Microbiology CH. 2 Study and Review

When the nucleus of an atom contains a constant number of protons but a variable number of neutrons, the atom is called a(n) __________.

isotope

Methane is classified as a compound because __________.

it contains atoms of more than one element

Pure water has a neutral pH because __________.

it dissociates into equal numbers of hydrogen and hydroxyl ions

Which of the following is NOT a type of lipid? waxes triglycerides peptidoglycan steroid

peptidoglycan

Cranberry juice has a pH of 2.4, while grape juice has a pH of 3.3; which juice is more acidic?

cranberry

If you know that sodium chloride molecules contain ionic bonds, which of the following electronegativity values would be appropriate for the elements sodium and chlorine?

0.9 and 3.0

An oxygen atom has two electron shells and 6 valence electrons. How many total electrons does this atom have?

8

Which of the following is NOT true of hydrogen bonds?

Hydrogen bonds are important only in the interaction between water molecules.

Which of the following is a molecule, but NOT a compound?

O2

If you know that a particular chemical reaction involves the production of smaller molecules from the breakdown of larger molecules, which of the following statements would you expect to be true?

The reaction releases energy.

What is the common trait of all lipids?

They are at least partially hydrophobic.

Which of the following is a bond in which electrons are shared unequally?

a polar covalent bond

KH2PO4 acts as a buffer by __________.

combining with hydrogen ions

Catabolism includes all of the following types of reactions EXCEPT __________. dehydration synthesis reactions decomposition reactions hydrolysis reactions exothermic reactions

dehydration synthesis reactions

Sucrose is an example of which of the following? - a nucleotide - steroid - a dipeptide - disaccharide

disaccharide

A synthesis reaction is also considered which of the following types of reactions?

endothermic

Which of the following subatomic particles does NOT have a charge?

neutron

Which of the following is the most alkaline (basic) pH? pH 2.0 pH 7.0 pH 9.0 pH 13.0

pH 13.0

An endothermic reaction __________.

requires energy

In discussions of atomic mass, electrons are often ignored because __________.

their mass makes a negligible contribution to the atom's overall mass