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