biology EXAM #3 pt. 3

Question 1

Living cells require a

All heterotrophs, including us, obtain

Energy flows into an ecosystem 
as

Answer 1

source of energy from the outside to perform their many tasks

energy for our cells by eating plants and 
other consumers

sunlight and leaves as heat

Question 2

Coupled reactions:
Anabolic pathways are coupled with

Catabolic pathways release

Electron transfer plays a

Answer 2

catabolic pathways as source of energy to perform work.

stored energy by breaking down complex molecules

major role in these pathways
These processes are central to cellular respiration

Question 3

The breakdown of organic molecules is

Fermentation is a

Aerobic respiration consumes

Anaerobic respiration is similar to

Answer 3

exergonic

partial degradation of sugars that occurs without O2

organic molecules and O2 and yields ATP

aerobic respiration but consumes compounds other than O2

Question 4

COMPLETE Cellular respiration includes both

Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the _____

formula of cellular respiration

Answer 4

aerobic and anaerobic respiration but is often used to refer to aerobic respiration

sugar glucose

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (ATP + heat)

Question 5

Redox reactions transfer

In oxidation, a substance

In reduction, a substance

Na + Cl  Na+ + Cl-
Here, Na is

Answer 5

electrons from one reactant to another by oxidation and reduction

loses electrons, or is oxidized. It is called reducing agent because it is the electron donor.

gains electrons, or is reduced. It is called the oxidizing agent because it is the electron acceptor.

Na is oxidized or reducing agent and Cl is reduced or oxidizing agent.

Question 6

Oxidation and reduction always

The electron donor is called

The electron acceptor is called

Answer 6

go hand in hand

the reducing agent, it reduces the electron acceptor

the oxidizing agent, it oxidizes the electron donor

Question 7

Instead of fully transferring electrons, some redox reactions :

Oxygen (O) atoms are very ________; they :

what constitutes a redox reaction?

For example, electrons are not completely transferred in the redox reaction between methane and O2

Answer 7

change electron sharing in covalent bonds

electronegative; they attract electrons and do not share them equally

The partial “gain” of electrons by O atoms and the partial “loss” of electrons by their bonding partners

Question 8

Some redox reactions do not completely:

They change :

Answer 8

exchange electrons

the degree of electron sharing in covalent bonds

Question 9

Photosynthesis
-formula

Hydrogen atoms are transferred from :

_________ is required and this comes in the form of :

Chloroplasts convert solar energy to ______ which is then used along with ___________ to:

Answer 9

energy + 6CO2+6H2O C6H12O6 + 6O2

water to carbon dioxide and glucose is formed

Energy; form of light energy from the sun

solar energy to ATP;
with hydrogen to reduce carbon dioxide to glucose

Question 10

During cellular respiration, the fuel (such as glucose) is ________-, and O2 is ________

Organic molecules with an abundance of hydrogen are:

Energy is released as

Answer 10

the fuel (such as glucose) is oxidized, and O2 is reduced

excellent sources of high-energy electrons

the electrons associated with hydrogen ions are transferred to oxygen, a lower energy state

Question 11

During cellular respiration, glucose is __________ and oxygen is _______

co2 is ______ and h2o is _______

Complete oxidation of a mole of glucose produces _____ kcal of energy (____ in the form of ATP)

This energy is used to form ____

Answer 11

glucose is oxidized and oxygen is reduced

co2 is oxidizes and h20 is reduced

686 kcal of energy; 262

ATP

Question 12

Catabolic pathways yield energy by:

Answer 12

oxidizing (loss of H+ or e-) organic fuels (Glucose is oxidized thus converted to CO2 and O2 is reduced and converted to H2O)

Question 13

cellular respiration

Is the most:

Consumes:

Yields how much ATP ?

Each ATP =

Answer 13

prevalent and efficient catabolic pathway

oxygen and organic molecules such as glucose

(32-34)

7.3 kcal

Question 14

About 34% of the energy in a glucose molecule is:

(7.3*32)/686 Kcal = 40% 34% efficiency
The rest = unused energy lost as heat

Answer 14

transferred to ATP during cellular respiration, making approximately 38 ATP

Question 15

One catabolic process, fermentation is a:

The biproducts:

Yields how much ATP ?

