Download 002 Chapter 2

Biochemistry
1. Which four elements make up 96 percent of matter found in living organisms?
A. hydrogen, carbon, oxygen, sulfur
C. hydrogen, carbon, oxygen, nitrogen
B. carbon, sulfur, nitrogen, iron
D. sulfur, hydrogen, oxygen, nitrogen
2. Which statement is NOT true about elements?
A. An element cannot be broken down into substances with different properties.
B. An element consists of atoms and molecules.
C. There is only one kind of atom in each type of element.
D. All atoms of an element contain the same number of protons.
E. Atoms of an element may contain different numbers of neutrons.
3. The characteristic way in which atoms of an element react is most related to the
A. number of electrons in the outermost shell.
C. number of neutrons in the nucleus.
B. number of electrons in the innermost shell.
D. size of the nucleus.
4. Which statement is NOT true about water's properties?
A. Water molecules are cohesive, able to cling to each other.
B. Water molecules are adhesive, able to wet substances other than water.
C. Water is a universal solvent due to its polar nature.
D. The temperature of water rises and falls very quickly.
E. Ice is less dense than water and floats on its surface.
5. Which term is based on the Greek root word for "water" and "fear"?
A. hydrostatic
D. hydrophilic
B. homeostatic
E. hyperphobic
C. hydrophobic
6. Which statement is NOT true about the pH scale?
A. The scale indicates the relative concentrations of hydrogen and hydroxyl ions in a solution.
B. The scale ranges from 1 to 15.
C. pH 7 has a balanced level of H+ and OH-.
D. Anything below pH 7 is acidic and above pH 7 is basic.
E. A change of one pH unit represents a ten-fold increase or decrease in hydroxyl ion concentration.
7. An acid is defined by which of the following?
A. It donates protons to other substances in a solution.
B. It accepts protons from other elements in a solution.
C. It is insoluble in water.
D. It has a high pH value.
8. What is the significance of buffers in biological systems?
A. They help maintain homeostasis with respect to pH.
B. They are usually involved in chemical reactions that result in energy production.
C. They are not present and are insignificant in biological systems.
D. They help maintain a constant temperature in biological systems.
9. What two functional groups are present in every amino acid?
A. a hydroxyl group and a carboxyl group
C. an amino group and a hydroxyl group
B. an amino group and a sulfhydryl group
D. an amino group and a carboxyl group
10. Monomers join to form polymers under what chemical conditions?
A. hydrolysis
C. catabolism.
B. dehydration
D. adding water
11. Complementary base pairing explained Chargaff’s findings—the fact that the number of cytosines in a DNA sample
equals the number of guanines, and the number of thymines equals the number of adenines. Complementary base pairing
is the formation of hydrogen bonds between antiparallel strands of the DNA molecule. Which statement regarding
complementary base pairing is correct?
A. Purines always pair with other purines, and pyrimidines always pair with other pyrimidines.
B. In DNA, the purine base adenine (A) always pairs with the pyrimidine base thymine (T).
C. The purine base cytosine (C) always pairs with the purine base guanine (G).
D. In DNA, the pairing of cytosine (C) with guanine (G) forms two hydrogen bonds.
12. In which of the following ways does DNA differ from RNA?
A. DNA contains deoxyribose sugar, while RNA contains ribose.
B. DNA is composed of nucleotides, while RNA is composed of amino acids.
C. DNA has a sugar-phosphate backbone, while RNA has a sugar-sulfate backbone.
D. The sugar-phosphate backbone of DNA is hydrophobic, while that of RNA is hydrophilic.
13. How do the hexoses glucose and galactose differ from one another?
A. They differ in the number of their carbon atoms.
B. They differ in the placement of their carbonyl group.
C. They differ in their chemical formula.
D. They differ in the spatial arrangement of their hydroxyl groups.
14. Saturated fatty acids and unsaturated fatty acids differ in:
A. the number of carbon-to-carbon bonds
B. the consistency at room temperature
C. the number of hydrogen atoms present
D. all of the choices are differences between saturated and unsaturated fatty acids
15. The lipids of the cell membrane and the lipids found in butter and vegetable oil differ in which of the following?
A. the number of fatty acids attached to the glycerol molecule
B. the glycerol molecule
C. the carbon to carbon bonds
D. lipids of the cell membrane do not have hydrophobic sections of the molecule
16. The extensive hydrogen bonding found among parallel glucose polymers of cellulose enables it to function in plants as
a(n) _____.
