2 primary roles:■ Storage roles (starch[plants] and glycogen[animals])■ Structural roles (cellulose[plants] and chitin[animals])■ (2) Lipids- hydrophobic molecules (not soluble in water); consist of hydrocarbons (do NOT form polymers)● Fats- major function is energy storage; constructed from glycerol (3 C alcohol) and fatty acids (long C chain)● Phospholipids- two fatty acids (hydrophobic tails) and a
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