Answer 15

partial degradation of sugars that occurs without oxygen

lactate-us, lactic acid, alcohol yeast-beer/wine or bacteria -tequila, citric acid…

(2)

Question 16

To keep working cells must________________– remember coupled reactions:

Catabolic pathways yield ________ due to the transfer of _________

Answer 16

regenerate ATP
anabolic and catabolic reactions simultaneously

energy; electrons

Question 17

Cellular respiration oxidizes __________ in a series of steps

Electrons from organic 
compound are usually 
first transferred to ______,
 which is a ________

Answer 17

glucose

NAD+, a coenzyme

Question 18

Each electron travels with a ________—thus, as a ______ ______

Answer 18

proton; hydrogen atom

Question 19

Hydrogen atoms are usually first passed to _______ _______, rather than directly to ____

Answer 19

electron carriers, rather than directly to O2

Question 20

As an electron acceptor, Nicotinamide adenine dinucleotide, NAD+ functions as an :

Each NADH (the reduced form of NAD+) represents:

Answer 20

oxidizing agent during cellular respiration

stored energy that is tapped to synthesize ATP

Question 21

NADH,
First – picks up the

If electron transfer is not stepwise….

Answer 21

electrons removed from food, then it passes the electrons to the electron transport chain

a large release of energy occurs (explosion), as in the reaction of hydrogen and oxygen to form water

Question 22

the electron transport chain passes:

then, uses the energy from the electron transfer to:

NADH up to (how much ATP)

FADH2 up to (how much ATP)

Answer 22

electrons in a series of steps instead of in one explosive reaction

form ATP (26-28 ATP by means of oxidative phosphorilation)

2.5 ATP in Oxidative phosphorilation

1.5

Question 23

NADH passes electrons to the :

O2, the _____ _______ ______, captures the:

The energy yielded is used to:

Answer 23

electron transport chain where they are transferred in a series of redox reactions, each releasing a small amount of energy

final electron acceptor; electrons and the hydrogen nuclei (H+), forming H2O

regenerate ATP

Question 24

Respiration is a cumulative function of

Answer 24

three (four) metabolic stages

Question 25

The process that generates almost 90% of the ATP is called ... because... A smaller amount of ATP is formed in ________ and the _________ by :

Answer 25

oxidative phosphorylation because it is powered by redox reactions formed in glycolysis and the citric acid cycle by substrate-level phosphorylation

Question 26

overview of cellular respiration Oxidation of glucose to carbon dioxide, water, and energy Exergonic reaction used to 4 phases of respiration are required for complete oxidation of glucose: Oxidation involves the

Answer 26

drive ATP synthesis which is endergonic glycolisis, preparatory reaction, citric acid cycle, electron transfer chain removal of hydrogen atoms from substrates by redox coenzymes NAD+ and FAD

Question 27

Glycolysis breaks down Glycolysis occurs in the _______ and has: 1) 2) Glycolysis occurs whether or not

Answer 27

glucose into two molecules of pyruvate occurs in the cytoplasm and has two major phases: Energy investment phase Energy payoff phase O2 is present

Question 28

Glycolysis: Transition rxn: The citric acid cycle completes the Oxidative phosphorylation is driven by:

Answer 28

breaks down glucose into two molecules of pyruvate (in cytoplasm 2 pyruvate to 2Acetyl CoA (cytoplasm –matrix) breakdown of glucose the electron transport chain and generates ATP

Question 29

Both glycolysis and the citric acid cycle can

Answer 29

generate ATP by substrate-level phosphorylation

Question 30

Glycolysis harvests energy by Glycolysis means: Breaks down glucose into Occurs in the

Answer 30

oxidizing glucose to pyruvate “splitting of sugar” pyruvate cytoplasm of the cell

Question 31

All of the carbon originally present in glucose is Glycolysis does not release any ____, and occurs whether or not ___ is present

Answer 31

accounted for in the two molecules of pyruvate CO2, and occurs whether or not O2 is present

Question 32

After pyruvate is oxidized, the citric acid cycle... Most of the energy in glucose remains In the presence of O2, pyruvate enters a

Answer 32

completes the energy-yielding oxidation of organic molecules stored in the pyruvate molecules produced by glycolysis mitochondrion (in eukaryotic cells), where the oxidation of glucose is completed

Question 33

Before the citric acid cycle can begin, pyruvate must be: This step is carried out by : (3)

