Chapter 7 Mastering Bio
In vertebrate animals, brown fat tissue's color is derived from abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that allows protons to diffuse across the inner mitochondrial membrane. Which of the following might be the function of the brown fat tissue?
to regulate temperature by converting most of the energy from NADH oxidation to heat
If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate completely oxidized to carbon dioxide and water?
14
For each molecule of glucose consumed in glycolysis, there is a net consumption of which of the following?
2 NAD+ and 2 ADP
Assuming that the y-axis tick marks will be separated by 1.0 (0.0, 1.0, 2.0, and so on), what is the largest value that should appear on the y-axis?
9.0
Which of the following statements is not true of most cellular redox reactions?
A hydrogen atom is transferred to the atom that loses an electron.
Which statement correctly describes how this increased demand would lead to an increased rate of ATP production?
ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Anion and cation.
How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)
Both electron transport and ATP synthesis would stop.
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?
Carbon dioxide
Select the correct statement about cellular respiration.
Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.
Sort the statements into the appropriate bin depending on whether or not they correctly describe some aspect of substrate-level phosphorylation in glycolysis.
Correct Statement: one of the substrates is a molecule derived from the breakdown of glucose.An enzyme is required in order for the reaction to occur.A bond must be broken between an organic molecule and phosphate before ATP can form. Incorrect statements: The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP.The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions.
Why is glycolysis described as having an energy investment phase and an energy payoff phase?
Early steps consume energy from ATP, and later steps store an increased amount of energy in ATP and NADH.
Which stage of glucose metabolism produces the most ATP?
Electron transport and chemiosmosis
Which term describes the degree to which an element attracts electrons?
Electronegativity
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?
Fermentation
Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?
Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.
Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP?
Glucose
What would happen to the cell's rate of glucose utilization?
Glucose utilization would increase a lot.
Which step of the cellular respiration pathway can take place in the absence of oxygen?
Glycolysis
Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed?
Hydrogen, polar.
Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. Which of these statements is the correct explanation for this observation? Hints
In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
Ionic.
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction. Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct.
It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.
A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose?
It is stored in NADH and FADH2
Assuming that the x-axis tick marks will be used to identify the thyroid hormone level of each type of rat, what bars should appear on the x-axis?
Low, Normal, Elevated
(?)is the compound that functions as the electron acceptor in glycolysis.
NAD+
The reduced form of the electron acceptor in glycolysis is (?).
NADH
Which of the following statements about the electron transport chain is true?
NADH and FADH2 donate their electrons to the chain.
Which of the following statements is true of the bonds in a water molecule?
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
Based on what you know about mitochondrial electron transport and heat production, predict which rats had the highest body temperature, and which had the lowest body temperature.
Rats with elevated thyroid hormone had the highest body temperature; rats with low thyroid hormone had the lowest.
Which of the following statements about the chemiosmotic synthesis of ATP is correct?
The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.
How will a healthy individual's ATP production change during an eight-hour fast?
The individual's ATP production will not change significantly.
Why are carbohydrates and fats considered high-energy foods?
They have a large number of electrons associated with hydrogen.
True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.
True
True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.
True
Do the results in the graph support the researchers' hypothesis?
Yes; cells that were exposed to elevated thyroid hormone levels showed increased oxygen consumption, indicating that the efficiency of the electron transport chain was reduced.
Which of these enters the citric acid cycle?
acetyl CoA
Which of these is NOT a product of the citric acid cycle?
acetyl CoA
Which cell type(s) had the highest rate of oxygen consumption?
cells from rats with elevated thyroid hormone
Which cell type(s) had the lowest rate of oxygen consumption?
cells from rats with low thyroid hormone
In glycolysis, the carbon-containing compound that functions as the electron donor is (?).
glucose
The complete oxidation of glucose in aerobic respiration occurs through which of the following sequence of metabolic reactions?
glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain
What process occurs in Box A?
glycolysis
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
glycolysis
When an electron is transferred to a more electronegative atom
it loses potential energy.
In muscle cells, fermentation produces _____.
lactate and NAD+
Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?
oxidative phosphorylation (chemiosmosis)
One primary function of both alcohol fermentation and lactic acid fermentation is to
oxidize NADH to NAD+.
1. When a compound donates (loses) electrons, that compound becomes (?) Such a compound is often referred to as an electron donor.
oxidized
What molecule is indicated by the letter D?
oxygen
What variable responded to thyroid hormone level (the independent variable), and what are the units for this variable?
oxygen consumption rate of liver cells, in nmol O2/min • mg cells
Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called (?).
pyruvate
In fermentation _____ is reduced and _____ is oxidized.
pyruvate ... NADH
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
pyruvate, ATP, and NADH
When a compound accepts (gains) electrons, that compound becomes (?). Such a compound is often referred to as an electron acceptor.
reduced
In the citric acid cycle, ATP molecules are produced by _____.
substrate-level phosphorylation
What process occurs within Box B?
the citric acid cycle
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is
the creation of a proton-motive force.
What variable did the researchers intentionally vary in the experiment, and what are the units for this variable?
thyroid hormone level of the rats chosen for the experiment, in relative units
In mitochondrial electron transport, what is the direct role of O2?
to function as the final electron acceptor in the electron transport chain
