Question 1

The active site of an enzyme ____.

Accepted Answer

The active site of an enzyme refers to the specific region or crevice of the enzyme that is complementary in shape and chemical properties to the substrate. It is where the catalysis of the chemical reaction takes place.

Question 2

Endergonic reactions ____.

Accepted Answer

Endergonic reactions require a net input of energy, meaning that more energy is required to form the products than is released by breaking down the reactants. This is the opposite of exergonic reactions, which release energy.

Question 3

What is the key activity of panel II in the accompanying figure?​

Accepted Answer

Panel II represents the conversion of substrates to products, which is the key activity of the enzyme. In this panel, the substrates are being transformed into products by the catalytic action of the enzyme. The other options (A, B, D, and E) either do not accurately represent the process depicted in Panel II or are not the key activity occurring in this step.

Question 4

The activation energy of a reaction refers to the minimum amount of energy ____.

Accepted Answer

Activation energy refers to the minimum amount of energy necessary to cause a reaction to proceed on its own. It is the energy required to overcome the energy barrier and start the reaction.

Question 5

What is the item labeled "C" in the accompanying figure?

Accepted Answer

The label "C" represents the active site, which is the specific region of an enzyme where a substrate molecule binds and undergoes a chemical reaction.

Question 6

What is the item labeled "B" in the accompanying figure?​

Accepted Answer

"B" is labeled as the substrate in the figure, which is the molecule that the enzyme binds to and acts upon.

Question 7

Enzymes ____.

Accepted Answer

The answer of Enzymes ____.
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Question 8

An enzyme lowers activation energy by ____.

Accepted Answer

An enzyme lowers activation energy by creating an environment that is conducive to the reaction, such as by excluding water molecules, which can interfere with the reaction.

Question 9

According to the first law of thermodynamics, ____.

Accepted Answer

The first law of thermodynamics states that energy cannot be created or destroyed in a chemical reaction, only transferred or converted from one form to another. Therefore, option C is the correct answer as it correctly summarizes the law.

Question 10

An enzyme is thought to optimize the fit between substrates by restraining and stretching or squeezing them into certain shapes and moving them to the transition state, as described by the ____ model of enzyme activity.

Accepted Answer

The induced-fit model of enzyme activity describes how enzymes optimize the fit between substrates by restraining and stretching or squeezing them into certain shapes and moving them to the transition state. In contrast, the lock and key model proposes that the enzyme active site is already in the perfect shape to fit the substrate, without any need for modification. The template model suggests that the enzyme acts as a physical mold that shapes the substrate as it binds. The activation model describes how enzymes lower the activation energy required for a reaction to occur by providing an alternative pathway. The conformational model refers to changes in the shape of the enzyme itself, rather than the substrate.

Question 11

What are the effects of long term excessive alcohol consumption on the liver?

Accepted Answer

Long term excessive alcohol consumption can lead to scarring (cirrhosis), hardening (fibrosis), and fat accumulation in the liver. This can lead to liver failure and increased risk of liver cancer. Other effects can include inflammation and damage to liver cells, impaired liver function, and increased risk of hepatitis C infection.

Question 12

What is a key characteristic of enzyme behavior?​

Accepted Answer

The key characteristic of enzyme behavior is that the active site of an enzyme orients its substrate molecules, thereby promoting interaction of their reactive parts. This allows enzymes to facilitate and accelerate specific chemical reactions in the cell. Enzyme shape may change during catalysis, enzymes may have multiple active sites, and enzyme activity is generally affected by pH and temperature. Not all enzymes require coenzymes for catalysis.

Question 13

Energy is commonly defined as ____.

Accepted Answer

Energy is defined as the capacity to do work. It is the ability of a system to perform work, either by itself or by interacting with other systems. Heat, thermodynamics, capacity to change, and ability to do work are all related concepts to energy but do not fully define it.

Question 14

CO₂ and H₂O will not form glucose on their own because ____.

Accepted Answer

The bonds of CO₂ and H₂O are too stable to be broken without an input of energy. Glucose formation from CO₂ and H₂O requires energy input through the process of photosynthesis.

Question 15

The second law of thermodynamics states that ____.

Accepted Answer

The second law of thermodynamics states that energy tends to flow from concentrated to less concentrated forms, which is also known as the law of entropy. The other choices are incorrect because they do not accurately reflect the second law of thermodynamics.

Question 16

In order to work best, enzymes ____.

Accepted Answer

Enzymes function best under specific environmental conditions such as optimal temperature, pH and concentration of substrate. These conditions differ for different enzymes, which means that each enzyme requires a specific set of environmental conditions to function at its best. Coenzymes may facilitate enzyme activity, but not all enzymes require them, and randomly grabbing surrounding molecules is not a mechanism by which enzymes function. High temperatures can denature enzymes, and low pH may not be optimal for all enzymes.

Question 17

The enzyme responsible for breaking down alcohol is ____.

Accepted Answer

Alcohol dehydrogenase is responsible for breaking down alcohol.

Question 18

What type of energy is the energy in chemical bonds?​

Accepted Answer

The energy in chemical bonds is potential energy because it is stored energy that has the potential to be released and/or transformed into other forms of energy.

Question 19

What statement is an application of the first law of thermodynamics?​

Accepted Answer

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, only transformed from one form to another. This means that the total amount of energy in the universe remains constant. Choice C directly applies this principle.

Question 20

What is a key characteristic of exergonic reactions?​

Accepted Answer

Exergonic reactions release energy, often converting some of it into less biologically useful forms, such as heat.

Quiz 5: Ground Rules of Metabolism