Honors Biology Fall Semester Critical Thinking Practice

This power point is designed to make you THINK This power point is designed to make you THINK. It is practice for the exam, but not necessarily a copy of the exam questions. As you will see, these are things that are similar to what we have done in class on tests and in labs. Graphs, diagrams, thinking questions, etc. These are designed to make you APPLY what we have learned, not just spit it back out to me.

Examine the following graph and answer the questions. Which colors of light are best for photosynthesis?

Examine the following graph and answer the questions. Which colors of light are best for photosynthesis? ANSWER: Although you may remember that it is red and blue, the graph shows us that the greatest amount of absorption is in the blue and red ranges for chlorophyll a and b. While there is a significant amount of absorption in the green and yellow range by phycoerythrin and phycocyanin, chlorophyll a and b are the PRIMARY pigments in a chloroplast and therefore their absorption ranges are most important.

Experimental Design Legolase (not to be confused with Legolas) is the enzyme that helps break apart those Legos that just won’t separate. (no, it is not a real enzyme) Design an experiment that would test the effectiveness of Legolase at different temperatures from 0oC to 100oC. Room temperature is about 25oC. Draw a line graph that would demonstrate expected outcome of this experiment.

Experimental Design: 1) Identify the variables Experimental Design: 1) Identify the variables. (Lego size, color, temperature) 2) Establish the controls (All Legos are the same size and color) 3) Establish the testing variables (Temperature) 4) Explain the basic procedure (Two blue Legos will be exposed to Legolase at temperatures ranging from 0 – 100 degrees at 5 degree intervals) 5) Explain expected results (Legolase showed little effectiveness at very low and very high temperatures and the greatest effectiveness around 25 degrees.) 6) Discuss results (Legos are typically played with at room temperature so the enzyme that breaks them apart is most effective at that same temperature. Extremes in temperature causes the enzyme to denature and stop working.)

Graph The graph would show a peak around 40oC. # of Legos Broken Apart

Experimental Analysis The following experiment was set up. Each tube contains a different type of substance and yeast. Bromothymol blue reacts with CO2 and turns yellow. Tube A contains Glucose, water, and yeast. Tube B contains Salt, water, and yeast. Tube C contains Water and yeast. Predict the outcome of this experiment and explain your prediction.

Tube A should cause a color change because the glucose will allow the yeast to undergo cellular respiration and produce CO2 which will cause the bromothymol blue to change to yellow. Tube B should not have a color change because the salt will dehydrate the yeast cells due to osmosis. The bromothymol blue will remain blue. Tube C is the control. The bromothymol blue will remain blue showing that the yeast alone, without a food source, will not produce CO2.

Graph interpretation: examine the following graph and answer the given questions. What is the probably hypothesis of this experiment? How much Oxygen was consumed by the germinating (sprouted) corn at 12 degrees after 15.0 minutes? What is the effect of temperature on the rate of oxygen consumption? Explain. What is the purpose of the non-germinated corn?

1) What is the probably hypothesis of this experiment 1) What is the probably hypothesis of this experiment? To determine the effect of temperature on the oxygen consumption of newly sprouted corn plants. 2) How much Oxygen was consumed by the germinating (sprouted) corn at 12 degrees after 15.0 minutes? 0.6 mL of Oxygen 3) What is the effect of temperature on the rate of oxygen consumption? Explain. As temperature increases so does the rate of oxygen consumption. This is due to the enzymes working at a faster rate because they are closer to their optimal temperature. 4) What is the purpose of the non-germinated corn? To act as a control to see how the oxygen would change without an active organism present.

Make sure you review your old labs and the calculations for change in mass, percent change in mass, and the calculations for calories. There are practice problems in the study guide with the answers.