21.) The cell needs energy to fuel endergonic reactions. Where does that energy come from?
a. ATP hydrolysis
b. Breakdown of glucose
e. A, B, D
22.) The polarity of water drives which of the following?
a. hydrogen bonding
b. protein folding
c. hydrophobic effect
d. B and C
e. A, B, and C
23.) The primary role of oxygen in cellular respiration is to _____.
a. yield energy in the form of ATP as it is passed down the respiratory chain
b. act as an acceptor for electrons and hydrogen, forming water
c. combine with carbon, forming CO2
d. combine with lactate, forming pyruvate
e. catalyze the reactions of glycolysis
24.) The reason that the genetic code can correctly specify the order of amino acids in a polypeptide is:
a. amino acids are covalently joined to the codons in an mRNA.
b. the ribosome recognizes codons and directly attaches amino acids.
c. specific tRNAs become attached to specific amino acids.
d. mRNAs form a shape that allows attachment of the right amino acid.
25.) What determines whether a chemical reaction is spontaneous?
a. if it increases the disorder, or entropy, of the substances involved
b. if it decreases the potential energy of the substances involved
c. the temperature only—reactions are spontaneous at high
d. temperatures and nonspontaneous at low temperatures
e. the combined effect of changes in potential energy and entropy
21) E- A, B, D
22) a- Hydrogen bonding.
I'd like to explain this as there might arise confusion and option e may seem correct too. I chose 'a' because
1. Protein folding is a result of hydrophobic force and not polarity of water.
2. Hydrophic effect does not occur due to polarity of water. It occurs because molecules are hydrophobic and acquire a state of lower energy when they bind to non-polar molecules. Like dissolves like. So entropy and enthalpy are driving force for hydrophobic effect.
23) b - Act as acceptor of electron and hydrogen forming water
24) c- specific tRNAs become attached to specific amino acids
25) e- The combine effect of changesin potential energy and entropy.
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