A water molecule is formed by _______bonds.
ionic
peptide
polar covalent
nonpolar covalent
The Correct Answer is C
A. Ionic: Ionic bonds involve the complete transfer of electrons from one atom to another, creating oppositely charged ions that attract each other. In water, oxygen and hydrogen share electrons rather than transfer them.
B. Peptide: Peptide bonds form between amino acids during protein synthesis, linking the carboxyl group of one amino acid to the amino group of another. Since water is a simple molecule, not a protein, peptide bonds are not involved in its formation.
C. Polar covalent: Polar covalent bonds occur when atoms share electrons unequally due to differences in electronegativity. In water, oxygen pulls the shared electrons closer to itself, creating a partial negative charge on oxygen and partial positive charges on the hydrogens.
D. Nonpolar covalent: Nonpolar covalent bonds involve equal sharing of electrons between atoms with similar electronegativity. Because oxygen is more electronegative than hydrogen, the sharing in water is unequal.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. Binding is limited to transport maximums: This concept applies to carrier-mediated transport where saturation can occur, but channel-mediated diffusion does not rely on binding and does not reach a transport maximum in the same way.
B. Substances bind to protein carriers: Carrier proteins facilitate movement by binding specific molecules and undergoing conformational changes. Channel-mediated facilitated diffusion does not involve this binding mechanism.
C. Substances move through fluid-filled, transmembrane proteins: In channel-mediated facilitated diffusion, specific substances pass through aqueous channels formed by transmembrane proteins. These channels allow ions or small polar molecules to move down their concentration gradients without energy input.
D. Facilitated active transport is necessary: Channel-mediated diffusion is passive and does not require ATP. Active transport involves energy to move substances against their concentration gradient, which is not the case here.
Correct Answer is B
Explanation
A. Hold carbohydrates and DNA in their 3-D shape: Carbohydrates rely more on glycosidic bonds and branching patterns for their structure, while hydrogen bonding has only a minor role. DNA, however, depends heavily on hydrogen bonds between nitrogenous bases for stability.
B. Hold proteins and DNA in their 3-D shape: Proteins maintain their secondary and tertiary structures through hydrogen bonds between amino acid side chains and peptide backbones. DNA depends on hydrogen bonds between complementary bases, which provide stability while still allowing strand separation during replication.
C. Hold carbohydrates and triglycerides in their 3-D shape: Triglycerides are primarily stabilized by ester bonds and hydrophobic interactions. Carbohydrates do not depend significantly on hydrogen bonds for their three-dimensional organization.
D. Hold proteins and RNA in their 3-D shape: While RNA can fold into complex structures stabilized partly by hydrogen bonds, proteins and DNA are more classically described as relying on hydrogen bonding for maintaining stable 3-D conformations.
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