ACTIVITY 17: GAS EXCHANGE Name Period SYSTEMS ANALYSIS: Complete the system analysis for the experiment performed in the Conservation of Mass: Chemical Change lab. Be sure to follow the systems analysis (SA) scoring guide and key provided. 25pts Systems Analysis (SA) What to look for: Student identifies the matter cycling and inputs/outputs of energy & matter in a system. INSTRUCTIONS: Circle the level that the student s response best fits. Level 4 Above and Beyond Level 3 Complete and Correct Level 2 Almost there Level 1 On your way Accomplishes Level 3 and goes beyond in a significant way. Includes: Showing the interaction with another system A subsystem within the system Student clearly, accurately, and completely illustrates: Whether the system is open or closed Inputs, outputs, and cycling of matter within the system Inputs & outputs of energy within the system Properly labels key components of the system. Student correctly identifies the boundary, matter, and energy in system, but: Incorrectly identifies whether the system is open or closed Omits key details of matter or energy within the system Doesn t follow key for coloring Student: Omits a boundary, matter, or energy within system Doesn t use color Score (circle one) Level 0 Response missing, unreadable, incomplete, or clearly not on topic 10 Figure is properly labeled and colored; Ruler was used for straight lines; Overall presentation is neat + 2 Quality Standard 20 16 13 11 1
THE RESPIRATORY SYSTEM: Your blood transports the nutrients that you eat to different parts of your body. It also carries oxygen from your lungs to other organs and tissues. Your lungs are part of your respiratory system. With every breath you take, you inhale oxygen and exhale carbon dioxide. Your body uses the oxygen to get energy from food. When your body breaks down food, it produces wastes. One of the wastes is carbon dioxide. ANALYSIS QUESTION: 1. Complete a system analysis of the respiratory & cardiovascular system in the diagram below. Be sure to follow the systems analysis (SA) scoring guide and key provided. 75 pts. Scoring = Incorrect or missing input/output/flow/boundary = - 5pts Incorrect or missing Labels = -2 pts 2
BACKGROUND: Indicators are chemicals that change their appearance in different types of solutions. They are used to test the ph, or how acidic or basic the solution is. You will work with the indicator bromthymol blue, also known as BTB. BTB can be either blue or yellow. When added to a solution containing carbon dioxide, BTB is yellow. For example, fish can only live within a small ph range. Indicators are useful to determine if the ph of the water is within a healthy range for fish. Below is a ph scale with common household items as well as the ph range that fish can survive in. Figure 1. ph Scale and Healthy Ranges for Organisms The human body also can only live within a certain ph range. Normal blood must be between a ph of 7.35-7.45. Serious problems occur if our ph goes above or below this range. These problems include loss of consciousness, increased heart rate, shortness of breath, and vomiting. It is mainly left up to the respiratory system to make sure the ph of our blood stays within a healthy range. The respiratory system does this by exhaling carbon dioxide (CO2). If carbon dioxide is not properly exhaled, the ph of the blood becomes acidic. That s because the carbon dioxide mixes with the water in your blood to make a weak acid called Carbonic acid. 3
PART A: SCIENTIFIC QUESTION: How can we test for carbon dioxide in your exhaled breath? PROCEDURE: 1. Follow procedure for Part A on page B-39. 2. Record data in Data Table 1. 3. Answer analysis questions 1 & 2 below. DATA: Data Table 1 - Using BTB to test for Carbon Dioxide (20 pt) A B C D E Initial BTB Color Final BTB Color After Adding NaOH X X X X X X ANALYSIS QUESTIONS: Write complete, quality, and correct sentences using at least 3 pieces of evidence. 1. What was the purpose of the solution in Cup A? (use at least 3 pieces of evidence). (10 pt) 2. Which of the solutions in Part A contained carbon dioxide? Support your answer with at least 3 pieces of evidence from your experimental results. (10 pt) 3. What does this tell you about the ph of exhaled breath of human beings? (10 pt) 4. Look at the table below. Compare the composition of air you breathe in to that of air you breathe out. Describe all the differences and explain why these happen. (20 pt) 4
PART B: QUESTION: How much carbon dioxide is in your exhaled breath? PROCEDURE: 1. Follow procedure for Part B on page B-40. 2. Record data in Data Table 2 with group station data. 3. Record data in Data Table 2 with entire class data 4. Answer analysis questions 3-5 below. DATA: Data Table 2 - Number of Drops NaOH to Neutralize CO2 Breathed in Bag (20 pt) Number of Drops 1 2 3 4 5 6 7 8 9 10 Station 1 Station 2 Station 3 Station 4 Station 5 Station 6 Station 7 Station 8 TOTALS ANALYSIS QUESTIONS: Write complete, quality, & correct sentences when answering these q s. 5. Use the Totals above to tell the High, Low, Range of the data collected, and the mean. (10 pt) High = Low = Range = Mean = 6. Follow the path of inhaled air, which contains a molecule of 0 2 (oxygen), into, through and back out of the respiratory/cardiovascular system. List all organs the molecule passes through along the way. (20 pt) 7. The molecule of O 2, mentioned above, picks up a carbon in the body and changes it to CO 2. Tell where in the body this process takes place. (10 pt) 8. What causes the BTB (bromthymol blue) solution to change color in this experiment? (10 pt) 9. Why do humans exhale CO 2 from our body? Specifically explain what would happen if we didn t exhale CO 2. (20 pt) 5