Midterm 2 Biology

Front 1

The light reactions of photosynthesis use _____ and produce _____

Back 1

water ... NADPH

Front 2

The light reactions of photosynthesis occur in the

Back 2

thylakoid membranes

Front 3

The oxygen released by photosynthesis is a by-product of which specific reaction?

Back 3

extraction of electrons from water molecules

Front 4

Which of the events listed below is part of the light reactions of photosynthesis?

Back 4

ADP is phosphorylated to form ATP.

Front 5

Where do the reactions of the Calvin cycle take place?

Back 5

stroma fluid of the chloroplast

Front 6

The light-driven movement of protons (H+) from the stroma to the inner thylakoid space across the thylakoid membrane occurs from ______ to ______ proton concentration.

Back 6

low; high

Front 7

The movement of protons (H+) through the ATP synthase occurs from ______ to ______ proton concentration.

Back 7

high; low

Front 8

In their FIRST step, the energy of which of the following is used by the chloroplasts light reactions to catapult electrons from low to high potential energy.

Back 8

Sunlight

Front 9

The light reactions convert the high potential energy of energized electrons to the energy stored in

Back 9

ATP and NADPH

Front 10

Fill in the blanks: In the model of the hydroelectric dam, water stands for ________, the turbine stands for ________, and the lit-up light bulb stands for _________.

Back 10

the protons (H+); the ATP synthase; the ATP produced

Front 11

True or False? If you could track carbon atoms, you would find carbon atoms from CO2 as part of sugar and starch molecules in plant leaves and also as a part of sugar and glycogen molecules in animals.

Back 11

False

Front 12

Which of the following statements is correct?

The light reactions provide the Calvin cycle with oxygen, and the Calvin cycle provides the water for the light reactions.

The light reactions provide ATP and NADPH, and the Calvin cycle provides sugar for the light reactions.

The light reactions provide the CO2 that is converted to sugar in the Calvin cycle.

The light reactions provide ATP and NADPH to the Calvin cycle.

Back 12

The light reactions provide ATP and NADPH to the Calvin cycle.

Front 13

Carbon dioxide containing bonds with ________ held electrons is converted to sugar molecules containing bonds with ______ held electrons in the Calvin cycle.

Back 13

tightly; loosely

Front 14

What is the primary function of the Calvin cycle?

Back 14

to synthesize a simple sugar (G3P) from carbon dioxide

Front 15

The glucose made in photosynthesis is used by the plant in three of the following processes. Find the exception.

cellulose synthesis

synthesis of starch as an energy store

to fuel the plants cellular respiration

synthesis of glycogen as an energy store

Back 15

synthesis of glycogen as an energy store

Front 16

Comparing the photosynthetic light reactions with the Calvin cycle, which CONSUME(S) ATP?

Back 16

only the Calvin cycle

Front 17

Comparing the photosynthetic light reactions with the Calvin cycle, which PRODUCE(S) NADPH?

Back 17

only the light reactions

Front 18

Comparing the photosynthetic light reactions with the Calvin cycle, which CONSUME(S) glucose?

Back 18

neither the light reactions nor the Calvin cycle

Front 19

The Calvin cycle converts _______ to _______.

Back 19

C=O bonds; C-H bonds

Front 20

Why do plants use the ATP made by ATP synthase to produce sugars?

Back 20

because ATP is too unstable to store for more than an instant

Front 21

Four of the following statements are correct. Find the one that is FALSE.
While performing photosynthesis during the day, the chloroplasts of a green leaf produce

ATP to be used in the Calvin cycle.

ATP as an energy source for the roots of the plant.

sugars for the green leafs cellular respiration at night.

sugars as an energy source for the roots of the plant.

sugars to fuel the growth of the plant.

Back 21

ATP as an energy source for the roots of the plant.

Front 22

Three of the four answers below explain why a plants green leaves typically have higher rates of photosynthesis compared with respiration. Find the exception.

The green leaf is only a small part of the plant and needs to produce enough energy-rich sugars to support all of the non-photosynthetic parts (like roots, non-green stems and trunks, or flowers).

Only when overall photosynthetic activity exceeds overall respiration activity of the whole plant can the plant grow and accumulate biomass.

Photosynthesis supports the energy needs of the plant during the day and the night.

The rate of photosynthesis is higher because leaves dont have mitochondria.

