MIDTERM 1 PROBLEM SETS Questions with Correct Solutions

MIDTERM 1: PROBLEM SETS Questions with Correct Solutions


Question:
1. lipids can be either:
(a) hydrophobic or hydrophilic
(b) hydrophobic or amphipathic
(c) amphipathic or hydrophilic
(d) amphipathic or amphoteric

Answer:
(b) hydrophobic or amphipathic


Question:
2. which of the following properties distinguish fungal and animal cells from bacterial cells?
1) presence of cell walls
2) presence of ribosomes
3) asexual reproduction
4) presence of membrane bound organelles

Answer:
4 only


Question:
3. what type of macromolecule is a saccharide?
(a) protein
(b) nucleic acid
(c) carbohydrate
(d) lipid

Answer:
(c) carbohydrate


Question:
4. which of the following functions describes the purpose of the lysosome membrane?
(a) creating a basic environment for hydrolytic enzymes of the lysosome within the cytoplasm
(b) creating an acidic environment for hydrolytic enzymes of the lysosome within the
cytoplasm
(c) serving as an alternate site for peptide bond formation during protein synthesis
(d) being a continuation of the nuclear envelope

Answer:
(b) creating an acidic environment for hydrolytic enzymes of the lysosome within the
cytoplasm

,Question:
5. which of the following structures is found in bacterial cells?
(a) nucleolus
(b) mitochondria
(c) ribosome
(d) smooth ER

Answer:
(c) ribosome


Question:
6. noncovalent bonds include all of the following except:
(a) a carbon-carbon double bond
(b) an ionic bond
(c) a hydrogen bond
(d) a van der Waals interaction

Answer:
(a) a carbon-carbon double bond


Question:
7. ligands, such as insulin, bind to their receptor in a reversible manner. what properties of
noncovalent bonds lend themselves to such interactions?
(a) the high energy state of each noncovalent bond
(b) the ability of noncovalent bonds to form very stable interactions
(c) the transient dynamic nature of multiple low-energy interactions
(d) the ability of enzymes to catalyze the making and breaking of noncovalent bonds

Answer:
(c) the transient dynamic nature of multiple low-energy interactions


Question:
8. biomembranes are stabilized by all of the following interactions except:
(a) van der Waals interactions between the hydrophobic side chains of phospholipids
(b) charge-dipole bonds that stabilize the interactions of the phospholipid polar head groups
with water
(c) hydrogen bonds that stabilize the interactions of the phospholipid polar head groups with
water
(d) carbon-carbon bonds between adjacent phospholipids

Answer:
(d) carbon-carbon bonds between adjacent phospholipids

, Question:
9. which of the following bonds are apt to be more common in the nonaqueous, interior
environment of a protein than in an aqueous environment of a protein?
(a) ionic bonds
(b) hydrophobic interactions
(c) hydrogen bonds
(d) covalent bonds

Answer:
(b) hydrophobic interactions


Question:
10. covalent bonds in contrast to noncovalent bonds:
(a) have an energy level of about 1 kcal/mol
(b) are stable relative to the average kinetic energy of molecules at room temperature
(c) are readily broken at room temp
(d) are the main force in maintaining the 3D structure of large molecules, such as proteins
and nucleic acids

Answer:
(b) are stable relative to the average kinetic energy of molecules at room temperature


Question:
11. a molecule that has both polar and nonpolar parts is:
(a) an isomer
(b) amphipathic
(c) an enantiomer
(d) hydrophobic

Answer:
(b) amphipathic


Question:
12. consider the following diagram illustrating hydrophobic bonding between X and Y in an
aqueous medium where each bent line symbolizes a water molecule. which of the following
most accurately describes the cause of the hydrophobic bond X-Y?
(a) an electrostatic attraction between X and Y
(b) the nonpolar force of attraction between X and Y
(c) net gain in entropy
(d) overall positive Gibbs free energy

Answer:
(c) net gain in entropy