1. Biology EOC Practice Exam Answers to Completion Questions 43 – 50

2. Number 43

4. 7 attributes are scored in a Procedure: 1.Manipulated Variable: Only one manipulated variable (temperature of potato juice) is identified or implied in the procedure or data table (if given). The manipulated variable must have at least three conditions to be credited. 2.Responding Variable: The responding variable (time for bubbling to stop) is identified or implied in the procedure or data table (if given). 3.Controlled Variables: At least two controlled variables are identified or implied in the procedure (e.g., volume of potato juice, volume of hydrogen peroxide, pH). 4.Record Measurements: The procedure states or implies measurements are recorded periodically or gives a data table. Take measurement cannot be used to mean record. 5.Trials are Repeated: More than one trial for all conditions is planned, or implied in a data table, to measure the responding variable. 6.Extra Validity Measure: The procedure includes a validity measure not included in the scenario experiment (e.g., more controlled variables, better measuring technique, increased range of conditions, or control for sample bias). 7.Logical Steps: The steps of the procedure are detailed enough to repeat the procedure effectively (examples of illogical steps: no ending time indicated

6. 2 point response Question: What is the effect of the temperature of potato juice on the time for bubbling to stop after hydrogen peroxide is added? Procedure: 1. Set up the graduated cylinders and put 10 milliliters of room temperature potato juice into beaker A. 2. Monitor the room temperature to make sure it stays the same throughout the experiment. 3. Add 5 milliliters of hydrogen peroxide to the cylinder, stir for two seconds, start timer. 4. Measure and record the time the mixture is bubbling. 5. Repeat steps 1-4 three more times only heat the potato juice to 72°F (label B) 82°F (label C) and 92°F (label D). Use the same thermometer for all temperatures 6. Clean all graduated cylinders. 7. Repeat steps 1-6 two times for Trials 2 and 3 to verify results 8. Calculate and record the average time the mixture bubbled for each temperature of potato juice.

8. What about this one? Question: What is the effect of the temperature of potato juice on the time for bubbling to stop after hydrogen peroxide is added? Procedure: 1. heat one beaker on the hot plate for 20 seconds with the potato juice in it. 2. pour H 2 O 2 in the beaker. stir 3. record the bubbles 4. repeat step 2 on unheated potato juice 0

9. This one? Question: What is the effect of the temperature of potato juice on the time for bubbling to stop after hydrogen peroxide is added? Procedure: 1)First put one drop of hydrogen peroxide on the potato juice that is room temp. Do this three times. and time how long it bubbles. Then get and average 2)Place one drop of hydrogen peroxide on potato juice that was kept in the refrigerater. Time how long it bubbles. 3)Repeat step 2 three times and get an adverage 4) Place one drop of hydrogen peroxide on potato juice that was put in the microwave for 30 seconds. Time how long it bubbles. 5) Repeat step 4 three times and get an average. 6)Compare the manipulated variable tests (hot and cold reactions) to the Room temp. reaction 1

10. Write steps for a procedure: Students sometimes write conclusions or predictions instead of the steps for a procedure. Students should have opportunities to practice with the format of the item. Correctly use the variables: The manipulated (independent) and responding (dependent) variables do not need to be specifically named or listed (e.g., Manipulated variable is water temperature) in order to receive credit for them; the variables just need to be used correctly in the procedure to be credited. Sometimes students switch the identities of the manipulated and responding variables and contradict their procedure. Be very clear about what should be measured: Many students write “record the data,” “measure the data,” or “watch what happens and record the measurements” without actually stating the responding variable. They should write things like “record the number of organisms in the sample area,” “measure the height of the plant,” or “measure the time for seeds to germinate” to earn credit for the responding variable. Write the procedure for the given question: Students need to write procedures that use the manipulated (independent) and responding (dependent) variables given in the new experimental or field study question. Many students use the same responding variable as was used in the original scenario. A procedure that does not use the correct manipulated variable cannot answer the investigative question and no points can be earned on the item. Advice from Scorers…

11. Number 44

14. 5 attributes are scored in a Conclusion: 1.Conclusive Statement – correctly answers the experimental question (or correctly states whether the hypothesis/prediction was correct) 2.Supporting Data - lowest condition of the changed variable 3.Supporting Data - highest condition of the changed variable 4.Explanatory Language – used to connect or compare the supporting data to the conclusive statement 5.Scientific Explanation – provides a plausible scientific reason that explains the trend seen in the data table in terms of established scientific knowledge

16. 2 Point Response Question: What is the effect of the acidity of potato juice on the volume of foam produced when hydrogen peroxide is added to potato juice? In this investigation, the prediction that if the acidity of potato juice is decreased then the volume of foam was increased was proven incorrect. Catalase is damaged by acid. The lowest foam volume was 24 ml with the highest acidity, pH6, However the highest foam volume was an average of 42 ml with the second lowest acidity level,pH8 The third highest volume was 35 ml with the second highest acidity level pH7, and the second lowest foam volume was 30 ml with the lowest acidity level pH9.