Back 22

The rate of photosynthesis is higher because leaves dont have mitochondria.

Front 23

Four of the five features below present a state of high chemical potential energy in photosynthesis. Find the exception.

glucose

excited electrons

NADPH

ATP

water

Back 23

water

Front 24

What is the final electron acceptor in cellular respiration?

Back 24

Oxygen is the final electron acceptor of cellular respiration.

Front 25

Which statement about the transport and use of oxygen in humans is FALSE?

Oxygen for cellular respiration is taken up by the lungs.

Hemoglobin transports oxygen from the lungs to body cells requiring ATP for cellular work.

Oxygen serves as the terminal electron acceptor in mitochondria.

Oxygen is converted to CO2 in mitochondria.

High CO2 levels decrease the oxygen-binding capacity of hemoglobin.

Back 25

Oxygen is converted to CO2 in mitochondria.

Front 26

Three of the four features below serve as DIRECT sources of high-energy electrons for cellular respiration. Which does not?

food molecules

C-H bonds

sugars

sunlight

Back 26

sunlight

Front 27

Where does glycolysis take place?

Back 27

cytosolic fluid

Front 28

Where are the proteins of the electron transport chain located in cellular respiration?

Back 28

in the mitochondrial inner membranes

Front 29

The oxygen consumed during cellular respiration participates most DIRECTLY in what process?

Back 29

accepting electrons at the end of the mitochondrial electron transport chain

Front 30

In mitochondrial electron transport, water is formed. Where does the oxygen for the formation of water come from?

Back 30

molecular oxygen (O2)

Front 31

Where does the CO2 released in cellular respiration come from?

Back 31

CO2 is what is left over from the carbon chain of glucose after the loss of H (electrons and H+).

Front 32

Glycemic index

Back 32

rapidity of conversion to glucose

Front 33

glycemic load

Back 33

Gl composition and the amount of food consumed

Front 34

High GL

Low GL

Back 34

Chronic elevated blood glucose

Balanced blood glucose level

High: white rice, soft drinks, candy

Low: vegetables, sweet potatoes, spicesn

Front 35

Where does the citric acid cycle take place?

Back 35

The matrix

Front 36

DOMAIN BACTERIA

Back 36

• single-celled
• found everywhere
• some cause disease in
humans, but most are
beneficial

Front 37

DOMAIN ARCHAEA

Back 37

• single-celled
• often live in extreme
conditions, such as
environments that are
very hot, salty, or acidic

Front 38

DOMAIN EUKARYA

Back 38

• single-celled or
• multicellular, larger, more
sophisticated cells

Front 39

“Pro-karyote”

“Eu-karyote”

Back 39

“before nucleus” (no nucleus = no
membrane around the DNA)

“Eu-karyote” = “real nucleus” (with
membrane around the DNA)

Front 40

Kingdom Plantae

Back 40

multicellular
• use sunlight to
produce sugars via
photosynthesis

Front 41

Kingdom Fungi

Back 41

• single-celled or
multicellular
• decompose and
digest dead
organisms

Front 42

Kingdom Animalia

Back 42

• multicellular
• eat and digest other
organisms

Front 43

Protists

Back 43

• single-celled or
multicellular
• catch-all category
for all remaining
eukaryotes
• includes many
kingdoms

Front 44

Similarities in all living cells

Back 44

• Nucleic acids (DNA) to store
genetic information for protein synthesis
• Proteins to perform diverse tasks (and
ribosomes to make proteins)
• Outer cell membrane to maintain a
suitable internal environment
• Ability to acquire energy from the
environment for ATP formation & the 3 types
of cellular work

Front 45

Differences in living cells

Back 45

Eukarya (Eukaryotes):

Larger cells,
compartmentation by
multiple inner membranes
for “multi-tasking”

Bacteria & Archaea:

Small cells; lack internal
compartmentation
(i.e., have no membrane around the DNA, no
mitochondria, no chloroplasts, no Golgi apparatus, no
rough or smooth ER),
different species specialize in unique
biochemical pathways

Front 46

Mitochondria

Back 46

the eukaryotic cell’s powerhouses

Role: Burn energy-rich molecules with O2
to gain lots of ATP energy for cellular work
Prokaryotes do not have
mitochondria; many prokaryotes
cannot burn food molecules with O2
and instead use fermentation to
make small amounts of ATP.

