Chapter 8: Photosynthesis
What happens to a pair of electrons after it reaches Qb?
It enters an electron transport chain in the thylakoid membrane
The synthesis of NADPH is catalyzed by what?
NADP+ reductase
How is NADPH formed in PSI?
NADP= reductase adds two electrons and a H+ to NADP+
What is the source of electrons used to reduce the C-O bond of 3-phosphoglycerate during the Calvin cycle?
NADPH
A(n) _____ ______ is a diagram that depicts the wavelengths of electromagnetic radiation that are absorbed by a pigment.
absorption spectrum
During noncyclic electron flow, electrons flow from water to?
photosystem II, then to photosystem I and ultimately are transferred to NADP+
During photosynthesis, NADPH is synthesized by?
photosystems I
RuBP carboxlse/oxygenase, also known as ____, is the most abundant protein in chloroplasts.
rubisco
Photosystems I and II are located in the?
thylakoid membrane
If 14CO2 (radioactive CO2) is added to plants, you might expect the 14C tagged carbon atom to be first found in___.
3-phosphoglycerate
What are the there phases of the Calvin Cycle?
1. Carbon fixation 2. Reduction and Carbohydrate Production 3. Regeneration of ribulose biphosphate
Which of the following is the key bond change that occurs during the reduction phase of the Clavin Cycle? 1. The molecule is phosphorylated 2. A six-carbon molecule is split into a three-carbon molecule 3. A C-O a C-H bond 4. A C-H bond to a C-O bond
A C-O to a C-H bond
The Calvin Cycle uses energy from ____, and high-energy _____ supplied by NADPH.
ATP and electrons
Why might plants contain a variety of pigments?
Because this feature enables plants to absorb light at many different wavelengths
In the first phase of the ____, atmospheric carbon dioxide is fixed into a five carbon sugar.
Calvin cycle
Why is the rate of photosynthesis slow in the green region of the visible light spectrum?
Green light is not absorbed by chlorophyll
The energy that is released as electrons pass from one electron carrier to the next is used to pump ____ ions into the thylakoid membrane
H+
___ excites electrons in pigment molecules in photosystems I and II.
Light
The flow of electrons from PSII to PSI is considered to be?
Linear electron flow
In the Calvin Cycle, CO2 is:
Reduced
In the last phase of the Calvin cycle, what molecule is regenerated so that the next cycle can occur?
Ribulose bisphophate
What enzyme is responsible for carbon fixation?
RuBP or rubisco
Following Qb excited elections pass down an electron transport chain that is arranged according to?
The electronegativity of electron carriers
What was the purpose of the experiment in which Calvin and his colleagues injected algae with C-labeled CO2, incubated the cells for carious time periods, and then separated the radio labeled molecules with paper chromatography?
To determine the order of reactions in the Calvin cycle
What molecule is produced by photosystems II?
Oxygen
In the process of carbon ____, carbon dioxide is incorporated into a molecule of ribulose diphosphate forming an unstable 6 carbon intermediate that immediate that immediately splits into two 3 carbon molecules
Fixation
After leaving P680, a high energy electron is transferred to___, which diffuses away from the reaction center.
Pheophytin, then to Qa and finally to Qb
Why is a three-carbon molecule reduced to another three-carbon molecule in phase 2 of the Calvin cycle?
Because the bonds in G3P store more energy and polymerize more readily
The end product of phase 2 of the Calvin cycle is G3P. This molecule is used to synthesize _____ and to regenerate the starting material _____ bisphosphate.
Carbohydrate and RuBP
What is carbon fixation?
Incorporation of carbon into an organic molecule that is not a gas.
In the light reactions, ATP is generated via
chemiosmosis
After incubating algae with 14C and incubating the cells for a short time, Calvin separated the radio labeled molecules that were present using a technique called paper ____.
chromatography
The synthesis of ATP using light as the ultimate energy source is called?
photophosphorylation