18. What about this one? Question: What is the effect of the acidity of potato juice on the volume of foam produced when hydrogen peroxide is added to potato juice? Ph8 has the most foam at 42. The more Ph does not mean the more foam, but the least Ph does mean the least foam. When the Ph got to 8 it went down again at ph9. Ph7 is higher that Ph9. Ph9 is higher that Ph6. Ph8 caused the most foam than any other. 1

19. And this one… Question: What is the effect of the acidity of potato juice on the volume of foam produced when hydrogen peroxide is added to potato juice? Acidy of potato juice’s effect on foam produced by adding hydrogen peroxide is it how quickly the 2H 2 O 2 converts into oxygen and water. The higher the pH, the less amount of bubbles (which means a slower reaction time). Acidity of 9 was 30 mL. 0

20. Advice from Scorers for Conclusions: Students need to write more decisive conclusive statements. They should not write, “the amount of water does have an effect on the plant height.” Students should write a complete comparison, for example:  Plant A grew the tallest;  Plant A grew taller than plant B and plant C;  The more water the plant had, the taller the plant grew. Students need to include supporting data and/or descriptive text from the data table. They should quote appropriately from the data table just like they quote a text from a passage in reading. Numbers (data) should not be rounded or qualified with phrases like around or about.

21. Number 45

23. 7 attributes are scored in a Procedure: 1.Method for collecting data (controlled variable): The procedure states or implies a consistent sampling strategy or technique (e.g., same stream, single day, same time of day). 2.Conditions to be compared (independent/manipulated variable): Only one independent variable (water depth) is identified or implied in the procedure or data table (if given). The independent variable must have at least three conditions to be credited. 3.Data to be collected (dependent/responding variable): The data collected to answer the field study question (water temperature) is identified or implied in the procedure or data table (if given). 4.Record measurements: The procedure states or implies measurements are recorded periodically or gives a data table (e.g., record the temperature for each water depth). “Take measurement” or “count” cannot be used to mean “record.” 5.Observations are repeated: More than one observation for all conditions is planned, or implied in a data table (e.g., find 3 locations for each water depth). 6.Record environmental conditions: The procedure identifies or implies recorded observations of at least one local environmental condition that might have an effect on the focus variables (e.g., record air temperature, record time of day). 7.Logical steps: The steps of the procedure are detailed enough to repeat the procedure effectively (examples of illogical steps: no ending time indicated; no limitation to the sampling area is given; recording vague data or results).

24. 2 Point Response Field Study Question: How does water depth affect the temperature of water in a stream? Procedure: 1. Record the temperature and weather conditions. 2. Measure the depth of the stream. 3. Place a thermometer on the surface of the stream. 4. Record the temperature. 5. Wait 5 minutes. 6. Repeat 3-5 for trials 2 and 3, placing the thermometer at the same spot. 7. Repeat steps 3-6 for half the depth of the stream and full depth of the stream. 8. Calculate the average temperature for each depth.

26. What about this one? Field Study Question: How does water depth affect the temperature of water in a stream? Procedure: The water closest to the top is usually warmer than near the bottom of the stream. In that case, you’d find the temperature of the water at the top then at the bottom of the stream. The time of year when being measured would also matter. It would be colder in the winter then in the summer, meaning you should check every season. You’d have to use an accurate thermometer. If it’s raining, the water will be colder than it would be if it was sunny, which would play a role in the scenario. 0

27. This one? Field Study Question: How does water depth affect the temperature of water in a stream? Procedure: 1) measure different depths of the stream (3ft, 5ft, 10ft). 2) collect data by checking the temperature of the different depts in the stream 3 different days. 3) record data found in a chart w/all 3 thats taken. 4) compare data and make a conclusion to tell how water dept affects the temperature of the water in the stream. 1

28. Advice from Scorers: Write steps for a procedure: Students sometimes write conclusions or predictions instead of the steps for a procedure. There is a difference between a field study procedure and a controlled investigation: Students sometimes miss the differences between controlled experiments and field studies when writing procedures. Many of those differences are defined by the bullets included with the item. For example, field studies include recording environmental conditions and describing the method for collecting data (e.g., a consistent sampling strategy). Write the procedure for the given question: Students need to write procedures that use the manipulated (independent) and responding (dependent) variables given in the new experimental or field study question. Many students use the same responding variable as was used in the original scenario. A procedure that does not use the correct manipulated (independent) or responding (dependent) variable cannot answer the given investigative question and no points can be earned on the item. Correctly use the variables: The manipulated (independent) and responding (dependent) variables do not need to be specifically named or listed as that type of variable (e.g., Manipulated variable is water temperature) in order to receive credit; the variables just need to be used correctly in the procedure to be credited. Know what you’re measuring: Students need to be very clear about what they are measuring. Many students write “record the data,” “measure the data,” or “watch what happens and record the measurements” without actually stating the responding variable. They should write things like “record the number of organisms in the sample area,” “measure the height of the plant,” or “measure the time for seeds to germinate” to earn credit for the responding variable. Students are expected to include at least three conditions of the manipulated/independent variable for both controlled experiments and field studies.

