Energy Transformations in Cells

Question 1

What is a concentration gradient?

Answer 1

A difference in solute concentration between two regions which can drive diffusion.

Question 2

What is diffusion?

Answer 2

The process of molecules moving from a higher concentration to a lower concentration.

Question 3

What is osmosis?

Answer 3

The movement of water across a selectively permeable membrane from lower solute (higher water potential) to higher solute (lower water potential).

It controls the balance of water, salt, and volume inside the cell.

Question 4

What is passive diffusion?

Answer 4

Also known as simple diffusion, it occurs when molecules move directly across the membrane.

Movement of small nonpolar molecules down their concentration gradient directly through the lipid bilayer; no energy required.

Question 5

What is facilitated diffusion?

Answer 5

The movement of larger molecules, including charged and polar solutes, through a carrier protein in the cell membrane.

Uses membrane proteins to move polar/charged solutes down their concentration gradient; no ATP required.

Question 6

What are the three types of transport?

Answer 6

• Passive Diffusion: Down the concentration gradient
• Facilitated Diffusion: Down the concentration gradient; no ATP required
• Active Transport: Against the concentration gradient; requires ATP

Question 7

What is active transport?

Answer 7

Moving solutes against their concentration gradient, requiring cellular energy or ATP.

Question 8

What are the two types of diffusion, and in what direction do molecules move in each?

Answer 8

• Passive diffusion - occurs by random motion.
• Facilitated diffusion - requires assistance from carrier proteins that move molecules through membrane channels.

Both move down the concentration gradient; facilitated uses proteins; no ATP.

Question 9

What is the role of the carrier protein in facilitated diffusion?

Answer 9

It assists in transporting small particles or ions across the cell membrane through a specific channel.

Carrier/channel proteins provide a pathway for specific solutes to move down their concentration gradient; no ATP required.

Question 10

What is thermodynamics?

Answer 10

It is the study of energy transfer involving heat, work, and temperature, and how these relate to entropy and the properties of matter.

Question 11

What is the first law of thermodynamics also known as?

Answer 11

The ‘Law of Conservation of Energy’

It states that energy cannot be created or destroyed, only transferred.

An example is when the chlorophyll absorbs light and transforms it into chemical energy.

Question 12

What is the second law of thermodynamics?

Answer 12

It states that the entropy in a system increases with time.

As time goes on Entropy- the disorder of energy- increases so there is less energy available to perform useful work

Question 13

What is the third law of thermodynamics?

Answer 13

It states that the degree of randomness, entropy, tends to a minimum value as the temperature approaches absolute zero.

The colder a system gets the less entropy, or disorder of energy, can be found.

Question 14

What is the absolute zero temperature in Kelvin?

Answer 14

0 Kelvin

Question 15

What is the relationship between kinetic energy and thermal energy?

Answer 15

• The higher the kinetic energy, the higher the thermal energy.
• The lower the kinetic energy, the lower the thermal energy.

Question 16

Explain the concept of entropy.

Answer 16

It is the measure of energy unavailable for performing useful work.

Question 17

What is anabolism?

Answer 17

Takes simpler molecules and builds them into more complex ones, generally using ATP in the process.

Energy is absorbed in anabolic reactions.

Examples:

• Building proteins for growth and muscle development.
• Synthesizing glucose for energy utilization.

Question 18

What is catabolism?

Answer 18

Breaks down complex molecules into simpler ones, releasing and producing ATP in the process.

Energy is released in catabolic reactions.
Examples: glycolysis, cellular respiration, ATP synthesis.

Question 19

What is metabolism?

Answer 19

The collection of all the chemical processes that occur within the body, encompassing both energy-producing and energy-consuming reactions.

Question 20

What is cellular respiration?

Answer 20

A group of reactions inside cells that harvest biochemical energy from nutrients to produce ATP.

Question 21

What are the steps of cellular respiration?

Answer 21

• Glycolysis
• Oxidative Decarboxylation
• Citric Acid Cycle
• Oxidative Phosphorylation

Question 22

What are amphibolic pathways?

Answer 22

Pathways that can be both anabolic or catabolic depending on the energy state of the body.

Example: The citric acid (TCA) cycle, or exercise.

Question 23

What is the difference between anabolic and catabolic pathways?

Answer 23

• Anabolic pathways join simple molecules to form complex ones, consuming energy.
• Catabolic pathways break down complex molecules into simpler ones, releasing energy.

Question 24

What is the role of ATP in metabolism?

Answer 24

Provides energy for cellular processes.

Question 25

What is a **redox reaction**?

Answer 25

An **oxidation-reduction** chemical reaction involves the **transfer of electrons** between two reactants. ## Footnote In this reaction, oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 26

What is a **half reaction**?

Answer 26

Shows either reduction **or** oxidation, but **not both**. ## Footnote Reduction potential can be used to predict the tendency of a chemical species to acquire electrons.

Question 27

What are the **roles** of oxidizing agents and reducing agents in redox reactions?

Answer 27

* **Oxidizing agents** are substances that are reduced in the reaction (gain electrons). * **Reducing agents** lose electrons donating them to the oxidizing agent. ## Footnote Redox reactions cannot occur without both oxidation and reduction.

Question 28

How can you identify an **oxidizing agent** in a redox reaction?

Answer 28

An atom or element that will **accept donated electrons** from another element in a redox reaction. ## Footnote Most commonly identified oxidizing agent in redox reactions is oxygen.

Question 29

How can you identify a **reducing agent** in a redox reaction?

Answer 29

An element or compound that **loses an electron and donates** it to another atom or element in a redox reaction. ## Footnote Once the reducing agent has lost its electrons, it is said to have been oxidized.

Question 30

What is the process of **cellular respiration** in redox reactions?

Answer 30

Converts consumed food into energy through a series of **redox reactions**, creating ATP and **releasing waste products**. ## Footnote 32 ATP molecules are created. ATP is the main energy molecule in the body. The creation of this molecule mostly takes place in the mitochondrial matrix.

Question 31

What is the process of **photosynthesis** in redox reactions?

Answer 31

Photosynthesis uses sunlight to **combine** carbon dioxide and water into glucose and oxygen. Water is **oxidized**, and carbon dioxide is **reduced**.

Question 32

During photosynthesis, what **energy source** for the plant is produced?

Answer 32

glucose

Question 33

What is the **first step** in balancing redox reactions?

Answer 33

Separating the equation into **two half reactions**.

Question 34

What should be **balanced** first in redox reactions, excluding oxygen and hydrogen?

Answer 34

all atoms

Question 35

What is the general form of a **decomposition reaction**?

Answer 35

AB -> A + B

Question 36

What does the mnemonic "**LEO the lion says GER**" describe in redox reactions?

Answer 36

* **LEO**: Lose electrons = Oxidation * **GER**: Gain electrons = Reduction

Question 37

What are some common **types of redox reactions**?

Answer 37

* Combination * Decomposition * Displacement * Combustion

Question 38

# Define: oxidative metabolism

Answer 38

Oxidative metabolism (cellular respiration) uses **oxygen** as the terminal electron acceptor to **oxidize** fuels and **generate ATP** via the electron transport chain.

Question 39

Why is **oxidative metabolism** important for cellular respiration?

Answer 39

The losing and gaining of electrons **generates energy**, which powers vital biological processes.