Quiz 2: Organic Molecules. Multiple Choice (46 pts) Directions: Circle the best answer.

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1 Biology II Ms. Chen Name: Date: Quiz 2: Organic Molecules Multiple Choice (46 pts) Directions: Circle the best answer. 1. Students digging near their school unearthed four objects. One of the objects was part of the exoskeleton of an insect. The table below shows the results of a chemical analysis of the objects. Obje Chemical Composition ct W chlorine, sodium X oxygen, silicon Y carbon, hydrogen, nitrogen, oxygen Z aluminum, silicon, oxygen, hydrogen Based on the chemical analysis, which object is most likely from the exoskeleton? A. object W B. object X C. object Y D. object Z 2. Scientists hypothesize that the microscopic organisms inside a termite s gut are responsible for breaking down the wood that the termite eats. To support this hypothesis, research results should show that the microscopic organisms can produce which of the following? A. ATP B. polysaccharides C. enzymes specific to cellulose D. nucleic acids that are double-stranded 3. Which of the following will most likely change when an enzyme is added to a reaction? A. the ph of the reaction B. the rate of the reaction C. the products of the reaction D. the temperature of the reaction

2 4. A scientist is analyzing a sample of tissue from a plant. Which of the following elements will be most abundant in the sample? A. zinc and copper B. sodium and chlorine C. carbon and hydrogen D. magnesium and calcium 5. The body structure of a reef-building coral consists of a hard skeleton covering soft tissue. Which of the following elements is most common in the coral s soft tissue? A. carbon B. chlorine C. sodium D. zinc 6. Resistance to antibiotics results from variations in the genetic code of Streptococcus pneumoniae. Which type of molecule encodes genetic information in Streptococcus pneumoniae? A. carbohydrate B. fatty acid C. nucleic acid D. protein 7. A student is preparing to run in a school track competition. For the quickest source of energy, the student should eat a food that contains a high percentage of A. carbohydrates. B. fat. C. proteins. D. sodium. 8. Which type of molecule in the yolk of a chicken egg provides the most energy for a developing chick? A. lipid B. nucleic acid C. salt D. water

3 9. The graph below shows how the activity of an enzyme changes over a range of ph values. Which of the following conclusions is supported by the data? A. The optimum ph of the enzyme is 6.6. B. The optimum ph of the enzyme is 5.8. C. The enzyme s activity is greater around ph 8.0 than around ph 5.0. D. The enzyme s activity continually increases as ph increases from 5.0 to An amoeba in a pond engulfs and consumes a paramecium. The amoeba uses which of the following to quickly break down the organic molecules in the paramecium? A. enzymes B. glucose C. polysaccharides D. water 11. Salivary amylase breaks down which class of organic molecules? A. carbohydrates B. lipids C. nucleic acids D. proteins 12. Fatty acids are one of the products that result from the action of lipase in the digestive system. What is one way that fatty acids are used in the body? A. for storing energy B. for encoding genetic information C. as the building blocks of antibodies D. as the building blocks of hemoglobin

4 13. The students also plan to conduct an experiment to study the effect of temperature on pepsin activity. Which of the following graphs shows the expected results of this experiment? A. B. C. D. 14. Which of the following is the main reason that humans need to include carbohydrates in their diet? A. Carbohydrates are broken down in cells for energy. B. Carbohydrates combine to form many different proteins. C. Carbohydrates act as catalysts to speed up chemical reactions. D. Carbohydrates are the building blocks for cell growth and repair.

5 15. Acetylcholine is an important chemical signal in the nervous system. Once acetylcholine is released, it is quickly broken down into other chemicals because of the activity of cholinesterase. Cholinesterase is which of the following? A. a hormone B. a lipid C. an enzyme D. an organelle 16. The graph below shows the rate of activity for the enzyme catalase at different temperatures. Catalase helps convert hydrogen peroxide to oxygen and water. The rate of catalase activity is directly related to the percent increase in oxygen. Based on the graph, which of the following conclusions can be made about the functioning of catalase? A. Catalase works best at. B. Catalase is destroyed at. C. Catalase cannot function at. D. Catalase functions most efficiently at.

6 17. One category of organic compounds contains molecules composed of long hydrocarbon chains. The hydrocarbon chains may be saturated or unsaturated. Which of the following categories of organic compounds contains these molecules? A. carbohydrates B. lipids C. nucleic acids D. proteins 18. Which of the following categories of organic molecules is correctly paired with one of its functions? A. nucleic acids digest dead cells B. lipids give quick energy to cells C. carbohydrates store genetic information D. proteins provide structure in skin, hair, and nails 19. Which of the following best explains why enzymes are necessary for many cellular reactions? A. Enzymes supply the oxygen necessary for the reactions. B. Enzymes change reactants from solid to liquid during the reactions. C. The reactions take up too much space in the cell if enzymes are missing. D. The reactions are too slow to meet the needs of the cell if enzymes are missing. 20. Which of the following types of molecules are primarily used for longterm energy storage in the lemur? A. lipids B. monosaccharides C. nucleic acids D. proteins 21. In the human body, fibrinogen is necessary for sealing cuts and stopping the loss of blood. Since fibrinogen is made of chains of amino acids, it is an example of which type of organic molecule? A. carbohydrate B. protein C. fatty acid D. nucleic acid

7 22. A diagram of an organic molecule is below. found at the positions marked by the dots ( ) in the molecule? Which element is A. carbon B. nitrogen C. phosphorus D. sulfur 22. Some bacteria live in hot springs. Their cells contain enzymes that function best at temperatures of 70 C or higher. At a temperature of 50 C, how will the enzymes in these bacterial cells most likely be affected? A. The enzymes will be destroyed by lysosomes. B. The enzymes will lose their bond structure and fall apart. C. The enzymes will require less energy to function than at 70 C. D. The enzymes will not increase the rate of reactions as much as they would at 70 C. 23. Many plants have waxy coatings on some surfaces. This coating reduces water loss because it is not water-permeable. This waxy coating is which of the following types of organic molecule? A. carbohydrate B. lipid C. nucleic acid D. protein

8 Enzyme Open Response (20 pts) Catalase is an enzyme that protects cells from damage by helping convert the toxin hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). A student is investigating how different ph values and different temperatures affect catalase activity. The table below shows the student s data. Test Tube Amount of Catalase (drops) Catalase Experiment Data Amount of Hydrogen Peroxide (ml) ph of Solution Temperat ure of Solution ( C) Relative Rate of Reaction no reaction no reaction no reaction very slow reaction slow reaction no reaction slow reaction rapid reaction no reaction a. Identify the test tube that most likely has physical conditions similar to the conditions in human cells. Explain your answer. b. Describe how catalase activity changes as ph decreases. Use data from the table to support your answer. c. Describe how catalase activity changes as temperature increases. Use data from the table to support your answer. d. Explain why temperature affects catalase activity in the way you described in part (c).