Question 1

All are characteristics of anabolism EXCEPT:
A) assembly of complex molecules.
B) formation of new covalent bonds.
C) ATP provides energy.
D) NADPH is an electron donor.
E) all are true.

Accepted Answer

All of the statements are true and are characteristics of anabolism. None of the statements are false so there is no exception.

Question 2

Most organisms show ____ in their major pathways of metabolism.
A) marked similarity
B) some similarity
C) minimal similarity
D) considerable diversity
E) major diversity

Accepted Answer

Most organisms show marked similarity in their major pathways of metabolism. This is because these pathways are fundamental to the survival of all living organisms and have been conserved throughout evolutionary time.

Question 3

All are characteristics of metabolism EXCEPT:
A) a process which synthesizes either energy or complex cellular substances.
B) a process of intermediates.
C) the conversion of food energy into energy of motion.
D) a free-flow unregulated process.
E) a process responding to the momentary energy requirements of a cell.

Accepted Answer

Metabolism is not a free-flow unregulated process. It is regulated by various enzymes and hormones to control the rate of metabolic reactions.

Question 4

In the case of shared anabolic and catabolic pathways, the ____ serve as the points of regulation.
A) largest enzymes
B) ATP producing enzymes
C) NADH utilizing enzymes
D) rate-limiting enzymes
E) all are true

Accepted Answer

Rate-limiting enzymes are the enzymes that control the overall rate of the metabolic pathway. These enzymes are typically located at key branching points in the pathway, where the pathway can be directed down different routes depending on the needs of the cell. By regulating the activity of these enzymes, the cell can control the flux of metabolites through the pathway and maintain a balance between anabolic and catabolic processes.

Question 5

Metabolon characteristics include all EXCEPT:
A) "units of metabolism".
B) discrete multienzyme complex.
C) soluble enzymes associated into stable multienzyme complexes.
D) membrane bound multienzyme systems.
E) all are characteristics.

Accepted Answer

Metabolons are characterized by all the listed features: they are considered "units of metabolism," can be discrete multienzyme complexes, involve soluble enzymes associated into stable multienzyme complexes, and can include membrane-bound multienzyme systems. Therefore, all the options listed are characteristics of metabolons.

Question 6

Which statement is most likely to be true concerning obligate anaerobes?
A) These organisms can use oxygen if it is present in their environment.
B) These organisms cannot use oxygen as their final electron acceptor.
C) These organisms carry out fermentation for at least 50% of their ATP production.
D) Most of these organisms are vegetative fungi.
E) None of the above.

Accepted Answer

Obligate anaerobes cannot survive in the presence of oxygen and therefore cannot use it as their final electron acceptor during cellular respiration. They rely on other molecules such as nitrate or sulfate as electron acceptors.

Question 7

Likely the most ancient of the metabolic pathways in which energy is released from glucose and captured in the form of ATP under anaerobic conditions is called:
A) photooxidation.
B) oxidative phosphorylation.
C) citric acid cycle.
D) glycolysis.
E) none of the above.

Accepted Answer

Glycolysis is the most ancient metabolic pathway where glucose is broken down to produce ATP under anaerobic conditions. It occurs in the cytoplasm and does not require oxygen or any organelles. The other options, such as photooxidation (A), oxidative phosphorylation (B), and citric acid cycle (C), all require oxygen and/or take place in specific organelles.

Question 8

Solar energy is converted to the chemical energy of organic molecules by ____, and ____ recover this energy by metabolizing the organic substrates.
A) photoautotrophs; heterotrophs
B) heterotrophs; chemoautotrophs
C) chemoautotrophs; heterotrophs
D) photoautotrophs; chemoautotrophs
E) none are true.

Accepted Answer

Photoautotrophs, such as plants and algae, convert solar energy into chemical energy through photosynthesis, producing organic molecules like glucose. Heterotrophs, such as animals and fungi, acquire organic substrates from other organisms and recover the chemical energy through cellular respiration, breaking down the organic molecules and using the released energy to perform cellular functions.

Question 9

All are true about the relationship between catabolism and anabolism EXCEPT:
A) They occur simultaneously.
B) Products of one process provide substrates for the other.
C) They occur in many of the same organelles.
D) The generation of ATP by catabolism provides the energy required by anabolism.
E) Anabolism is endergonic while catabolism is exergonic.

