Question 1

In cells relying exclusively upon glycolysis and substrate-level phosphorylation for ATP production, why is the production of reduced intermediates from pyruvate so essential?

Accepted Answer

The reduction of pyruvate to lactate or other products allows for the oxidation of NADH to NAD+, which is crucial for the continuation of glycolysis. Glyceraldehyde phosphate dehydrogenase, an enzyme in the glycolytic pathway, requires NAD+ as a substrate to continue converting glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate, thereby facilitating the ongoing production of ATP through substrate-level phosphorylation.

Question 2

Fluorescein 18 emission from tumor cells is detected by _________________ detector.

Accepted Answer

Fluorescein 18 emits photons when excited by external light. Therefore, the emission can be detected by a photon detector such as a camera or a spectrometer. X-ray, positron, or electron detectors are not suitable for detecting fluorescein 18 emission.

Question 3

Why has the pharmaceutical industry drastically cut resources devoted to the development of new antibiotics? (Select all correct choices)

Accepted Answer

The answer of Why has the pharmaceutical industry drastically cut...

Question 4

Tumor imaging can exploit soft tissue differences between normal and malignant cells by using all of the following EXCEPT:

Accepted Answer

Tumor imaging techniques like X-rays, CAT scans, and positron emission tomography (PET) scans are commonly used because they can effectively differentiate between normal and malignant tissues based on density and metabolic activity. Infrared light, however, is not typically used for deep tissue imaging due to its limited penetration depth and inability to provide detailed information about tissue composition at the level required for tumor detection.

Question 5

2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG)accumulates within tumor cells engaging in higher than normal glycolytic activity. Which reactive functional group is missing in FDG, permitting its accumulation in tumor cells and their detection through PET scans?

Accepted Answer

FDG is a modified form of glucose with the hydroxyl group on the C2 carbon replaced by a radioactive fluorine atom. This modification ensures that FDG is not further metabolized by the cell, allowing it to accumulate within tumor cells with high glycolytic activity. Therefore, the missing functional group in FDG is a hydroxyl group.

Question 6

Advantages derived from the use of a circadian oscillator regulatory mechanism include:

Accepted Answer

The use of a circadian oscillator regulatory mechanism allows for the prediction of the need for photosynthesis-related molecules, which can be used to maximize photosynthesis during daylight hours. This can increase overall efficiency of photosynthesis and contribute to plant growth and productivity. Options A, B and C are not directly related to the advantages of the use of a circadian oscillator regulatory mechanism.

Question 7

Evidence suggests that lower levels of insulin in the blood may be important in promoting longevity. Which animal models have been used to gather this evidence? (Select all that apply)

Accepted Answer

The answer of Evidence suggests that lower levels of insulin...

Question 8

Other than controlling the synthesis of photosynthesis-related proteins and other factors, which process has been observed in plants to be regulated by the circadian oscillator?

Accepted Answer

The answer of Other than controlling the synthesis of photosynthesis-related...

Question 9

Which statements regarding the diagnosis and detection of brain tumors are INCORRECT? (Select all incorrect choices)

Accepted Answer

A) This statement is incorrect because PET scanners do not directly detect positrons emitted from fluorescein 18 incorporated into 2-deoxy- D-glucose, but rather indirectly detect the emitted photons resulting from positron annihilation with electrons in the surrounding tissues.
C) This statement is incorrect because tumor localization within the skull relies on tracking a pair of photons back to the point where they diverged in position, not positrons.

Question 10

Using an imaging technique such as positron emission tomography (PET)to detect cancer has all the advantages described EXCEPT:

Accepted Answer

PET scans are highly effective for detecting metabolic activity and the physiological changes in tissues, such as those caused by cancerous tumors. However, predicting the exact next area of invasion or metastasis based on PET data is not straightforward. PET scans provide valuable information on the metabolic activity and can indicate areas of high activity which might suggest rapid growth or aggressive behavior of the tumor, but they do not directly predict the specific future pathways of tumor expansion or metastasis.

Question 11

If people are kept on diets containing about 25% fewer calories than would be required to maintain their initial body weight, what happens? (Select all correct responses)

Accepted Answer

When people are kept on diets containing about 25% fewer calories than would be required to maintain their initial body weight, their insulin levels are lowered which can help with weight loss as insulin promotes fat storage. Also, LDL cholesterol levels are lower which can help to reduce the risk of heart disease. A reduction in body temperature has not been reported as a result of calorie restriction. DNA damage can increase due to increased oxidative stress, but this is not a guaranteed result of calorie restriction. Therefore, options A and D are incorrect.

