chapter 10: photosynthesis (test 4) Flashcards
•___ 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
Photosynthesis
___ 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
Autotrophs
___ 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
Heterotrophs
photoautotrophs
- 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
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just review
•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
just review
- Mesophyll cells have ___ chloroplasts each
- Chloroplasts are bounded by a ___ composed of the inner and outer membranes
40-200
double membrane
- The ___ is the semi-fluid medium within the inner membrane
- Disk-shaped sacs called ___ found within the stroma in stacks called grana
•
stroma
thylakoids
(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
Light
sunlight energy
energy carrier molecules ATP and NADPH
(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
glucose
(Light Dependent Reactions)
•Captured sunlight energy is stored as chemical energy in two carrier molecules
– ___
– ___
Adenosine triphosphate (ATP)
Nicotinamide adenine dinucleotide phosphate (NADPH)
(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
electromagnetic energy
Visible light
particles, called photons
(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 ___
reflected or transmitted
chlorophyll reflects and transmits green light
___ 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
Chlorophyll a
carotenoids
•Photosystems are ___
–Two Photosystems (PSI and PSII) on thylakoid membranes
–Each Photosystem is associated with an ETC (electron transport chain)
–
assemblies of proteins, chlorophyll, & accessory pigments
(Light-Dependent Reactions)
Steps of the light reactions:
- Accessory pigments in Photosystems absorb light and pass energy to ___ containing chlorophyll
- Reaction centers receive energized electrons…
reaction centers
(Light-Dependent Reactions)
- Energized electrons then passed down a series of electron carrier molecules ___
- Energy released from passed electrons used to synthesize ATP
●
5.Energized electrons also used to make ___
(Electron Transport Chain)
NADPH
(Photosystem II Generates ATP)
Steps of ATP generation by PSII:
- ___ 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…
Two
two
(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)
carrier molecules
H+ into thylakoid compartment from stroma
(Photosystem I Generates NADPH)
5.___ absorbed by Photosystem I
•Energy passed to reaction center chlorophyll
- ___ boosted and ejected from reaction center
- Electrons passed down electron transport chain for PS I…
Photons of light
Two high energy electrons
(Photosystem I Generates NADPH)
- Two electrons, NADP+, and H+ ion used to form 1 ___ molecule
- H+ ion obtained from the splitting of H2O into 2 ___
NADPH
H+ and ½O2
(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
(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 ___
NADPH and ATP
not directly necessary
Calvin-Benson Cycle or C3 Cycle
(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
(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…
•
Carbon fixation
(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 …
•
Glyceraldehyde 3-Phosphate (G3P)
(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
Ribulose bis-phosphate (RuBP)
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
“left over” G3P molecules
(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
ATP and NADPH
