About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements makeup approximately 96% of living matter?
A) carbon, sodium, chlorine, nitrogen
B) carbon, sulphur, phosphorus, hydrogen
C) carbon, hydrogen, nitrogen, oxygen
D) carbon, oxygen, sulphur, calcium
C) Carbon, Hydrogen, Nitrogen and Oxygen
Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates?
A) Nitrogen
B) Iodine
C) Sodium
D) Phosphorus
B) Iodine
Atoms whose outer electron shells contain eight electrons tend to
A) form ionic bonds in aqueous solutions.
B) be stable and chemically nonreactive,or inert.
C) be unstable and chemically very reactive.
D) be isotopes and very radioactive.
B) Be stable and chemically nonreactive or inert.
A covalent chemical bond is one in which
A)electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged.
B) protons and neutrons are shared by two atoms so as to satisfy both atoms.
C) Outer-shell electrons of two atoms are shared so as to fill the outer electron shells of both atoms.
D) outer-shell electrons of one atom are transferred to the inner electron shells of another atom.
C) Outer-shell electrons of two atoms are shared so as to fill the outer electron shells of both atoms.
The ionic bond of sodium chloride is formed when
A) chlorine
gains an electron from sodium.
B) sodium and chlorine share an
electron pair.
C) sodium and chlorine both lose electrons from
their outer valence shells.
D) sodium gains an electron from
chlorine.
E) chlorine gains a proton from sodium.
A) chlorine gains an electron from sodium.
Which of the following explains most specifically the attraction of
water molecules to one another?
A) nonpolar covalent bond
B) polar covalent bond
C) ionic bond
D) hydrogen
bond
E) hydrophobic interaction
D) hydrogen bond
Van der Waals interactions result when
A) hybrid orbitals
overlap.
B) electrons are not symmetrically distributed in a
molecule.
C) molecules held by ionic bonds react with
water.
D) two polar covalent bonds react.
E) a hydrogen
atom loses an electron.
B) electrons are not symmetrically distributed in a molecule.
Which two functional groups are always found in amino acids?
A) hydroxyl and carboxyl
B) ketone and methyl
C) amino and
sulfhydryl
D) carboxyl and amino
E) carbonyl and amino
D) carboxyl and amino
What is the chemical reaction mechanism by which cells make polymers
from monomers?
A) phosphodiester linkages
B)
hydrolysis
C) dehydration reactions
D) ionic bonding of
monomers
E) the formation of disulfide bridges between monomers
C) dehydration reactions
All of the following statements concerning saturated fats are true,
except...
A) They are more common in animals than in
plants.
B) They have multiple double bonds in the carbon chains
of their fatty acids.
C) They generally solidify at room
temperature.
D) They contain more hydrogen than unsaturated fats
having the same number of carbon atoms.
E) They are one of
several factors that contribute to atherosclerosis.
B) They have multiple double bonds in the carbon chains of their fatty acids.
A strong covalent bond between cysteine amino acids that functions in maintaining a polypeptide's specific three-dimensional shape is a(an)
A) ionic bond.
B) hydrophobic interaction.
C) disulphide bond.
D) hydrogen bond.
C) disulphide bond.
Which of the following statements about prokaryotic and eukaryotic cells is not correct?
A) Prokaryotic cells contain small membrane-enclosed organelles.
B) Eukaryotic cells contain amembrane-bound nucleus.
C)DNA ,or deoxy ribonucleic acid, is present in both prokaryotic cells and eukaryotic cells.
D)DNA or deoxy ribonucleic acid is present in the nucleus of eukaryotic cells
A) Prokaryotic cells contain small membrane-enclosed organelles.
Prokaryotic and eukaryotic cells generally have which of the following features in common?
A)a membrane-bounded nucleus
B)ribosomes
C) flagella or cilia that contain microtubules
D) linear chromosomes made of DNA and protein
B) Ribosomes
Which of the following best describes the flow of information in
eukaryotic cells?
A) DNA → RNA → proteins
B) RNA →
proteins → DNA
C) proteins → DNA → RNA
D) RNA → DNA →
proteins
E) DNA → proteins → RNA
A) DNA → RNA → proteins
Which of the following are nitrogenous bases of the purine
type?
A) cytosine and guanine
B) guanine and adenine
C) adenine and thymine
D) thymine and uracil
B) guanine and adenine
The difference between the sugar in DNA and the sugar in RNA is that
the sugar in DNA
A) is a six-carbon sugar and the sugar in RNA
is a five-carbon sugar.
B) can form a double-stranded
molecule.
C) is in the α configuration and the sugar in RNA is
in the β configuration.
D) contains one less oxygen atom.
D) contains one less oxygen atom.
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
A)lipids
B)starches
C)proteins
D)steroids
C) Proteins
Which structure is the site of the synthesis of proteins that may be exported from the cell?
A) rough endoplasmic reticulum
B) lysosomes
C) plasmodesmata
D) Golgi vesicles
A) rough endoplasmic reticulum