AP Bio

Changing the deoxyriboses to riboses by adding −OH groups

A student wants to modify model 1 so that it represents an RNA double helix instead of a DNA double helix. Of the following possible changes, which would be most effective in making model 1 look more like RNA than DNA?

The ability to form a covalent bond with both its NH2 group and its COOH group

As shown in Figure 1, an amino acid must have which of the following properties in order to be incorporated into a polypeptide?

The increase in atmospheric CO2 resulted in a greater increase in plant growth under stressed conditions than under ideal conditions.

Based on the figure, which statement best describes the observed relationship between atmospheric CO2 enrichment and plant growth under ideal and stressed conditions?

Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.

Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?

Bonds Y and Z at the same time

Figure 1 represents a segment of DNA. Radiation can damage the nucleotides in a DNA molecule. To repair some types of damage, a single nucleotide can be removed from a DNA molecule and replaced with an undamaged nucleotide. Which of the four labeled bonds in Figure 1 could be broken to remove and replace the cytosine nucleotide without affecting the biological information coded in the DNA molecule?

The R-group of the new amino acid, valine, has different chemical properties than the R-group of cysteine. This will cause the protein to misfold and not function properly in the cell.

How might this change affect the structure and function of the protein?

Which of the following is responsible for the cohesive property of water?

Hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule.

Which of the following best predicts how the amino acid deletion will affect the structure of the CFTR protein?

It will affect the primary, secondary, and tertiary structures of the CFTR protein.

Which of the following describes a key difference among the 20 amino acids that are used to make proteins?

Some amino acids are hydrophobic.

Water and the xylem are both polar. Water molecules have the ability to form hydrogen bonds with each other and with the walls of the xylem.

The diagram shows how water can adhere to the xylem in the stems of plants, which contributes to water movement in the plant. Which of the following best explains how water is able to move upward from the roots of a plant, through its xylem in the stem, and out to the leaves?

Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process?

The high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas.

Which of the following best depicts the tertiary structures of the two proteins in water? The diagrams in the options are not drawn to the same scale as those in Figure 1 and Figure 2.

The hydrophilic middle of the protein chain would be attracted to the water molecules, and the hydrophobic ends would be repelled. Hydrophobic portions of proteins in water tend to be found near the center of the tertiary structure, as far from the water as possible.

Which of the following best describes how amino acids affect the tertiary structure of a protein?

The interactions of the different R-groups with other R-groups and with their environment determine the tertiary structure of the protein.

Which of the following best describes the structures of carbohydrates?

They occur as monomers, chains of monomers, and branched structures.

The linear sequence of the base pairs

Which feature of model 1 best illustrates how biological information is coded in a DNA molecule?

Starch and cellulose are composed of repeating glucose monomers; however, in cellulose every other glucose monomer is rotated 180 degrees.

Which of the following best compares the atomic structures of starch and cellulose?

The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.

Which of the following best describes a structural difference between DNA and RNA?

Both molecules contain nucleotides that form base pairs with other nucleotides, which allows each molecule to act as a template in the synthesis of other nucleic acid molecules.

Which of the following best describes a structural similarity between the two molecules shown in Figure 1 that is relevant to their function?

The water molecules in ice are farther apart than those in liquid water, so the ice floats, maintaining the warmer, denser water at the lake bottom.

Which of the following best describes how the structure of ice benefits the organisms that live in the water below?

Chemical structure of cysteine

Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of the proteins?

The change leads to increased protein stability because of an increased number of S-S bonds in the tertiary structure of the proteins.

Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of the proteins?

A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H2O.

Which of the following best describes the formation of the bond shown in Figure 1 ?

A specific enzyme removes the hydrogen (H) from the monosaccharide and the hydroxide (OH) from the polysaccharide, creating a bond between the two and creating a water (H2O) molecule.

Which of the following best describes the process that adds a monosaccharide to an existing polysaccharide?

The identity of each nitrogenous base

Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA?

Nucleic acid #1 contains adenine-thymine base pairs, whereas nucleic acid #2 does not.

Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic #2?

The formation of a covalent peptide bond in a dehydration synthesis reaction

Which of the following is an accurate description of the process shown in Figure 1 ?

Monomers are joined by a covalent bond, and a water molecule is produced.

Which of the following is common feature of the illustrated reactions showing the linking of monomers to form macromolecules?

The phosphorus-starved plant was unable to synthesize both the required nucleic acids and lipids, limiting growth

Which of the following is the most likely reason for the difference in leaf growth?

The ammonia molecules released by the fish are converted by the bacteria to nitrates, which are used by the plants to make proteins and nucleic acids.

Which of the following statements best describes how molecules released by the fish become nutrients for the plants?

Rabbits eat plants and break down plant molecules to obtain carbon and other atoms that they rearrange into new carbon-containing molecules.

Which of the following statements best describes how organisms such as rabbits obtain the carbon necessary for building biological molecules?

The differences in the assembly and organization of the monomers of these two polymers result in different chemical properties.

Which of the following statements best describes the different functions of starch and cellulose in plants?

It is DNA because of the nucleotides present.

Which of the following statements is correct about the molecule shown in Figure 1 ?

Cattle would no longer be able to use cellulose as a primary source of glucose.

Which of the following would most likely occur if cattle lost the ability to maintain a colony of microorganisms in their digestive tract?

The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.

Which statement best helps explain the formation of the hydrogen bond represented in the figure?

As water exits the leaf, hydrogen bonding between water molecules pulls more water up from below.

Which statement describes how water is pulled up through the xylem to the leaves of the plant?

It represents a polypeptide chain that is broken down through a hydrolysis reaction.

Which statement is the most accurate description of the reaction shown in Figure 1?