Answer 33

converted to acetyl coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle a multienzyme complex that catalyzes three reactions: 1)Oxidation of pyruvate and release of CO2 2)Reduction of NAD+ to NADH 3)Combination of the remaining two-carbon fragment and coenzyme A to form acetyl CoA

Question 34

Before the citric acid cycle can begin, pyruvate must first be converted to Loss of

Answer 34

acetyl CoA, which links the cycle to glycolysis two C molecules in the form of CO2

Question 35

The citric acid cycle, also called ___________, completes the: The citric acid cycle oxidizes: Takes place in the: Substrate level phosphorilation Loss of

Answer 35

the Krebs cycle energy-yielding oxidation of organic molecules organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn matrix of the mitochondrion 4 C molecules in the form of CO2

Question 36

The citric acid cycle has The acetyl group of acetyl CoA joins the cycle by The next seven steps : The NADH and FADH2 produced by the cycle relay

Answer 36

eight steps, each catalyzed by a specific enzyme combining with oxaloacetate, forming citrate decompose the citrate back to oxaloacetate, making the process a cycle electrons extracted from food to the electron transport chain

Question 37

Oxygen is taken in by breathing Digested food contains glucose Oxygen and glucose are carried to cells by the bloodstream Glucose and oxygen enter cells where respiration occurs Carbon dioxide is taken by the bloodstream to the lungs

Answer 37

leer

Question 38

for glucose: 2C acetyl group from prep reaction combines with a 4C molecule to produce 6C citrate Oxidation of citrate by removal of hydrogens Produces 3 NADH and 1 FADH2 per cycle Produces 1 ATP by direct substrate phosphorylation per cycle Cycle turns twice per glucose Total yield:

Answer 38

6 NADH, 2 FADH2, 2 ATP, 4 CO2

Question 39

Following glycolysis and the citric acid cycle, These two electron carriers donate electrons to the _______________, which :

Answer 39

NADH and FADH2 account for most of the energy extracted from food electron transport chain, which powers ATP synthesis via oxidative phosphorylation

Question 40

Molecules of the electron transport chain are The membrane is folded into In prokaryotes, the electron transport chain is

Answer 40

embedded in the inner mitochondrial membrane (cristae) in eukaryotic cells cristae to increase surface area for electron transport chains embedded in the plasma membrane

Question 41

Most of the chain’s components are _____, which exist in : Electrons drop in ___________ as they : Electron carriers alternate between:

Answer 41

proteins; multiprotein complexes free energy as they go down the chain and are finally passed to O2, forming H2O reduced and oxidized states as they accept and donate electrons

Question 42

Electrons are transferred from NADH or FADH2 to the Electrons are passed through a number of The electron transport chain generates It breaks the :

Answer 42

electron transport chain proteins to O2 no ATP directly large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts

Question 43

In the electron transport chain, electrons from NADH and FADH2 : A series of

Answer 43

lose energy in several steps redox reactions

Question 44

NADH and FADH2 donate electrons to At the end of the chain, electrons are passed to:

Answer 44

different electron acceptors early in the chain oxygen, forming water

Question 45

At certain steps along the electron transport chain, electron transfer causes H+ then moves

Answer 45

protein complexes to pump H+ from the mitochondrial matrix to the intermembrane space down its concentration gradient back across the membrane, passing through the protein complex ATP synthase

Question 46

The resulting H+ gradient stores ... and drives...

Answer 46

stores energy and drives chemiosmosis in ATP synthase

Question 47

Chemiosmosis is referred to as a Is an

Answer 47

proton-motive force energy-coupling mechanism that uses energy in the form of a H+ gradient across a membrane to drive cellular work

Question 48

ATP synthase is the

Answer 48

enzyme that actually makes ATP

Question 49

During cellular respiration, most energy flows in this sequence: About __% of the energy in a glucose molecule is ....., making about # ATP The rest of the energy is lost as

Answer 49

glucose → NADH → electron transport chain → proton-motive force → ATP 34% ; transferred to ATP during cellular respiration; 30-32 heat

Question 50

cellular respiration old 3: glycolisis, citic acid cycle, oxidative/electron trans.../chemi new 4:glycolisis, pyruvate oxidation, citic acid cycle, oxidative/electron trans.../chemi

Question 51

There are three reasons why the number of ATP is not known exactly:

