Bio 181 Quiz 1 Grand Canyon University QUESTIONS WITH COMPLETE SOLUTIONS

Observation correct answer: 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 correct answer: 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. Hypothesis-Based Approach correct answer: Systematic trial and error Predominant Essential Elements in Living Matter correct answer: 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 correct answer: Sharing of a pair of valence electrons by two atoms. Non Polar Covalent Bond correct answer: 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 correct answer: When an atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally. (H2O). Ionic Bond correct answer: 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 correct answer: 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 correct answer: 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 correct answer: 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 correct answer: The slightly positive hydrogen of one molecule is attracted to the slightly negative oxygen of a nearby molecule. These two molecules are held together.