All eukaryotes have mitochondria for
making lots of ATP: plants, animals,
fungi, protists

Front 47

Chloroplasts

Back 47

solar energy collectors/converters

Role: Convert solar energy
into energy-rich sugars in
photosynthesis

Prokaryotes do not have chloroplasts;
(photosynthetic bacteria perform
photosynthesis using other structures)

Chloroplasts occur only in
plants & algae

Front 48

Mitochondria and chloroplast both

Back 48

possess their own DNA, ribosomes, and a double membrane – as if they
were independent organisms engulfed by a bigger cell by
endocytosis.

Front 49

Q1. A cell that contains enzymes, DNA,
ribosomes, a cell membrane, and mitochondria
could be a cell from

Back 49

a plant or an animal.

Front 50

Prokaryotes vs. Mitochondrian

Back 50

Prokaryotes do not have mitochondria; many prokaryotes cannot burn food molecules with O2 and instead use fermentation to make smaller amounts of ATP

Front 51

a hexose

Back 51

6-carbon monosaccharide

Front 52

Carbohydrates function as

Back 52

• Energy supply
• Building blocks
• Gene regulators

Front 53

polysaccharides

Back 53

- Carb. polymers

- are built from the simplest sugars (monosaccharides)

Front 54

The names of simple sugars
often end in “ose"

Back 54

as in glucose, fructose,
galactose
These three all are hexose
sugars with 6 carbons =
C6H12O6 = (CHOH)6

Front 55

Q2. Predict the energy content of sugar: A sugar should have
____________ energy content compared to a fatty acid with
the same number of C atoms.
A) a similar
B) about twice the
C) about half the
D) about one quarter the

Back 55

B

Front 56

Carbon based food molecules are combined with what to release energy?

Back 56

Carbon-based food molecules are burned with oxygen
to release ENERGY

Front 57

Burning sugars with oxygen produces what?

Back 57

energy-poor waste products carbon dioxide and water

Front 58

Photosynthesis takes energy-poor, CO2, and H2O and uses sunlgiht to....

Back 58

Photosynthesis takes energy-poor, non-reactive CO2 and
H2O and uses sunlight to turn these into energy-rich sugars

Front 59

Is ATP used in cellular respiration and photosynthesis?

Back 59

ATP is produced not only in cellular respiration,
ATP but also as an intermediate in sugar production in photosynthesis

Front 60

C-H bonds as energy storage

Back 60

Therefore, C-H bonds in energy-rich molecules like sugars are instead used for energy storage – and the sugars need to broken down again later to ATP.

Front 61

(anabolism

Back 61

production of energy-rich molecules and/or of the organism’s material substance

Front 62

catabolism

Back 62

degradation of energy-rich food
and/or of the organism’s material substance

Front 63

Nonpolar bonds

Back 63

Nonpolar bonds have high chemical potential energy and low stability; C-H bonds serve as an energy source

C-H, sugar

Front 64

Polar

Back 64

Polar bonds have low chemical potential energy and high stability; these molecules are not an energy source

CO2, H2O

Front 65

Monosaccharides

Back 65

Glucose and Fructose and Galatose

Front 66

Disaccharide

Back 66

Sucrose (glucose plus fructose)

Lactose (glucose plus galatose)

Front 67

When is a disaccharide formed?

Back 67

A disaccharide is formed when dehydration
synthesis (-H2O) joins two monosaccharides

Front 68

Predict the formula for a disaccharide made from two hexoses.

A) C2H4O2
B) C6H12O6
C) C12H24O12
D) C12H22O11
E) C12H20O10

Back 68

D

Front 69

HFCS formula

Back 69

55% fructose /
45% glucose

Front 70

Problems with HFCS

Back 70

Sugar transporter in human gut is best at taking up 1
glucose + 1 fructose;
is slow in taking up extra fructose
~30% of US pop. suffer varying degrees of
fructose mal-absorption

Front 71

Q4. Draw conclusions about lactose intolerance. Choose the best answer.

