Biological Molecules and Their Functions Part 1

Humans and mice differ because:

A) their cells make different types of lipids.
B) their cells have some differences in the sequence of nucleotides in their nucleic acids.
C) their cells make different types of large biological molecules.
D) their cells make different types of proteins.
E) their cells have different small organic molecules

Molecules with which functional groups may form polymers via dehydration reactions?

A) hydroxyl groups
B) either hydroxyl or carboxyl groups
C) carbonyl groups
D) either carbonyl or carboxyl groups
E) carboxyl groups

Which of these molecules is not formed by dehydration reactions?

A) DNA
B) protein
C) amylase
D) disaccharides
E) fatty acids

Which of these classes of biological molecules consist of both small molecules and macromolecular polymers?

A) carbohydrates
B) lipids, carbohydrates, proteins, and nucleic acids all consist of only macromolecular polymers
C) nucleic acids
D) lipids
E) proteins

Which of the following is not a polymer?

A) chitin
B) cellulose
C) starch
D) glucose
E) DNA

What is the chemical reaction mechanism by which cells make polymers from monomers?

A) ionic bonding of monomers
B) phosphodiester linkages
C) hydrolysis
D) dehydration reactions
E) the formation of disulfide bridges between monomers

Which of the following best summarizes the relationship between dehydration reactions and
hydrolysis?

A) Dehydration reactions can occur only after hydrolysis.
B) Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers.
C) Dehydration reactions eliminate water from lipid membranes, and hydrolysis makes lipid membranes water permeable.
D) Dehydration reactions ionize water molecules and add hydroxyl groups to polymers;
hydrolysis reactions release hydroxyl groups from polymers.
E) Hydrolysis creates monomers, and dehydration reactions break down polymers.

Which of the following polymers contain nitrogen?

A) glycogen
B) starch
C) chitin
D) cellulose
E) amylopectin

The molecular formula for glucose is C6H1206. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions?
A) C18 H32 016
B) C18 H10 O15
C) C18 H36 018
D)C3 H6 O3
E) C6 H10 O5

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the "a" form. Which of the following could amylase break down?

A) chitin
B) glycogen and chitin only
C) cellulose
D) glycogen
E) glycogen, cellulose, and chitin

On food packages, to what does the term insoluble fiber refer?

A) amylopectin
B) cellulose
C) chitin
D) polypeptides
E) starch

molecule with the chemical formula C6 H12 O6 is probably a

A) lipid.
B) carbohydrate and monosaccharide only.
C) carbohydrate and lipid only.
D) monosaccharide
E) carbohydrate.

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one, galactose molecule. How is lactose classified?

A) as a hexose
B) as a monosaccharide
C) as a pentose
D) as a disaccharide
E) as a polysaccharide

All of the following are polysaccharides except

A) cellulose.
B) lactose.
C) glycogen.
D) chitin.
E) amylopectin.

Which of the following is true of both starch and cellulose?

A) They are both structural components of the plant cell wall.
B) They are cis-trans isomers of each other.
C) They can both be digested by humans.
D) They are both used for energy storage in plants.
E) They are both polymers of glucose

Which of the following is true of cellulose?

A) It is a polymer composed of enantiomers of glucose, it is a storage polysaccharide for energy in plant cells, it is digestible by bacteria in the human gut, and it is a major component of plant cell walls.
B) It is digestible by bacteria in the human gut.
C) It is a major structural component of plant cell walls.
D) It is a storage polysaccharide for energy in plant cells.
E) It is a polymer composed of enantiomers of glucose.

Humans can digest starch but not cellulose because

A) humans have enzymes that can hydrolyze the a glycosidic linkages of starch but not the glycosidic linkages of cellulose.
B) the monomer of starch is glucose, while the monomer of cellulose is glucose with a
nitrogen-containing group.
C) humans have enzymes that can hydrolyze theglycosidic linkages of starch but not the a
glycosidic linkages of cellulose.
D) the monomer of starch is glucose, while the monomer of cellulose is galactose.
E) humans harbor starch-digesting bacteria in the digestive tract.

Which of the following statements conceming saturated fats is not true?