Accepted Answer

Catabolism and anabolism often occur in different organelles within a cell. For example, catabolic processes like glycolysis and the citric acid cycle primarily occur in the cytosol and mitochondria, respectively, while anabolic processes such as fatty acid synthesis occur in the cytosol and endoplasmic reticulum. This separation helps the cell regulate and balance these opposing processes efficiently.

Question 10

Which of the following is the major advantage of a multi-enzyme complex?
A) it's large size enables it to span an entire membrane
B) the product of one enzyme is passed directly to the next enzyme without the possibility of diffusion
C) multi-enzyme complexes are much less likely to be inhibited
D) all of the above
E) none of the above

Accepted Answer

The major advantage of a multi-enzyme complex is that the product of one enzyme is passed directly to the next enzyme without the possibility of diffusion, thereby increasing the efficiency of the enzymatic reaction. Option A is incorrect because the size of a multi-enzyme complex may vary and it is not necessary for it to span an entire membrane. Option C is partially correct but not a major advantage compared to the direct transfer of product from one enzyme to the next. It is also possible for multi-enzyme complexes to be inhibited. Thus, option D is incorrect, and option E is incorrect because there is at least one correct option.

Question 11

What are the final products of aerobic catabolism? A) pyruvate and H₂O. B) acetyl-CoA and CO₂. C) CO₂ and H₂O. D) pyruvate and acetyl-CoA. E) ammonia and O₂.

Accepted Answer

The final products of aerobic catabolism are carbon dioxide (CO2) and water (H2O), which correspond to choice C.

Question 12

Since both glycolysis and gluconeogenesis are spontaneous pathways, which of the following explains how this is true?
A) glycolysis uses 10 enzyme catalyzed steps while gluconeogenesis uses 11
B) the three irreversible steps of glycolysis have alternate routes for gluconeogenesis
C) glycolysis converts glucose to pyruvate while gluconeogenesis converts pyruvate to glucose
D) glycolysis is oxidative while gluconeogenesis is reductive
E) glycolysis is catabolic while gluconeogenesis is anabolic

Accepted Answer

The three irreversible steps of glycolysis are bypassed in gluconeogenesis by using alternate routes, which allows for the reaction to occur spontaneously in both directions.

Question 13

What is the relationship between photoautotrophs and heterotrophic cells? A) Photoautotrophs use light energy for synthesis of organic molecules while heterotrophs metabolize organic substances for fuel and building blocks. B) photoautotrophs use organic compounds as a source of carbon while heterotrophs use CO₂ as a source of carbon. C) Photoautotrophs synthesize CO₂ while heterotrophs synthesize O₂. D) Heterotrophs convert solar energy into chemical energy while photoautotrophs break down organic molecules. E) There is no relationship between the two.

Accepted Answer

Photoautotrophs are able to use light energy to synthesize organic molecules, while heterotrophic cells rely on the breakdown and metabolism of organic compounds to fuel their processes and build their structures. This relationship highlights the importance of photosynthesis for autotrophic organisms and the central role of organic compounds in cellular metabolism.

Question 14

The definition of an amphibolic pathway is:
A) a pathway found in animals living in both land and water.
B) a pathway that is carried out both in water and organic solvents.
C) a pathway found on both sides of the mitochondrial membrane.
D) a pathway that is both anabolic and catabolic in nature.
E) all of the above.

Accepted Answer

An amphibolic pathway is one that can be both anabolic and catabolic in nature, meaning it can both synthesize and break down molecules depending on cellular needs. It is not specific to animals living in both land and water, nor is it limited to being carried out in certain environments or on certain sides of membranes.

Question 15

In phototrophs, ____ and ____ are the two energy-rich primary products from the transformation of light energy into chemical energy. A) ATP; NAD⁺ B) NADPH; ATP C) NADH; NADPH D) ATP; NADH E) ATP; NADH.

Accepted Answer

Phototrophs use photosynthesis to convert light energy into chemical energy. The two primary products of this process are NADPH and ATP. NADPH is used in biosynthetic pathways to reduce carbon dioxide, and ATP is used as an energy source for cellular processes. Choice A is incorrect because NAD⁺ is not a known molecule involved in photosynthesis. Choice C is incorrect because NADH is not produced in photosynthesis. Choice D is incorrect because NADH is not a primary product of photosynthesis. Choice E is incorrect because only ATP is a primary product of photosynthesis.

