Ap Biology College board questions

Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membrane. Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions? A. They have rigid, nonfluid membranes. B. They have highly folded membranes. C. They have membranes composed of many carbohydrates. D. They have double membranes, with one membrane enclosed within the other.

The answer is B. Compared with a smooth membrane, a highly folded membrane has a greater surface area that increases the rate of material transport across the membrane and provides more support for membrane-associated processes.

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. According tot he results of this experiment, germination of tobacco seeds during the first week is A. Increased by exposure to light B. Unaffected by light intensity C. Prevented by paper towels D. Accelerated in green-leaved seedlings

The correct answer is A.

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs within the Golgi complex? A. Enzymatic modification of newly synthesized integral membrane proteins B. Synthesis of cytosolic proteins based on the nucleotide sequences of mRNAs C. Degradation of proteins by hydrolytic enzymes contained within the complex D. Synthesis of various types of lipids

The correct answer is A. The Golgi complex is a membrane-bound structure to which some proteins are moved from the rough endoplasmic reticulum, where they are enzymatically modified before being sent to a cellular membrane.

A researcher claims that some bacteria contain factors that influence the function of a particular enzyme but other bacteria do not. To test the claim experimentally, the researcher will grow two different bacterial strains in separate liquid cultures and isolate the contents of the cells in each culture. The researcher will add different combinations of cellular contents, substrate, and enzyme to test tubes containing a buffer solution adjusted to the optimal pH of the enzyme and then measure the rate of production formation. The design of the researcher's experiment is presented in Table 1. Which of the following statements best justifies the inclusion of test tubes 3 and 7 in the experiment? A. They will show whether the isolated cellular contents have enzymatic activity. B. They will show whether environmental pH affects the function of the enzyme. C. They will show the rate of product formation in the absence of bacterial factors. D. They will show the rate of product formation in the absence of the substrate.

The correct answer is A. The researcher will add cellular contents and the substrate but not the enzyme to test tubes 3 and 7. As such, test tubes 3 and 7 will show whether the cellular contents have enzymatic activity.

Which of the following statements best describes how organisms such as rabbits obtain the carbon necessary for building biological molecules? A. Rabbits eat plants and use energy absorbed from the plants to make carbon atoms from electrons, protons, and neutrons in the air. B. Rabbits eat plants and break down plant molecules to obtain carbon and other atoms that they rearrange into new carbon-containing molecules. C. Rabbits eat plants and use water absorbed from the plants to hydrolyze CO2, which the rabbits breathe in from the air and use a carbon source. D. Rabbits eat plants and make carbon-containing molecules by using carbon atoms that the plants absorbed from the soil and stored in the cells of their leaves.

The correct answer is B.

Water and Ammonia interact to form hydrogen bonds, as represent in the figure. Which statement best helps explain the formation of the hydrogen bond represented in the figure? A. The oxygen has a partial positive charge, and the nitrogen had a partial negative charge. B. The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge. C. The hydrogen attached to the oxygen has a partial negative charge, and the nitrogen also has a partial negative charge. D. The nitrogen has a partial positive charge, and the hydrogen attached to the oxygen also has a partial positive charge.

The correct answer is B. The greater electronegativity of oxygen and nitrogen compared to hydrogen makes for unequal sharing of electrons, which associated with the oxygen and nitrogen atoms and partial positive charges associated with the hydrogen atoms in both molecules. The attraction between opposite charges results in formation of the hydrogen bond represented in the figure.

A feature of organic compounds NOT found in inorganic compounds in the presence of A. Ionizing chemical groups B. Electrons C. Carbon atoms covalently bonded to each other D. Oxygen E. Hydrogen bonds

The correct answer is C.

Which of the following is responsible for the cohesive property of water? A. Hydrogen bonds between the oxygen atoms of two adjacent water molecules. B. Covalent bonds between the hydrogen atoms of two adjacent water molecules. C. Hydrogen bonds between the oxygen atoms of one water molecule and a hydrogen atom of another water molecule. D. Covalent bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule. E. Hydrogen bonds between water molecules and other types of molecules.

The correct answer is C.

Which of the following best describes the formation of the bond shown in Figure 1? A. An ionic bond is formed between a carbon atom of one amino acid and the nitrogen atom of the other amino acid. B. An ionic bond is formed when the negative charge of an OH group is balanced by the positive charge of a hydrogen ion. C. A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H2O. D. A covalent bond is formed that replaces the hydrogen bond between the OH group and the H atom.

The correct answer is C. Even though the water molecule that is produced is not shown in Figure 1, it shows the formation of the peptide bond and the missing H and OH.

What most likely causes the trends in oxygen concentration shown in the graph above? A. The water becomes colder at night and thus holds more oxygen. B. Respiration in most organisms increases at night C. More organisms are respiring at night than during the day D. Photosynthesis produces more oxygen than is consumed by respiration during the day.

The correct answer is D.

Which of the following is most directly responsible for water''s unique properties? A. It contains oxygen atoms. B. It contains hydrogen atoms. C. It is an ionic compound. D. It forms hydrogen bonds. E. It is nonpolar.

The correct answer is D.

Figure 1 is a diagram of water molecule at the air-water interface at the surface of a pond. 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. A. Covalent bonds between water molecules and the air above provide cohesion, which causes tiny bubbles to form under the feet of the insect. B. Ionic bonds between molecules at the surface of the water provide at electric charge, which attracts the feet of the insect, keeping it on the surface. C. Polar covalent bonds between molecules at the surface of the water provide adhesion, which supports the weight of the insect. D. 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 correct answer is D. Hydrogen bonds form between water molecules due to the partial charges produced as a result of the polarity of the water molecule. The strength of the attraction between the water molecules allows organisms to walk across the surface without breaking the hydrogen bonds.

Which statement is the most accurate description of the reaction shown in Figure 1? A. It represents monomers linked by dehydration synthesis. B. It represents a polypeptide chain that folds to form a tertiary structure. C. It represents a polypeptide chain that is denatured into the primary structure. D.It represents a polypeptide chain that is broken down through a hydrolysis reaction.

The correct answer is D. The reaction shows the polypeptide being split into two smaller units with the addition of a hydroxide ion and a hydrogen ion from water. This facilitates the breaking of the bond holding the polypeptide together.

Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. Which of the following difference between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them? A. Rough ER breaks down toxic substances, and smooth ER only transports them out of the cell. B. Rough ER can synthesize and package lipids for exports and smooth ER cannot. C. Rough ER can produce ATP, and smooth ER cannot. D. Rough ER can synthesize and package proteins for exports, and smooth ER cannot.

The correct answer is D. The ribosomes associated with rough ER synthesize proteins that are then exported from the cell.

Which of the following is an accurate description of the process shown in figure 1? A. The linking of amino acids with an ionic bond as an initial step in the protein synthesis process. B. The formation of a more complex carbohydrate with the covalent bonding of two simple sugars. C. The hydrolysis of amino acids with the breaking of covalent bonds with the release of water. D. The formation of a covalent peptide bond in a dehydration synthesis reaction.

The correct answer is D. This reaction combines two smaller amino acids to form a dipeptide (a step in the formation of a protein) with the release of water. The presence of nitrogen is consistent with the both amino acids and proteins. The combining of smaller molecule with the release of water is a dehydration synthesis reaction.

The synthesis of protein or carbohydrate polymers always produces which of the following as a byproduct. A. ATP B. Oxygen C. Carbon Dioxide D. Urea E. Water

The correct answer is E.