A. energy source
C. structural polysaccharide
B. storage polysaccharide
D. transport molecule.
17. A lipid is a polymer made up of which kind of monomers?
A. glucose or modified glucose molecules
B. amino acids
C. nucleotides
D. alternating sugar and phosphate groups
E. fatty acids and glycerol
18. A dehydration reaction can also be called a _________ reaction since it forms water.
A. a condensation
D. an energy-releasing
B. a hydrolysis
E. monomer formation
C. an isomeric
19. Which of the following lipids forms a bilayer between two watery regions, such as in the plasma membrane of a cell?
A. steroids
C. waxes
B. neutral fats
D. phospholipids
20. Cholesterol belongs to which of the following groups?
A. steroids
B. neutral fats
C. waxes
D. phospholipids
21. What is an important function of glycoproteins in animal cells?
A. Glycoproteins are important in cell-cell recognition.
B. Glycoproteins contribute to the hydrophobicity of the cell membrane.
C. Glycoproteins catalyze metabolic reactions.
D. Glycoproteins serve as shuttles bringing molecules into a cell.
22. A peptide bond is found in which type of biological molecule?
A. carbohydrate
C. nucleic acid
B. lipid
D. protein
23. The alpha helix and beta sheet are found at which level of protein organization?
A. primary structure
C. tertiary structure
B. secondary structure
D. quaternary structure
24. A nucleic acid is a polymer made up of which kind of monomers?
A. amino acids
D. alternating sugar and phosphate groups
B. nucleotides
E. fatty acids and glycerol
C. glucose or modified glucose molecules
25. Which of the following lipids function in energy storage in both animals and plants?
A. steroids
C. triglycerides
B. phospholipids
D. isoprenes
26. The diversity of organic molecules is due to all of the following EXCEPT the fact that
A. carbon needs four electrons to complete its outer shell.
B. carbon can form single and double bonds with itself and other elements.
C. organic molecules always contain covalent bonds.
D. carbon can bond with as many as four other elements.
27. Fats, oils, and steroids are
A. proteins.
B. nucleic acids.
C. polysaccharides.
D. lipids
28. Which of the following could be added to a system to make the reaction occur faster?
A. substrate
D. water
B. oxygen
E. enzymes
C. product
29. Which best describes the first law of thermodynamics?
A. Energy is not created nor destroyed, but it can change into matter.
B. Energy is not created nor destroyed, but it can change from one energy form to another.
C. Energy can be created from matter or used to produce matter.
D. Some useful energy is lost as heat whenever an energy transfer occurs.
E. Energy transfers are always 100% efficient in changing energy from one useful form to another.
30. Which of the following is characteristic of enzymes?
A. They lower the energy of activation of a reaction by binding the substrate.
B. They raise the energy of activation of a reaction by binding the substrate.
C. They lower the amount of energy present in the substrate.
D. They raise the amount of energy present in the substrate.
31. An enzyme is generally named by adding _____ to the end of the name of the ______.
A. "-ose," cell in which it is found
D. "-ase," substrate
B. "-ase," cell in which it is found
E. "-ase," coenzyme
C. "-ose," substrate
32. Lactose is milk sugar, and humans produce substantial lactase enzyme to digest it when we are infants. However, we
soon lose some or even all of our lactase after childhood. In such cases, undigested lactose passes to the lower intestine
where bacteria break it down into lactic acid and CO2, causing painful gas bloating. This problem could be avoided by
A. avoiding all dairy products containing lactose.
B. taking lactase enzyme tablets when consuming lactose products.
C. taking any enzyme tablets when consuming dairy products.
D. consuming lactose in tablet form.
E. Both taking lactase enzyme and avoiding all dairy products would be correct.
33. Which statement is NOT true about the effects of various conditions on the activity of an enzyme?
A. Higher temperatures generally increase the activity of an enzyme up to a point.
B. Above a certain range of temperatures, the protein of an enzyme is denatured.
C. A change in pH can cause an enzyme to be inactivated.
D. An enzyme's activity is generally reduced by an increase in substrate concentration.
In the following diagram of the changes in free energy during a chemical reaction, match the letters (a)–(e) with
the correct term listed below.
34. activation energy
35. overall change in free energy (ΔG)
36. products
37. reactants
38. transition state
In the following diagram of a nucleotide, match the letters (a)–(c) with the correct structure listed below.
39. phosphate group
40. sugar
41. nitrogenous base