Chapter 6
How does adenosine triphosphate (ATP) drive energy‑required reactions in the cell?
☐ ATP lowers the activation energy of a reaction. ☐ ATP allows metabolic reactions to proceed without an enzyme. ☐ The hydrolysis of ATP releases heat to drive energy‑requiring reactions. ☑ The hydrolysis of ATP is coupled to a non‑spontaneous reaction. ☐ ATP generates a proton gradient to drive reactions.
Based on the pie charts in Infographic 6.4, approximately how many days would it take for someone to lose 1 pound if the only change the person made was to stand approximately 25% more every day? See Infographic 6.4: https://i.imgur.com/3cZTMP0.png
☐ Approximately 20 days ☐ Approximately 5 days ☐ Approximately 1 day ☑ Approximately 10 days ☐ Approximately 30 days
Which cellular respiration process takes place in the cytoplasm?
☐ FADH2 and NADH production ☐ Carbon dioxide production ☑ Glycolysis ☐ Citric acid cycle ☐ Electron transport
Why is cellular respiration referred to as an aerobic process?
☐ It requires a cell to be motile. ☐ It generates energy as a product. ☐ It does not require oxygen to occur. ☐ It generates water as a product. ☑ It requires oxygen to occur.
Cellular respiration consumes glucose during glycolysis. What product of glycolysis can be subsequently modified to enter the citric acid cycle under aerobic conditions?
☐ NADH ☐ acetyl‑CoA ☐ lactic acid ☑ pyruvate ☐ ADP
Both photosynthesis and cellular respiration are cellular processes that involve glucose. How do these two processes differently affect the metabolism of glucose?
☐ Plants use photosynthesis to release energy from glucose, whereas animals use cellular respiration to release energy from glucose. ☑ Glucose is produced during photosynthesis to hold the energy gathered from light, whereas glucose is broken down during cellular respiration to release stored cellular energy. ☐ Both processes build glucose, but in photosynthesis, glucose stores energy gathered from light, whereas in cellular respiration, glucose stores energy gathered from heat. ☐ Photosynthesis releases energy from the breakdown of glucose molecules, whereas cellular respiration harvests energy from light and stores it in glucose molecules.
A moderately active 21-year-old female has a choice of eating a 2,500-Calorie meal that is primarily protein or a 2,500-Calorie meal that is primarily sugar. What would be the result, in terms of energy, of choosing one over the other?
☐ She would store the excess calories as protein if she ate the protein meal, and as glycogen if she ate the sugar meal. ☐ Nothing; given her age, gender, and activity, she would burn all of these calories. ☐ She will store the excess calories as protein, regardless which meal she ate. ☑ In either case, once her glycogen stores are replenished, she will store the excess calories as fat. ☐ Regardless of the number of calories, she will get more energy from the sugar meal.
Anaerobic respiration allows a cell to break down carbohydrates in the absence of oxygen. Identify how NAD+NAD+ is used by animal cells during anaerobic respiration.
☐ When NADH is converted to NAD+ during fermentation, energy needed to make pyruvate is released. ☐ NAD+ is converted to NADH during fermentation and used for anaerobic respiration to begin. ☑ Glycolysis requires NAD+ produced from fermentation to produce ATP. ☐ In anaerobic conditions, the NAD+ produced during fermentation is used as energy in place of ATP. ☐ The ATP made during fermentation is needed to start the reactions of anaerobic respiration.
During aerobic respiration, NADH gives up electrons to regenerate NAD+ by giving electrons to
☐ another NAD+. ☐ glucose. ☐ oxygen. ☐ pyruvate. ☑ the electron transport chain.
Excess energy can be stored for short periods of time in the muscle and liver tissue as _____ , and for long periods of time as _____ in fat cells.
☐ triglycerides; glycogen ☐ triglycerides; calories ☐ glycogen; calories ☑ glycogen; triglycerides ☐ calories; calories
Some molecules that leave the chloroplasts at the end of photosynthesis will be used in cellular respiration. Which molecules are these?
☐ water, oxygen ☐ sugars, carbon dioxide ☐ NADPH, oxygen ☑ sugars, oxygen
Under aerobic conditions, when is pyruvate produced and consumed?
☑ It is produced in glycolysis and consumed in the citric acid cycle. ☐ It is produced in glycolysis and consumed in fermentation. ☐ It is produced in the citric acid cycle and consumed in fermentation. ☐ It is produced in electron transport and consumed in glycolysis. ☐ It is produced in the citric acid cycle and consumed in electron transport.
What difference might explain why the French weigh less on average than Americans, despite eating meals with higher fat content?
