AP Bio Chapter 7
Red blood cells (RBCs) do not perform aerobic respiration, but they do perform glycolysis. Provide the reasoning necessary to explain why all cells need an energy source, and predict what would happen if glycolysis were blocked in a sample of RBCs.
Cells require energy to perform certain basic functions. Blocking glycolysis in RBCs causes imbalance in the membrane potential, leading to cell death.
Which of the following fermentation methods can occur in animal skeletal muscles?
lactic acid fermentation.
Drawing upon your understanding of metabolic strategies to evaluate their differences: Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis?
Plants generally use starch molecules for storage while animals use glycogen and fats for storage
What happens when a chemical is reduced during a reaction?
an electron is added to the chemical
Which of the following enzymes has the greatest control over glycolysis?
phosphofructokinase
How many NADH molecules are produced on each turn of the citric acid cycle?
3
Examine the data pictured. The table shows the amount of oxygen consumed (third column) by different animals (first column) at different temperatures. The type of apparatus employed in this investigation measures the changes in volume of air to detect the removal of oxygen. However, organisms produce carbon dioxide as they take in oxygen. Predict what you would need to add to the setup in order to provide accurate measurements.
A substance that removes carbon dioxide gas
What is the most important energy currency used by cells?
ATP
Which of the following reactions releases energy?
ATP + H2O = ADP + phosphate
During the second half of glycolysis, what occurs?
ATP is produced
Apply your understanding of how living organisms use energy to argue in favor of why it is either beneficial or detrimental for cells to use ATP rather than directly using the energy stored in the bonds of carbohydrates to power cellular reactions.
ATP is readily available in the form of a single unit that provides a consistent, appropriate amount of energy. The cell would need to tailor each reaction to each energy source if it harvested energy from different compounds.
What would be the outcome if hydrogen ions were able to diffuse through the mitochondrial membrane into the mitochondria without the need for integral membrane proteins?
ATP would not be produced
What type of cellular respiration is represented in the following equation, and why? CO2+H2+NADH→CH4+H2O+NAD+
Anaerobic respiration, because NADH donates its electrons to a methane molecule
Make a claim to identify the lipids that are connected to glucose catabolism pathways, and support your claim with evidence of how the lipids are connected to those pathways.
Cholesterol and triglycerides can be converted to glycerol-3-phosphate that continues through glycolysis.
Examine and compare the statements below, each of which proposes the specific mechanism by which citrate from the citric acid cycle affects glycolysis. Which statement offers an accurate description of this effect?
Citrate and ATP are negative regulators of phosphofructokinase
Apply your understanding of the various components of the electron transport chain to evaluate how the roles of ubiquinone and cytochrome c differ from those of the other components.
CoQ and cytochrome c are mob electron carriers while NADH dehydrogenase and succinate dehydrogenase are bound to the inner mitochondrial membrane.
Which of the following best describes complex IV in the electron transport chain?
Complex IV consists of an oxygen molecule held between the cytochro... and copper ions. The electrons flowing finally reach the oxygen, producing water.
Evaluate the process represented by the diagram. Predict the most direct result of blocking structure Z.
Cytochrome c would not pass electrons from complex III to complex IV
Which pair of molecules are both oxidizing agents?
FAD+ and NAD+
What compound receives electrons from NADH?
FMN
Review the process of fermentation, as illustrated here by lactic acid fermentation. Which of the following statements best compares fermentation and anaerobic respiration and accurately highlights their differences?
Fermentation uses only glycolysis and its final electron acceptor is an organic molecule, whereas anaerobic respiration uses glycolysis, TCA and the ETC but finally give electrons to an inorganic molecule.
Which of the following statements about catabolic pathways is false?
Glycerol can be broken down into glucose and feed into glycolysis.
Nearly all organisms on Earth carry out some form of glycolysis. Provide an accurate argument that explains how this fact either supports or refutes the assertion that glycolysis is one of the oldest metabolic pathways.
Glycolysis is present in nearly all organisms because it is an advanced and recently evolved pathway that has been widely used as it is so beneficial.
You read the claim that glycolysis is an older and more conserved pathway than the citric acid cycle. Evaluate the statements below to select the evidence that provides the strongest support for this claim.
Glycolysis is the primitive pathway as it is found in all three domains. it also occurs in anaerobic conditions and the cytosol.
Review the diagram of the citric acid cycle. Evaluate how the citric acid cycle relates to glycolysis, oxidative phosphorylation, and chemiosmosis. Which of the following best describes the relationship between these processes?
