Practice Quiz 2

Common factors affecting the fluidity of a membrane include a. All of the above b. temperature. c. length of the phospholipid fatty acid chains. d. number of double bonds in the fatty acid chains.

All of the above

Lipids play a major role in cells as a. part of the cell signaling function. b. components of cell membranes. c. All of the above d. a form of energy storage.

All of the above

Nucleotides have an important function in cells as a. intracellular signal molecules. b. building blocks for nucleic acids. c. All of the above d. carriers of chemical energy.

All of the above

RNA in cells can serve as a a. regulator of gene expression. b. carrier of information from the nucleus to the cytoplasm. c. catalyst or enzyme. d. All of the above

All of the above

Which of the following are involved in forming the tertiary structure of proteins? a. Ionic bonds b. H bonds c. All of the above d. Hydrophobic interaction

All of the above

Proteins are polymers of how many different amino acids? a. 20 b. 16 c. 36 d. 24

a. 20

In DNA, a. G pairs with C and A pairs with T. b. G pairs with C and U pairs with A. c. G pairs with A and C pairs with T. d. G pairs with T and A pairs with C.

a. G pairs with C and A pairs with T

What is the major carbohydrate-storage molecule in plants? a. Starch b. Deoxyribonucleic acid c. Glycogen d. Cellulose

a. Starch

The three-dimensional structure of a protein is analyzed most definitively by a. X-ray crystallography. b. light microscopy. c. electron microscopy. d. subcellular fractionation.

a. X-ray crystallography

Steroid hormones are derivatives of a. cholesterol. b. sugars. c. phospholipids. d. amino acids.

a. cholesterol.

A few sugars joined together are called a(n) a. oligosaccharide. b. starch. c. glycoside. d. polysaccharide.

a. oligosaccharide

In the primary structure of a protein, amino acids are joined together by .......... bonds. a. peptide b. phosphodiester c. hydrophobic d. glycosidic

a. peptide

Serine, threonine, asparagine, and glutamine are all .......... amino acids. a. polar b. acidic c. nonpolar d. basic

a. polar

Sphingomyelin contains two hydrocarbon chains linked to a. serine. b. glycerol. c. choline. d. glycine.

a. serine.

Which of the following is not one of the ways in which DNA differs from RNA? a. DNA contains deoxyribose sugars. b. DNA can form hydrogen bonds with complementary sequences. c. DNA is usually a double-stranded molecule. d. DNA contains thymine as one of its bases.

b. DNA can form hydrogen bonds with complementary sequences.

The scientist who first determined the complete amino acid sequence of a protein (insulin) was a. Linus Pauling. b. Frederick Sanger. c. Christian Anfinsen.

b. Frederick Sanger.

Which of the following is not a basic amino acid? a. Histidinee. b. Glutamine c. Arginine

b. Glutamine

What is the effect of a beta barrel on the permeability of a membrane? a. beta barrels are never found in membranes. b. It increases permeability. c. It has no effect. d. It decreases permeability.

b. It increases permeability

Transport across biological membranes is speeded by what class of biological molecules? a. Carbohydrates b. Proteins c. Lipids d. Nucleic acids

b. Proteins

In the fluid mosaic model of biological membrane structure, transmembrane proteins are a. weakly held in place on the surface of the lipid bilayer. b. embedded nearly randomly in the lipid bilayer. c. almost completely surrounded by membrane lipid. d. segregated into large protein clusters or rafts.

b. embedded nearly randomly in the lipid bilayer.

Sugars can cyclize if they contain .......... or more carbons. a. six b. five c. seven d. four

b. five

An amphipathic molecule is a. hydrophilic. b. part water-soluble and part water-insoluble. c. water-soluble. d. water-insoluble.

b. part water-soluble and part water-insoluble

The most common molecules in cellular membranes are the a. glycolipids. b. phospholipids. c. cholesterol molecules. d. proteins.

b. phospholipids.

The interaction of the α and β subunits to form the hemoglobin molecule is an example of .......... structure. a. primary b. quaternary c. secondary d. tertiary

b. quaternary

Proteins can be covalently modified by the addition of phosphate groups to all but which of the following amino acids? a. Serine b. Threonine c. Arginine d. Tyrosine

c. Arginine

Which of the following store most chemical energy per unit weight? a. Nucleic acids b. Carbohydrates c. Lipids d. Proteins

c. Lipids

Molecules that are partly water-soluble and partly water-insoluble are a. hydrophilic. b. hydrophobic. c. amphipathic. d. allosteric.

c. amphiphathic

Cholesterol affects the fluidity of membranes by a. decreasing membrane fluidity at all temperatures. b. increasing membrane fluidity at high temperatures and decreasing membrane fluidity at low temperatures. c. decreasing membrane fluidity at high temperatures and increasing membrane fluidity at low temperatures. d. increasing membrane fluidity at all temperature

c. decreasing membrane fluidity at high temperatures and increasing membrane fluidity at low temperatures

Complementary base pairs form .......... bonds to direct replication of DNA. a. covalent b. glycosidic c. hydrogen d. phosphodiester

c. hydrogen

Lipids with unsaturated fatty acids a. decrease the fluidity of membranes. b. are present only on the inner side of the plasma membrane. c. increase the fluidity of membranes. d. increase the charge associated with the inner face of a membrane.

c. increase the fluidity of membranes.

Introducing a double bond into a fatty acid has the effect of putting a(n) .......... into the conformation of the molecule. a. reinforcing rod b. amino acid bulge c. kink d. reverse spiral

c. kink

The unique properties of different membranes are primarily a function of their a. cholesterol molecules. b. glycolipids. c. proteins. d. phospholipids.

c. proteins

Fatty acids are stored in fat droplets in the form of a. cholesterol. b. glycolipids. c. triacylglycerols. d. phospholipids.

c. triacylglycerols

The most abundant molecules in cells are: a. lipids. b. carbohydrates. c. water. d. proteins.

c. water

Which of the following is not one of the four major classes of organic molecules in the cell? a. Carbohydrates b. Proteins c. Lipids d. Water

d. Water

Cholesterol, a membrane lipid in animals, has a chemical structure similar to a. phosphatidylinositol. b. thymine. c. triacylglycerol. d. estradiol.

d. estradiol

Phospholipids consist of a 3-carbon core to which fatty acids and a phosphate group are linked. The most common 3-carbon core is a. dihydroxyacetone. b. glyceraldehyde. c. serine. d. glycerol.

d. glycerol

In polysaccharides, sugars are linked together by means of .......... bonds. a. phosphodiester b. peptide c. hydrophobic d. glycosidic

d. glycosidic

The major bonds in glycogen are .......... glycosidic bonds. a. β(1→4) b. α(1→6) c. β(1→6) d. α(1→4)

d. α(1→4)