Bio 181 Quiz 1 Grand Canyon University with 100% correct answers

Observation Gathering information, either through direct use of the senses or with the help of tools such as microscopes, thermometers, and balances that extend our senses. Can reveal valuable information about the natural world Hypothesis Tentative answer to a well-framed question -- an explanation on trial. A rational account for a set of observations, based on the available data and guided by inductive reasoning. 00:12 01:41 Hypothesis-Based Approach Systematic trial and error Predominant Essential Elements in Living Matter Humans need 25, plants need 17. Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N) -- make up 96% of living matter. Calcium (Ca), Phosphorus (P), Potassium (K), Sulfur (S), and a few other elements account for most of the remaining 4% of an organism's mass. Covalent Bond Sharing of a pair of valence electrons by two atoms. Non Polar Covalent Bond Two atoms of the same element share electrons equally because the two atoms have the same electronegativity -- the tug-of-war is at a standoff. Polar Covalent Bond When an atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally. (H2O). Ionic Bond Opposite charges, cations and anions attract each other. Any two ions of opposite charge can form this. The ions do not need to have acquired their charge by an electron transfer with each other. Hydrogen Bond When a hydrogen atom is covalently bonded to an electronegative atom, the hydrogen atom has a partial positive charge that allows it to be attracted to a different electronegative atom nearby. Attraction between a hydrogen and an electronegative atom. Van der Waals Interactions Electrons are not always evenly distributed; at any instant, they may accumulate by chance in one part of a molecule or another. The results are ever-changing regions of positive and negative charge that enable all atoms and molecules to stick to one another. Chemical Equilibrium The point at which the reactions offset one another exactly. Dynamic equilibrium; reactions are still going on, but with no net effect on the concentrations of reactants and products. Example of a Hydrogen Bond The slightly positive hydrogen of one molecule is attracted to the slightly negative oxygen of a nearby molecule. These two molecules are held together. 00:02 01:41 Cohesion Hydrogen bonds hold the substance together. Contributes to the transport of water and dissolved nutrients against gravity in plants. Adhesion The clinging of one substance to another. Helps counter the downward pull of gravity when hydrogen bonds to the molecules of cell walls. Hydrophilic Affinity for water. Substances can be this without actually dissolving. Hydrophobic Substances that are nonionic and non polar (or otherwise cannot form hydrogen bonds) actually seem to repel water. Buffer The presence of substances called this allows biological fluids to maintain a relatively constant pH despite the addition of acids or bases. A substance that minimizes changes in the concentrations of H+ and OH- in a solution. It does so by accepting hydrogen ions from the solution when they are in excess and donating hydrogen ions to the solutions when they have been deplete. Organic Molecules In this, carbon usually forms sing or double covalent bonds. Each carbon atom acts as an intersection point form which a molecule can branch off in as many as four directions. This enables carbon to form large, complex molecules. Hydrocarbons Organic molecules consisting of only carbon and hydrogen. Atoms of hydrogen are attached to the carbon skeleton wherever electrons are available for covalently bonding. Not prevalent in most living organisms. Functional Groups Groups in which chemical groups are directly involved in chemical reactions. Each has certain properties, such as shape and charge, that cause it to participate in chemical reactions in a characteristic way. Seven Chemical Groups Most Important in Biological Processes Hydroxyl, carbonyl, carboxyl, amino, sulfate, hydroxyl, phosphate, and methyl. Hydroxyl Group (-OH) Polar due to electronegative oxygen. Forms hydrogen bonds with water, helping dissolve compounds such as sugars. Compound name: Alcohol Example: Ethanol Carbonyl Group (>C == O) Sugars with ketone groups are called ketoses; those with aldehydes are called aldoses. Compound name: Ketone (is within carbon skeleton) or aldehyde (is at the end of a carbon skeleton) Example: Acetone: the simplest ketone; Propanal: an aldehyde Carboxyl Group (--COOH)