29. Number 46

31. How would you score this? 0

32. This? 2

33. One more… 1

34. Number 47

37. 4 attributes are scored in the first part of a Scientific Design Process: 1.Research the Problem: Information needed to solve the problem is described or pertinent questions are given (e.g., what type of soil do worms survive in, how much water do worms need, find out how long worms live). 2.Scientific Research: Related scientific information (e.g., predators/diseases of worms, nutritional needs of worms) OR how to scientifically collect related data is described (e.g., ask a biologist about the life cycle of worms, test the survival rate of worms in different temperature soils). 3.Explore Ideas: More than one idea that could solve the problem is described (e.g. add compost, keep the soil moist, put mulch on top of the soil, bring in young worms). 4.Explore Scientific Ideas: An idea includes scientific concept(s) for considering the idea (e.g., add dark mulch on top of the soil to increase the temperature and hold in moisture).

40. 2 Point Response Problem: Increase the population of worms in the soil Research the Problem: What kind of worms are in the soil? Collect worms and ask science teacher what nutrients they need. What is the best temperature? How much water is good for worms? Google worm environment. Explore Ideas: Cover with black plastic to increase temperature. Count worms before and after putting down plastic. Add compost to the soil as food for worms.

41. What about this one? Problem: Increase the population of worms in the soil Research the Problem: Find out what worms like to eat. They might like a certain amount of water or live in warmth better than cold. I would go to a garden store and ask a master garderer. There are books or google the information Explore Ideas: Make sure the soil is wet enough for worms. I might also have to add sand to the soil 1

42. What about this one? Problem: Increase the population of worms in the soil Research the Problem: Find out where to buy worms Explore Ideas: Dump worms on the soil 0

43. Number 48

48. Advice from Scorers for Short Answer Questions: When answering short answer questions that have two bullets after an “in your description, be sure to” statement, students sometimes only answer the first bullet. These questions generally ask students to do the actions in both bullets twice as shown in the following example. Describe two constraints, other than cost, that scientists could encounter while trying to solve a problem. In your description be sure to: o Identify two constraints other than cost o Describe why each constraint is a limitation

49. 2 Point Response Forest edge habitat results: The forest edge habitat has more sun. The edge has 16 plants and the forest has 4. Forest habitat results: The forest habitat has the least plants. The forest is drier because the rain can’t get through the trees.

50. What about this one? Forest edge habitat results: There is better soil in the forest edge. Forest habitat results: There is less water in the forest. 0

51. What about this one? Forest edge habitat results: The forest edge has more birds eating berries and has 12 more plants than the forest. Forest habitat results: This is because the forest is shady and it is hard for the plants to grow. 1

52. Number 49

56. Advice from Scorers for Criteria and Constraints Questions: When given the “Criteria & Constraints” item, students struggle with describing constraints(limitations of possible solutions) in the design process. Students should be made aware that: o Items may be credited for constraints that involve cost as long as the description is not limited to the fact that the constraint costs money. For example, “The solution will require training a large number of people,” may be a creditable constraint even though training workers involves a cost. o Responses stating only “This solution won’t work” cannot be credited. “The solution won’t work because...”

57. 2 Point Response One constraint: One constraint that rangers could encounter while trying to trap and relocate the bear population is that the bears might find their way back to the campground. This is a limitation because they will have to be trapped again to remove them. Another constraint: The traps will have to be very large to contain the bears. Moving the traps will require special equipment.

58. What about this one? One constraint: The rangers might get other animals in there traps. Another constraint: The bears might be too fast and get away from the rangers. 0

59. What about this one? One constraint: One problem is that bears will be hurt by the way they are trapped. Another constraint: The traps will get the attention of people. People could interfere with the traps or be caught in them. 1

60. Number 50

65. 2 Point Response One unintended consequence: All of the moths will die or have the poison on them and get into the water supply. That will pollute the water and kill the animals that drink it. Another unintended consequence: All the moths will be gone and no more will be reproduced. This means that the birds will die because their food source will be gone.

66. What about this one? One unintended consequence: The insecticides could kill the tree and other insects. Another unintended consequence: The insecticides could get into the water and pollute the water. 0

67. What about this one? One unintended consequence: One unintended consequence is that the birds or other animals will lose their food causing a chain reaction in the food chain. Another unintended consequence: Second if a bird eats a moth that is infected with the insecticides it will cause biological magnification through the food chain until the parts per million is deadly for the apex preditor 1

68. Advice from Scorers: When given the “Unintended Consequences” item, many students are able to describe two unintended consequences, but often do not attempt to describe how the unintended consequences could affect a specified component of the given system, or describe a vague effect of the unintended consequence on a specified component of the given system.