Unit 1 Quiz Questions

B

he molecule in the accompanying figure is the pyrimidine ____, which is typically found in DNA but not RNA. a. adenine b. thymine c. guanine d. cytosine e. uracil

C

The two strands of a DNA double helix are held to each other by ____ bonds between nitrogenous bases. a. glycosidic b. disulfide c. hydrogen d. peptide e. phosphodiester

True

The types of functional groups on a molecule are important to its function. True or False?

C

The unique sequence of monomer subunits in a protein is the ____ structure of the protein. a. tertiary b. secondary c. primary d. linear e. quaternary

B

The two amino acids in the accompanying figure both have side groups ( R groups) that are ____. a. uncharged and polar b. basic and polar c. acidic and polar d. acidic and nonpolar e. uncharged and nonpolar

E

A fatty acid has a(n)____ group at the end of a hydrocarbon chain. a. phosphate group b. amino group c. hydroxyl group d. carbonyl group e. carboxyl group

A

A hydrogen bond between the amino acid side groups (R groups) of two different polypeptide chains in a multichain protein would be considered part of the ____ structure of the protein. a. quaternary b. primary c. secondary d. tertiary e. linear

B

A large molecule whose subunits consist of a sugar and a nitrogenous base is called a ____. a. nucleotide b. nucleoside c. nuclear unit d. nucleic acid e. nucleosome

False

A saturated fatty acid is a molecule comprised of a long chain of carbon atoms that contain one or more carbon-to-carbon double bonds. True or False?

True

All steroids have the same basic structure of four attached carbon rings. True or False?

D

Amino acids are linked together by ____ bonds. a. phosphodiester b. hydrogen c. glycosidic d. peptide e. disulfide

False

Amino acids that have a net positive charge at physiological pH are considered basic amino acids. True or False?

True

Amino acids that have a net positive charge at physiological pH are considered basic amino acids. True or False?

True

Amino acids, the monomer units comprising proteins, contain two functional groups, amino and carboxyl. True or False?

False

Animal cells store energy-providing carbohydrates as starch. True or False?

A

Approximately how many base pairs comprise one turn of the double helix in DNA? a. 10 b. 20 c. 2.5 d. 50 e. 5

False

Carbon dioxide, CO2, is considered an organic molecule. True or False?

B

Chaperonins assist with ____. a. assembly of DNA strands b. protein folding c. forming the DNA double helix d. proteins synthesis e. polysaccharide synthesis

C

Check My Work Why is there an upper limit to the surface area-to-volume ratio in a cell? a. The cells require a balance between endocytosis of precursor molecules to transporters in the membrane. b. The size of a cell is limited by the number of mitochondria. c. The surface area must be sufficient to provide adequate nutrient and waste exchange to sustain the chemical activities of the cell. d. The volume of the cell maximizes the use of phospholipids. e. The organelles in cells require communication with the extracellular environment to support internal functions.

E

Compared to saturated fatty acids, unsaturated fatty acids _____. a. are derived from animals b. tend to have a higher melting temperature c. are solids at room temperature d. have more hydrogen atoms e. are healthier for humans

D

E. coli is propelled by ____. a. a single cilium b. rotating bundles of cilia c. rotating bundles of pili d. rotating bundles of flagella e. a single flagellum

B

Glucagon, a peptide hormone, is upregulated when blood sugar levels are low. Which molecules in or on the plasma membrane would enable a cell to respond to glucagon and initiate its effects? a. glycolipids b. receptor proteins c. recognition proteins d. cholesterol e. phytosterols

True

High temperatures can permanently alter protein conformations. True or False?

B

In addition to serving as building blocks of DNA, what other function do nucleotides perform in a cell? a. chaperone protein folding b. regulate cellular activity c. trigger muscle contractions d. regulate gene expression e. activate vesicular transport

C

In an aqueous environment, the phospholipids of a membrane ____. a. are arranged in a single layer b. are arranged in a bilayer but the phospholipids have no specific orientation c. are arranged in a bilayer with the polar heads of each layer located at the membrane surface d. dissociate into their lipid and protein components e. are arranged in a bilayer with the fatty acid tails located at the membrane surface

True

In double-stranded DNA, the base adenine pairs with the base thymine. True or False?

