Chapter 8B: Photosynthesis Part 2
Carbohydrates are very important to plant cells because they: (2 answers)
1.Can be used as an energy reserve 2.Form the building block for many organic macromolecules
The sequence of the calvin cycle from first to last (3)
1.Carbon fixation 2.Reduction and carbohydrate production 3.Regeneration of ribulose bisphosphate
In C4 plants, the first product of carbon fixation is _____
A four carbon molecule
In cyanobacteria, the calvin cycle occurs in the ________ of the cells
Cytoplasm
True or false: glucose is the primary output of the calvin cycle
False
In PSII water is "split" and the electrons are used to replenish excited electrons that are lost from the photosystem. The loss of electrons during the oxidation of water, results in the formation of ___________ ___
Oxygen gas
What differentiates PEP carboxylase from rubisco?
PEP carboxylase does not bind oxygen
What chemical reaction is catalyzed by the enzyme PEP carboxylase?
Phosphoenolpyruvate + CO2 -->Oxaloacetate
Resonance energy transfer
The process by which energy (not an electron itself) can be transferred to adjacent pigment molecules during photosynthesis
_____ plants avoid water loss by closing their stomata during the day and opening them at night
CAM
____ plants only uptake CO2 at night because they close their ________ during the day
CAM; stomata
What molecule is reduced in the calvin cycle?
CO2
In the first phase of the ________, atmospheric carbon dioxide is fixed into a five carbon sugar
Calvin Cycle
The end product oh phase 2 of the Calvin Cycle is G3P. This molecule is used to synthesize _________ and to regenerate the starting material _______ bisphosphate
Carbohydrates ; RuBP
What molecule is released during photorespiration?
Carbon dioxide
What is the origin of the carbons in a carbohydrate generated by photosynthesis?
Carbon dioxide in the atmosphere
Carbon fixation
Carbon has been removed from the atmosphere and fixed into an organic molecule that is not a gas
What chemical reaction is catalyzed by the enzyme rubisco?
Chemical reaction: Carbon fixation
The light reactions of photosynthesis require water to supply two ______ that are transferred to P680+
Electrons
After _____ molecules are made, they may be linked together in a polysaccharide called starch
Glucose
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?
RuBP (ribulose bisphosphate)
True or false: Water is oxidized during the light reactions of photosynthesis
True
What is the role of the reaction center in a photosystem?
It transfers a high energy electron to another molecule
What are components of both PSI and PSII?
A reaction center and a light harvesting complex
What is the source of electrons used to reduce the C-O bond of 3-phosphoglycerate during the calvin cycle?
NADPH
All the products of the light reactions of photosynthesis that are used as reactants in the Calvin Cycle....
NADPH and ATP
During the calvin cycle, high energy electrons are provided by _____, and the source of energy for the reactions is ______
NADPH; ATP
The G3P produced at the end of the second phase of the calvin cycle is directly used for which of the following? (2)
1.Make glucose or other carbohydrates 2.Regenerate ribulose bisphosphate (RuBP)
What advantages do C4 plants have over C3 plants in warm, dry climates? (2 advantages)
1.They can keep their stomata partially closed during the day to conserve water 2.They can minimize photorespiration
What conditions affect the way the Calvin cycle operates in photosynthetic organisms? (3)
1.Water availability 2.Temperature 3.Light intensity
Photorespiration is favored when plants are exposed to a ______ and _____ environment
Hot; Dry