☑ The French engage in more NEAT activities such as household chores, shopping, and dog walking. ☐ The French only eat one meal a day. ☐ The French snack and skip meals. ☐ The French are less active than Americans, so they feel less hungry. ☐ The French eat at restaurants more often than Americans.
In eukaryotic cells, each stage of cellular metabolism generates a different net amount of ATP. Which stage directly generates the greatest number of ATP molecules per metabolized glucose molecule?
☑ electron transport chain and ATPATP synthase ☐ citric acid cycle (Krebs cycle) ☐ fermentation ☐ glycolysis
During fermentation, NADH gives up electrons to regenerate NAD+ by giving electrons to
☑ pyruvate. ☐ the electron transport chain. ☐ glucose. ☐ another NAD+. ☐ O2.
What is the role of pyruvate under anaerobic conditions? Select the TWO answers that are correct.
☑ to produce NAD+ from NADH ☑ to generate ATP and lactic acid ☐ to facilitate fermentation of NAD+ ☐ to produce ATP in the citric acid cycle ☐ to move NADH through electron transport
Which statement correctly reflects the interactions between aerobic respiration and photosynthesis?
☐ The energy captured and stored in ATP through aerobic respiration comes from high-energy bonds in oxygen. ☐ Photosynthesis produces water, which is then used as an energy source in aerobic respiration. ☐ The carbon dioxide we breathe out comes from inorganic carbon dioxide that we breathe in. ☐ The oxygen we use in aerobic respiration is the same oxygen used by plants in photosynthesis. ☑ The carbon in the glucose that plants make is the same carbon in the carbon dioxide we breathe out.
Why is it recommended that anyone trying to lose weight should avoid alcoholic beverages?
☐ The fermentation process used to make alcohol produces a low-energy beverage that causes lethargy. ☐ Drinking alcoholic beverages increases fermentation in the body, which leads to weight gain. ☐ Fermentation is an inefficient form of aerobic respiration. ☑ The fermentation process used to make alcohol does not fully break down glucose, resulting in a high-carbohydrate beverage. ☐ Drinking alcoholic beverages decreases fermentation in the body, which leads to weight gain.
Fermentation in animals produces _____ , whereas fermentation in brewer's yeast produces _____ .
☐ alcohol; lactic acid ☐ oxygen; alcohol ☐ lactic acid; glucose ☐ alcohol; oxygen ☑ lactic acid; alcohol
Pyruvate is a product of glycolysis and is subsequently converted to acetyl‑CoA. Acetyl‑CoA is a substrate for the citric acid cycle (CAC). Exactly how many molecules of glucose must be oxidized in glycolysis to provide the input for four turns of the CAC?
☐ eight ☐ four ☑ two ☐ one
Sam is a 5'8" tall adult who weighs 115 pounds. See Graph: https://i.imgur.com/ZPYMnRK.jpg Based on the body mass index (BMI) graph provided, he is
☐ extremely obese ☐ normal ☐ overweight ☑ underweight ☐ obese
If you exercise for an extended period of time, you will use energy first from _____ , then from _____ .
☐ fats; glycogen ☐ glycogen; proteins ☐ proteins; fats ☐ fats; proteins ☑ glycogen; fats
What molecule provides long-term energy storage in the body?
☐ fatty acid ☐ phospholipid ☑ triglyceride ☐ glycogen ☐ glycerol
What molecule provides short-term energy storage in the body?
☐ glycerol ☐ glucose ☐ glucagon ☑ glycogen ☐ glycine
What stage of aerobic respiration produces the most ATP?
☐ glycolysis ☐ citric acid cycle ☑ electron transport ☐ fermentation ☐ Krebs cycle
In the presence of oxygen, humans use _____ to fuel ATP production from glucose. Glucose is initially formed by plants through _____ .
☐ glycolysis; photosynthesis ☐ aerobic respiration; aerobic respiration ☐ fermentation; aerobic respiration ☑ aerobic respiration; photosynthesis ☐ fermentation; photosynthesis
Where in the cell does fermentation take place?
☐ mitochondria ☐ cytoplasm and mitochondria ☑ cytoplasm ☐ nucleus ☐ Fermentation does not occur in cells; it occurs in circulating blood.
Compared to aerobic respiration, fermentation produces _____ ATP.
☐ much more ☐ zero ☐ the same amount of ☑ much less ☐ a little less
A calorie is defined as the energy needed to increase the temperature of
☐ one kilogram of water by one degree Celsius. ☐ a liquid by one degree Celsius. ☑ one gram of water by one degree Celsius. ☐ water by one degree Celsius.
Which type of organic molecule stores the most energy per gram?
☐ proteins ☑ fats ☐ starch ☐ glycogen ☐ nucleic acid
The purpose of aerobic respiration is to , _____ which is used to _____ .
