Unit 3
The rate of oxygen consumption in germinating pea seeds at 26ºC is
A) 0.05 mL / min
During aerobic cellular respiration, oxygen gas is consumed at the same rate as carbon dioxide gas is produced. In order to provide accurate volumetric measurements of oxygen gas consumption, the experimental setup should include which of the following?
A) A substance that removes carbon dioxide gas
Which of the following descriptions of photosynthesis best explains the results of the experiment?
A) Availability of electrons for transfer to DCPIP depends on light energy.
An increase in the rate of oxygen production by algae would be accompanied by a comparable increase in the rate of production of which of the following substances?
A) C6H12O6
The figures can best assist in answering which of the following questions?
A) Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?
You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave her body?
A) It was released as CO2 and H2O.
A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes. Which of the following must remain the same for all trials of this experiment?
A) The initial concentration of the substrate
According to the data, the mice at 10˚C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25˚C. This is most likely explained by which of the following statements?
A) The mice at 10˚C had a higher rate of ATP production than the mice at 25˚C.
Two nutrient solutions are maintained at the same pH. Actively respiring mitochondria are isolated and placed into each of the two solutions. Oxygen gas is bubbled into one solution. The other solution is depleted of available oxygen. Which of the following best explains why ATP production is greater in the tube with oxygen than in the tube without oxygen?
A) The rate of proton pumping across the inner mitochondrial membrane is lower in the sample without oxygen.
According to the results of this experiment, germination of tobacco seeds during the first week is
A) increased by exposure to light
Which of the following is the best explanation for the pattern of change in mass of the organisms over time?
B) Cellular respiration
Which of the following provides the best indication that light is required for the activation of electron transfer reactions in chloroplasts?
B) Comparing the observed results for sample 2 and sample 3
If the input water is labeled with a radioactive isotope of oxygen, 18O, then the oxygen gas released as the reaction proceeds is also labeled with 18O. Which of the following is the most likely explanation?
B) During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released.
A researcher claims that different metabolic pathways allow bacteria to use different molecules as sources of matter and energy. Which of the following statements best helps justify the researcher's claim by providing a relevant example?
B) E. coli bacteria reproduce in liquid media containing either glucose or galactose.
The most probable cause for the difference in mean stem length between plants in dish A and plants in dish B is which of the following?
B) Elongation of seedlings in response to the lack of light
Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms from all three domains, Archaea, Bacteria, and Eukarya. Which of the following hypotheses could be best supported by this evidence?
B) Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life.
The researcher claimed the color change in the culture was the result of an adaptation allowing greater photosynthesis. Which of the following provides the best reasoning to justify the researcher's claim?
B) In green light, more phycoerythrin molecules are produced, allowing more green light to be absorbed, thus increasing photosynthesis
Which of the following statements best helps justify the inclusion of test tube 5 as a control in the experiment?
B) It will provide a measurement of product formation in the presence of a denatured enzyme.
Based on the data shown, changes in the light intensity resulted in changes in the rate of which of the following processes?
B) Photosynthesis
Which of the following can be used to determine the rate of enzyme-catalyzed reactions?
B) Rate of disappearance of the substrate
Which of the following statements best helps explain how the enzyme speeds up the reaction?
B) The enzyme's active site binds to and stabilizes the transition state, which decreases the activation energy of the reaction.
In cellular respiration, the energy for most ATP synthesis is supplied by
B) a proton gradient across a membrane.
The primary role of oxygen in cellular respiration is to
B) act as an acceptor for electrons and hydrogen, forming water.
It is most reasonable to hypothesize that, in the breakdown of glucose, substance X is
B) an inhibitor
Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be
B) to test for liberation of O2 in the light.
Which of the following best accounts for the shape of the solid line between points A and D?
C) ATP acted as an allosteric inhibitor on one or more of the enzymes.
If an additional sample containing the chloroplast/DCPIP solution was placed at a distance of 90 cm from the lamp, which of the following predictions would be most consistent with the experimental results?
C) The change in absorbance over time in the solution will be less than that of the other samples.
Which of the following statements best helps explain the reaction specificity of an enzyme?
C) The shape and charge of the substrates are compatible with the active site of the enzyme.
According to the data, the crickets at 25˚C have greater oxygen consumption per gram of tissue than do the crickets at 10˚C. This trend in oxygen consumption is the opposite of that in the mice. The difference in trends in oxygen consumption among crickets and mice is due to their
C) mode of internal temperature regulation
Additional observations were made on day 21, and no yellow-leaved seedlings were found alive in either dish. This is most likely because
C) yellow-leaved seedlings were unable to convert light energy to chemical energy
Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?
D) A buildup of lactic acid in the muscle tissue due to fermentation
A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants. Which of the following statements best supports the researcher's claim?
D) Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.
Which of the following conclusions is best supported by the data?
D) In pea seeds an increase in temperature results in an increase in oxygen consumption.
P680+ is said to be the strongest biological oxidizing agent. Given its functions, why is this necessary?
D) It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.
The rate of oxygen production equaled the rate of oxygen consumption during which of the following time periods?
D) J to K
Which of the following can be reasonably concluded from the experimental results?
D) Light from a lamp can substitute for sunlight in stimulating chloroplast processes.
What most likely causes the trends in oxygen concentration shown in the graph above?
D) Photosynthesis produces more oxygen than is consumed by respiration during the day.
Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled?
D) The existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
A molecule that is phosphorylated
D) has an increased chemical potential energy; it is primed to do cellular work.
Assume a 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?
D) the synthesis of ATP
