Biology Ch. 6 Energy & Metabolism
When two reactions are coupled in a cell, what determines if they will both proceed spontaneously? a. The sum of ΔG of the two coupled reactions (the overall ΔG) should be negative. b. At least one of the reactions should have a negative ΔG. c. Each of the coupled reactions should have a negative ΔG. d. The sum of ΔG of the two coupled reactions (the overall ΔG) should be positive.
a. The sum of ΔG of the two coupled reactions (the overall ΔG) should be negative
Enzyme-mediated chemical reactions take place when the substrate molecules bind to the of an enzyme.
active site
The hydrolysis of ATP has ______. a. a ΔG of zero b. a negative ΔG c. a positive ΔG
b. a negative ΔG
A is a sequence of reactions occurring in an individual cell that are organized so that the product of one reaction becomes the substrate of the next.
biochemical pathway
Which of the following describe how energy is used in chemical reactions? a. Energy stored in certain chemical bonds is transformed into kinetic energy which breaks those bonds (as atoms move quickly apart). b. Energy stored in chemical bonds is always converted to heat energy, some of which has the capacity to perform work. c. Energy stored in certain chemical bonds can be used to make new bonds.
c. Energy stored in certain chemical bonds can be used to make new bonds.
The process of influencing chemical bonds to lower the activation energy of a reaction is called Blank______.
catalysis
Any agent that speeds up the rate of a chemical reaction without being permanently changed or consumed by it is known as a(n)
catalyst
Certain reactions in cells are endergonic. How do cells make those reactions proceed? a. They use enzymes to turn them into exergonic reactions. b. They couple them with other endergonic reactions. c. They couple them with ATP hydrolysis. d. They couple them with ATP synthesis.
ATP hydrolysis
All activities of living organisms involve changes in , which is the ability to do work.
energy
All living things require which of the following, in order to carry out chemical reactions and thereby survive?
energy
The branch of chemistry that studies changes is called thermodynamics.
energy
What is the term for the ability to do work? Multiple choice question. Energy
energy
Work in the cell or in the physical world can only be done with expenditure of _______________; it is defined as the capacity to do work.
energy
stored in the chemical bonds of a molecule can be used to make new bonds in a different molecule.
energy
According to the second law of thermodynamics, increases when energy is transferred from one form to another and some energy is lost as heat in the process
entropy
Which of the following is another way to state the second law of thermodynamics?
entropy increases
Each in a biochemical pathway acts on the products of the previous reaction.
enzyme
are proteins or RNA molecules that act as catalysts to speed up reactions in living organisms.
enzymes
The energy available to do work in a system is called energy.
free
What is the term used to describe the energy of a system that is available to do work?
free energy
, or reactants, are molecules that bind to an enzyme and are converted to products in chemical reactions.
substrates
With very few exceptions, all energy that enters biological systems ultimately comes from the
sun
The energy that flows through most biological systems on Earth ultimately comes from which source?
the sun
Which of the following is the branch of chemistry concerned with energy changes?
thermodynamics
The two main steps in the ATP cycle are the synthesis of from and Pi, and the subsequent hydrolysis of ATP, which releases that drives endergonic reactions.
ADP, energy
All cells use a molecule called to carry and release energy
ATP
The optimum pH of most enzymes is:
6 to 8
What is a substrate?
A reactant molecule that forms a temporary association with an enzyme before being converted to a product
What molecule is a common energy source for living organisms?
ATP
Which of the following are included in metabolism? a. Neither the synthesis nor the breakdown of organic molecules b. Only the breakdown of organic molecules c. Both the synthesis and breakdown of organic molecules d. Only the synthesis of organic molecules
Both the synthesis and breakdown of organic molecules
Select reasons why metabolic pathways are regulated.
By regulating metabolic pathways, cells conserve raw materials. By regulating metabolic pathways, cells waste less energy. Regulation allows cells to operate efficiently.
Which of the following describes the active site of an enzyme?
It is the part of the enzyme where the substrate fits.
What statement describes metabolism?
Metabolism refers to the sum of all chemical reactions that occur within an organism.
What are enzymes?
Proteins or RNA molecules that act as catalysts.
Select the steps in the ATP cycle.
Synthesis of ATP using energy released from exergonic reactions Hydrolysis of ATP to release energy that can be used to drive endergonic reactions
What is the second law of thermodynamics?
The transformation of energy from one form to another increases entropy.
Heat is a measure of the random of molecules
movement
When several enzymes that catalyze different steps of a sequence of reactions are associated with one another in a noncovalently bonded assembly, they form a(n) complex.
multienzyme
Is any energy released during ATP hydrolysis and if so, how much?
Yes, a considerable amount of energy is released.
The bacterial enzyme pyruvate dehydrogenase contains multiple copies of each of three enzymes for a total of 60 protein subunits. This is an example of Blank______.
a multienzyme complex
Heat is a form of ______ energy, because it reflects the random motion of molecules.
kinetic
In order to function efficiently and to conserve energy and raw materials, a cell Blank______.
maintains biochemical pathways active only when their products are needed