Glycolysis produces pyruvate, which is converted to acetyl-CoA and enters the citric acid cycle. This cycle produces NADH and FADH2, which donates electrons to the electron transport chain to pump proton and produce ATP through chemiosmosis. Production of ATP using an electron transport chain and chemiosmosis is called oxidative phosphorylation.
GLUTs are integral membrane proteins that assist in the facilitated diffusion of glucose into and out of cells. What reaction in glycolysis prevents glucose from being transported back out of the cell?
Hexokinase phosphorylates glucose using ATP, creating a glucose molecule that can't cross the hydrophobic interior of the plasma membrane
Which of the following does not occur as ATP concentration increases relative to ADP?
Increased activity of pyruvate kinase
Would you describe metabolic pathways as inherently wasteful or inherently economical? Justify your answer by explaining why you chose it.
Metabolic pathways are economical due to feedback inhibition. Also, intermediates from one pathway can be utilized by other pathways.
Consider that the number of ATP molecules formed through cellular respiration varies. Identify the claim that accounts for these differences.
Most of the ATP's produced are rapidly used for the phosphorylation of certain compounds found in plants.
What role does NAD+ play in redox reactions?
NAD+, an oxidizing agent, can accept electrons and protons from organic molecules and get reduced to NADH
Why might negative feedback mechanisms be more common than positive feedback mechanisms in living cells?
Negative feedback mechanisms maintain homeostasis whereas positive feedback drives the system away from equilibrium
Which molecules are produced in glycolysis and used in fermentation?
Pyruvate and NADH.
What three steps are included in the breakdown of pyruvate?
Pyruvate dehydrogenase removes a carboxyl group from pyruvate producing carbon dioxide. Dihydrolipoyl transacetylase oxidizes a hydroxyethyl group to an acetyl group, producing NADH. Lastly, and enzyme-bound acetyl group is transferred to CoA, producing a molecule acetylCoA.
Which statement best explains how electrons are transferred and the role of each species. Remember that R represents a hydrocarbon molecule and RH represents the same molecule with a particular hydrogen identified. RH+NAD+→NADH+R
RH acts as a reducing agent and donates its electrons to the oxidizing agent NAD+ forming NADH and R.
. Cellular respiration breaks down glucose and releases carbon dioxide and water. Which steps in the oxidation of pyruvate produces carbon dioxide?
Removal of a carboxyl group from pyruvate releases carbon dioxide. The pyruvate dehydrogenase complex comes into play.
Evaluate the diagram of the electron transport chain. Based on your understanding of this part of glucose metabolism, where do the electrons that are moving along the membrane come from, and where do the electrons end up?
The electrons are released by NADH and FADH2 and finally accepted by oxygen to form water.
What is the primary difference between a circular pathway and a linear pathway?
The reactant and the product are the same in a circular pathway but different in a linear pathway.
What is removed from pyruvate during its conversion into an acetyl group?
carbon dioxide
What are the products of alcohol fermentation?
ethanol and NAD+
In the first step of glycolysis, what is glucose transformed into?
glucose-6-phosphate
A new species of obligate anaerobe, a bacterium, has been found that lives in hot, acidic conditions. While other pathways may also be present, which metabolic pathway is the most likely to be present in this species?
glycolysis
Glucose catabolism pathways are sequential and lead to the production of ATP. What is the correct order of the pathways for the breakdown of a molecule of glucose as shown in the formula? C6H12O6+O2→CO2+H2O+energyC6H12O6+O2→CO2+H2O+energy
glycolysis - oxidation of pyruvate - citric acid cycle-oxidative phosphorylation
During the chemiosmosis phase of cellular respiration, what is moved? Where does this occur?
hydrogen ions across a mitochondrial membrane
What is the role of electrons in the electron transfer chain?
to power active transport
GTP, which can be converted to ATP, is produced during which reaction of the citric acid cycle?
succinyl-CoA into succinate
Where in a cell does glycolysis take place in both prokaryotes and eukaryotes?
the cytosol
How many ATP molecules are used and produced per molecule of glucose during glycolysis?
the first half uses 2 ATP and the second half produces 4 ATP
What is Structure X in the graphic?
the inner mitochondrial membrane
What is beta-oxidation?
the main process used to break down fatty acids
Evaluate the table pictured. 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 mice. Make a claim to explain the reason for this difference in trends in oxygen consumption among crickets and mice.
their difference in metabolic heat production
What do the electrons added to NAD+ do in aerobic respiration?
they go to another pathway for ATP production
What impact, if any, do high levels of ATP have on glycolysis?
they increase the activity of enzymes involved with glycolysis
