Biology SAT Subject Test Questions And Answers

Biology SAT Subject Test ground state - electrons of an atom are in the lowest energy level, closest to the nucleus excited state - electrons of an atom are in the highest energy level, farthest from the nucleus isotopes - atoms of an element with different # of neutrons (same # of protons and electrons, ex: carbon-12 and carbon-14) radioisotopes - isotopes that are radioactive, used for fossil analysis, medical diagnosis and treatment (ex: I-131 used to treat thyroid diseases) ionic bonds - bonds formed with the transfer of electrons, atoms lose or gain electrons anion - negatively charged ion (ex: Na+) cation - positively charged ion (ex: Cl-) covalent bonds - bonds formed with the sharing of electrons, result in a molecule, single, double, or triple polar covalent bond - electrons are shared unequally, formed between two unlike atoms (ex: H2O, CO) nonpolar covalent bond - electrons are shared equally, formed between two alike atoms (ex: H2, O2) polar-polar attraction - molecule is polar on one end, nonpolar on the other end, polar attraction is stronger than nonpolar (ex: H2O) hydrogen bonding - - positive hydrogen of H2O is attracted to negative oxygen of another H2O molecule - important for holding DNA together, properties of water nonpolar molecules - weakest attraction, happens between nonpolar molecules (ex: CO2) hydrophobic - water-fearing, separates from water, does not dissolve hydrophilic - water-loving, mixes and combines with water like dissolves like - solutes will dissolve in solvents of the same polarity, polar in polar, nonpolar in nonpolar characteristics of water - 1. high specific heat - high heat needed to raise temperature, important for keeping stable temperature (coasts, oceans) 2. high heat of vaporization - high heat needed to evaporate water 3. adhesion properties - water clings to other substances, important for plant survival, water flows up 4. universal solvent - all ionic and polar substances dissolve in water 5. cohesion-tension - water molecules stick to each other, water moves up trees 6. ice is less dense than water - allows ice to float, sustaining life living below and above adhesion - water sticking to other molecules cohesion - water sticking to itself pH - measures acidity or alkalinity, ranges 0 - 14 (0 - 6.9 = acidic, 7.1 - 14 = basic, 7 = neutral) buffer - substance that resists change in pH, absorbs excess H+ / donates H+ to maintain a constant pH, homeostasis bicarbonate - buffer used in human blood carbohydrates - - supply quick energy - storage - structure - monosaccharides, disaccharides, polysaccharides monosaccharides - - one sugar structure - C6H12O6 - glucose, fructose, galactose disaccharides - - to monosaccharides bonded together - C12H22O11 - maltose, lactose, sucrose - formed with dehydration synthesis polysaccharide - chain of carbohydrates cellulose - polysaccharide that makes up plant cell walls starch - the way plants store carbohydrates chitin - polysaccharide that makes up exoskeletons and fungi cell walls glycogen - the way animals store carbohydrates, stored in liver and skeletal muscle