Answer 51

Photophosphorylation and the redox reactions are not directly coupled; the ratio of NADH to ATP molecules is not a whole number ATP yield varies depending on whether electrons are passed to NAD+ or FAD in the mitochondrial matrix The proton-motive force is also used to drive other kinds of work

Question 52

Fermentation and anaerobic 
respiration enable cells to Most cellular respiration depends on Without oxygen, In that case, glycolysis

Answer 52

produce ATP without the use of oxygen
 electronegative oxygen to pull electrons down the transport chain the electron transport chain will cease to operate couples with anaerobic respiration or fermentation to produce ATP

Question 53

Anaerobic respiration uses an... , for example, ______. some organisms use a sulfate ion (SO42-) as a final electron acceptor In this case, H2S (hydrogen sulfide) is made as a by-product instead of H2O Fermentation uses

Answer 53

electron transport chain with a final electron acceptor other than oxygen; for example, sulfate substrate-level phosphorylation instead of an electron transport chain to generate ATP

Question 54

Glycolysis can produce ATP: Couples with:

Answer 54

with or without oxygen, in aerobic or anaerobic conditions fermentation to produce ATP

Question 55

Fermentation consists of Two common types are

Answer 55

glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis alcohol fermentation and lactic acid fermentation

Question 56

In alcohol fermentation, ___________ is converted to ___________ in two steps: 1) 2) Alcohol fermentation by yeast is used in brewing, winemaking, and baking

Answer 56

pyruvate is converted to ethanol in two steps: 1)The first step releases CO2 from pyruvate 2)The second step produces NAD+ and ethanol

Question 57

In lactic acid fermentation, _______ is reduced by ________, forming: Lactic acid fermentation by some fungi and bacteria is used to make cheese and yogurt Human muscle cells use lactic acid fermentation to

Answer 57

pyruvate is reduced by NADH, forming NAD+ and lactate as end products, with no release of CO2 generate ATP during strenuous exercise when O2 is scarce

Question 58

Both fermentation and cellular respiration use glycolysis to Fermentation and cellular respiration differ in their Another difference is the Fermentation produces (ATP) Cellular respiration harvests ATP by oxidative phosphorylation, # ATP.  This sums up to # ATP total in aerobic respiration

Answer 58

oxidize glucose and other organic fuels to pyruvate final electron acceptor amount of ATP produced per glucose molecule  2 ATP by substrate-level phosphorylation 26-28 ATP 30-32 ATP

Question 59

Obligate anaerobes carry out Yeast and many bacteria are ______________, meaning:

Answer 59

fermentation or anaerobic respiration and cannot survive in the presence of O2 facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration

Question 60

Glycolysis is Early prokaryotes likely used glycolysis to produce ATP before Used in both cellular respiration and fermentation, it is the This pathway occurs in the

Answer 60

an ancient process O2 accumulated in the atmosphere most widespread metabolic pathway on Earth cytosol so does not require the membrane-bound organelles of eukaryotic cells

Question 61

Glycolysis and the citric acid cycle connect to: Catabolic pathways : -Funnel... -Proteins used for fuel must be ... -Nitrogenous waste is excreted as...

Answer 61

many other metabolic pathways -electrons from many kinds of organic molecules into cellular respiration -digested to amino acids and their amino groups must be removed in a process called deamination -ammonia (NH3), urea, or other products

Question 62

Fats are digested to Fatty acids are broken down by An oxidized gram of fat produces more than twice as much ATP as an

Answer 62

glycerol and fatty acids beta oxidation and yield acetyl CoA, NADH, and FADH2 oxidized gram of carbohydrate

Question 63

The body uses small molecules to These small molecules may come directly from

Answer 63

build other substances food or through glycolysis or the citric acid cycle

Question 64

Cellular respiration: Feedback inhibition is the Is controlled by If ATP concentration drops, ______________; if there is plenty of ATP, ______________ Catabolism is controlled by

Answer 64

most common mechanism for metabolic control because it prevents wasteful production allosteric enzymes at key points in glycolysis and the citric acid cycle respiration speeds up; .........., respiration slows down regulating the activity of enzymes at strategic points in the pathway

Question 65

Certain electron carriers in the electron transport chain In this way, the energy stored in a H+ gradient across a membrane couples the The H+ gradient is referred to as a

Answer 65

accept and release H+ along with the electrons redox reactions of the electron transport chain to ATP synthesis proton-motive force, emphasizing its capacity to do work