Biology Keystone Exam Review

Which statement best describes how channel and carrier proteins in the plasma membrane are similar? A. Both allow for the flow of molecules into and out of a cell. B. Both directly connect the membrane to the nucleus of a cell. C. Both use energy to continuously move water molecules out of a cell. D. Both cause the phospholipid bilayer to form a rigid membrane for a cell.

A. Both allow for the flow of molecules into and out of a cell.

Which action must occur for an enzyme to catalyze a chemical reaction? A. A competitive inhibitor must first bind to an active site. B. A substrate must bind to an active site of the enzyme. C. A substrate must bind to an allosteric site of the enzyme. D. A noncompetitive inhibitor must first bind to an active site.

B. A substrate must bind to an active site of the enzyme.

Which statement correctly describes how a protein is formed? A. A monosaccharide bonded to a side chain is broken apart. B. Amino acids are bonded together in a long chain to form a new molecule. C. A molecule containing glycerol bonded to three fatty acids is broken apart. D. A nitrogenous base, a sugar, and a phosphate group combine to form a new molecule.

B. Amino acids are bonded together in a long chain to form a new molecule.

Lipase is an enzyme that breaks down lipids in the digestive system of humans. It functions best at a pH range of 4.0 to 5.0. When a person takes an antacid tablet to relieve heartburn, the antacid increases the pH to around 7 in certain areas of the digestive system. Which initial effect would most likely be caused by a change in pH? A. More lipids would be digested. B. Fewer lipids would be digested. C. The production of lipase molecules would increase. D. The production of lipase molecules would decrease.

B. Fewer lipids would be digested.

Carbon can combine with many different elements but frequently combines with oxygen, hydrogen, and nitrogen to form organic molecules. Which statement best explains why carbon is able to form a large number of different molecules? A. Carbon forms only ionic bonds. B. Carbon can form only ring structures. C. Carbon can form four covalent bonds. D. Carbon forms small, simple structures.

C. Carbon can form four covalent bonds.

A cell in the leaf of a green plant performs both photosynthesis and cellular respiration, often at the same time. Which statement best describes how these processes are related to each other? A. Both processes produce carbon dioxide. B. Both processes require energy directly from the Sun. C. Products of one process are used as some of the reactants for the other process. D. Thermal energy from one process is used as the energy source for the other process.

C. Products of one process are used as some of the reactants for the other process.

Which characteristic is shared by both prokaryotes and eukaryotes? A. have organ systems B. make their own food C. contain genetic material D. need oxygen gas to breathe

C. contain genetic material

A scientist observed that during the course of a chemical reaction the number of ATP molecules was reduced. What did the scientist most likely learn from the observation? A. The reaction produced water. B. The reaction consumed water. C. The reaction caused an output of energy. D. The reaction required an input of energy.

D. The reaction required an input of energy.

Use the lists below to answer the question. Cell Structures Observed in Two Organisms: Cell Structures in Organism 1 • cell wall • endoplasmic reticulum • Golgi body • chloroplasts • mitochondria • nucleus • ribosomes • vacuole Cell Structures in Organism 2 • cell membrane • endoplasmic reticulum • Golgi body • mitochondria • nucleus • ribosomes A student made lists of structures observed in cells from two different organisms. Which statement describes the most likely difference in the way that organism 1 and organism 2 obtain energy? A. Only organism 1 uses solar energy to make energy-rich compounds. B. Only organism 1 stores solar energy until it is needed for its life processes. C. Only organism 2 produces molecules for long-term energy storage. D. Only organism 2 transforms food energy into ATP during cellular respiration.

A. Only organism 1 uses solar energy to make energy-rich compounds.

Use the chart below to answer the question. Biological Molecule Information Molecule 1: -a molecule made mostly of carbon with two nonpolar chains and a polar head -is a component of plasma membranes Molecule 2: -a polar molecule made of repeating units of sugar bonded to a phosphate and a nitrogenous base -stores genetic information Which biological molecules are most likely represented by molecules 1 and 2? A. molecule 1: lipid molecule 2: nucleic acid B. molecule 1: lipid molecule 2: protein C. molecule 1: carbohydrate molecule 2: nucleic acid D. molecule 1: carbohydrate molecule 2: protein

A. molecule 1: lipid molecule 2: nucleic acid