☐ remove waste carbon dioxide from the blood; create new nutrient subunits ☑ create energy-rich ATP molecules; power functions of the cell ☐ remove waste carbon dioxide from the blood; power functions of the cell ☐ create new nutrient subunits; create energy-rich ATP molecules ☐ create energy-rich ATP molecules; remove oxygen from the bloodstream
What bonds in an ATP molecule store the chemical energy used by cells?
☐ the bonds between riboses ☑ the bonds between phosphates ☐ the bonds between adenines ☐ the bonds between adenine and ribose ☐ the bonds between ribose and phosphate
Once excess calories are stored as triglycerides, it is more difficult to release this energy because
☐ triglycerides are used for short-term energy storage only. ☐ the body breaks down liver tissue instead. ☐ triglycerides are hard to find in order to break down. ☐ triglycerides are stored in muscle tissue, which makes them hard to release. ☑ the body utilizes food molecules in the bloodstream and stored glycogen first.
If you ingest carbon in the form of sugar, that carbon is released from your body as
☑ CO2. ☐ fat. ☐ sugar. ☐ protein. ☐ part of urine.
Glycolysis is a step in the breakdown of glucose. Which statements describe glycolysis?
☑ It breaks down glucose to two pyruvate molecules. ☐ It occurs only when an animal is breathing. ☑ It is common to aerobic and anaerobic respiration. ☐ It occurs in a cell's mitochondria.
Although the path of one glucose molecule through glycolysis generates a total of four ATP molecules, there is a net gain of only two ATP for each glucose molecule that enters the pathway. Why does the passage of one glucose molecule through glycolysis have a payoff of only two ATP molecules?
☑ Two ATP molecules are used in the initial phase of glycolysis, reducing the net gain to two ATP. ☐ Two ATP molecules are generated by each of the pyruvic acid molecules generated by glycolysis. ☐ Two ATP molecules are used to convert pyruvic acid to a form that can enter the citric acid cycle. ☐ Two ATP molecules are used to synthesize two NADH molecules in the second phase of glycolysis.
The cellular respiration process that requires the presence of oxygen is
☑ the electron transport chain. ☐ the citric acid cycle. ☐ glycolysis.
What roles does the circulatory system play in aerobic cellular respiration? Select the TWO answers that are correct.
☑ transport glucose from the digestive system to body tissues ☐ transport glycogen from the liver to body tissues ☐ transport ATP from the digestive system to body tissues ☐ transport oxygen from the small intestine to the lungs ☑ transport oxygen to body tissues and carbon dioxide to the lungs
Use the cellular respiration interactive to help you answer the questions. 1. Which cellular respiration disruptor was given to Leif the action figure in each image? 2. Use the drop‑down menu to complete each sentence.
1. Left: low oxygen Middle: arsenic Right: DNP (diet pill) 2. < [ DNP (diet pill) ] > disrupts cellular respiration by destroying the proton gradient in the mitochondrion. < [ Arsenic ] > disrupts cellular respiration by stalling the conversion of pyruvate to acetyl CoA. < [ Low oxygen ] > disrupts cellular respiration by stalling the electron transport chain. See Answer Image: https://i.imgur.com/AIZQLp8.jpg
Use the cellular respiration interactive to answer the questions. See Respiration Interactive: https://imgur.com/a/CXglMN5 1. Why does the disruption of oxidative phosphorylation also disrupt other cellular processes? 2. Why does arsenic and limited oxygen result in fermentation?
1. Oxidative phosphorylation generates ATP,ATP, which is required for many cellular processes. 2. Arsenic prevents acetyl‑CoA formation, whereas limited oxygen disables the electron transport chain.
Use the cellular respiration interactive to help you complete the passage. 2,4‑dinitrophenol (DNP)(DNP) was a popular ingredient in diet pills in the 1930s before it was discovered that moderate doses of the compound cause exceptionally high body temperature and even death. Complete the passage detailing how DNPDNP's mechanism of action explains why it causes both high body temperature and weight loss.
2,4‑dinitrophenol (DNP)(DNP) causes < [ protons ] > to pass directly across the inner mitochondrial membrane instead of returning to the mitochondrial matrix through < [ ATP synthase ] > proteins. Because of DNPDNP's effect on the mitochondrion, less energy is captured in the form of < [ ATP ] > and more energy is instead wasted as heat.
Cellular respiration is carried out in the presence of oxygen (aerobic conditions) or the absence of oxygen (anaerobic conditions). Determine whether each event occurs under aerobic conditions, anaerobic conditions, or both aerobic and anaerobic conditions.
