homework ch. 6

Question 1

Which of the following is the branch of chemistry concerned with energy changes?

Answer 1

thermodynamics

Question 2

What is the term for the ability to do work?

Answer 2

energy

Question 3

With very few exceptions, all energy that enters biological systems ultimately comes from the ____

Answer 3

sun

Question 4

Which of the following describe how energy is used in chemical reactions?

Answer 4

Energy stored in certain chemical bonds can be used to make new bonds.

Question 5

All activities of living organisms involve changes in ______ which is the ability to do work.

Answer 5

energy

Question 6

The branch of chemistry that studies _____ changes is called thermodynamics.

Answer 6

energy

Question 7

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.

Answer 7

energy

Question 8

Heat is a measure of the random ___ of molecules.

Answer 8

motion

Question 9

The energy that flows through most biological systems on Earth ultimately comes from which source?

Answer 9

sun

Question 10

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.

Answer 10

entropy or disorder

Question 11

__ stored in the chemical bonds of a molecule can be used to make new bonds in a different molecule.

Answer 11

energy

Question 12

All living things require which of the following, in order to carry out chemical reactions and thereby survive?

Answer 12

energy

Question 13

What is the term used to describe the energy of a system that is available to do work?

Answer 13

free energy

Question 14

Which of the following is the branch of chemistry concerned with energy changes?

Answer 14

thermodynamics

Question 15

Any agent that speeds up the rate of a chemical reaction without being permanently changed or consumed by it is known as a(n) _____

Answer 15

catalyst

Question 16

Heat is a form of ____ energy, because it reflects the random motion of molecules.

Answer 16

kinetic

Question 17

What molecule is a common energy source for living organisms?

Answer 17

ATP

Question 18

Which of the following is another way to state the second law of thermodynamics?

Answer 18

Entropy increases.

Question 19

The hydrolysis of ATP has Blank______.

Answer 19

a negative ΔG

Question 19

The energy available to do work in a system is called ____ energy.

Answer 19

free

Question 20

Cells use ___ hydrolysis to drive endergonic reactions.

Answer 20

ATP

Question 21

The process of influencing chemical bonds to lower the activation energy of a reaction is called Blank______.

Answer 21

catalysis

Question 22

Select the steps in the ATP cycle.

Answer 22

Hydrolysis of ATP to release energy that can be used to drive endergonic reactions
Synthesis of ATP using energy released from exergonic reactions

Question 23

All cells use a molecule called to carry and release energy cyclically.

Answer 23

ATP

Question 24

What are enzymes?

Answer 24

Proteins or RNA molecules that act as catalysts.

Question 25

______ or reactants, are molecules that bind to an enzyme and are converted to products in chemical reactions.

Answer 25

substrates

Question 26

Hydrolysis of which covalent bonds in ATP releases a considerable amount of energy?

Answer 26

Phosphate-phosphate bond

Question 27

Where does a substrate bind on an enzyme in order for a chemical reaction to take place?

Answer 27

active site

Question 28

Certain reactions in cells are endergonic. How do cells make those reactions proceed?

Answer 28

They couple them with ATP hydrolysis.

Question 29

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

Answer 29

multienzyme or multi-enzyme

Question 30

The two main steps in the ATP cycle are the synthesis of ATP from _______ and Pi, and the subsequent hydrolysis of ATP, which releases _______ that drives endergonic reactions.

Answer 30

ADP, energy

Question 31

The optimum pH of most enzymes is

Answer 31

6-8
usually around 7

Question 32

What is a substrate?

Answer 32

A reactant molecule that forms a temporary association with an enzyme before being converted to a product

Question 33

Which of the following describes the active site of an enzyme?

Answer 33

It is the part of the enzyme where the substrate fits.

Question 34

Which of the following are included in metabolism?

Answer 34

Both the synthesis and breakdown of organic molecules

Question 35

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______.

Answer 35

a multienzyme complex

Question 36

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.

Answer 36

biochemical pathway

Question 37

In order to function efficiently and to conserve energy and raw materials, a cell Blank______.

Answer 37

maintains biochemical pathways active only when their products are needed

Question 38

What statement describes metabolism?

Answer 38

Metabolism refers to the sum of all chemical reactions that occur within an organism.

Question 39

Each _____ in a biochemical pathway acts on the products of the previous reaction.

Answer 39

enzyme

Question 40

Select reasons why metabolic pathways are regulated.

Answer 40

By regulating metabolic pathways, cells conserve raw materials.
By regulating metabolic pathways, cells waste less energy.
Regulation allows cells to operate efficiently.