A) They contain more hydrogen than unsaturated fats having the same number of carbon atoms.
B) They are one of several factors that contribute to atherosclerosis.
C) They are more common in animals than in plants.
D) They have multiple double bonds in the carbon chains of their fatty acids.
E) They generally solidify at room temperature.

A molecule with the formula C18 H36 O2 is probably a

A) carbohydrate.
B) nucleic acid.
C) protein.
D) hydrocarbon.
E) fatty acid.

Which of the following statements is true for the class of biological molecules known as lipids?

A) They are made from glycerol, fatty acids, and phosphate.
B) They contain less energy than proteins and carbohydrates.
C) They contain nitrogen.
D) They are made by dehydration reactions.
E) They are insoluble in water.

The label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. What is the result of adding hydrogens to vegetable oil?

A) The hydrogenated vegetable oil has more "kinks" in the fatty acid chains.
B) The hydrogenated vegetable oil has fewer trans fatty acids.
C) The hydrogenated vegetable oil stays solid at room temperature.
D) The hydrogenated vegetable oil has a lower melting point.
E) The hydrogenated vegetable oil is less likely to clog arteries

Which of the following is true regarding saturated fatty acids?

A) They have double bonds between carbon atoms of the fatty acids.
B) They are usually produced by plants.
C) They are the predominant fatty acid in com oil.
D) They are the principal molecules in lard and butter.
E) They are usually liquid at room temperature.

Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement?

A) cellulose
B) DNA
C) a contractile protein
D) an enzyme
E) a steroid

Which modifications of fatty acids will best keep triglycerides solid at warmer temperatures?

A) creating cis double bonds to the fatty acids
B) adding hydrogens and trans double bonds to the fatty acids
C) creating trans double bonds to the fatty acids
D) adding hydrogens to the fatty acids
E) adding cis double bonds and trans double bonds to the fatty acids

Why are human sex hormones considered to be lipids?

A) They are not soluble in water.
B) They contribute to atherosclerosis.
C) They are hydrophilic compounds.
D) They are made of fatty acids.
E) They are essential components of cell membranes.

All of the following contain amino acids except

A) hemoglobin.
B) antibodies.
C) insulin.
D) cholesterol.
E) enzymes.

The bonding of two amino acid molecules to form a larger molecule requires

A) the addition of a water molecule.
B) the release of a water molecule.
C) the release of a nitrous oxide molecule.
D) the release of a carbon dioxide molecule.
E) the addition of a nitrogen atom

There are 20 different amino acids. What makes one amino acid different from another?

A) different structural and optical isomers
B) different asymmetric carbons
C) different side chains (R groups) attached to the amino groups
D) different side chains (R groups) attached to a carboxyl carbon
E) different side chains (R groups) attached to an a carbon

The bonding of two amino acid molecules to form a larger molecule requires which of the following?

A) removal of a water molecule
B) both removal of a water molecule and formation of a hydrogen bond
C) formation of a hydrogen bond
D) addition of a water molecule
E) formation of a glycosidic bond

Polysaccharides, triacylglycerides, and proteins are similar in that they

A) are synthesized from subunits by dehydration reactions.
B) all contain nitrogen in their monomer building blocks.
C) are decomposed into their subunits by dehydration reactions.
D) are synthesized as a result of peptide bond formation between monomers.
E) are synthesized from monomers by the process of hydrolysis.

Dehydration reactions are used in forming which of the following compounds?

A) triacylglycerides and proteins only
B) triacylglycerides
C) triacylglycerides, polysaccharides, and proteins
D) polysaccharides
E) proteins

What aspects of protein structure are stabilized or assisted by hydrogen bonds?

A) secondary structure
B) quaternary structure
C) primary structure
D) secondary, tertiary, and quaternary structures, but not primary structure
E) tertiary structure

Which bonds are created during the formation of the primary structure of a protein?

A) peptide bonds
B) peptide bonds, hydrogen bonds, and disulfide bonds
C) disulfide bonds
D) phosphodiester bonds
E) hydrogen bonds

What maintains the secondary structure of a protein?

A) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond
B) disulfide bonds
C) hydrophobic interactions
D) peptide bonds
E) hydrogen bonds between the R groups

Which type of interaction stabilizes the a helix and the "B" pleated sheet structures of proteins?

