Chapter 9 & 10 Mastering Biology

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is 1) oxygen. 2) NAD+. 3) water. 4) ADP. 5) pyruvate.

1

When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by _____. 1) splitting water 2) breaking down ATP 3) removing them from NADPH 4) fixing carbon 5) oxidizing glucose

1

Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration? 1) transforming the energy in glucose and related molecules in a chemical form that cells can use for work 2) the breakdown of glucose to carbon dioxide and water 3) producing complex molecules from chemical building blocks 4) breaking down ATP, so that ADP and P can be reused 5) catabolism of sugars and related compounds

1

Which of the following statements is a correct distinction between autotrophs and heterotrophs? 1) Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic. 2) Only heterotrophs require oxygen. 3) Cellular respiration is unique to heterotrophs. 4) Only heterotrophs require chemical compounds from the environment. 5) Only heterotrophs have mitochondria.

1

How is photosynthesis similar in C4 plants and CAM plants? 1) Both types of plants make sugar without the Calvin cycle. 2) In both cases, rubisco is not used to fix carbon initially. 3) Both types of plants make most of their sugar in the dark. 4) In both cases, thylakoids are not involved in photosynthesis. 5) In both cases, only photosystem I is used.

2

New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels? 1) During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions and muscles begin to cramp, thus athletic performance suffers. 2) During fermentation lactate levels increase, which indicates insufficient oxygen is reaching the muscles causing athletic performance to suffer. 3) During aerobic respiration, muscles cells produce too much lactate which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH. 4) During fermentation muscle cells receive too little pyruvate, thus athletes experience cramping and fatigue.

2

Select the most accurate statement describing the basic function of the light reactions of photosynthesis. 1) The basic function of the light reactions of photosynthesis is the trapping of light energy. 2) The basic function of the light reactions of photosynthesis is the conversion of solar energy to chemical energy. 3) The basic function of the light reactions of photosynthesis is the production of glucose.

2

The light reactions of photosynthesis supply the Calvin cycle with 1) sugar and O2. 2) ATP and NADPH. 3) light energy. 4) CO2 and ATP. 5) H2O and NADPH.

2

The oxidation of glucose in the presence of oxygen involves glycolysis, pyruvate oxidation, and the citric acid cycle (Krebs cycle). Some energy is captured in glycolysis when glucose is converted to pyruvate (pyruvic acid). In the citric acid cycle (Krebs cycle), more energy is captured in the form of reduced electron carriers, NADH and FADH2. Select the best explanation for why the eventual reoxidation of NADH and FADH2 is crucial for the continuation of the citric acid (Krebs) cycle. 1) Phosphate cannot attach to ADP to form ATP without oxidized electron carriers. 2) In order for the cycle to continue, oxidized electron carriers must be available. 3) The presence of reduced forms of the electron carriers prevents the formation of ATP. 4) Without oxidized electron carriers, oxygen will not accept the electrons at the end of the electron transport chain.

2

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? 1) The electrons gain free energy. 2) The pH of the matrix increases. 3) ATP synthase pumps protons by active transport. 4) NAD+ is oxidized. 5) The cytochromes phosphorylate ADP to form ATP.

2

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? 1) synthesis of acetyl CoA from pyruvate 2) glycolysis 3) the electron transport chain 4) reduction of pyruvate to lactate 5) the citric acid cycle

2

Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? 1) The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2. 2) The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP. 3) The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA.

2

Why are plants classified as producers? 1) Plants are classified as producers because they are at the bottom of the food chain. 2) Plants are classified as producers because they fix inorganic carbon into organic molecules. 3) Plants are classified as producers because they produce oxygen.

2

A young dog has never had much energy. He is brought to a veterinarian for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition? 1) His cells cannot move NADH from glycolysis into the mitochondria. 2) His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA. 3) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. 4) His cells contain something that inhibits oxygen use in his mitochondria. 5) His cells lack the enzyme in glycolysis that forms pyruvate.

3

ATP synthase is a key enzyme of mitochondrial energy conversion. Mitochondrial ATP synthase deficiency is due to a mutation in a gene important for the formation of a subunit in the ATP synthase complex. Scientists could use cells with this gene mutation to investigate which of the following questions? 1) What effect does the mutation have on the number of water molecules formed at the end of the electron transport chain? 2) What effect does the mutation have on the number of protons pumped into the intermembrane space of the mitochondria? 3) What effect does the mutation have on the amount of ATP synthesized during cellular respiration? 4) What effect does the mutation have on the movement of electrons between the electron carriers of the electron transport chain?

3

How will a healthy individual's ATP production change during an eight-hour fast? 1) The individual's ATP production will increase significantly. 2) The individual's ATP production will decrease significantly. 3) The individual's ATP production will not change significantly.

3

In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain? 1) The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates. 2) The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor. 3) The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.

3

Select the correct statement about cellular respiration. 1) Animals carry out cellular respiration whereas plants carry out photosynthesis. 2) Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis. 3) Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.

3

Select the correct statement about the Calvin cycle. 1) The Calvin cycle takes place primarily in the dark. 2) The basic function of the Calvin cycle is the conversion of solar energy to chemical energy. 3) The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RuBP.

3

Which of the following is a product of the light reactions of photosynthesis? 1) glyceraldehyde-3-phosphate 2) NADP+ and RuBP 3) oxygen, ATP, and NADPH 4) water and CO2 5) high-energy photons

3

Which of the following sequences correctly represents the flow of electrons during photosynthesis? 1) NADPH → chlorophyll → Calvin cycle 2) H2O → photosystem I → photosystem II 3) H2O → NADPH → Calvin cycle 4) NADPH → O2 → CO2 5) NADPH → electron transport chain → O2

3

Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle. 1) reduced...oxidized 2) consumed...reduced 3) reduced...reduced 4) oxidized...reduced 5) consumed...consumed

4

Most CO2 from catabolism is released during 1) glycolysis. 2) lactate fermentation. 3) electron transport. 4) oxidative phosphorylation. 5) the citric acid cycle.

5

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the: 1) transfer of phosphate to ADP. 2) affinity of oxygen for electrons. 3) flow of electrons down the electron transport chain. 4) oxidation of glucose and other organic compounds. 5) H+ concentration across the membrane holding ATP synthase

5

In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis? 1) four ATP 2) none, because in the absence of oxygen, no ATP can be made 3) none, because all of the available energy remains in either lactate or ethanol 4) up to 30 ATP 5) two ATP

5 (Four ATP are made, but two ATP are consumed to start the process of glycolysis.)