Unit 1 AP Review

Scientists examined the folded structure of a purified protein resuspended in water and found that amino acids with nonpolar R groups were primarily buried in the middle of the protein, whereas amino acids with polar R groups were primarily on the surface of the protein. Which of the following best explains the location of the amino acids in the folded protein?

• Polar R groups on the surface of the protein can form ionic bonds with the charged ends of the water molecules

• Polar R groups are too bulky to fit in the middle of the protein and are pushed toward the protein's surface

• Nonpolar R groups from different parts of the protein form covalent bonds with each other to maintain the protein's structure

• Nonpolar R groups that cannot form hydrogen bonds with water are pushed into the middle of the protein

Answer explanation

Nonpolar groups are formed from nonpolar covalent bonding (equal sharing of electrons) which results in no

partial charge. The absence of the partial charge inhibits the hydrogen bonding with water molecules which

are polar.

Rosalind Franklin's x-ray diffraction images taken in the 1950s most directly support which of the following claims about DNA?

• The ratios of base pairs are constant

• The nucleotide sequence determines genetic information

• The two strands of DNA are antiparallel

• The basic molecular structure is a helix

Answer explanation

The image clearly shows a circular shape with an X through the middle. This demonstrates there are two

strands or a double helix (circular shape) with binding in the middle of nitrogenous bases (making the X

shape).

Which of the following does not result from hydrogen bonding in water molecules?

• Cohesion

• Adhesion

• Surface tension

• Dissolving fats

Answer explanation

Dissolving fats involves the water molecules surrounding the fat molecule creating a hydration shell. The fats are nonpolar while the water molecules are polar, which means there are no hydrogen bonds formed between these two.

Why is water considered polar?

• Nonpolar covalent bonds in structure

• Ionic bonds in structure

• Polar bonds in structure

• Hydrophobic interaction in structure

Answer explanation

Polar covalent bonds are the result of unequally sharing valence electrons. This unequal sharing results in partial charges that allow for the polar nature of water.

Which macromolecule(s) have nitrogen?

• Carbohydrates

• Proteins

• Nucleic Acids

• Nucleic Acids & Proteins

Answer explanation

Nucleic acids have nitrogen in their nitrogenous bases and proteins have nitrogen in their amino group.

Which Macromolecule(s) have phosphorus?

• Carbohydrates

• Proteins

• Nucleic Acids

• Fats

Answer explanation

Nucleic acids are made up of carbon, hydrogen, oxygen, nitrogen, and phosphorus.

Which macromolecule(s) have sulfur?

• Carbohydrates

• Proteins

• Nucleic Acids

• Fats

Answer explanation

Proteins are made up of carbon, hydrogen, oxygen, nitrogen, and sulfur

Describes the forming of a bond between monomers with the removal of a water molecule

• Hydrolysis

• Dehydration

Answer explanation

Dehydration involves forming a water molecule and forming a bond between monomers of a polymer. The hydroxyl group combines with the hydrogen resulting in the water molecule that is removed.

Describes the breaking of a bond within a polymer using water.

• Hydrolysis

• Dehydration

Answer explanation

Hydrolysis involves breaking a water molecule to break a bond between monomers of a polymer.

Which of the following is NOT in the monomer of a nucleic acid?

• pentose sugar

• nitrogenous base

• phosphate

• amino acid

Answer explanation

Amino acids are the monomer for proteins and not found in the nucleotide monomer.