A) Lactose tolerance is the original human condition for adults
from the time of hunter-gatherers.
B) Lactose intolerance is the original human condition for adults
from the time of hunter-gatherers.
C) In those ancient human populations that raised dairy cows,
adults who were lactose intolerant had a lesser chance of
survival and reproduction.
D) B and C
E) A and C

Back 71

D

Front 72

Large Carbohydrates = Polysaccharides

Back 72

Starch (energy storage carbohydrate in plants)
Glycogen (energy storage carbohydrate in animals)
Cellulose (cell wall for structural support in plants)

Front 73

Alpha (α) glucose

Back 73

forms the spiraling helices of the
easy-to-digest storage carbohydrates starch & glycogen

Front 74

Beta (β ) glucose

Back 74

forms straight fibers
of the hard-to-digest structural carbohydrate cellulose

Front 75

Cellulose

Back 75

makes up the tightly-packed
fiber structure of plant cell walls

Front 76

High blood glucose

Back 76

stimulates fat storage

Foods with more slowly digestible carbohydrates contain non-digestible cellulose and slowly digestible straches

Front 77

amylose

Back 77

The long, unbranched strands of amylose (in, e.g., beans) are slowly digested.

Front 78

amylopectin

Back 78

The highly branched amylopectin (e.g., in rice, white flour,
or baking potatoes) is quickly digested (amylopectin is
even more rapidly digested than the free sugar sucrose).

Front 79

Glycogen

Back 79

Humans store glycogen in the liver as a quickly mobilized energy source

quickly mobilized & quickly exhausted:
Good for sprint/mental tasks

High consumption of dietary sugars and quick-burning
starches triggers energy storage – some as glycogen in the
liver, the majority as visceral fat.

Front 80

Fat

Back 80

slowly mobilized & more lasting:
Good for extended exercise/marathon

Front 81

Q5. “Fast-twitch” muscle fibers are used for sprints
and “slow-twitch” fibers for extended exercise.
Predict which is correct:
A) Fast-twitch fibers store mostly fat, while slow-twitch
fibers store mostly glycogen
B) Fast-twitch fibers store mostly glycogen, while
slow-twitch fibers store mostly fat
C) Both fiber types store mostly glycogen
D) Both fiber types store mostly fat

Back 81

B

Front 82

ATP energy
H shuttle NADPH

Back 82

shuttles H (as H+ and electrons) derived from H2O to where
CO2 is converted to the C-H bonds in sugar

Front 83

HIGH-ENERGY
MOLECULES

Back 83

ATP and NADPH

Front 84

Q6. Predict the relative rates of photosynthesis
versus respiration in a green leaf.
A) Overall photosynthesis rates and respiration
rates should be the same.
B) Overall photosynthesis rates should be higher.
C) Overall respiration rates should be higher.

Back 84

B

Front 85

Stroma

Back 85

Fluid space: Conversion of CO2 to
sugars in the Calvin cycle

Front 86

Do you need ATP in the Calvin Cycle?

Back 86

For conversion of CO2 to sugar, we
need ATP energy and H (energized electrons +H+)
for loosely held electrons in C-H bonds

Front 87

What does sunlight provide?

Back 87

Sunlight provides the energy to make ATP and
to extract electrons from water, energize these
and load them (and H+) onto the H shuttle
NADPH

ATP and NADPH

Sunlight powers the splitting of H2O
into H+, O2, and electrons+

Sunlight provides the energy to excite
electrons to become high-energy
electrons

Front 88

What provides energy for the ATP formation?

Back 88

Downhill flow of excited
electrons from high to
low energy (indirectly)
provides the energy for
ATP formation; ATP is
used in the Calvin cycle
for sugar formation

Front 89

After the electrons are energized again, where are they loaded?

Back 89

Sunlight energizes electrons again;
energized electrons (and H+) are loaded
onto NADP+; the H shuttle NADPH
provides high-energy electrons and H+ for
the C-H bonds in sugars

Front 90

Summary of Electrons through the thylakoid

Back 90

1. Light energizes electrons to high-energy electrons
2. Downhill electron flow energizes active uphill transport
of H+ from low H+ in stroma to high H+ inside thylakoids
3. Downhill H+ flow (from within thylakoids to stroma) energizes ATP formation
4. Light energizes electrons again for loading onto NADP+

Front 91

Protons are pumped where?

ATP is formed where?

Back 91

Protons are pumped uphill into the inner thylakoid space
(pile up like water behind a dam)
and ATP is formed in the stroma

Inner thylakoid space, thylakoid membrane, and stroma

Front 92

ATP Synthase

Back 92

Thylakoid space H+ powers the turbine

Stroma is where phosphorylation is

Front 93

Q7. Fill in the blanks: When comparing photosynthetic
electron transport to the model of a hydroelectric dam, water
stands for ________, the turbine stands for ________, and
the lit-up light bulb stands for _________.

