(A) Glucose (B) Amino acids (C) Fatty acids (D) Nucleotides (E) Monosaccharides

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1 High School Biology - Problem Drill 02: The Chemical Basis of Life Question No. 1 of Proteins are composed of which of these monomers? Question #01 (A) Glucose (B) Amino acids (C) Fatty acids (D) Nucleotides (E) Monosaccharides Glucose does not make up proteins. It makes up carbohydrates. B. Correct! Proteins are made of amino acids. Lipids are made of fatty acids and glycerol. Nucleic acids are made of nucleotides. Monosaccharides are the monomers for carbohydrates. The following is the list of organic molecules and their monomers: Polysaccharides Monomer unit: monosaccharide Store energy, provide building unit Lipids Monomer unit: fatty acids, glycerol Store energy, membrane construction, hormones Proteins: Monomer unit: amino acids Structure protein, enzymes Nucleic Acids: Monomer unit: nucleotides Genetic material The correct answer is (B).

2 Question No. 2 of There are proteins that can reduce the ΔG of a reaction and, therefore, accelerate the reaction rate. What are they called? Question #02 (A) Hormones (B) Enzymes (C) Phospholipids (D) Cofactors (E) None of the above Hormones are proteins that have an effect on a target cells. B. Correct! Enzymes are proteins that can reduce ΔG of a reaction and, therefore, accelerate the reaction rate. Phospholipids are molecules found in the plasma membrane. Cofactors are inorganic molecules that aid enzymes by accepting or donating electrons and hydrogen. The answer is found in the choices above. Many biosynthesis reactions are coupled to ATP hydrolysis, which can provide energy and, therefore, the overall reaction can be ΔG negative. If ΔG is negative, then the reaction is spontaneous. If ΔG is positive, then reaction is nonspontaneous. Enzymes help to lower the activation energy for a reaction. Enzymecatalyzed reactions have lower activation free energy but do not change the ΔG. The correct answer is (B).

3 Question No. 3 of Which of the following bonds store more energy? Question #03 (A) C-C (B) C=C (C) C C (D) NaCl (E) All have the same amount of energy. A single covalent bond does store a good deal of energy, but there is an answer that holds more energy. A double covalent bond does store a good deal of energy but there is an answer that holds more energy. C. Correct! A triple covalent bond does store the most energy of the choices available. This is an ionic bond and it does not hold a lot of energy and quickly dissociates in water. These bonds do not have equal amounts of energy. Chemical bonds store energy. For covalent bonds, the more electrons a bond shares, the more energy it stores. Ionic bond: An ionic bond forms when atoms lose or gain electrons. Covalent bond: Covalent bonds form when atoms share electrons, very strong bonds. It is the major one in organic chemicals. Hydrogen bond: Weak electrical attraction between the positive end of one molecule and the negative end of another The correct answer is (C).

4 Question No. 4 of A chemical bond between two water molecules is. Question #04 (A) Nonpolar covalent bond (B) Ionic bond (C) Hydrogen bond (D) Polar bond (E) None of the above A nonpolar covalent bond is formed when atoms want to equally share electrons. An ionic bond is a bond formed solely on the attraction of oppositely charged ions. A hydrogen bond is a bond between partially positive-charged hydrogen and a partially negative-charged other atom. D. Correct! A polar bond is a bond where atoms will unequally share their electrons. The correct answer is found as one of the choices. Chemical bonds store energy. For covalent bonds, the more electrons a bond shares, the more energy it stores. Ionic bond: An ionic bond forms when atoms lose or gain electrons. Covalent bond: Covalent bonds form when atoms share electrons, very strong bonds. It is the major one in organic chemicals. Polar bonds are unequal sharing Nonpolar bonds are equal sharing. Hydrogen bond: Weak electrical attraction between the positive end of one molecule and the negative end of another The correct answer is (D).

5 Question No. 5 of How many more H + ions does a solution containing a ph of 5 have than a solution of ph 7? Question #05 (A) 2 (B) 50 (C) 100 (D) 200 (E) 1000 ph reading is separated by a factor of 10, so this could not be the answer. ph reading is separated by a factor of 10, so this could not be the answer. C. Correct! ph reading is separated by a factor of 10 so there would be 10 x 10, which equals 100. ph reading is separated by a factor of 10, so this could not be the answer. ph reading is separated by a factor of 10 so this could not be the answer. This is because there are only two factors between ph 5 and ph 7. ph: ph represents the concentration of hydrogen ions [H + ] in solution. ph = -log [H + ] At ph 7, there are equal amounts of hydrogen and hydroxide ions. The correct answer is (C).

