Bio U3

1. A spectrophotometer is used to measure the relative absorbance of light by certain substances. It measures the intensity of light as a function of wavelength. In the following experiment, researchers analyzed the absorption spectrum of chlorophyll a. In a subsequent experiment, researchers evaluated the effects of Cobalt on algae. Heavy metals are prevalent in poorly regulated industrial water supplies and may alter the productivity of aquatic ecosystems. Researchers analyzed the effect of Cobalt on Chlorella pyrenoidosa, a freshwater algae: specifically the concentration of chlorophyll a and an accessory pigment, chlorophyll b. Results are seen on the image. Which of the following conclusions could be reached regarding Cobalt pollution based on the data provided?

High levels of Cobalt have negative effects, while low levels of Cobalt have positive effects, on the rate of photosynthesis in algae

2. A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask.

The dissolved oxygen in the flask with algae will be higher in the light, but lower in the dark

3. Many aquatic animals can hold their breath and dive underwater for long periods of time. During long dives, lactic acid builds in tissues of the organism. The graphs above shows blood lactate levels following dives of different duration for three species. Lactate is produced when lactic acid is dissolved in the blood and becomes ionized. Based on the data, propose a hypothesis to explain the change in blood lactate levels in Weddell seals for dives lasting longer than 20 minutes. Why do the Weddell seals make lactic acid in the first place? (FRQ)

As oxygen becomes limiting during dives lasting longer than 20 minutes, cells rely on glycolysis for ATP production. Weddell seals make lactic acid because reducing pyruvate to lactate oxidizes NADH back into NAD+, which allows glycolysis to continue producing ATP in anaerobic conditions.

4. In order to figure out what is happening in photosynthesis and respiration, the thing to follow are the

Electrons

5. Here is the simplified equation for photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2. According to the image, which of the following choices correctly trace the oxygen identified with the arrow

(b)

6. An airtight, temperature-controlled glass box containing actively growing tomato plants was placed under a light source. Plastic wrapping that only transmits green light was placed over the box, and two days later air samples from inside the box were collected and analyzed. The most likely change in air quality is

An increase in carbon dioxide

7. An experiment was done with temperature versus rate of maltose digestion by maltase. There are obviously two parts of the graph. Your job is to explain what is going on during these two parts of the experiment. Be complete in explaining why the graph looks like this relative to the enzymes and how they are functioning with the substrate. (1) Explain what occurs to the rate of reaction between 20-30 degrees (2) Explain what happens to the rate after 50 degrees (FRQ)

Between 20-30°C, the reaction rate increases because rising temperature increases molecular kinetic energy, leading to more frequent and productive collisions between maltase and maltose. Above 50°C, the reaction rate drops sharply because excess thermal energy disrupts the tertiary structure of maltase, causing the enzyme to denature so its active site can no longer bind the substrate effectively.

8. In which reaction is a net gain of ATP finally realized from glycolysis? Choose the correct letter answer from the 9.2 diagram

E

9. Some photosynthetic organisms contain chloroplast that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be

To test for release of O2 in the light

10. The enzyme phosphofructokinase (PFK) is regulated through allosteric activation and inhibition. PFK catalyzes the following reaction: Fructose-6-phosphate + ATP → Fructose-1, 6-biphosphate + ADP. ATP acts as an allosteric inhibitor, while AMP acts as an allosteric activator of PFK. Using the graph, compare PFK activity under the following two conditions when the fructose-6 phosphate concentration is 0.5 mM: Condition 1: 1 mM ATP + 0.1 mM AMP | Condition 2: 5 mM ATP. How many times greater is PFK activity under Condition 1 compared with Condition 2?

20 times

11. Which reaction shows a split of one molecule into two smaller molecules? Choose the letter from the 9.2 diagram to answer the question

B

12. Assume the thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?

The synthesis of ATP

13. The color of light least effective in driving photosynthesis is

Green

14. A spectrophotometer is used to measure the relative absorbance of light by certain substances. It measures the intensity of light as a function of wavelength. In the following experiment, researchers analyzed the absorption spectrum of chlorophyll a. In a subsequent experiment, researchers evaluated the effects of Cobalt on algae. Heavy metals are prevalent in poorly regulated industrial water supplies and may alter the productivity of aquatic ecosystems. Researchers analyzed the effect of Cobalt on Chlorella pyrenoidosa, a freshwater algae: specifically the concentration of chlorophyll a and an accessory pigment, chlorophyll b. Results are seen on the image. According to the graph, which of the following statements could be posed regarding the absorbance of specific wavelengths of light by the pigment chlorophyll a?

Why does chlorophyll a not absorb green light well?

15. Carbon dioxide is known to be a greenhouse gas, meaning that the CO2 in the atmosphere traps heat energy in the atmosphere causing the temperature to rise. A virus is found that is infecting plants. This virus kills plants by disabling the rubisco enzyme. What do you think the disabling of rubisco will do to the temperature of the Earth and why? (FRQ)

Disabling rubisco halts carbon dioxide fixation in the Calvin Cycle. As a result, plants take up less atmospheric carbon dioxide, causing CO2 to accumulate in the atmosphere, strengthening the greenhouse effect and increasing global temperatures over time.

