AP Biology Winter Final

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

• The 5' to 3' orientation of the nucleotide chain

• The identity of each nitrogenous base

• The charges on the phosphate groups

• The type of bond linking the nucleotides together

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

• The carbohydrates have the same properties because they have the same number of carbon, hydrogen, and oxygen atoms.

• The carbohydrates have the same properties because they each have a single carbon-oxygen double bond.

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

• The carbohydrates have different properties because they have different numbers of carbon-carbon bonds.

The CFTR protein is made up of 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 have no observable effect on the structure of the CFTR protein.

• It will affect the primary structure of the CFTR protein, but the other levels of protein structure will not be affected.

• It will affect the secondary and tertiary structures of the CFTR protein, but the primary structure will not be affected.

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

Answer explanation

The response indicates that the slightly negatively charged O atom in one water molecule is attracted to one of the slightly positively charged H atoms in another water molecule, so that a weak hydrogen bond forms between the two water molecules. The response explains that the strong electronegativity of O pulls the electrons shared with each H atom within a single water molecule toward the O atom, concentrating more negative charge at the O end of the molecule and giving the H atoms a slight positive charge.

Explain why the arrangement of water molecules is different in ice and water.

Answer explanation

The response indicates that as water cools, the water molecules slow down and, as a result, the hydrogen bonds between them become more stable. Hence, as ice forms the hydrogen bonds cause the water molecules to space out in a crystalline form. Since the liquid water molecules are at a greater temperature, the molecules are moving more rapidly and are constantly forming and breaking their hydrogen bonds.

To help explain surface tension, use a single water molecule in the template and draw arrows representing the possible locations of hydrogen bonds formed by the molecule. The possible hydrogen bonds formed by a water molecule below the surface are shown.

Answer explanation

The response has arrows drawn from one of the water molecules at the surface of the water that show possible hydrogen bonds to other water molecules alongside and just below the molecule at the surface.

The arrangement of the water molecules in ice causes the ice to float. Explain how ice floating on the surface

Answer explanation

The response indicates that the floating ice will reduce heat loss from the water below the ice, resulting in warmer water that is not likely to freeze to the bottom of the body of water.

The stems and fruits of pineapple plants contain a group of protein-digesting enzymes collectively called bromelain and often used as an antibrowning agent for fruits and vegetables. Fruits and vegetables brown when they are bruised during transport or sliced and exposed to air. This browning is controlled by enzymatic pathways that produce brown pigments. The browning of fruits and vegetables reduces the nutritional value of the food, so antibrowning agents such as bromelain are used. Identify the type of monomer of which this enzyme is composed.

Answer explanation

The response indicates that amino acids are the monomers of which this enzyme is composed.

Bromelain works by breaking the enzymes that cause browning into smaller molecules. Explain how the reaction that breaks up the enzymes occurs.

Answer explanation

The response indicates that bromelain acts by enabling the hydrolysis of the protein/polypeptide/amino acid chain, breaking apart the peptide bonds holding the amino acids together OR that bromelain breaks the bond between amino acids by using water as a reactant.

The pH of a solution determines the charge of certain R groups. The of pineapple fruit ranges from 3.5 to

5.2. Predict the effect on the activity of bromelain if it is used in a product with a of 11. Provide reasoning to justify your prediction.

Answer explanation

The response indicates that the activity of bromelain will decrease. The response indicates that changes in pH will affect the interactions between amino acid R-groups in the enzyme, which will change the folding of the enzyme and thus change its shape and ultimately its function.