6 Question No. 6 of What is equal to the number of protons in an atom? Question #06 (A) Isomer (B) Neutron (C) Atomic number (D) Mass number (E) Isotope An isomer has the same molecular formula but different structural formula. Neutrons are the subatomic particles found in the nucleus of the atom, which do not have a charge. C. Correct! The atomic number is equal to the number of protons in the atom s nucleus. The mass number is equal to the number of protons plus the number of neutrons in the atom. Isotopes are atoms that have the same number of protons but different number of neutrons so they have different mass numbers. Atoms are made of: o Electrons: both energy and substance particles o Neutrons o Protons Isotope: Atoms have the same proton numbers but may differ in neutron numbers. Energy shell: Electrons occupy orbital around nucleus; these are called energy shells. The most inner shell (K) contains 2 electrons maximum, the L and M shell contain 8 maximum each. Isomers: Chemicals that have the same molecular formula but different structure formula. Atomic number is equal to the number of protons in the nucleus of the atom. The mass number is equal to the number of protons and neutrons in the nucleus of the atom. The correct answer is (C).

7 Question No. 7 of What is a bond between a positive end of one molecule and the negative end of another molecule? Question #07 (A) Hydrogen bond (B) Ionic bond (C) Polar bond (D) Covalent bond (E) None of the above A. Correct! A hydrogen bond is a bond between a positive end of one molecule and the negative end of another molecule. Ionic bonds are bonds where atoms lose or gain electrons. Polar bonds are bonds where there is unequal sharing of electrons. A covalent bond is one in which there is equal sharing of electrons. The correct answer is one of the choices above. Chemical bonds store energy. For covalent bonds, the more electrons a bond share, the more energy it stores. Ionic bond: An ionic bond forms when atoms lose or gain electrons. Covalent bond: Covalent bonds form when atoms share electrons, very strong bonds. The major one in organic chemicals. Polar bonds are unequal sharing Nonpolar bonds are equal sharing. Hydrogen bond: Weak electrical attraction between the positive end of one molecule and the negative end of another The correct answer is (A).

8 Question No. 8 of What substance can accept protons and donate electron pairs? Question #08 (A) Acid (B) Carbon (C) Base (D) Vinegar (E) None of the above An acid is a compound that, when dissolved in water, has a ph of less than 7. Carbon is an atom that is found in all organic molecules. C. Correct! A base is a substance that can accept protons and donate electron pairs. Vinegar is an example of an acid. The correct answer is among the choices available. An acid is a compound that when dissolved in water has a ph of less than 7. It will donate a hydrogen ion to a base. A base is a substance that accepts protons and can donate electron pairs. The correct answer is (C).

9 Question No. 9 of What solution resists changes in its ph? Question #09 (A) Buffer (B) Acid (C) Electrolyte (D) Isotope (E) Base A. Correct! A buffer is a solution that resists changes in ph when small amounts of an acid or base are added to it or when it is diluted. An acid donates hydrogen ions to a base. An electrolyte consists of free ions and is electrically conductive. An isotope is a molecule that has the same numbers of protons but different number of neutrons. A base is a molecule that can accept protons and donate electron pairs. Buffers: s that resist change in ph, upon addition of small amounts of acid or base. Electrolytes: Chemicals that can release ions into solutions. The correct answer is (A).

10 Question No. 10 of In which reaction are two substituents removed from a molecule? Question #10 (A) Oxidation (B) Group Transfer (C) Isomerization (D) Hydrolysis (E) Elimination In oxidation reactions, hydrogen and electrons are lost. In group transfer reactions, compounds are exchanged for each other. In isomerization, there is a transformation of a molecule into a different isomer. In a hydrolysis reaction, a molecule of water is split and an organic molecule is broken apart. E. Correct! In elimination reaction, two substituents are removed from a molecule. In oxidation reactions, hydrogen and electrons are lost. In elimination reaction, two substitutes are removed from a molecule. In a hydrolysis reaction, a molecule of water is split and an organic molecule is broken apart. In isomerization, there is a transformation of a molecule into a different isomer. In group transfer reactions, compounds are exchanged for each other. The correct answer is (E).