Biology Chapter 5 MindTap

A reaction is a process in which molecules are changed in some way. The following diagram illustrates a reaction in which molecules made of hydrogen atoms (H ) and molecules made of oxygen atoms (O ) rearrange to form two molecules of water (H2O ). In the following diagram, choose the answer that will correctly label which molecules are the reactants of the reaction and which molecules are the products of the reaction. (Hint: The arrow indicates the direction of the reaction, meaning that it starts with the molecules that exist before the reaction starts and points to the molecules that exist when the reaction is over.) Homework: Ground Rules of Metabolism

A Reactants B Products

What distinguishes a linear metabolic pathway from a cyclic metabolic pathway? Quiz: Ground Rules of Metabolism

A linear pathway runs straight in one direction from reactant to product.

How can an active site best be described? Learn It: Enzymes

A pocket on an enzyme where substrate binds

What is the minimum amount of energy required to start a chemical reaction? Quiz: Ground Rules of Metabolism

Activation energy

Which of the following reaction elements can be changed by an enzyme? Select all that apply. Learn It: Enzymes

Activation energy Time required for many reactions to occur

Case Study: One Tough Bug

Based on this graph, it appears that carboxylesterase is most active at a pH of 1.5 This enzyme does not appear to have a significant level of activity at a pH of 5.

Which of the following apply to some of the energy released by an exergonic reaction? Select all that apply. Learn It: Exergonic and Endergonic Reactions

Be lost to the environment in the form of heat Provide energy to drive an endergonic reaction End up being stored into new chemical bonds

Where is the energy used to power our bodies stored? Learn It: Exergonic and Endergonic Reactions

Chemical bonds

Endergonic reactions do which of the following? Select all that apply. Learn It: Exergonic and Endergonic Reactions

Consume energy Are nonspontaneous

Grasses collect energy from sunlight. Rabbits collect energy by eating grasses. Coyotes collect energy by eating rabbits. Which of the following organisms has the least amount of energy available to them (as compared to the amount of solar energy that hits Earth from space)? Homework: Ground Rules of Metabolism

Coyotes, because some of the original amount of energy was lost as body heat in grasses and rabbits

Enzymes catalyze chemical reactions by doing which of the following? Learn It: Enzymes

Decreasing the activation energy of the reaction

Which of the following defines the first law of thermodynamics? Quiz: Ground Rules of Metabolism

Energy cannot be created or destroyed

Based on this, you can conclude that the reaction discussed above is an --------- reaction Homework: Ground Rules of Metabolism

Exergonic

What is a regulatory mechanism in which a reaction product slows or stops a metabolic pathway that produces it? Quiz: Ground Rules of Metabolism

Feedback inhibition

During oxidative phosphorylation, which answer choice best describes how electrons move? Learn It: The ATP/ADP Cycle

From electron carrier to electron carrier.

Which two of the following apply to the products of an exergonic reaction? Learn It: Exergonic and Endergonic Reactions

Have less energy than the reactants Are less ordered than the reactants

When comparing the solute concentrations of two fluids, the fluid with the higher solute concentration will be which of the following? Quiz: Ground Rules of Metabolism

Hypertonic

How does an enzyme affect a chemical reaction? Select all that apply. Quiz: Ground Rules of Metabolism

Increases the rate of the reaction Lowers the activation energy

Which electron carrier delivers electrons to the electron transport chain? Learn It: The ATP/ADP Cycle

NADH

Which of the statements about diffusion are true? Select all that apply. Quiz: Ground Rules of Metabolism

Negatively charged solutes diffuse toward regions of positive charge. Solutes diffuse from a region of higher concentration to a region of lower concentration. Lower temperatures will slow rates of diffusion.

How do enzymes lower the activation energy of chemical reactions? Select all that apply. Learn It: Enzymes

Orienting reactants correctly in space for chemical reactions to occur Bringing reactants closer to one another

Which of these processes are membrane-crossing mechanisms that require no energy input? Select all that apply. Quiz: Ground Rules of Metabolism

Osmosis Facilitated diffusion

What factors of the physical environment impact enzymatic activity? Select all that apply. Quiz: Ground Rules of Metabolism

Salt concentration pH concentration Changes in temperature

What are the features of an energy-requiring reaction? Select all that apply. Quiz: Ground Rules of Metabolism

Small molecules are converted into complex organic compounds. The reaction requires an input of energy.

Which of the following compounds can diffuse through the lipid bilayer of a cell membrane? Select all that apply. Quiz: Ground Rules of Metabolism

Small polar molecules like water Gases and hydrophobic molecules

Which of these transport pathways require ATP? Select all that apply. Quiz: Ground Rules of Metabolism

Sodium-potassium pump Calcium pump

In the following chemical reaction, which compounds are the products? Carbon dioxide + Water → Sugar + Oxygen Quiz: Ground Rules of Metabolism

Sugar and oxygen

Which of the following best describes the activation energy of a reaction? Learn It: Enzymes

The amount of energy required for a reaction to start

Where in the cell are the electron carrier proteins responsible for oxidative phosphorylation located? Learn It: The ATP/ADP Cycle

The inner mitochondrial membrane

During oxidative phosphorylation, where is the concentration of protons highest? Learn It: The ATP/ADP Cycle

The intermembrane space

What is the active site of an enzyme? Quiz: Ground Rules of Metabolism

The part of an enzyme where substrates bind and a reaction occurs

What is exocytosis? Quiz: Ground Rules of Metabolism

The process by which a cell expels the contents of an internal vesicle to the extracellular fluid

Enzymes decrease the activation energy of a reaction by ----- the reactants and ----- the reaction. After the reaction has finished, the enzyme ------- Learn It: Enzymes

binding to catalyzing remains unchanged

----- (such as animals) ingest energy when they eat other organisms. Homework: Ground Rules of Metabolism

consumers

Endergonic and exergonic reactions are often coupled, with the energy released by the ----- reaction used to power the ---- reaction Learn It: Exergonic and Endergonic Reactions

exergonic endergonic

Your body stores energy in the form of fat and other organic molecules. When your body needs extra energy, it breaks apart the molecules of fat to release that energy (sometimes called "burning fat"). That energy is used to power cellular reactions or is lost as heat. The total amount of energy used by your body or lost as heat equals the amount of energy the molecules of fat originally stored before breaking apart. This process is an example of the ---- law of thermodynamics. Homework: Ground Rules of Metabolism

first

Most organisms cannot use the raw energy that hits Earth. Energy is captured by ------- (such as plants) and stored in organic molecules. Homework: Ground Rules of Metabolism

producers

During oxidative phosphorylation ---- are pumped into the intermembrane space, and then pass through ----- , back to the mitochondrial matrix. Learn It: The ATP/ADP Cycle

protons ATP synthase

Look again at the reaction shown in the previous question. Use the diagram here to identify the relative free energy state of each molecule. According to the diagram, if this reaction occurred, energy would be ------ Homework: Ground Rules of Metabolism

released if the reaction occurred

Most of the energy that reaches environments on Earth comes from Homework: Ground Rules of Metabolism

the sun