MG Sci Acids and Bases

Transcription

1 Sunflower CCSD Assessment Science (MS Framework) Grades 9-12 ID: MG Sci Acids and Bases Directions: Read the question. Fill in the bubble next to the corresponding question number on your answer sheet.

2 1 The table shows three solutions and their ph values. Which list has the solutions placed in order of increasing H + concentration? A X, Y, Z B Y, Z, X C Z, Y, X D X, Z, Y 2 Which statement correctly describes a solution with a ph of 7.5? A It has a much higher concentration of OH - than H O. 3 B It has a slightly higher concentration of OH - than H O. 3 C It has a much higher concentration of H O than OH 3 -. D It has a slightly higher concentration of H O than OH Which happens to the concentration of hydronium ions as a ph of a solution is changed from 4 to 7? A decrease by a factor of 100 B decrease by a factor of 1000 C increase by a factor of 100 D increase by a factor of 1000 All content is the private property of the copyright holders. Page 1

3 4 The graph contains information on the rate of activity of two human enzymes at various ph levels. At which ph level do both pepsin and trypsin function? A 2.5 B 5.5 C 7.0 D 9.5 All content is the private property of the copyright holders. Page 2

4 5 Use the table to answer the question. Acidic waste from a mine drains into a stream and causes its ph level to change from 7.0 to 5.5. Which species will die in the stream with the lowered ph? A clam only B brook trout and bullfrog C rainbow trout, bullfrog, and brook trout D rainbow trout, smallmouth bass, clam, and crayfish All content is the private property of the copyright holders. Page 3

5 6 Enzymes are critical to nearly all biological processes in the human body. With reference to the graph, what would be true about the optimum environment required for this enzyme to function properly? A It would have a high concentration of hydrogen ions. B It would have a high concentration of hydroxide ions. C It would have no hydrogen or hydroxide ions. D It would have relatively equal concentrations of hydrogen and hydroxide ions. 7 Acid indigestion is caused when a person's stomach ph is too low. To counteract this, an antacid is taken. What type of ions does the antacid form to reduce the acid in the stomach? A chlorine B covalent C hydrogen D hydroxide All content is the private property of the copyright holders. Page 4

6 8 Enzymes are critical to nearly all biological processes in the human body. What can be inferred from this graph of enzyme activity vs. ph for a particular digestive enzyme? A The ph does not affect the activity of this enzyme. B The enzyme functions best at acidic ph values. C The enzyme functions best at basic ph values. D The enzyme functions best at a neutral ph. 9 The process of adding limestone to fish ponds surrounded by soils that have high acid content raises the ph of the water and increases the availability of nutrients from the pond. What direct effect does this process have on the fish ponds? A It increases the alkalinity of the pond. B It decreases the alkalinity of the pond. C It increases the oxygen content of the pond. D It decreases the carbon dioxide content of the pond. All content is the private property of the copyright holders. Page 5

7 10 The table lists the ph values of some common food ingredients. Which food ingredient has the lowest concentration of hydrogen ions? A apple juice B butter C tomato puree D vinegar 11 The table shows the ph value of different food materials. Mold grows rapidly in highly acidic foods. If the food materials mentioned in the table are left open at room temperature, which one will most likely be the first to show mold growth? A cranberry juice B honey C shrimp D tomato juice All content is the private property of the copyright holders. Page 6

8 12 Examine the table. Which substance has the greatest concentration of hydroxide ions? A baking soda B tomato juice C toothpaste D vinegar 13 The carbonic acid buffer system functions in the blood plasma. The equilibrium of the system is maintained by carbonic acid (H 2 CO 3 ) and hydrogen carbonate ions (HCO 3 - ). The equation shows the two in equilibrium. What is the purpose of this buffer in the blood plasma? A It helps resist the change in blood ph. B It helps maintain the liquid nature of blood. C It helps remove nitrogenous wastes from blood. D It helps control the temperature changes in blood. All content is the private property of the copyright holders. Page 7