A

In his experiments, Anfinsen treated a protein with a chemical that broke disulfide bonds and then removed the chemical to see how this would affect the function of the molecule. What did he conclude from these experiments? a. The information for determining the three-dimensional shape of ribonuclease lies in its amino acid sequence. b. Disulfide bonds are unnecessary for proper protein function. c. Altering the three-dimensional shape of the protein is irreversible. d. Protein conformation is maintained when disulfide bonds are disrupted. e. The disulfide bonds are essential for quaternary, but not tertiary, protein structure.

C

In prokaryotes, photosynthesis occurs in the ____. a. mitochondria b. ribosomes c. plasma membrane d. nucleoid e. chloroplasts

D

In prokaryotes, the rigid layer of material outside the plasma membrane is a ____. a. slime layer b. nucleoid c. flagella d. cell wall e. ribosome

C

In proteins, structural segments called ____ provide flexibility that allow parts of the protein to bend, fold, or move. a. β sheets b. peptide bonds c. random coils d. α helices e. β polysaccharides

D

In the fluid mosaic model, ____ represent the "fluid", and ____ represent the "mosaic". a. proteins; phospholipids b. integral proteins; phospholipids c. glycoproteins; integral proteins d. phospholipids; proteins e. proteins; glycoproteins

E

Many prokaryotes have a specialized structure called a glycocalyx. What is the purpose of this structure? a. to propel the cells through liquid and provide movement b. to assemble amino acids into proteins c. to provide nourishment for the cell d. to transport materials into and out of the cell e. to protect the cells from drying out

False

Nucleosidic bonds are used to link nucleotides together to form nucleic acids. True or False?

B

Nucleotides are joined together to make a nucleic acid strand by ____ bonds. a. hydrogen b. phosphodiester c. glycosidic d. disulfide e. peptide

False

One important way in which RNA differs from DNA is that RNA is missing a key hydroxyl group on its sugar. True or False?

C

Proteins are polymers of ____. a. monosaccharides b. phospholipids c. amino acids d. steroids e. nucleotides

true

RNA molecules differ from DNA molecules in the bases that comprise them, their sugars, and their structure. True or False?

A

Structural isomers differ from each other ____. a. in the arrangement of their covalent bonds b. by having different atomic isotopes in their molecules c. in their molecular formulas d. by having double covalent bonds instead of single bonds e. by being mirror images that cannot be superimposed on each other

C

The image in the accompanying figure is an example of a(n) ____. a. β polysaccharide b. double helix c. β sheet d. random coil e. α helix

D

The linkage commonly found between subunits in a chain of monosaccharides is called a ____ bond. a. phosphodiester b. peptide c. disulfide d. glycosidic e. hydrogen

D

The major structural components of a cell membrane are ____. a. glycolipids and proteins b. phospholipids and cellulose c. phospholipids and glycolipids d. phospholipids, protein, and sterols e. protein and sterols

saturated; no carbon-carbon double bonds

The molecule in the accompanying figure is ____, and has ____. (A only)

triose

The molecule in the accompanying figure is glyceraldehyde, an example of a ____ sugar.

steroid

The molecule shown above is a(n) ____.

False

The most abundant organic molecules in the world are nucleic acids. True or False?

