biology test 1
What could happen if a mutation in a gene caused a hydrophobic amino acid in a polypeptide to be replaced by a hydrophilic amino acid?
The new amino acid would not form the same interactions with hydrophobic R groups, and the protein's shape would likely be affected.
Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNADNA?
5′-ATGC-3′5′-ATGC-3′ with 5′-GCAT-3′
If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?
75
Which of the following statements about the formation of polypeptides from amino acids is true?
A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.
Which of the following statements is correct regarding starch and cellulose?
They are polymers of glucose.
Which of the following identifies the chemical relationship between glucose and fructose?
They are structural isomers.
What do DNA, proteins, and fats have in common?
They contain carbonyl groups.
Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In which of the following ways do these molecules differ from each other?
They have different functional groups attached to the same carbon skeleton.
Which statement about unsaturated fats is true?
They have double bonds in their fatty acid chains.
True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.
True
True or false? Peptidoglycan is a polysaccharide found only in bacteria.
True
Which of the following categories includes all others in the list?
carbohydrate
The large diversity of shapes of biological molecules is possible because of the extensive presence of __________ in the molecules.
carbon
Which of the following functional groups gives amino acids their acidic character?
carboxyl
Which two functional groups are always found in amino acids?
carboxyl and amino groups
Starch is composed of which of the following?
branched amylopectin and unbranched amylose
The term insoluble fiber on food packages refers to which of the following molecules?
cellulose
Which of these is a polysaccharide?
cellulose
_____ is the most abundant organic compound on Earth.
cellulose
Which polysaccharide is an important component in the structure of many animal and fungal cells?
chitin
The secondary structure of a protein results from _____.
hydrogen bonds
The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.
hydrogen bonds
What is the name of the process during which a bond between two monomers is broken?
hydrolysis
What holds phospholipids together in a bilayer formation?
hydrophilic and hydrophobic interactions with water
In the reaction that builds a fat,________ groups react with ________ groups.
hydroxyl; carboxyl
Polymers that contain sugars ...
(a), (b), and (c). Submit
What do fats, steroids, and waxes have in common?
(b) Low solubility in water.
Primary structure is the sequence of amino acids in a protein.
1
How many fatty acids are in a phospholipid?
2
Secondary structure describes the alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms located near each other in the polypeptide chain.
2
How many molecules of water are required for the polymerization of a 22 monomer-long cellulose molecule?
21
Tertiary structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids.
3
If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand?
3'-TAAACG-5' Submit
Quaternary structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex.
4
Which molecule is less soluble in water--a fat or a phospholipid? Why?
A fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has.
Which molecule is a nucleotide?
ATP
Which of the following statements about ADP/ATP is true?
ATP can have four negative charges.
Identify the functional groups.
Amino and carboxyl are functional groups.
Which complex carbohydrate contains only a-1,4-glycosidic linkages?
Amylose
Which of the following is not attached to the central carbon atom in an amino acid?
An oxygen
Which of the following complex carbohydrates is listed with its correct function?
Cellulose: structural component of plant cell walls Submit
The presence of many C-C and C-H bonds causes fats to be ...
Both (a) and (b).
Triglycerides vary with respect to the number of ...
Both (b) and (c).
Visualize the structural formula of each of the following hydrocarbons. Which hydrocarbon has a double bond in its carbon skeleton?
C2H4
Which part of an amino acid is always acidic?
Carboxyl functional group
Plant cell walls consist mainly of __________.
Cellulose
Which of the following best compares dehydration reactions and hydrolysis?
Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart.
Which statement about isomers is correct?
Enantiomers differ in biological activity.
Variations in the reactive properties of different organic molecules are most closely associated with __________.
Functional groups are the most common participants in chemical reactions.
Why can humans digest starch but not cellulose?
Humans have enzymes that can hydrolyze the α-glycosidic linkages of starch but not the β-glycosidic linkages of cellulose.
Which of the following is true of carbon?
It can form both polar and nonpolar bonds.
A compound contains hydroxyl groups as its predominant functional group. Which of the following properties of the molecule can be predicted with the information provided?
It should dissolve in water.
Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, which of the following statements best describe a hydrocarbon chain with the same number of carbon atoms but with one or more double bonds?
It will be more constrained in structure.
Which molecule is not a carbohydrate?
Lipid
Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; what are enantiomers?
Molecules that are mirror images of each other.
Which of the following statements about monosaccharide structure is true?
Monosaccharides can be classified according to the spatial arrangement of their atoms. Submit
The building blocks ( monomers) of nucleic acid molecules are called __________.
