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