Question 12

You isolate the enzyme that synthesizes folic acid in bacteria and conduct some enzyme kinetics experiments. You find, not surprisingly, that sulfa drugs inhibit the enzyme's activity. What happens to the V_max and K_Mof this enzyme when it is treated with sulfa drugs? (Select all the correct statements relating to this experiment)

Accepted Answer

Sulfa drugs are competitive inhibitors, which means they compete with the substrate for binding to the active site. In competitive inhibition, Vmax remains unchanged, but Km increases because a higher substrate concentration is needed to reach half of Vmax.

Question 13

Fluorescein 18 emits ________________________ as it decays to another isotope.

Accepted Answer

Fluorescein 18, also known as Fluorine-18, is a positron-emitting radioisotope used in positron emission tomography (PET) scans.

Question 14

If mice are maintained on very strict diets with reduced caloric intake, what happens to their life span as compared to littermates fed diets with normal caloric content and why? (Select all correct responses)

Accepted Answer

Studies have shown that mice on calorie-restricted diets tend to live significantly longer (30-40% longer) than those on normal diets, partly because they experience less oxidative stress, leading to less free radical damage. This is supported by the increased synthesis of antioxidants such as superoxide dismutase, which helps to neutralize free radicals.

Question 15

Which statements accurately describe the metabolism and detection of tumor cells? (Select all that are correct choices)

Accepted Answer

A) Tumor cells are known to rely on anaerobic activity more than healthy cells, which is why they exhibit the Warburg effect.
B) The Warburg effect is a phenomenon where tumor cells choose to metabolize glucose anaerobically, which is a hallmark of cancer.
C) FDG (fluorodeoxyglucose) is a radioactive glucose analog that accumulates in tumor cells, allowing them to be detected using PET (positron emission tomography) imaging.

Question 16

When using 2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG)uptake by tumor cells to detect cancerous masses, fluorescein 18 decays releasing __________. This in turn reacts with __________ and releases pairs of _________________ which are ultimately detected by the diagnostic scanner.

Accepted Answer

Fluorescein 18 decays and releases a positron, which reacts with an electron and produces a pair of photons. This process is known as positron emission, and it is the principle behind positron emission tomography (PET) scans used to detect cancerous masses. Therefore, the correct option is B, which states that fluorescein 18 releases a positron and reacts with an electron to produce photons.

Question 17

2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG)acts as a competitive inhibitor of ______________.

Accepted Answer

The answer of 2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG)acts as a competitive inhibitor...

Question 18

Plants can regulate proteins, chlorophylls and other factors required for photosynthesis via a light/dark independent regulatory mechanism known as a _______________________.

Accepted Answer

The light/dark independent regulatory mechanism in plants that regulates proteins, chlorophylls, and other factors required for photosynthesis is known as a circadian oscillator. This mechanism controls various processes in plants that exhibit daily rhythms, such as leaf movement, stomatal conductance, and metabolic processes.

Question 19

What is responsible for the periodicity that controls the production of essential photosynthetic enzymes and factors through the circadian oscillator?

Accepted Answer

The periodicity that controls the production of essential photosynthetic enzymes and factors through the circadian oscillator is primarily due to a protein network that is synchronized through light sensitivity. This network involves various proteins that can sense and respond to light, thereby adjusting the biological clock and its associated processes in accordance with the day-night cycle.

Question 20

If you were comparing circadian oscillator structures between plant species, where might you predict that there would be the greatest differences?

Accepted Answer

The greatest differences in circadian oscillator structures would be expected between plant species from vastly different environments. Tropical orchids and arctic tundra wildflowers experience vastly different day lengths, temperature ranges, and light intensities, which could impact the evolution of their circadian oscillator structures.

Quiz 3: Bioenergetics, Enzymes and Metabolism

In cells relying exclusively upon glycolysis and substrate-level phosphorylation for ATP production, why is the production of reduced intermediates from pyruvate so essential?

Fluorescein 18 emission from tumor cells is detected by _________________ detector.

Why has the pharmaceutical industry drastically cut resources devoted to the development of new antibiotics? (Select all correct choices)

Tumor imaging can exploit soft tissue differences between normal and malignant cells by using all of the following EXCEPT:

2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG) accumulates within tumor cells engaging in higher than normal glycolytic activity. Which reactive functional group is missing in FDG, permitting its accumulation in tumor cells and their detection through PET scans?

