chapter 10: photosynthesis (test 4)

Question 1

•___ is the ability to capture sunlight energy and convert it to chemical energy

•

•Early cells evolved the ability to perform photosynthesis about 2 billion years ago

Answer 1

Photosynthesis

Question 2

___ sustain themselves without eating anything derived from other organisms

Autotrophs are the producers of the biosphere, producing organic molecules from CO2 and other inorganic molecules

Photosynthesis occurs in plants, algae, certain other unicellular eukaryotes, and some prokaryotes

Answer 2

Autotrophs

Question 3

___ obtain their organic material from other organisms

Heterotrophs are the consumers of the biosphere

Almost all heterotrophs, including humans, depend on ___for food and O2

Answer 3

Heterotrophs

photoautotrophs

Question 4

• Flattened leaf shape exposes large surface area to catch sunlight
• Upper and lower leaf surfaces of a leaf comprise the epidermis
• Waxy, waterproof cuticle on outer surfaces reduces water evaporation

•

Answer 4

just review

Question 5

•Adjustable pores called stomata allow for entry of air with CO2

•

• Vascular bundles (veins) consist of xylem that supply water and minerals to the leaf while phloem carries sugars away.
• Inner mesophyll cell layers contain majority of chloroplasts

Answer 5

just review

Question 6

• Mesophyll cells have ___ chloroplasts each
• Chloroplasts are bounded by a ___ composed of the inner and outer membranes

Answer 6

40-200

double membrane

Question 7

• The ___ is the semi-fluid medium within the inner membrane
• Disk-shaped sacs called ___ found within the stroma in stacks called grana

•

Answer 7

stroma

thylakoids

Question 8

(Two Groups of Reactions are localized in chloroplasts)

1.___-dependent reactions (“photo part”)

–Chlorophyll and other molecules of the thylakoids capture ___

–Sunlight energy is converted to the ___

–Oxygen gas is released as a by-product

Answer 8

Light

sunlight energy

energy carrier molecules ATP and NADPH

Question 9

(Two Groups of Reactions are localized in chloroplasts)

2.Light-independent reactions (synthesis part)

–Enzymes in the stroma synthesize ___ and other organic molecules using the chemical energy stored in ATP and NADPH

Answer 9

glucose

Question 10

(Light Dependent Reactions)

•Captured sunlight energy is stored as chemical energy in two carrier molecules

– ___

– ___

Answer 10

Adenosine triphosphate (ATP)

Nicotinamide adenine dinucleotide phosphate (NADPH)

Question 11

(The Nature of Sunlight)

Light is a form of ___, measured in different wavelengths

___ consists of wavelengths (including those that drive photosynthesis) that produce colors we can see

Light also behaves as though it consists of discrete ___

Photons are packets of energy with different energy levels

Answer 11

electromagnetic energy

Visible light

particles, called photons

Question 12

(Photosynthetic Pigments: The Light Receptors)

Pigments are substances that absorb visible light

Different pigments absorb different wavelengths

Wavelengths that are not absorbed are ___

Leaves appear green because ___

Answer 12

reflected or transmitted

chlorophyll reflects and transmits green light

Question 13

___ is the main photosynthetic pigment

Accessory pigments, such as chlorophyll b, broaden the spectrum used for photosynthesis

Accessory pigments called ___ absorb excessive light that would damage chlorophyll

Answer 13

Chlorophyll a

carotenoids

Question 14

•Photosystems are ___

–Two Photosystems (PSI and PSII) on thylakoid membranes

–Each Photosystem is associated with an ETC (electron transport chain)

–

Answer 14

assemblies of proteins, chlorophyll, & accessory pigments

Question 15

(Light-Dependent Reactions)

Steps of the light reactions:

1. Accessory pigments in Photosystems absorb light and pass energy to ___ containing chlorophyll
2. Reaction centers receive energized electrons…