Aerobic Conditions: citric acid cycle (Krebs cycle), electron transport chain Anaerobic Conditions: fermentation Both: glycolysis See Answer Image: https://i.imgur.com/EbOiNvj.jpg
Identify compounds that are required for the electron transport chain and compounds that are produced by the electron transport chain. Not all the potential reactants or products are given. Place all the compounds.
Compounds that enter the electron transport chain: NADH, FADH2, O2, ADP Compounds produced by the electron transport chain: NAD+, FAD, H2O, ATP See Answer Image: https://i.imgur.com/J38I285.jpg
Electron carrier molecules transfer electrons between metabolic pathways. Choose the electron carriers that transfer electrons from glycolysis to the electron transport chain and from the citric acid cycle to the electron transport chain. One of the molecules will be placed more than once. More than one molecule may act as an electron carrier in these two pathways.
From Glycolysis to the Electron Transport Chain: NADH From the Citric Acid Cycle to the Electron Transport Chain:NADH, FADH2 See Answer Image: https://i.imgur.com/21PfBav.jpg
For each example, identify if the food contains mostly saturated or unsaturated fatty acids.
Olive oil, which is a liquid at room temperature, is used in cooking pasta. < [ unsaturated ] > Coconut oil, which is a solid at room temperature, can be used as an alternative to butter. < [ saturated ] > Butter, which is solid at room temperature, is often used in cooking. < [ saturated ] > The oil inside flaxseed oil pills is liquid at room temperature. < [ unsaturated ] >
In humans, why is the process of fermentation unable to sustain life?
☐ Fermentation is not a process that occurs in human cells. ☐ Fermentation causes glycolysis to stop. ☑ Fermentation is not efficient at using the energy sources we eat to make ATP. ☐ Fermentation in human cells produces toxic products that rapidly destroy cells. ☐ Humans are unable to use the ATP produced by fermentation.
During aerobic respiration, which molecule holds and carries electrons stripped from food?
☐ H2O ☑ NADH ☐ O2 ☐ pyruvate ☐ NAD+
Which statement best explains why fermentation occurs in mammals?
☐ It breaks down lactic acid to generate a small amount of ATPATP under anaerobic conditions. ☐ It produces an acid that maintains blood pH within a narrow range. ☐ It enables mammals to generate additional ATPATP in an oxygen‑rich environment. ☐ It generates ethanol, which can be used as an alternative source of energy. ☑ When oxygen concentration is low, it replenishes NAD+NAD+ needed during glycolysis.
Why is photosynthesis important to both plants and animals? Select the TWO answers that are correct.
☐ It produces lactate. ☑ It produces glucose. ☐ It produces water. ☑ It produces oxygen. ☐ It produces pyruvate.
What products of aerobic respiration are used in photosynthesis? Select the TWO answers that are correct.
☐ NADH ☑ carbon dioxide ☑ water ☐ oxygen ☐ lactic acid
Why does anaerobic respiration yield less energy than aerobic respiration?
☐ Oxygen cannot donate protons under anaerobic conditions. ☑ The citric acid cycle and electron transport are not used in anaerobic respiration. ☐ Fermentation uses oxygen less efficiently than electron transport. ☐ Electron transport generates much less ATP under anaerobic conditions. ☐ Glycolysis generates only one pyruvate per glucose instead of two.
Compare and contrast lactic acid fermentation and ethanol fermentation (alcohol fermentation). Move each phrase to the appropriate category. If a phrase describes both types of fermentation, classify it as both.
Ethanol fermentation: used by yeast cells, generates ethanol Both: occurs under anaerobic conditions, regenerates NAD+ that can be used in glycolysis Lactic acid fermentation: used by animal cells, produces lactic acid (lactate) See Answer Image: https://i.imgur.com/TYHDpvG.jpg
Use the cellular respiration interactive to answer the questions. Which steps of cellular respiration generate NADH or FADH2 as products, and which steps receive those molecules as inputs?
Generates NADH or FADH2: Glycolysis, Acetyl-CoA Production, Citric Acid Cycle Receives NADH or FADH2: Oxidative Phosphorylation See Answer Image: https://i.imgur.com/4iTXv0b.jpg
Place the products and reactants of the citric acid cycle, also called the Krebs cycle or the tricarboxylic acid cycle, in order. Some compounds will be placed more than once.
Pyruvate >> Acetyl CoA >> Citric Acid >> Isocitric Acid >> CO2 + α-Ketoglutaric acid >> CO2 + Succinyl CoA >> ATP + Succinic Acid >> Fumaric Acid >> Malic Acid >> Oxaloacetic Acid See Answer Image: https://i.imgur.com/icCRPBw.jpg