AP Biology Final

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

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

Ultraviolet (UV) radiation can damage DNA by breaking weak bonds. Which of the following best explains how this occurs?

UV radiation disrupts the double helix structure by breaking the hydrogen bonds between the nitrogenous base pairs.

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

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 correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide?

A. look at ap classroom

If 30% of the nucleotides in a single-stranded RNA molecule are adenine, then what percent are expected to be thymine?

0%

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

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

Amylase is an enzyme that converts carbohydrate polymers into monomers. Glycogen synthase is one of the enzymes involved in converting carbohydrate monomers into polymers. Which of the following best explains the reactions of these enzymes?

Amylase aids in the addition of a water molecule to break covalent bonds whereas glycogen synthase aids in the removal of a water molecule to form covalent bonds.

A common test for liver function involves sprinkling sulfur powder onto a sample of urine (mostly water with dissolved bodily waste). Sulfur powder sprinkled on a sample from an individual with impaired liver function will sink because the urine contains a high level of bile salts, while the sulfur powder sprinkled on normal urine samples will float. Which of the following best explains why bile salts cause the sulfur powder to sink?

Bile salts decrease the surface tension of the urine sample.

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

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

Which of the following best describes the process by which gas from the atmosphere is obtained by plants and used to build lipids?

Gas is directly obtained by plants as part of the carbon cycle.

A researcher measured the temperature at which two different samples of double-stranded DNADNA denature (separate into single strands). Sample 11 denatured at a significantly lower temperature than sample 22 did. Based on the data, the researcher claims that the DNADNA in sample 22 is composed of a higher percentage of guanine and cytosine than the DNADNA in sample 11 is. Which of the following best supports the researcher's claim?

Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do.

Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water's surface?

Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.

The CFTR protein is made up of 1,4801,480 amino acids linked together in a chain. Some humans produce a version of the CFTR protein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino acid chain. 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

A typical bag of fertilizer contains high levels of nitrogen, phosphorus, and potassium but trace amounts of magnesium and calcium. Which of the following best matches the fertilizer component with the molecule in which it will be incorporated by organisms in the area?

Nitrogen will be incorporated into nucleic acids.

The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these two segments would differ?

Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three.

Which of the following best describes the hydrolysis of carbohydrates?

The addition of a water molecule breaks a covalent bond between sugar monomers.

Which of the following statements about glucose, galactose, and fructose is most likely true?

The carbohydrates have different properties because they have different arrangements of carbon, hydrogen, and oxygen atoms.

A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of the amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a nonpolar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has much lower activity than the normal enzyme does. Which of the following most likely explains how the amino acid substitution has resulted in decreased catalytic activity by the mutated enzyme?

The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does.

Which of the following best describes the structures of carbohydrates?

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

A culture of Spirogyra (an autotrophic alga) is maintained in a water solution containing dissolved carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher determines the rates of synthesis of several organic compounds found in the Spirogyra before and after several weeks in the water solution. Which of the following graphs best illustrates a likely result of the experiment?

This option is correct. Without a source of nitrogen, the Spirogyra cannot synthesize proteins or nucleic acids, both of which contain nitrogen. This answer reflects that the student is able to represent graphically the exchange of molecules between an organism and its environment and the use of these molecules in synthesis.

Bacteriophages are viruses that infect bacteria. In an experiment, bacteriophages were labeled with either radioactive phosphorus or radioactive sulfur. The labeled bacteriophages were incubated with bacteria for a brief amount of time and then removed. The infected bacteria cells were found to contain significant amounts of radioactive phosphorus but not radioactive sulfur. Based on the results of the experiment, which of the following types of molecules did the bacteriophages most likely inject into the bacteria cells?

amino acid

Researchers compared similar proteins from related organisms in different habitats. They found that the proteins from organisms living in harsh environments had a greater number of cysteine amino acids than did proteins from organisms not living in harsh environments. The structure of cysteine is shown. Bonds can form between the sulfur atom of different cysteine amino acids (S-S bonds). Figure 1. 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.