Advantages derived from the use of a circadian oscillator regulatory mechanism include:

Evidence suggests that lower levels of insulin in the blood may be important in promoting longevity. Which animal models have been used to gather this evidence? (Select all that apply)

Other than controlling the synthesis of photosynthesis-related proteins and other factors, which process has been observed in plants to be regulated by the circadian oscillator?

Which statements regarding the diagnosis and detection of brain tumors are INCORRECT? (Select all incorrect choices)

Using an imaging technique such as positron emission tomography (PET) to detect cancer has all the advantages described EXCEPT:

If people are kept on diets containing about 25% fewer calories than would be required to maintain their initial body weight, what happens? (Select all correct responses)

Fluorescein 18 emits ________________________ as it decays to another isotope.

If mice are maintained on very strict diets with reduced caloric intake, what happens to their life span as compared to littermates fed diets with normal caloric content and why? (Select all correct responses)

Which statements accurately describe the metabolism and detection of tumor cells? (Select all that are correct choices)

When using 2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG) uptake by tumor cells to detect cancerous masses, fluorescein 18 decays releasing . This in turn reacts with and releases pairs of _________ which are ultimately detected by the diagnostic scanner.

2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG) acts as a competitive inhibitor of ______________.

Plants can regulate proteins, chlorophylls and other factors required for photosynthesis via a light/dark independent regulatory mechanism known as a _______________________.

What is responsible for the periodicity that controls the production of essential photosynthetic enzymes and factors through the circadian oscillator?

If you were comparing circadian oscillator structures between plant species, where might you predict that there would be the greatest differences?

Quiz 3: Bioenergetics, Enzymes and Metabolism

In cells relying exclusively upon glycolysis and substrate-level phosphorylation for ATP production, why is the production of reduced intermediates from pyruvate so essential?

Fluorescein 18 emission from tumor cells is detected by _________________ detector.

Why has the pharmaceutical industry drastically cut resources devoted to the development of new antibiotics? (Select all correct choices)

Tumor imaging can exploit soft tissue differences between normal and malignant cells by using all of the following EXCEPT:

2-[18F] fluoro-2-deoxy-D-glucose (FDG) accumulates within tumor cells engaging in higher than normal glycolytic activity. Which reactive functional group is missing in FDG, permitting its accumulation in tumor cells and their detection through PET scans?

Advantages derived from the use of a circadian oscillator regulatory mechanism include:

Evidence suggests that lower levels of insulin in the blood may be important in promoting longevity. Which animal models have been used to gather this evidence? (Select all that apply)

Other than controlling the synthesis of photosynthesis-related proteins and other factors, which process has been observed in plants to be regulated by the circadian oscillator?

Which statements regarding the diagnosis and detection of brain tumors are INCORRECT? (Select all incorrect choices)

Using an imaging technique such as positron emission tomography (PET) to detect cancer has all the advantages described EXCEPT:

If people are kept on diets containing about 25% fewer calories than would be required to maintain their initial body weight, what happens? (Select all correct responses)

Fluorescein 18 emits ________________________ as it decays to another isotope.

If mice are maintained on very strict diets with reduced caloric intake, what happens to their life span as compared to littermates fed diets with normal caloric content and why? (Select all correct responses)

Which statements accurately describe the metabolism and detection of tumor cells? (Select all that are correct choices)

When using 2-[18F] fluoro-2-deoxy-D-glucose (FDG) uptake by tumor cells to detect cancerous masses, fluorescein 18 decays releasing __________. This in turn reacts with __________ and releases pairs of _________________ which are ultimately detected by the diagnostic scanner.

2-[18F] fluoro-2-deoxy-D-glucose (FDG) acts as a competitive inhibitor of ______________.

Plants can regulate proteins, chlorophylls and other factors required for photosynthesis via a light/dark independent regulatory mechanism known as a _______________________.

What is responsible for the periodicity that controls the production of essential photosynthetic enzymes and factors through the circadian oscillator?

If you were comparing circadian oscillator structures between plant species, where might you predict that there would be the greatest differences?

2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG) accumulates within tumor cells engaging in higher than normal glycolytic activity. Which reactive functional group is missing in FDG, permitting its accumulation in tumor cells and their detection through PET scans?

When using 2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG) uptake by tumor cells to detect cancerous masses, fluorescein 18 decays releasing . This in turn reacts with and releases pairs of _________ which are ultimately detected by the diagnostic scanner.

2-[¹⁸F] fluoro-2-deoxy-D-glucose (FDG) acts as a competitive inhibitor of ______________.