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Biology; Chapter 6 Energy And Metabolism > Chapter 6 Energy And Metabolism > Flashcards

Chapter 6 Energy And Metabolism Flashcards

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1
Q

What is Thermodynamics?

A

Thermodynamics is a branch of chemistry concerned with energy changes.

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2
Q

Define Energy.

A

Energy is the capacity to do work.

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3
Q

What are the two states energy can exist in?

A

Energy can exist as kinetic energy and potential energy.

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4
Q

Define kinetic energy.

A

Kinetic energy is energy in motion, moving objects perform work by causing other matter to move.

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5
Q

What is potential energy?

A

Stored energy, objects that are not actively moving but have the capacity do so possess potential energy.

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6
Q

Give an example of the many forms energy can exist in.

A

Mechanical energy, heat, sound, electric current, light, or radioactivity.

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7
Q

What is the most convenient way of measuring energy?

A

Heat, all forms of energy can be converted into heat.

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8
Q

What is a unit of heat commonly measured in biology?

A

Kilocalories (kcal)

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9
Q

How many calories (cal) is in one kilocalorie (kcal)?

A

1 kcal = 1000 cal = 1 Cal

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10
Q

____________ is the heat required to raise the temperature of one gram of water one degree Celsius (C).

A

One calorie

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11
Q

Where does energy flow into our biological world from?

A

The sun: it provides the earth with more than 40 million billion calories per second, photosynthetic organisms only capture a fraction of this light through photosynthesis.

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12
Q

What does photosynthesis do?

A

Absorbs energy from sunlight to combine water and carbon dioxide into sugars..

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13
Q

Photosynthesis converts carbon from an ____________ form to an organic form.

A

Inorganic

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14
Q

Energy from sunlight is stored as ___________ energy in the covalent bonds between atoms in the sugar molecules.

A

Potential

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15
Q

True/false: Breaking bonds between atoms requires energy.

A

True

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16
Q

How is the strength of a covalent bond measured?

A

The strength of a covalent bond is measured by the amount of energy required to break it.

Example, it takes 98.8 kcal to break one mole (6.023x10^23) of the carbon-hydrogen (C-H) bonds found in carbon molecules.

Fat molecules have many C-H bonds, breaking those bonds provides lots of energy. This is one reason animals store fat. The oxidation of one mole of a 16-carbon fatty acid that is completely saturated with hydrogens yields 2340 kcal.

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17
Q

True/false: energy stored in chemical bonds may be used to make new bonds.

A

True

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18
Q

An atom or molecule that loses an electron is said to be ___________. And the process by which this occurs is called ___________.

A

Oxidized, oxidation.

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19
Q

An atom or molecule that gains an electron is said to be __________, and the process is called __________.

A

Reduced, reduction.

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20
Q

Which form of a molecule is in a higher level energy? Its reduced form or oxidized form?

A

Reduced form.

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21
Q

True/false: Oxidation and reduction never take place together.

A

False, oxidation and reduction reactions always take place together, every electron that is lost by one atom through oxidation is gained by another atom through reduction.

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22
Q

What are reactions that have oxidation and reduction occurring called?

A

Oxidation-reduction reactions; redox reactions. They play a key role in the flow of energy through biological systems.

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23
Q

What is the first law of thermodynamics?

A

Energy cannot be created or destroyed; only change; total amount of energy in the universe remains constant.

Example: you eating an apple is not creating energy, you are transferring the potential energy stored in the apple’s tissue to your body.

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24
Q

From each energy conversion, some of the energy dissipates into the environment as ________.

A

Heat. Energy is always being shifted to other molecules and being stored in different chemical bonds with it being lost as heat on the way.

25
Q

What is heat? Does it measure kinetic energy or potential energy?

A

Heat is the measure of the random motion of molecules (and therefore a measure of one form of kinetic energy.)

26
Q

Energy continuously flows through the biological world in one direction, with new energy from the ______ constantly entering the system to replace energy dissipated as _______.

A

Sun, heat.

27
Q

Can heat be harnessed to do work? If so, how?

A

Yes it can, it can do work only when there is a heat gradient with a temperature difference between two areas.

28
Q

Can cells use heat to perform work?

A

No, they are too small to maintain significant internal temperature differences, so heat energy is incapable of doing the work of cells.

29
Q

Cells rely on __________ reactions for energy.

A

Chemical

30
Q

Although the total amount of energy in the universe remains constant, the energy available to do work __________ as more of it is progressively _______ as _________.

A

Decreases, lost, heat

31
Q

What is the second law of thermodynamics?

A

Entropy increases, disorder is more likely than order.

Energy transformations proceed spontaneously to convert matter from a more ordered, less stable form to a less ordered, but more stable form.

32
Q

It takes _________ to break the chemical bonds that hold the atoms in a molecule together.

A

Energy.

33
Q

Heat energy, because it increases atomic motion it easier for the atoms to _______ _________.

A

Pull apart.

34
Q

Chemical bonding _________ disorder; heat ________ it.

WORD BANK

  • Increases
  • Reduces
A

Reduces, increases

35
Q

What is free energy? How is it related to chemical bonding?

A

Free energy is defined as the energy available to do work in any system.