9 14 Finely ground limestone is added to soil to increase its ph. This helps farmers grow crops in soil with an ideal ph range between 6.0 and 7.0. Which soil type would likely require the addition of limestone for better plant growth? A soil with ph below 5.0 B soil with ph around 7.0 C soil with ph around 8.0 D soil with ph above A condition known as acidosis will result if the ph of human blood drops below 7.4. How does the human body maintain the blood ph level, thus protecting from large changes in ph? A It produces specialized white blood cells that neutralize the blood's ph. B It produces buffers that maintain equilibrium of the blood's ph level. C The excess acid in the blood diffuses out of the red blood cells to maintain homeostasis. D The excess acid is neutralized by water that enters the red blood cells by osmosis to maintain homeostasis. 16 One human digestive enzyme that helps to break down lipids is known to exist almost exclusively in the stomach. A team of biologists wants to isolate and study this enzyme in the lab. What is a reasonable ph that the biologists should select for culturing and studying this enzyme? A 2 B 7 C 10 D 14 All content is the private property of the copyright holders. Page 8

10 17 The ph scale generally ranges from 0 to 14 with most substances falling somewhere in-between. Of the substances listed, which one contains the greatest concentration of hydroxide ions? A bleach B milk C ocean water D tomato juice 18 Rosa is experiencing acid reflux, in which excess acid produced in the stomach travels upwards from the stomach through the esophagus. The ph level of her esophagus is 3.8. Rosa takes a medicine with ph of around 8.5. How does the medicine work to control acid reflux? A The medicine prevents the stomach from producing any acids. B The medicine makes the stomach alkaline by decreasing the ph. C The medicine neutralizes the acids in the stomach by increasing the ph. D The medicine causes water retention in the stomach that dilutes the acids. All content is the private property of the copyright holders. Page 9

11 19 Blood has a normal ph value of around 7.4. During intense exercise, hydrogen ions are released into the blood. What will be the ph of blood after the release of hydrogen ions into the blood? A greater than 10.0 B less than 4.0 C greater than 7.4 but less than 10 D less than 7.4 but greater than 4 20 Why is it important for stomach acid to maintain a ph of 2? A B If the ph of the stomach changes too much, the cellular membrane of stomach cells will change shape. The low concentration of H+ in the stomach helps to break down cellulose from fruits and vegetables. C Without a ph of 2, the digestive enzymes in the stomach will change shape and will not function properly. D Maintaining a ph of 2 is critical for the function of DNA, which produces digestive enzymes. 21 Sodium bicarbonate (NaHCO 3 ) is often used as an antacid to reduce acid indigestion in the stomach. How does sodium bicarbonate act as an antacid? A It increases the stomach s rate of excretion of acids. B It makes the stomach cells produce basic digestive juices. C It neutralizes acidity by increasing ph levels. D It inhibits cells in the stomach that produce acids. All content is the private property of the copyright holders. Page 10

12 22 Nettle plants have tiny stinging hairs that contain formic acid. This causes a painful, reddish itchy rash if the hairs come in contact with human skin. A paste made of baking soda and water is used to relieve the pain. How does the baking soda relieve a nettle sting? A The baking soda forms a protective layer over the skin. B The baking soda neutralizes the acid in the nettle sting. C The baking soda decreases the temperature of the skin. D The baking soda increases the blood flow to the affected area. 23 The graph shows the optimum ph for the survival of different categories of bacteria. How does the optimum ph for acidophiles compare to that for neutrophiles? A It is 4 times more acidic than that for neutrophiles. B It is 5 times more acidic than that for neutrophiles. C It is 40 times more acidic than that for neutrophiles. D It is 10,000 times more acidic than that for neutrophiles. All content is the private property of the copyright holders. Page 11

13 24 Several biology students are doing an experiment and tested the ph of a solution. The color on the ph test strip matched the color chart indicating the ph shown by the arrow on the scale. How should the ph of the solution be described? A 10.0 and acidic B 10.0 and basic C 10.0 and neutral D 100 and alkaline All content is the private property of the copyright holders. Page 12

14 25 The graph contains information on the rate of activity of two human enzymes at various ph levels. At which ph level do both pepsin and trypsin function? A 2.5 B 5.5 C 7.0 D 9.5 All content is the private property of the copyright holders. Page 13