Nucleotides
Which monomers make up RNA?
Nucleotides
A hydrophobic amino acid R group (side group) would be found where in a properly folded protein?
On the inside of the folded chain, away from water molecules Submit
Which polysaccharide contains a modified monosaccharide?
Peptidoglycan Submit
Which polymers are composed of amino acids?
Proteins
Which of these is NOT a lipid?
RNA
Which feature of large biological molecules explains their great diversity?
The many ways that monomers of each class of biological molecule can be combined into polymers Submit
What structural difference accounts for the functional differences between starch and cellulose?
Starch and cellulose differ in the glycosidic linkages between their glucose monomers. Submit
What functional group is commonly used in cells to transfer energy from one organic molecule to another?
The addition and release of phosphate groups to and from ADP and ATP is how cells store chemical energy and expend it to accomplish work.
Which of the functional groups shown above is most likely to gain a proton and become positively charged?
The amino group is most likely to gain a proton.
Enzymes that break down DNADNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNADNA molecules treated with these enzymes?
The phosphodiester linkages of the polynucleotide backbone would be broken.
Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure.
The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene.
Dr. Haxton told one of his students, "To move in the bloodstream, fats need the help of phospholipids." What would a good student say?
Yes. Nonpolar molecules aren't compatible with water.
Glycogen is _____.
a polysaccharide found in animals
Proteins are polymers of _____.
amino acids Submit
People who are lactose intolerant cannot extract energy from milk because ________.
an enzyme is not functioning correctly
A function of cholesterol that does not harm health is its role _____.
as a component of animal cell membranes
Palm coconut oils are more like animal fats than other plant oils. Because they __________ than other plant oils, they may contribute to cardiovascular disease.
contain fewer double bonds
A carbon atom is most likely to form what kind of bond(s) with other atoms?
covalent
What is another name for a condensation reaction?
dehydration
Which of the following factors determines whether a carbon atom's covalent bonds with other atoms are in a tetrahedral configuration or a planar configuration?
double bonds between the carbon atom and other atoms
In fat synthesis,________and fatty acids combine to make fats plus________.
glycerol; water
The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are in the αα form. Which of the following could amylase break down?
glycogen, starch, and amylopectin
Sucrose is formed when glucose is joined to fructose by a(n) _____. See Concept 5.2 (Page)
glycosidic linkage
glucose + glucose —> _____ by _____.
maltose + water ... dehydration synthesis
Which of the following functional groups is unreactive but when added to bases of DNA can alter gene expression?
methyl
Which statement about a methyl functional group is correct?
methyl group consists of a carbon bonded to three hydrogen atoms.
The characteristic that all lipids have in common is __________.
none of them dissolves in water
The results from Stanley Miller's 1953 experiments can best be used to support which of the following hypotheses?
organic molecules can be synthesized abiotically under conditions that may have existed on early Earth
Miller's classic experiment demonstrated that a discharge of sparks through a mixture of gases could result in the formation of a large variety of organic compounds. Miller did not use which one of the following gases in his experiment?
oxygen
What type of bond joins the monomers in a protein's primary structure?
peptide
Tertiary structure is NOT directly dependent on _____.
peptide bonds
The structural level of a protein least affected by a disruption in hydrogen bonding is the
primary level.
The four main categories of large biological molecules present in living systems are __________.
proteins, nucleic acids, carbohydrates, and lipids
Some regions of a polypeptide may coil or fold back on themselves. This folding is called __________, and the coils or folds are held in place by __________.
secondary structure, hydrogen bonds
An atom has four electrons in its valence shell. What type(s) of covalent bonds is it capable of forming with oxygen?
single and double bonds
Which of the following characteristics is responsible for the complexity and variety of organic molecules?
the chemical versatility of carbon atoms
Which of the following statements is correct for organic molecules with only hydrogens and five carbon atoms?
the molecule cannot have enantiomers
The most unsaturated fats have ...
the most double bonds. Submit
The difference between an aldose sugar and a ketose sugar is ________.
the position of the carbonyl group
Which of the following best describes cis-trans isomers?
they differ in their spatial arrangement around inflexible double bonds
Differences in which of the following chemical characteristics are responsible for the uniqueness of individuals organisms?
types and relative amounts of organic molecules synthesized by each organism
A dehydration reaction (or condensation reaction) is the process in which __________.
water molecules are produced as a polymer formed from monomers
Maltose is a disaccharide that can easily be digested into glucose molecules. Which type of glycosidic linkage connects glucose molecules in maltose?
α 1-4