Answer 15

reaction centers

Question 16

(Light-Dependent Reactions)

3. Energized electrons then passed down a series of electron carrier molecules ___
4. Energy released from passed electrons used to synthesize ATP

●

5.Energized electrons also used to make ___

Answer 16

(Electron Transport Chain)

NADPH

Question 17

(Photosystem II Generates ATP)

Steps of ATP generation by PSII:

1. ___ photons absorbed by Photosystem II

–Light energy passed between pigment molecules

2.At reaction center, ___ electrons boosted out of two chlorophyll molecules when energy arrives…

Answer 17

Two

two

Question 18

(Photosystem II Generates ATP)

3.First electron carrier accepts two energized electrons

–Electrons then passed between ___

–Energy released from electrons used to pump ___

4.H+ ion concentration gradient used to drive ATP synthesis (chemiosmosis/photophosphorylation)

Answer 18

carrier molecules

H+ into thylakoid compartment from stroma

Question 19

(Photosystem I Generates NADPH)

5.___ absorbed by Photosystem I

•Energy passed to reaction center chlorophyll

6. ___ boosted and ejected from reaction center
7. Electrons passed down electron transport chain for PS I…

Answer 19

Photons of light

Two high energy electrons

Question 20

(Photosystem I Generates NADPH)

8. Two electrons, NADP+, and H+ ion used to form 1 ___ molecule
9. H+ ion obtained from the splitting of H2O into 2 ___

Answer 20

NADPH

H+ and ½O2

Question 21

(Maintaining Electron Flow (from PSII into PSI)

•Electrons leaving PS II replaced when H2O is split:

•

– H2O –> ½O2 + 2H+ + 2e-

–Two electrons from water replace those lost when 2 photons boost 2 electrons out of PSII

–Two hydrogen ions used to form NADPH

–Oxygen atoms combine to form O2

Question 22

(Light-Independent Reactions)

• ___ from light-dependent reactions used to power glucose synthesis
• Light ___ for light-independent reactions if ATP & NADPH available
• Light-independent reactions called the ___

Answer 22

NADPH and ATP

not directly necessary

Calvin-Benson Cycle or C3 Cycle

Question 23

(The C3 Cycle)

• 6 CO2 used to synthesize 1 glucose (C6H12O6)
• Carbon dioxide is captured and linked to ribulose bisphosphate (RuBP)
• ATP and NADPH from light dependent reactions used to power C3 reactions

Question 24

(C3 Cycle Has Three Parts)

1.___ (carbon capture)

–6 Ribulose bisphosphate (RuBP) molecules combine with 6CO2

–Fixation step and subsequent reactions yield twelve 3-carbon phosphoglyceric acid (PGA) molecules…

•

Answer 24

Carbon fixation

Question 25

(C3 Cycle Has Three Parts)

2.Synthesis of ___

–Energy is donated by ATP and NADPH

–Phosphoglyceric acid (PGA) molecules are converted into glyceraldehyde 3-Phophate (G3P) molecules …

•

Answer 25

Glyceraldehyde 3-Phosphate (G3P)

Question 26

(C3 Cycle Has Three Parts)

3.Regeneration of ___

–10 of 12 G3P molecules converted into 6 RuBP molecules

–2 of 12 G3P molecules used to synthesize 1 glucose

–ATP energy used for these reactions

Answer 26

Ribulose bis-phosphate (RuBP)

Question 27

Question 28

Glucose Synthesis

• One cycle of the C3 Cycle produce two ___
• Two G3P molecules (3 carbons each) used to form 1 glucose (6 carbons)
• Glucose may later be broken down during cellular respiration or stored in chains as starch or cellulose

Answer 28

“left over” G3P molecules

Question 29

(Relationship Between Reactions)

• Light dependent reactions produce ___ which is used to drive light-independent reactions
• Depleted carriers (ADP and NADP+) return to light-dependent reactions for recharging

Answer 29

ATP and NADPH