CH 7
Which of the following is a reasonable claim based on the data presented in the graph?
The rate of O2 consumption by germinating peas at 22 C is approximately twice that of O2 germinating peas at 12 C
Which of the following conclusions is supported by the data shown in the graph?
The rate of cellular respiration increases as the temperature increases in both germinating and nongerminating peas
Based on your understanding of reactions and gas laws, what results would you predict in an experiment that measures the rate of respiration in germinating peas at two different temperature: 12 C and 22 C?
The rate of respiration will be higher in the peas at 22 C because it is closer to the optimum temperature for the enzymes of cellular respiration
Why is the line for net primary productivity always below that for gross primary productivity?
Net primary productivity is what remains after cellular respiration by the producers is subtracted
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
O2
If you had a sample organism and wanted to measure its rate of cellular respiration, which of the following methods would provide useful information? Study the equation for cellular respiration to have a clear sense of what is consumed and what is produced before answering the question.
- Measure the amount of glucose consumed - Measure the amount of oxygen consumed - Measure the amount of carbon dioxide produced
A student team plants approximately 50 plants, and on day 7 of the experiment, they select 10 plants, rinse the soil from their roots, and carefully blot the plants dry. The total wet mass of these 10 plants is measured as 18.3 grams. Using the experimental results, calculate the values to complete the following chart: Terms: - 2.26 - 28.4 - 3.2 - 22.6 - 79.6 - 0.32 - 0.284 Table contents: - Age of plant (days) = 7 - Wet mass in grams (10 plants) = 18.3 - Dry mass in grams (10 plants) = 5.2 - Percent of wet mass that is biomass = ____ - Energy content of 10 plants (g biomass X 4.35 kcal/g) = ____ - NPP per day per plant (kcal) = ____
- Percent of wet mass that is biomass = 28.4 - Energy content of 10 plants (g biomass X 4.35 kcal/g) = 22.6 - NPP per day per plant (kcal) = 0.32
Using the data provided in the following graph, what is the rate of O2 consumption in germinating peas at 22 C over the first 10 minutes?
0.08 mL O2 per minute
What is the reading in the pipette to the nearest 0.01 mL?
0.25 mL
To calculate the energy production per individual, you will need to know the following: - Larvae percent biomass = dry mass / wet mass - From published data, we know that there is an average value of 5.5 kcal of energy per gram of larval biomass - Energy production per individual = individual wet mass X percent biomass X 5.5 kcal Ten larvae have a total wet mass of 2.7g and a dry mass of 0.83g. Calculate the energy production per individual larva
0.46 kcal - Individual wet mass = 2.7g / 10 = 0.27g - Percent biomass = 0.83 / 2.7 = 0.31 - Energy production per individual = 0.27g X 0.31 X 5.5 kcal/g
The overall efficiency of respiration (the percentage of the energy released that is saved in ATP) is approximately ____
34%
For a primary consumer, such as butterfly larvae, what is the source of energy? Where does this energy go? Place terms in correct areas Terms: - kcal light energy - kcal frass - kcal cellular respiration - kcal biomass - kcal food energy Locations: - A - B - C - D
A = kcal food energy B = kcal frass C = kcal cellular respiration D = kcal biomass
When conducting an experiment to compare the rate of respiration in germinating peas at two different temperatures-- 12 C and 22 C--what would be a good control for this experiment?
A vial with an equal volume of glass beads
Energy from catabolism provides the energy to form ATP from ADP plus inorganic phosphate. The breakdown of ATP to ADP plus inorganic phosphate provides energy for cellular work. Which of the following is the correct interpretation of these statements?
ATP is a molecule that acts as an intermediary to store chemical energy for cellular work. (ATP is a renewable resource that can be regenerated by the addition of inorganic phosphate to ADP. Energy released by catabolism in the cell is used to phosphorylate ADP, regenerating ATP. Chemical energy store in ATP drives most cellular work)
Which of the following substances is/are involved in oxidative phosphorylation?