A) peptide bonds
B) ionic bonds
C) disulfide bonds
D) hydrogen bonds
E) hydrophobic interactions

Which level of protein structure do the "a" helix and the "B" pleated sheet represent?

A) secondary
B) primary
C) tertiary
D) primary, secondary, tertiary, and quaternary
E) quaternary

The amino acids of the protein keratin are arranged predominantly in an "a" helix. This secondary structure is stabilized by:

A) ionic bonds.
B) hydrogen bonds.
C) peptide bonds.
D) covalent bonds.
E) polar bonds.

The tertiary structure of a protein is the:
A) Organization of a polypeptide chain into a "A" helix or "B" pleated sheet
B) Overall protein structure resulting from the aggregation of two or more polypeptide subunits
C) Bonding together of several polypeptide chains by weak bonds
D) unique three-dimensional shape of the fully folded polypeptide
E) Order in which amino acids are joined in polypeptic chain

Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are
associated with an accumulation of misfolded polypeptides?

A) diabetes mellitus only
B) Alzheimer's and Parkinson's only
C) Alzheimer's, Parkinson's, and diabetes mellitus
D) Parkinson's only
E) Alzheimer's only

What methods may be used to elucidate the structures of purified proteins?

A) X-ray crystallography
B) both X-ray crystallography and NMR spectroscopy
C) NMR spectroscopy
D) bioinformatics
E) analysis of amino acid sequence of small fragments

In a normal cellular protein, where would you expect to find a hydrophobic amino acid like valine?

A) in the interior of the folded protein, away from water
B) on the exterior surface of the protein, interacting with water
C) in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty acid chains
D) anywhere in the protein, with equal probability
E) in the transmembrane portion interacting with lipid fatty acid chains

Which of the following techniques uses the amino acid sequences of polypeptides to predict a protein's threedimensional structure?

A) bioinformatics
B) analysis of amino acid sequence of small fragments
C) NMR spectroscopy
D) high-speed centrifugation
E) X-ray crystallography

One of the primary functions of RNA molecules is to:

A) transmit genetic information to offspring
B) Form the genes of higher organisms
C) Act as a pattern or blueprint to form DNA
D) Function in the synthesis of protiens
E) make a copy of itself, thus ensureing genetic continuity

Which of the following descriptions best fits the class of molecules known as nucleotides?

A) a pentose sugar and a purine or pyrimidine
B) a nitrogenous base and a pentose sugar
C) a phosphate group and an adenine or uracil
D) a nitrogenous base and a phosphate group
E) a nitrogenous base, a phosphate group, and a pentose sugar

Which of the following are nitrogenous bases of the pyrimidine type?

A) ribose and deoxyribose
B) guanine and adenine
C) adenine and thymine
D) cytosine and uracil
E) thymine and guanine

Which of the following are nitrogenous bases of the purine type?

A) adenine and thymine
B) cytosine and guanine
C) uracil and cytosine
D) guanine and adenine
E) thymine and uracil

Which of the following is an example of hydrolysis?

A) the reaction of a fat, forming glycerol and fatty acids with the consumption of water
B) the reaction of two monosaccharides, forming a disaccharide with the release of water
C) the synthesis of a nucleotide from a phosphate, a pentose sugar, and a nitrogenous base with the production of a molecule of water
D) the synthesis of two amino acids, forming a peptide with the release of water
E) the reaction of a fat, forming glycerol and fatty acids with the release of water

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?
A) 5'-ATGC-3' with 5'-GCAT-3'
B) 5'-AGCT-3' with 5'-TCGA-3'
C) 5'-purine-pyrimidine-purine-pyrimidine-3' with
3'-purine-pyrimidine-purine-pyrimidine-5'
D) 5'-GCGC-3' with 5'-TATA-3'
E) All of these pairs are correct.

Molecules with which functional groups may form polymers via dehydration reactions?

a)carbonyl groups
b)carboxyl groups
c)either carbonyl or carboxyl groups
d)hydroxyl groups
e)either hydroxyl or carboxyl groups

Which of these molecules is not formed by dehydration reactions?

a)disaccharides
b)fatty acids
c)protein
d)DNA
e)amylose