Question 1

When a car burns gasoline, much of the energy is released in the form of heat.Which of the following best describes this process in relation to the first law of thermodynamics?

Accepted Answer

Energy can be changed from one form to another, in this case, chemical energy (gasoline) is converted to thermal energy (heat).

Question 2

Simple diffusion across a plasma membrane is called passive transport because it

Accepted Answer

Simple diffusion is a type of passive transport because it does not require energy from the cell; molecules move down their concentration gradient from high to low concentration.

Question 3

Which of the following is a mechanism used to regulate enzyme activity?

Accepted Answer

Feedback inhibition is a mechanism used to regulate enzyme activity, where the product of a reaction inhibits the enzyme that helped produce it, thus preventing the overproduction of the product.

Question 4

ATP breakdown provides the energy necessary for muscle contraction. This is an example of which concept?

Accepted Answer

Coupled reactions involve the use of energy released from one process (such as ATP breakdown) to drive another process (such as muscle contraction).

Question 5

Less energy is needed to bring about a reaction when an enzyme is present.

Accepted Answer

Enzymes lower the activation energy required for a reaction, thus making it easier and faster for the reaction to occur.

Question 6

ATP releases energy when

Accepted Answer

ATP (adenosine triphosphate) releases energy when a phosphate group is removed, converting it to ADP (adenosine diphosphate) or AMP (adenosine monophosphate) depending on the number of phosphates removed. This process is a fundamental energy transfer mechanism in cells.

Question 7

Which of the following is best associated with a coupled reaction?

Accepted Answer

Coupled reactions involve using the energy released from one process (like the breakdown of ATP) to drive another process. The breakdown of ATP into ADP and a phosphate group releases energy, part of which is then used to power another metabolic reaction, often requiring less energy than what is released, making choice C the best association with a coupled reaction.

Question 8

What function do the carrier proteins embedded in the cell membrane serve?

Accepted Answer

Carrier proteins in the cell membrane facilitate the transport of substances across the membrane by binding to them and changing shape, a process known as facilitated diffusion.

Question 9

Energy of activation

Accepted Answer

The energy of activation is the minimum amount of energy required for reactants to undergo a chemical reaction. It does not inherently require enzymes, act on products, involve feedback inhibition, or measure solar radiation.

Question 10

Which of the following is an example of potential energy rather than kinetic energy?

Accepted Answer

Potential energy is stored energy or the energy of position. An apple made up of energy-rich macromolecules contains chemical potential energy stored in its molecular bonds, which can be released when the apple is consumed.

Question 11

Which of the following correctly lists the order in which energy flows through an ecosystem?

Accepted Answer

Solar energy is captured by chloroplasts in plants to produce food (photosynthesis), and then this energy is transferred to other organisms through consumption, where it is used in mitochondria for cellular respiration.

Question 12

The opposite of a turgid plant cell is a

Accepted Answer

A turgid plant cell is one that is full of water, making it firm. The opposite condition, where a cell has lost water and the cell membrane pulls away from the cell wall, is known as plasmolysis, making the correct answer a plasmolyzed plant cell.

Question 13

The part of the enzyme into which the substrate fits is called the

Accepted Answer

The active site is the region on an enzyme where the substrate binds and the chemical reaction occurs. This site is specifically shaped to fit the substrate, facilitating the enzyme's ability to catalyze the reaction.

Question 14

Molecules move from greater to lesser concentration through a carrier protein in

Accepted Answer

Facilitated diffusion is the process where molecules move across the cell membrane through carrier proteins from an area of higher concentration to an area of lower concentration without the use of energy.

Question 15

Which of the following terms best describes entropy?

Accepted Answer

Entropy is best described as disorder. It is a measure of the randomness or disorder in a system, often associated with the second law of thermodynamics, which states that the total entropy of an isolated system can never decrease over time.

Question 16

What process typically regulates the enzymes involved in metabolic reactions?

Accepted Answer

Feedback inhibition is a common regulatory mechanism in metabolic pathways where the end product of the pathway inhibits an enzyme that acts earlier in the pathway, thus controlling the production of itself and maintaining homeostasis.

Question 17

What prevents a plant cell from bursting in a hypotonic solution?

Accepted Answer

The presence of a cell wall in plant cells provides structural support and limits the amount of water that can enter, thus preventing the cell from bursting in a hypotonic solution.

Question 18

Which of the following statements about ATP is inaccurate?

Accepted Answer

ATP is comprised of a sugar (ribose), a base (adenine), and three phosphate groups, not two. This makes statement C inaccurate.

Question 19

Considering the ATP cycle, which of the following would have the most potential energy to perform work for cell activities?

Accepted Answer

ATP (adenosine triphosphate) has the most potential energy for cell activities because it contains three phosphate groups. The breaking of the bond between the second and third phosphate group releases energy that cells can use for work.

Question 20

Simple diffusion of molecules occurs

Accepted Answer

Simple diffusion occurs in both nonliving and living systems, as it is a fundamental process driven by the random movement of molecules from areas of higher concentration to areas of lower concentration, not requiring any biological machinery or specific state of matter.

Quiz 5: The Dynamic Cell