D

The most commonly used unit for measuring cell size is a ____. a. nanometer (nm) b. millimeter (mm) c. centimeter (cm) d. micrometer (μm) e. decimeter (dm)

C

The prokaryotic chromosome is comprised of a ____. a. loosely folded mass of a single, linear molecule of DNA b. highly folded mass of a single, linear molecule of DNA c. highly folded mass of a single, circular molecule of DNA d. highly folded mass of a double, circular molecule of DNA e. loosely folded mass of a single, circular molecule of DNA

A

The selective permeability of a cell membrane is due to ____. a. the hydrophobic core formed by the phospholipid tails b. the hydrophilic surface facing the cell's exterior c. the position of cholesterol in the membrane bilayer d. the hydrophilic core formed by the phospholipid tails e. glycolipids on the surface of the membrane

E

The sugar in DNA is comprised of ____ carbons. a. three b. four c. seven d. six e. five

False

The tertiary structure of proteins is the three-dimensional shape comprised of two or more polypeptides. True or False?

C

Two structural differences between a uridine monophosphate and thymidine monophosphate are ____ and ____. a. the number of hydrogen bonds formed between it and its matching base; the presence of a methyl group on the nitrogen base b. the number of hydrogen bonds formed between it and its matching base; the location of the ribose attachment to the nitrogenous base c. the presence of a methyl group on the nitrogen base; the presence of a hydroxyl group on the ribose d. the presence of a methyl group of the nitrogen base; the location of the ribose attachment to the nitrogenous base e. the number of hydrogen bonds formed between it and its matching base; the presence of a hydroxyl group on the ribose

C

What allows the human body to distinguish between estrogen and testosterone? a. Testosterone is only produced in males and estrogen only in females. b. Testosterone and estrogen receptors distinguish differences in the stereoisomers of the steroid hormones. c. Testosterone and estrogen receptors distinguish differences in functional groups on the carbon backbone. d. Testosterone receptors are located only in males and estrogen receptors only in females. e. Testosterone and estrogen receptors perform different functions in males and in females.

D

What is a function of prokaryotic common pili? a. protein polymerization b. energy production c. transfer of DNA d. biofilm formation e. lipid synthesis

D

What is the function of cholesterol in the plasma membrane? a. to increase membrane fluidity, thereby allowing proteins to move freely at all times b. to maintain membrane fluidity at high temperatures and reduce it at low temperatures c. to decrease membrane fluidity, thereby preventing proteins from moving freely at all times d. to reduce membrane fluidity at high temperatures and maintain it at low temperatures e. to alter membrane fluidity based on extracellular cues from signaling moLECULES

A

What is the function of sex pili in prokaryotes? a. transfer of DNA b. lipid synthesis c. biofilm formation d. energy production e. protein polymerization

B

When DNA is heated, the hydrogen bonds break and allow the two strands of DNA to separate from one another. Which sequence of DNA would be most resistant to heating, and therefore, stay double stranded longer? a. TACCAATT b. AGGAGCTC c. AATTGGCC d. ATGCATTC e. TGGCTTAG

E

Which amino acid can be involved in special covalent "disulfide bridges" that, when present, help to stabilize the tertiary and quaternary structure of proteins? a. alanine b. methionine c. proline d. leucine e. cysteine

D

Which functional group acts as an organic base? a. hydroxyl b. carboxyl c. phosphate d. amino e. carbonyl

D

Which membrane component plays an important role in cell-cell recognition? a. glycolipids b. gap junctions c. carrier proteins d. glycoproteins e. receptor proteins

D

Which proteins form channels in the membrane that allow selected polar molecules and ions to pass through and across the membrane? a. recognition proteins b. cell adhesion proteins c. receptor proteins d. transport proteins e. nuclear proteins

D

Which two nucleotides also serve as transporters of chemical energy? a. CTP and TTP b. ATP and CTP c. CTP and UTP d. ATP and GTP e. ATP and TTP

E

Which type of lipid is most important to the structure of biological membranes? a. neutral fat b. wax c. fat d. triglyceride e. phospholipid

A

Why are cells very small? a. Large cells cannot efficiently exchange nutrients and waste efficiently. b. Small cells require less energy for optimal function. c. Large cells are too susceptible to infection by viruses and bacteria. d. Large cells cannot generate enough lipids to support all the internal membranes. e. Cells are programmed to divide when DNA content is too dilute.