It is the amount of energy available to break and subsequently form other chemical bonds.

36
Q

What symbol is used to denote free energy (under conditions that a molecule exists in a cell where pressure and volume did not change).

A

It is donated as G

37
Q

What does each letter stand for?

G = H - TS

A

G is equal to the energy contained in a molecule’s chemical bonds (called enthrall you and designed H) together with he tears (TS) related to the degree of disorder in the system, where S is the symbol for entropy and T is the absolute temperature expressed in the Kelvin scale (K = C + 273)

38
Q

Chemical reactions break some bonds in the reactants and form new ones in the produces, consequently reactions produce changes in free energy.

Thus when a chemical reaction under conditions of constant temperature, pressure, and volume, as do most biological reactions–the change is symbolized by a Greek capital letter ______.

A

Delta

Thus

DELTA G = DELTA H - T DELTA S

39
Q

The change in free energy is useful because it allows us to predict whether a particular chemical reaction is _____________ or not.

A

Spontaneous.

40
Q

How do you calculate the change in free energy?

A

The change in free energy is calculated as energy of products minus the energy of reactants.

41
Q

If the products have more free energy than the reactants, DELTA G is _________.

WORD BANK

  • Positive
  • Negative
A

Positive.

42
Q

If DELTA G is positive, then the reaction will not be ______________. Why? What type of reaction do we call this?

A

Spontaneous, because it requires an input of energy. We call this an endergonic reaction. This presents itself as an “uphill” reaction when presented graphically with free energy (G) being higher in products than reactants as the course of the reaction proceeds.

43
Q

If the products have less free energy than the reactions, DELTA G is __________, and the reaction will be ____________.

WORD BANK

  • NEGATIVE, POSITIVE
  • SPONTANEOUS, NONSPONTANEOUS
A

Negative, spontaneous

44
Q

Reactions that release excess free energy as heat are called _____________ reactions. How is this type of reaction represented graphically?

A

Exergonic reactions. Our plot of free energy for the reaction is now “downhill” and the reaction is spontaneous with less free energy in the products than the reactants.

45
Q

Chemical reactions are reversible, a reaction that is exergonic in the forward direction will be _____________ in the reverse direction.

A

Endergonic

46
Q

For each reaction, an equilibrium exists at some point between the relative amounts of reactants and products. This equilibrium has a numeric value and is called the ____________ ___________.

A

Equilibrium constant.

47
Q

An exergonic reaction has an equilibrium favoring the ____________, while an endergonic reaction has an equilibrium favoring the ____________.

WORD BANK
Products
Reactants

A

Products, reactants.

48
Q

If all chemical reactions that release free energy tend to occur spontaneously, why haven’t all such reactions already occurred?

A

It is because even spontaneous reactions requiring an input of energy to get started.

49
Q

Before new chemical bonds can form, even bonds that contain less energy, existing bonds must be broken, and requires energy input. What is the extra energy needed to destabilize existing chemical bonds and initiate a chemical reaction called?

A

Activation energy.

50
Q

The rate of an ___________ reaction depends on the activation energy required for the reaction to begin.

WORD BANK
EXERGONIC
ENDERGONIC

A

Exergonic.

51
Q

TRUE/FALSE: reactions with smaller activation energies tend to proceed more slowly because fewer molecules succeed in getting over the initial energy hurdle.

A

False, they would proceed faster. It is reactions with larger activation energies that tend to proceed more slowly because fewer molecules succeed in getting over the initial energy hurdle.

52
Q

What are the two ways you can increase the rate of a reaction?

A

Increase the energy of reacting molecules such as heating up the reactants or lowering the activation energy by using a catalyst.

53
Q

Stressing particular chemical bonds can make them easier to _________.

A

Break.

54
Q

The process of influencing chemical bonds in a way that lowers the activation energy needed to initiate a reaction is _____________, and substances that accomplish this are known _________.

A

Catalysis, catalysts.

55
Q

Catalysts exert their action by affecting an intermediate stage in the reaction—the ____________ state. The energy needed to reach this ______________ state is the ______________ ______________.

A

transition, transition, activation energy.

Catalysts stabilize this transition state, thus lowering energy.

56
Q

True/false Catalysts can make an endergonic reaction proceed spontaneously.

A

False, catalysts cannot violate the basic laws of thermodynamics; they cannot make an endergonic reaction proceed spontaneously.

57
Q

True/false: By reducing the activation energy, a catalyst accelerates both the forward and the reverse reactions by exactly the same amount.

A

True, therefore a catalyst does not alter the proportion of reactant ultimately converted into product.

58
Q

What determines the direction a chemical reaction proceeds?

A

The direction in which a chemical reaction proceeds is determined solely by the difference in free energy between reactants and products.

Like digging away the soil below the bowling ball on the hill, catalysts reduce the energy barrier that is preventing the reaction from proceeding.

59
Q

Only exergonic reactions can proceed spontaneously, and catalysts cannot change that. But what can a catalyst do for a reaction?

A

A catalyst can make a reaction proceed much faster. In living systems, enzymes act as catalysts.

Biology; Chapter 6 Energy And Metabolism (1 decks)

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