All of the listed substances are involved in oxidative phosphorylation - Oxygen - ATP - ADP
This graph shows productivity is an aquatic environment, determined by the amount of oxygen produced. At what light intensity do you expect there to be no net primary productivity?
Any intensity below 10%
What process occurs in Box A? (Glucose ---> Pyruvate
Glycolysis
During intense exercise, as human muscle cells switch from respiration to fermentation, the cells will increase their catabolism of which of the following energy-containing molecules?
Carbohydrates only
In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive oxygen. The mice were closely monitored, and after a few minutes radioactive oxygen atoms showed up in ____
Carbon dioxide
A good question is testable and uses what is known about the experimental organism and the concept investigated to test new ideas about the factors that can result in a change. A good question will always be rooted in prior scientific knowledge, often relating to the evolutionary history of the organism or process. Using this information as a guide, which of the following would be the most valid scientific question to pose considering the evolutionary history of peas?
Do pea roots have a higher rate of cellular respiration than pea leaves?
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
Glycolysis
In ecosystems, as in our own daily lives, there is a budget-an energy budget for the ecosystem and a financial budget for us. There is only so much energy or money available, and it can be allocated in different ways. In general, ecosystems with higher productivity will have greater species diversity, which is the variety of different kinds of organisms that make up the community. Consider the following two ecosystems, located at the same latitude, and using the information you learned in this investigation choose the most accurate answer. Ecosystem A: - 175 sunny days/year - 113 frost-free days/year - 39" rain/year Ecosystem B: - 274 sunny days/year - 266 frost-free days/year - 23" rain/year
Ecosystem B would be expected to have the higher gross primary productivity because of more sunny days and a longer growing season
Of the following molecules in the glycolytic pathway (the process of glycolysis), the one with the most chemical energy is ____
Fructose-1, 6-biosphosphate
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the ____
H+ concentration across the membrane holding ATP synthase
Where do the reactions of glycolysis occur in a eukaryotic cell?
In the cytosol
The electron transport chain involved in cellular respiration is located in/on the ____
Inner membrane of the mitochondrion
Molecular oxygen (O2) has what role in aerobic cellular respiration?
It is the final electron acceptor at the end of the electron transport chain
In the absence of oxygen, cells need a way to regenerate which compound following glycolysis?
NAD+
After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of ____
NADH
What is net primary productivity and how is it calculated?
Net primary productivity is a measure of the organic products of photosynthesis that accumulate after cellular respiration. You calculate net primary productivity by subtracting the energy consumed is respiration from the total energy captured in photosynthesis
A covalent bond is likely to be polar when
One of the atoms sharing electrons is more electronegative than the other [When an atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally and a polar covalent bond is formed. Such bonds vary in their polarity, depending on the relative electronegativity of the two atoms. Atoms that have similar (or the same) electronegativities will form a nonpolar covalent bond. For example, a C-H bond is nonpolar because C and H have similar electronegativities]
Which of the following is a correct description and sequence of events in cellular respiration?
Oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation
Which of the following metabolic pathways occur(s) in mitochondria?
Oxidation of pyruvate to acetyl CoA and the citric acid cycle
What molecule is indicated by the letter D?
Oxygen
Light energy is converted to chemical energy in the form of glucose (C6H12O6) through the process of photosynthesis in plants and other producers. This chemical energy is used for movement, growth, reproduction, heat generation, and other cellular processes-including cellular respiration-in producers and organisms that eat producers. To understand energy flow from producers to consumers, you must have a firm grip on the summary equations for both photosynthesis and cellular respiration. Place the reactants and products in their correct locations, labels may be used more than once. Photosynthesis: 6 ____ + 6 ____ (water) + ____ ----> ____ + 6 ____ Cellular Respiration: ____ + 6 ____ ----> 6 ____ + 6 ____ (carbon dioxide) + ____ Terms: - CO2 - H2O - Light Energy - C6H12O6 - O2 - ATP Energy
Photosynthesis: 6 CO2 + 6 H2O + Light energy ----> C6H12O6 + 6 O2 Cellular Respiration: C6H12O6 + 6 O2 ----> 6 H2O + 6 CO2 + ATP Energy
Ideal gas law equation: PV = nRT In a sealed respirometer, CO2 molecules are being removed from the vial as precipitate; thus, "n" decreases. Refer again to the equation. What effect would decreasing the number of gas molecules in the vial have on pressure within the vial and movement of water through the pipette?
