Liberty University BIOL 101 QUIZ 3

Living Systems Require a Flow of Energy

In a phrase, how do physicists define “energy”?

How would a cell biologist define “energy”?

The physicist’s definition of energy is not _______________ for use in defining energy changes within a living cell.

List five major sorts or categories of energy change within the cell.

On a cold day, which of the following processes do your cells depend on to maintain an operating temperature of 37 degrees Celsius?

a. shivering

b. muscle contraction

c. respiration energy production

d. metabolic heat generation

e. all of the above

Sometimes the cell pumps substances against diffusion forces that would carry those substances the other way.  What term would we give to this process?

6.2

Laws of Energy Flow in the Living World

______ is freely convertible from one form to another but _______ can never be created or destroyed.

Systems that convert energy from one form to another are not 100% efficient, thus the amount of useful energy ___________.

In nature, as energy freely changes from one form to another, the total amount of energy _________ _________.

In living things, energy conversion is inefficient, with much energy being lost in the form of _______.

What form of energy do producers use when they set about to generate chemical energy—the energy of C?H and C?O?H bonds.

Thus, a producer organism is called a “producer” because it produces usable ______ _______.

When your car engine burns the octane in gasoline, in what form does at least 50% of the energy of the octane end up?

A lit match cannot continue to burn when the wood of the match stick is consumed.  This statement illustrates what general law of energy flow?

In a crowded, unventilated room, what causes the temperature to rise?

6.3

Energy Flows in Chemical Reactions

Existing chemical bonds between atoms are broken and new ones are formed between different atoms.  In the broadest sense, this is the definition for a _______ _________.

Give an example of a chemical reaction.

Whenever chemical bonds are broken, energy is __________.  Whenever chemical bonds form, energy is __________.

Does an endergonic reaction require the input of energy, or does it give off energy?

What term is given to the amount of energy required to break the bonds in reactant molecules?

What is true of the bonds in reactant molecules that keeps most chemical reactions in nature from occurring?

When ________ energy is not available for a given chemical reaction, the reaction will not go.

6.4

Enzymes Direct Energy Flow

How is the activation energy of desired reactions lowered in living things, so that the desired reactions are able to go forward?

What words best describe the way in which enzymes bind to reactant molecules?

What exactly does an enzyme do the chemical bonds within the reactant molecule?

By binding to reactant molecules, what effect does an enzyme have on the activation energy for a given reaction?

6.5

Energy Flow in Reaction Pathways:  Metabolism

What name do we give to sequences of chemical reactions within cells?

In a (n) ________ the product of one reaction becomes the reactant of the next reaction and so on.

If the final end product of a metabolic pathway is continually removed and used elsewhere, then the reactions of the entire pathway will be pulled in the direction of making more _____ ____________.

Suppose an excess amount of product accumulates at the end of a metabolic pathway.  The product then binds to the allosteric site of the first enzyme along the pathway, shutting down the pathway.  What do we call this regulatory process?

An allosteric enzyme has a second binding site other than its own active site for converting substrate to product.  What does this second site bind to?

If the final product of a metabolic pathway begins to build up in excess, the pathway can often be slowed down by a process called ______________ ____________.

A single regulatory molecule can shut down multiple metabolic pathways if it is able to add _________ groups that alter the active site of the first enzyme in each pathway.

6.6

Energy Pools in the Cell:  ATP

Three phosphate groups linked to a ribose sugar which, in turn, is linked to a pyrimidine base known as adenine:  this phrase describes the structure of _______.

Where in the ATP molecule is the “high energy” bond that carries potential energy and is easily broken?

To derive energy from an ATP molecule, what bond must be broken? 

Energy-releasing reactions drive biosynthetic ones forward by contributing to a pool of _____   molecules.

The substance _______ would most likely enable a flagellum to drive a bacterium forward through the medium in which it is swimming.

6.7

Energy Flow from Carbohydrates to ATP:  Respiration

In respiration, chemical energy is transferred from glucose to ATP.  The energy transfer, however, is not 100% efficient.  In the transfer, some of the energy is lost as _______.  (Review Section 6.2 above)

In what major cellular process are three interrelated, exergonic pathways and oxygen used to generate large amounts of ATP from glucose molecules?

The term ___________________ could be defined as about 30 individual, sequential chemical reactions that form three metabolic pathways: one in the cytoplasm and two within the mitochondrion.

List the reactants and products of the summary reaction for aerobic respiration.

Write out the summary reaction for aerobic respiration.

Name the three stages of aerobic respiration.

The three metabolic pathways that make up aerobic respiration are really all parts of one larger pathway because the products of early pathways (like NADH) become _______ in the last one.

Aerobic Respiration:  Stage 1 - Glycolysis

What is the first stage of aerobic respiration?

In the process of glycolysis, one molecule of _______ is converted to two molecules of __________.

Is carbon dioxide either a reactant in or product of glycolysis?

Glycolysis is valuable to a cell because it produces _______ for driving biosynthetic processes.

Glycolysis is valuable to a cell because supplies minimal energy without requiring the presences of __________ as a reactant.

Glycolysis is valuable to a cell because it generates _____ that can be “cashed in” for ATPs later.

Glycolysis is valuable to a cell because it produces ___________, which the Krebs cycle can further degrade for more energy.

Aerobic Respiration:  Stage 2 – The Krebs Cycle

All of the six carbon atoms in each glucose molecule leave respiration in the form of carbon dioxide.  Most of them leave during which part of aerobic respiration?

Which of the following is not a product of the Krebs cycle?

a.FADH2

b. carbon dioxide

c. ATP

d. NAD

e. NADH

The Krebs cycle’s NADH products are of value.  In what way?

The most energetic and useful product of the Krebs cycle is ________.

Aerobic Respiration:  Stage 3 – Electron Transfer Phosphorylation

What is the immediate source of electrons for electron transfer phosphorylation?

The final stage of aerobic respiration involves the phosphorylation of ____ to ____ by transfer of electrons.

During the electron transfer reactions, protons (H+ ions) are pumped (moved) to one side of the inner membrane of the mitochondrion.  The value of this pumping is that the resulting proton gradient is then used to ____________.

What is the most valuable product, energetically, of electron transfer phosphorylation?

The value of the three stages of aerobic respiration is their ability to break down glucose, a single molecule, with the resultant production of about ____ ATP molecules.

6.9

Energy Flow from Photons to Carbohydrates:  Photosynthesis

________organisms build their own energy-rich molecules using solar energy.

Plants are considered autotrophic because their cells contain what critical molecule?

Name a process that uses chlorophyll molecules to produce high-energy carbohydrates.

List the reactants and products for the overall process of photosynthesis.

In photosynthesis, the H atoms used to make high-energy carbohydrates like glucose come from which reactant molecule?