16. A spectrophotometer is used to measure the relative absorbance of light by certain substances. It measures the intensity of light as a function of wavelength. In the following experiment, researchers analyzed the absorption spectrum of chlorophyll a. In a subsequent experiment, researchers evaluated the effects of Cobalt on algae. Heavy metals are prevalent in poorly regulated industrial water supplies and may alter the productivity of aquatic ecosystems. Researchers analyzed the effect of Cobalt on Chlorella pyrenoidosa, a freshwater algae: specifically the concentration of chlorophyll a and an accessory pigment, chlorophyll b. Results are seen on the image. Which of the following predictions is possible based upon the data regarding Cobalt pollution in freshwater algae?

At high concentrations, Cobalt inhibits the functioning of the electron transport system due to an inability of the cell to produce chlorophyll.

17. All of the following are functions of the Krebs cycle except

Adding electrons and protons to oxygen to form water

18. The calvin cycle requires all of the following molecules except

Glucose

19. Many aquatic animals can hold their breath and dive underwater for long periods of time. During long dives, lactic acid builds up in tissues of the organism. The graph above shows blood lactate levels following dives of different duration for three species. Lactate is produced when lactic acid is dissolved in the blood and becomes ionized. Describe the most likely shape of the curve if blood oxygen levels of Weddell seals were plotted rather than blood lactate levels. Include in your description the likely shape of the curve between 0 and 20 minutes and the shape of the curve after 20 minutes. (FRQ)

Between 0 and 20 minutes, the blood oxygen curve will steadily decrease as aerobic respiration consumes stored oxygen during the dive. After 20 minutes, the oxygen curve will flatten out near a low minimum level as available oxygen becomes depleted and anaerobic metabolism predominates.

20. The figure illustrates the similarities between ATP synthesis in mitochondria and chloroplasts. The figure can assist in answering which of the following questions?

Do electron transport chains create a proton gradient so that ATP synthase can generate ATP molecules?

21. Which of the following questions is most relevant to understanding the Calvin Cycle?

How is the ATP used in the formation of 3-carbon PGAL

22. Many different fermentation pathways occur in different organisms in nature. For example, skeletal muscle cells convert pyruvate (pyruvic acid) into lactic acid when no oxygen is present. Yeast cells can produce alcohol and carbon dioxide under the same circumstances. However, regardless of the specific reactions, the purpose of fermentation is an important one. Which of the statement best describes the importance of fermentation?

Fermentation re-oxidizes NADH into NAD+ so that glycolysis can continue

23. Which of the following is an important difference between light-dependent reaction and the Calvin Cycle of photosynthesis

The light dependent reactions produce ATP and NADPH; the Calvin Cycle reactions use energy stored in ATP and NADPH make G-3-P

24. Many aquatic animals can hold their breath and dive underwater for long periods of time. During long dives, arctic acid builds up in tissues of the organism. The graph above shows blood lactate levels following dives of different duration for three species. Lactate is produced when lactic acid is dissolved in the blood and becomes ionized. Which of the animals listed in the graph would have the lowest duration of time diving and justify your answer with numbers supporting your choice? (FRQ)

Emperor penguins have the lowest duration of aerobic diving. This is justified by the graph showing their blood lactate levels rising steeply starting around 5 to 8 minutes and reaching approximately 13 mM near 8 minutes, much earlier than the seals.

25. ATP is produced in all of the following except

Calvin cycle

26. A biologist isolated a sample of the enzyme lactase. Lactase breaks down the disaccharide lactose into a molecule of glucose and a molecule of galactose. The biologist performed two series of experiments. First she made up 10% lactose solutions with different concentrations of enzymes and measured the rate at which galactose was produced. In the second series of experiments, she prepared 2% enzyme solution with different concentrations of lactose and again measured the rate of galactose production. Explain the relationship between the reaction rates and the enzyme concentration for Table A. Explain the relationship between the reaction rate and the substrate concentration for Table B. (FRQ)

Table A: The reaction rate increases proportionally with increasing enzyme concentration because adding more lactase provides more active sites to catalyze lactose breakdown. Table B: The reaction rate increases as substrate concentration rises initially, but then plateaus at higher substrate concentrations because the enzyme becomes saturated with substrate and is operating at maximum velocity (Vmax).

27. The general equation for photosynthesis is: 2 H2O + CO2 + light → carbohydrate (CH2O)n + O2. Which of the following could be used to determine the rate of photosynthesis?

How many molecules of oxygen are produced for one mole of carbohydrate produced

28. Hydrogen ions flowing through a cylinder causing the cylinder and attached rod to rotate like rushing steam turns a water wheel is an analogy that best describes

ATP synthase activity

29. Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acidic?

Curve 4

30. In addition to ATP, what are the ends products of glycolysis?

NADH and pyruvate

31. During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level therefore making the least amount of ATP?

FADH2

32. Which curve in the image was generated using an enzyme taken from a bacterium that lives in hot springs at temperatures of 70 degrees C or higher?

Curve 3

33. During aerobic respiration, electrons travel downhill in which sequence?

Glucose → NADH → electron transport chain → oxygen

34. A young relative has experienced low energy levels for most of his life. After visiting a doctor, he undergoes several tests that reveal an unusual metabolic condition: his mitochondria can use fatty acids and amino acids for cellular respiration but cannot effectively use glucose-derived pyruvate. His cells also produced higher-than normal levels of lactate.

His mitochondria lacks the transport protein that moves pyruvate across the outer mitochondrial membrane