Pressure would decrease and water would enter through the pipette
In a sealed respirometer, what effect would decreasing the ambient temperature have on the pressure within the vial and the movement of water through the pipette?
Pressure would decrease and water would enter through the pipette
Using the equation for cellular respiration as a guide, sort the following items depending on whether they are the reactants or products of cellular respiration. Items: - C6H12O6 - O2 - H2O - Energy - CO2
Products: - H2O - Energy - CO2 Reactants: - C6H12O6 - O2
In mitochondria, exergonic redox reactions
Provide the energy that establishes the proton gradient
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ ----> Lactate + NAD+
Pyruvate
Which chemical process generates the ATP produced in glycolysis?
Substrate-level phosphorylation
Why is the citric acid cycle called a cycle?
The 4-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the pathway
Most CO2 from catabolism is released during
The citric acid cycle
Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes?
The citric acid cycle
What process occurs in Box B?
The citric acid cycle
Another technique for collecting data to measure the rate of cellular respiration involves placing the study organism into a closed chamber with a probe inserted, to measure the concentration of either O2 or CO2. Most probe systems allow for rapid collection of data combined with programs to graph the results Consider an experiment in which CO2 sensor probes are inserted into two chambers: - Chamber A keeps mealworms at 10 C - Chamber B keeps mealworms at 25 C What results would you expect?
The level of CO2 would increase more rapidly in chamber B than in chamber A
What difference, if any, would you expect in the rate of cellular respiration in the germinating peas in vial #1 compared to the nongerminating peas in vial #2?
The nongerminating peas will show a smaller change in gas volume compared to the germinating peas due to cellular respiration
When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
The pH of the matrix increases
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy [Chemical reactions are classified based on their free-energy changes. An exergonic reaction proceeds with a net release of free energy, whereas an endergonic reaction is one that absorbs free energy from its surroundings. If a chemical process is exergonic (downhill), releasing energy in one direction, then the reverse process must be endergonic (uphill), using energy]
Because CO2 and O2 are produced and consumed in equal amounts during cellular respiration, any changes in the sealed container will be caused by a change in gas volume due to cellular respiration, assuming that temperature and pressure remain constant. When the pipette tip is submerged in water, any change in gas volume will allow water to enter or leave the pipette. As O2 is consumed in cellular respiration and CO2 is removed as a solid precipitate, pressure within the respirometer decreases and water enters the pipette. Predict the result if KOH were NOT added to the vial
The volume of gases in the vial would remain constant as each molecule of O2 sued in cellular respiration would be replaced by a molecule of CO2
What is the primary role of oxygen in cellular respiration?
To serve as an acceptor for electrons and protons, forming water
In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH, and one FADH2 are produced. For each glucose molecule that enters glycolysis, how many ATP, NADH, and FADH2 are produced in the citric acid cycle?
Two ATP, six NADH, two FADH2
Which of the following is true of the energy levels of electrons in shells?
Valence electrons have a higher energy level than those in other filled shells. [The negatively charged electrons of an atom are attracted to the positively charged nucleus. It takes work to move a given electron farther away from the nucleus so the more distant an electron is from the nucleus, the greater its potential energy. The valence electrons, located in the outermost electron shell (the valence shell), have the highest energy level]
Predict what would happen if the respirometer were not tightly sealed
Water will enter the vial, and it will no longer be possible to measure changes in gas pressure