Question 16

Photoheterotrophs require:
A) organic carbon sources and light.
B) carbon dioxide and light.
C) organic carbon sources and oxidation-reduction reactions.
D) carbon dioxide and inorganic compounds.
E) carbon dioxide and oxidation-reduction reactions.

Accepted Answer

Photoheterotrophs obtain their energy from sunlight, but require organic carbon sources for their carbon needs. This is in contrast to photoautotrophs that obtain both their energy and carbon from sunlight and inorganic carbon sources (such as carbon dioxide).

Question 17

Which of the following statements is true regarding metabolic pathways? A) catabolic pathways are generally reductive while anabolic pathways are generally oxidative B) catabolic pathways use a wide variety of substrates to produce a small number of waste products. C) an amphibolic pathway is extremely wasteful because it simultaneously operates as both an anabolic pathway and a catabolic pathway. D) NAD⁺ is used as a reducing agent in catabolic pathways while NADPH is used as an oxidizing agent in anabolic pathways E) none of the above

Accepted Answer

Catabolic pathways involve the breakdown of complex molecules into simpler ones, resulting in the release of energy. They use a wide variety of substrates (such as carbohydrates, fats, and proteins) to produce a relatively small number of waste products (such as CO2, water, and nitrogenous waste). This statement is true as it describes the characteristics of catabolic pathways. The other choices have incorrect or misleading statements regarding metabolic pathways.

Question 18

All of the following are chemoheterotrophs EXCEPT:
A) Staphylococci aureus.
B) fungi.
C) algae.
D) animals.
E) non-photosynthetic roots.

Accepted Answer

Chemoheterotrophs are organisms that obtain energy and carbon both from organic compounds. Algae, on the other hand, are photoautotrophs that obtain energy from sunlight and carbon from carbon dioxide. Therefore, algae are not chemoheterotrophs.

Question 19

Some species can adapt to anaerobic conditions by substituting other electron acceptors for oxygen in their energy-producing pathways and are called:
A) aerobes.
B) obligate aerobes.
C) facultative anaerobes.
D) obligate anaerobes.
E) none of the above.

Accepted Answer

Facultative anaerobes are organisms that can survive in both aerobic and anaerobic conditions by switching their metabolic pathways to use other electron acceptors such as nitrate, sulfate or carbon dioxide instead of oxygen.

Question 20

Many of the catabolic pathways converge to the common two-carbon intermediate:
A) alanine.
B) acetyl group of acetyl-CoA.
C) lactic acid.
D) glucose.
E) carbon dioxide.

Accepted Answer

The acetyl group of acetyl-CoA is a common intermediate in many catabolic pathways, including the breakdown of fatty acids, amino acids, and carbohydrates. It is a highly energetic molecule and can be further oxidized in the citric acid cycle to generate ATP.

Quiz 17: Metabolism: an Overview

All are characteristics of anabolism EXCEPT:

Most organisms show ____ in their major pathways of metabolism.

All are characteristics of metabolism EXCEPT:

In the case of shared anabolic and catabolic pathways, the ____ serve as the points of regulation.

Metabolon characteristics include all EXCEPT:

Which statement is most likely to be true concerning obligate anaerobes?

Likely the most ancient of the metabolic pathways in which energy is released from glucose and captured in the form of ATP under anaerobic conditions is called:

Solar energy is converted to the chemical energy of organic molecules by , and recover this energy by metabolizing the organic substrates.

All are true about the relationship between catabolism and anabolism EXCEPT:

Which of the following is the major advantage of a multi-enzyme complex?

What are the final products of aerobic catabolism?

Since both glycolysis and gluconeogenesis are spontaneous pathways, which of the following explains how this is true?

What is the relationship between photoautotrophs and heterotrophic cells?

The definition of an amphibolic pathway is:

In phototrophs, and are the two energy-rich primary products from the transformation of light energy into chemical energy.

Photoheterotrophs require:

Which of the following statements is true regarding metabolic pathways?

All of the following are chemoheterotrophs EXCEPT:

Some species can adapt to anaerobic conditions by substituting other electron acceptors for oxygen in their energy-producing pathways and are called:

Many of the catabolic pathways converge to the common two-carbon intermediate: