Q: Refer to the seventh image. What is the correct chemical equation for ATP hydrolysis, and what does it demonstrate?

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy}$$; this is an exergonic reaction that releases energy.

Question 1

Which of the following best describes the role of enzymes in metabolic pathways, as illustrated in the first image?

Accepted Answer

Enzymes catalyze each step, lowering the activation energy and allowing the pathway to proceed efficiently.

Question 2

Based on the second image, which law of thermodynamics is illustrated by the bear releasing heat while running?

Accepted Answer

The second law: every energy transfer increases the entropy of the universe.

Question 3

Refer to the third image. What do all three scenarios (gravitational motion, diffusion, chemical reaction) have in common regarding free energy and stability?

Accepted Answer

They all demonstrate spontaneous processes where free energy decreases ($$\Delta G \u003c 0$$), and the system becomes more stable.

Question 4

Using the fourth image, which statement correctly distinguishes exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions have $$\Delta G  0$$ and require energy input.

Question 5

What does the fifth image (hydroelectric system) illustrate about equilibrium in biological systems?

Accepted Answer

A closed system at equilibrium cannot do work, similar to a dead cell.

Question 6

In the sixth image, what does the continuous flow of water represent in the context of cellular metabolism?

Accepted Answer

The constant input and output of materials in living cells, preventing equilibrium and allowing work to continue.

Question 7

Refer to the seventh image. What is the correct chemical equation for ATP hydrolysis, and what does it demonstrate?

Accepted Answer

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy}$$; this is an exergonic reaction that releases energy.

Question 8

In the context of the eighth image, what is the role of sucrase in the hydrolysis of sucrose?

Accepted Answer

Sucrase lowers the activation energy, allowing sucrose to be converted to glucose and fructose more rapidly.

Question 9

Based on the ninth image, what does the peak of the curve represent in a chemical reaction?

Accepted Answer

The activation energy ($$E_a$$), or the energy required to reach the transition state.

Question 10

What is the main effect of an enzyme on a reaction, as shown in the tenth and eleventh images?

Accepted Answer

It lowers the activation energy ($$E_a) $$without affecting the overall free energy change ($$\Delta G).$$

Question 11

According to the twelfth image, what happens to $$\Delta G$$ when an enzyme catalyzes a reaction?

Accepted Answer

$$\Delta G$$ remains unchanged.

Question 12

What does the thirteenth image demonstrate about enzyme specificity?

Accepted Answer

The active site of an enzyme binds specifically to its substrate, forming an enzyme-substrate complex.

Question 13

Based on the sixteenth image, what is the correct sequence of events in the enzyme catalytic cycle?

Accepted Answer

Substrate enters active site, enzyme-substrate complex forms, activation energy is lowered, substrate is converted to product, product is released, enzyme is available again.

Question 14

Refer to the seventeenth and eighteenth images. How do temperature and pH affect enzyme activity?

Accepted Answer

Each enzyme has an optimal temperature and pH, and activity decreases outside these conditions.

Question 15

What is the difference between competitive and noncompetitive inhibition, as shown in the nineteenth image?

Accepted Answer

Competitive inhibitors bind to the active site; noncompetitive inhibitors bind elsewhere, changing enzyme shape.

Question 16

Based on the twentieth image, how does feedback inhibition regulate metabolic pathways?

Accepted Answer

The end product binds to an allosteric site on an early enzyme, inhibiting the pathway and preventing overproduction.

Question 17

Which of the following best explains why living cells are considered open systems, as illustrated in the sixth image?

Accepted Answer

They exchange matter and energy with their surroundings, preventing equilibrium and allowing continuous work.

Question 18

Which of the following is an example of an inorganic cofactor required for enzyme activity?

Accepted Answer

A zinc ion ($$\mathrm{Zn}^{2+})$$

Question 19

A firefly converts luciferin and oxygen to oxyluciferin and light. Which of the following best describes this process?

Accepted Answer

Chemical energy transformed into light energy

Chapter 8: An Introduction to Metabolism – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard