Chapter 6

The degree of disorder, or number of microstates, is called:

entropy

Based on what you know of ATP's chemistry, which of the substances is most likely to have similar functions in energy-management processes?

guanosine nucleotide triphosphate

Which organisms are considered heterotrophs?

most bacteria and dogs

Chemical reactions that have a positive ΔG are:

non-spontaneous.

Escherichia coli bacteria in your colon are categorized as:

chemoheterotrophs

As a cat pounces on a mouse, its muscles consume 10 units of potential energy (which the cat previously gained from the food it consumed). However, the pounce itself only required 4 units of kinetic energy. How many units of energy were dissipated as heat?

6

Consider the refrigerator in your kitchen. Based on what you know about the first and second laws of thermodynamics, how does a refrigerator most likely work?

A refrigerator removes heat from its interior and transports this energy outside, into the kitchen.

Enzymes in your gastrointestinal tract digest your lunch. These chemical reactions are categorized as:

Catabolism

The first law of thermodynamics states that:

Energy cannot be created or destroyed

The lid of a container containing a gas is removed. As a consequence, the molecules of the gas can leave the container and have more space available to them to spread out. For the gas released from the container, which of the following increases?

Entropy

Which of the following is a correct description of the role of enzymes in catalyzing biochemical reactions?

Enzymes stabilize the transition state and decrease its free energy.

You are talking with one of your friends. He states that evolution has actually violated the second law of thermodynamics, because complex living organisms are more ordered than the nucleic acids, amino acids, and other molecules that compose them. Why doesn't evolution contradict the second law of thermodynamics?

Even though evolution may decrease the entropy of living organisms, it increases the entropy of the Earth (or the universe), as the chemical reactions that are required to make organisms release heat.

During a chemical reaction, atoms of hydrogen can be transformed into carbon atoms by the addition of protons to the nucleus.

False

Which molecule has the greatest chemical potential energy?

Glucose

_____ are organisms that derive carbon from organic compounds.

Heterotrophs

In the pathway leading from threonine to isoleucine, when isoleucine is abundant, which of the intermediates in the pathway is produced?

None of the intermediates is produced.

Phosphofructokinase is an allosteric enzyme in the pathway that breaks down glucose to produce ATP. Regulation of glycolysis is directly related to the level of ATP and citrate. If ATP or citrate levels are high, phosphofructokinase is inhibited. What will happen to this enzyme when ATP levels drop?

Phosphofructokinase is activated.

_____ are organisms that derive energy from sunlight.

Phototrophs

Which of the statements represent the laws of thermodynamics?

The amount of energy in the universe is constant.The energy available to do work decreases as energy is transformed from one form to another.

A biologist working in a lab adds a compound to a solution that contains an enzyme and substrate. This particular compound binds reversibly to the enzyme at the active site. Once the compound is bound to the enzyme, the catalysis of substrate to product stops. Which of the statements is true of the compound?

The effect of the compound can be overcome by adding more substrate.

Which of the statements are true?

The energy for a reaction equals the sum of the energy in the product plus energy released as heat and disorder.The amount of usable energy resulting from a reaction is always less than the total energy available at the start of the reaction.

Imagine that several atoms bond to form a carbohydrate, creating a more orderly system. Which statement is true regarding the universe after this carbohydrate forms?

The entropy of the universe increases.

You walk out of your warm house on a cold winter's day. What is different between the air inside and outside of your house in this scenario?

The molecules in the warm air of your house are moving faster than those outside.

Which statements are true of an inhibitor that binds the active site of an enzyme?

These inhibitors compete with the substrate for the active site of the enzyme.These inhibitors are structurally similar to the normal substrate of an enzyme.Adding more substrate can reduce the effect of these inhibitors

Suppose that, in a given reaction, the enthalpy (H) increases by 10 units, and the disorder (TS) increases by 12 units. Would this reaction be considered spontaneous?

Yes

In a reaction, enzymes change the:

activation energy

Of the choices, which can be a product of a catabolic reaction?

an amino acid like tryptophan

The assembly of glucose molecules into polysaccharides is a(n) _____ process.

anabolic

Carbon dioxide dissolves in water to form:

carbonic acid

During ______, large molecules are broken down and energy is released.

catabolism

You have entered a 5K race. As you finish the last 500 meters, your body has converted _____ energy to _____ energy, and has lost some of this energy as _____.

chemical potential; kinetic; heat

Imagine that you discover a microbial deep-sea organism that can derive energy from (inorganic) hydrogen gas (H2). In addition, this microbe can synthesize organic compounds from carbon-containing inorganic molecules in the ocean. This microbe is a:

chemoautotroph

Imagine that you discover a carnivorous deep-sea fish that cannot utilize the carbon in carbonic acid, or any other inorganic molecule, present in seawater to form glucose, or other organic molecules. Living so far beneath the water's surface, this fish is also incapable of harnessing energy from the sun. This fish would be considered a:

chemoheterotroph

Animals such as cats, worms, and butterflies are classified as:

chemoheterotrophs

Glycolysis, the breakdown of a glucose molecule to two molecules of pyruvate, is an example of a series of reactions that is:

exergonic and catabolic.

Plant cells rely on energy obtained directly from the sun to carry out cellular processes and derive energy from sugars only as a backup on cloudy days.

false

Which molecule has the greatest chemical potential energy?

glucose

In chemical reactions, most of the entropy increase occurs as:

heat

Enzymes are typically:

highly specific

Which has the most entropy, individual nucleotides or a nucleic acid?

individual nucleotides

ATP is a good energy currency for cells because it has a(n) _____ amount of Gibbs free energy.

intermediate

In a metabolic pathway, a series of enzymatic reactions catalyzes the conversion of molecule A to molecule E. Several intermediate steps are involved in which the product of one reaction becomes the substrate for the next. Overall, this _____, based on the changes in free energy that take place as A is converted to E.

is an anabolic pathway

A cougar chases its prey. Running is a form of:

kinetic energy

Oak trees are categorized as:

photoautotrophs

A carbohydrate such as glucose has a great deal of ______ energy.

potential

Organic molecules store _____energy in their _____ bonds.

potential; covalent

Converting glucose to glycogen:

requires energy

You have entered a 5K race. As you finish the last 50 meters, you are breathing harder than at the start of the race and sweating profusely. This is an example of the _____ law of thermodynamics because _____ is increasing.

second; entropy

Reactions in which there is a negative change in free energy (-ΔG) are:

spontaneous and exergonic.

In a given reaction, which of the following has the highest amount of free energy?

the transition state when the reaction is not catalyzed by an enzyme

Nearly all cells use ATP as their primary energy source. This is evidence that:

the use of ATP by cells evolved early in the history of life and has been conserved over time

The second law of thermodynamics states that:

there is an increase in disorder in the universe over time

Carbon-carbon covalent bonds, such as the ones in carbohydrates and lipids, are _____ and have _____.

weak; a lot of potential energy