Back 93

C

Front 94

ATP is formed in chloroplasts & mitochondria

Back 94

Intermembrane space = thylakoid space

Inner membrane = thylakoid membrane

Matrix = Stroma

Front 95

Q8. What force drives the build-up of the proton (H+) gradient
across the photosynthetic membrane that subsequently
serves to drive ATP formation?
A) an ATP-fueled proton pump
B) water
C) light-driven electron transport
D) ATP
E) an ATP-fueled electron pump

Back 95

C

Front 96

Outer cell membrane

Back 96

Bring in food & building blocks; eliminate waste;
keep out unwanted materials

Front 97

•Internal membranes of chloroplasts & mitochondria

Back 97

Platform for energy transformations via electron
transport chains & ATP synthase turbines; these
membranes act like dams, behind which protons can be
accumulated like water behind a dam

Front 98

Which of the following represent a state of high energy?

A) excited electrons
B) the H+ gradient across the thylakoid membrane
C) the H (electrons + H+) loaded onto NADPH
D) the ATP formed
E) all of the above

Back 98

E

Front 99

Hemoglobin

Back 99

Hemoglobin in red blood cells transports O2 from the lungs to body cells
that burn energy-rich C-H bonds from food to CO2 and H2O in cellular
respiration to produce ATP; CO2 from the body cells is then transported
back to the lungs by hemoglobin (red blood cells).

Front 100

O2 binding capacity is affected by what?

Binding capacity cycle

Back 100

Hemoglobin’s O2 binding capacity
is affected by CO2 concentration

Muscle releases CO2 (from cellular respiration) into blood fluid, which results in a decrease in hemoglobin's O2 binding capacity

CO2 is released through lungs into the air, the drop in CO2
concentration in the blood fluid increases
hemoglobin’s O2 binding capacity; O2 inhaled by the lungs binds tightly to hemoglobin

Front 101

Q10. Hemoglobin _____ O2 in the lungs and _____ O2 in
the muscle; the binding capacity of hemoglobin for O2 is
____ in the lungs and _____ in the muscle region.
A) binds; releases; low; high
B) releases; binds; high; low
C) binds; releases; high; low
D) binds; releases; low; high

Back 101

C

Front 102

Molecular mechanism

Back 102

Adding CO2 to water makes the water acidic by increasing the H+ concentration

This causes ocean acidification
as well as acidification of the
blood fluid around respiring cells;
the high H+ concentration lowers
hemoglobin’s O2-binding capacity

Front 103

Extracts high energy electrons

Back 103

To extract their high-energy electrons, sugars are broken down in steps, starting with glycolysis in cytosol

Front 104

Where does glycolysis take place?

Back 104

cytosol, cytoplasm

Front 105

Extracted energy is transferred where? to make what?

Back 105

Energy is extracted from C-H bonds by transfer of high-energy electrons + H+ to NADH and then into electron transport to make lots of ATP

Front 106

What does NADH do?

Back 106

Feeds high-energy electrons into electron transport chain to make lots of ATP.

Front 107

Most ATP is formed by?

Back 107

Electron transport

Front 108

What happens in the mitochondrial
matrix?

Back 108

Citric acid cycle

Front 109

What happens in folded inner mitochondrial membranes?

Back 109

Electron transport chain & ATP formation

Front 110

In both mitochondria and chloroplasts:

Carbon conversion cycles in fluid space

Back 110

Calvin cycle (in chloroplast stroma) or
citric acid cycle (in mitochondrial matrix)

• Electron transport chain (downhill electron flow
from high to low energy) &
ATP synthase on inner membranes (thylakoids or
inner mitochondrial membranes)

Front 111

terminal electron acceptor”

Back 111

Oxygen serves as the “terminal electron acceptor” in mitochondrial respiration (oxidative
phosphorylation)

Without oxygen, ATP levels drop quickly, and we die.

Front 112

Q11. After ATP fuels the Na+/K+ pump at the cell membrane in an animal cell, where do the “used-up” ADP and P go?

Back 112

D

Front 113

Q12. Cells use the energy of energy-rich food
molecules to form ATP. Which of the following
represents a state of high energy?
A) the C-H bonds in food molecules
B) the H (electrons + H+) loaded onto NADH
C) The H+ gradient across the mitochondrial
membrane
D) the ATP formed
E) all of the above

Back 113

E

Front 114

Q13. Humans generate much more heat than alligators. This
is due to
A) a greater number of energy transformations per minute in
humans.
B) a higher percentage of energy loss per transformation in
humans.
C) Both A and B

Back 114

C

Front 115

Brown Fat Cells

Back 115

produce heat in newborns, small
mammals in cold climates, & hibernating animals.

Brown fat cells have
many mitochondria

and use an uncoupling protein to uncouple electron transport from ATP formation to generate only heat and no ATP at all

Front 116

Mitochondrial uncoupling protein

Back 116

The mitochondrial uncoupling
protein provides a channel
across the membrane
through which protons (H+)
flow back downhill without
making ATP,
releasing all energy as heat

Front 117

Q16. Where does the oxygen produced in
photosynthesis come from?
A) CO2
B) OH groups of glucose
C) C6H12O6
D) H2O
E) chlorophyll

Back 117

D

Front 118

Q17. Both mitochondria and chloroplasts produce
which of the following?
A) ATP
B) sugars
C) oxygen
D) carbon dioxide
E) A and C

Back 118

A

Front 119

Q18. Which of these molecules are the least stable?
A) sugars and fats
B) ATP and NADH
C) H2O and CO2

Back 119

B

Front 120

Purpose of Cellular Respiration and Photosynthesis

Back 120

ATP is too unstable to serve as a storage form of energy.
• Therefore, C-H bonds in molecules (e.g., sugars) are used for energy storage.
• Sugars are made with solar energy (via ATP) in Photosynthesis, and Cellular Respiration converts
the energy of sugars back to ATP as needed.

Front 121

Q19. What does NOT require a direct association with
membranes in both mitochondria and chloroplasts?

A) carbon conversion cycles
B) ATP synthesis by ATP synthase
C) build-up of a proton (H+) gradient
D) electron transport chains

Back 121

A)

Occurs in the matrix/ stroma aka in the fluid space, not a direct association

Front 122

Q20. The energy released by electrons flowing downhill along
either the photosynthetic or mitochondrial electron transport chain
is DIRECTLY converted to the energy of
A) Glucose
B) an H+ gradient
C) ATP
D) H2O
E) NADH

Back 122

B

Front 123

Q21. While __________ are generated by mitochondria,
________ are generated by chloroplasts.
A) water and oxygen; sugar and carbon dioxide
B) water and carbon dioxide; sugar and oxygen
C) sugar and oxygen; water and oxygen
D) sugar and water; oxygen and carbon dioxide
E) oxygen and carbon dioxide; energy-rich macromolecules

Back 123

B

Front 124

Difference between dissociation of H2O and H+

Back 124

No electrons are removed from O2

Photosynthesis extracts electrons from water
2 H2O to 4 H+ + 4 electrons + O2
& cellular respiration re-combines O2 with 4 electrons to re-form 2 H2O

Front 125

Glycolysis is outside mitochondria

Back 125

•Only when oxygen is present can glucose be broken down completely in the mitochondria for highest ATP energy yield

Front 126

Anaerobic respiration =

Aerobic =

Back 126

fermentation

oxidative respiration

Front 127

Fast-twitch

Back 127

Fast-twitch glycolytic fibers (for sprint) use glycolysis - quick, but does not provide much energy.

Front 128

Slow-twitch

Back 128

Slow-twitch oxidative fibers (with many mitochondria for extended exercise) use oxidative respiration - slower, but yields much more ATP energy.

Front 129

Low and High Demand plant growth

Back 129

Low demand for
sugars by the rest of
the plant when plant is
not growing --- Starch stores in leaves

High demand for
sugars by the rest of
the plant when the
plant grows rapidly -- energy burned in growing plants

Front 130

Q22) Which took place in the ABSENCE OF molecular
oxygen (O2) or ozone (O3).
A) evolution of organisms from the ocean to the terrestrial
(land) habitat
B) evolution of multi-cellular organisms
C) evolution of prokaryotes that use fermentation
D) evolution of ATP formation in mitochondria
E) evolution of plants and animals

Back 130

C

Front 131

Biofuels

Back 131

Ethanol from:

Starch 22

Sucrose 56

Cellulose 91

Front 132

Starch

Back 132

Starch is easy to convert to hexoses.

HOWEVER: Annual crop, high input of fertilizer (produced with fossil fuels); only small portion of plant mass used

Huge food versus fuel conflict: Price of corn has more than tripled over the last decade

Front 133

Sucrose

Back 133

: major carbohydrate in sugar cane &
sugar beet; only 1 step to split sucrose into hexoses (for conversion to ethanol)

Seven harvests of cane before replanting is necessary.

Cane waste is burned for power & heat.

Still: food versus fuel conflict

Front 134

Cellulosic ethanol

Back 134

Only some microbes have enzymes to break bond in cellulose

Front 135

When leaf pores (stomates) open to allow CO2 to move in, a lot of H2O is lost at the same time.

Back 135

C3 plants: 400-500 g H2O lost per g CO2 fixed

C4 plants: 250-300 g H2O lost per g CO2 fixed

Front 136

Rubisco fixes CO2 efficiently only
at high, but not at low, CO2
concentrations.

Back 136

CO2 concentration in Earth’s
atmosphere:
High when Rubisco evolved billions
of years ago
Low when C4 plants evolved

Front 137

C4 Plants

Back 137

have an additional enzyme that fixes CO2 efficiently under low internal CO2 concentrations; they then re-release high
concentrations of CO2 near Rubisco, which allows Rubisco to re-fix CO2 efficiently.

C4 plants fix CO2 at much lower internal concentrations than C3 plants; C4 plants use TWO CO2-fixing cycles in series that both use ATP energy.

Front 138

Q23. Predict features of C3 and C4 plants resulting from the fact
that (i) C4 plants operate two CO2-fixing cycles instead of only one
like C3 plants and that (ii) C4 plants are able to fix CO2 at much
lower concentrations than C3 plants.
A) C4 plants do not need to open their leaf pores as widely as C3
plants to do photosynthesis.
B) C4 plants lose less water than C3 plants through their leaf
pores.
C) C4 plants need more energy from sunlight than C3 plants
D) A and B
E) A, B, and C

Back 138

E

Front 139

Q24. Predict in which environments C3 plants versus C4 plants
should each be most successful. C3 plants will be most
successful in __________ environments, and C4 plants will be
most successful in __________ environments.
A) sunnier and drier; less sunny but moister
B) less sunny but moister; sunnier and drier
C) less sunny but drier; sunnier and moister
D) sunnier and moister; less sunny but drier

Back 139

B

Front 140

Q25) Four of the statements below are false. Find the one that
is TRUE.
A) C3 plants are able to fix CO2 with their stomates (leaf pores)
less widely open than C4 plants.
B) C3 plants are more productive in dry climates than C4
plants.
C) C4 plants need more water than C3 plants.
D) C4 plants need more energy (sunlight) to make sugars than
C3 plants.
E) C3 plants operate two CO2 fixation cycles.

Back 140

D

Front 141

Q26) Ethanol is produced as a biofuel by fermentation of
monosaccharides. Which of the plant sources below is
DIFFICULT to break down into monosaccharides?
A) sucrose from sugarcane
B) starch from corn
C) starch from grasses
D) cellulose from grasses
E) sucrose from C4 plants

Back 141

D

Front 142

Quickly digested vs. non digestable

Back 142

Non-digestible cellulose and
slowly digested amylose
starch

Sugar or rapidly digested
amylopectin starch

Front 143

Glycemic Index

Glycemic Load

Back 143

• Glycemic index (GI) = Rapidity of conversion to glucose
• Glycemic load (GL) = GI x amount of food consumed

Front 144

Q27. Predict which type of fruit should be most likely
to contain fructose?
A) one growing in a region with year-round fruit
availability
B) one growing in a region with fruit availability only in
a single season
C) a fruit eaten by animals that do not detect fructose
well
D) a large fruit

Back 144

B

Front 145

correctly describes the endosymbiont theory.

Back 145

Eukaryotes acquired mitochondria and chloroplasts by engulfing prokaryotes.

Front 146

Four of the findings below provide evidence in support of the endosymbiont theory of eukaryote evolution. Find the exception.

Back 146

DNA in nucleus

Front 147

Energy can be extracted from which parts of the sugar molecule?

Back 147

C-H

Front 148

The uncoupling protein converts the energy provided by ______ to _______ .

Back 148

glucose heat