GRE Subject Test: Biology : Understanding Plant Metabolism and Photosynthesis
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Example Questions
Example Question #1 : Plant Biology
The Calvin cycle takes place in the __________ and occurs __________.
stroma . . . only during the absence of light
stroma . . . whenever the appropriate nutrients are present
cytoplasm . . . only during the absence of light
cytoplasm . . . whenever the appropriate nutrients are present
stroma . . . whenever the appropriate nutrients are present
The Calvin cycle takes place in the stroma of the chloroplast, which is the region in the chloroplast lumen outside of the thylakoids. It does not actually matter whether or not light is present for the reactions of the Calvin cycle to take place. They are light independent, but light will not prevent the reactions from occurring, similar to how glycolysis is independent of oxygen. As long as the appropriate nutrients and reactants are present, including ATP and NADPH generated from the light reactions, the Calvin cycle will occur.
Example Question #1 : Plant Biology
What is the purpose of photosystem II in photosynthesis?
Split water to create a high concentration of hydrogen ions
Sequester carbon dioxide and facilitate its binding to rubisco
Donate electrons to NADP+ reductase
None of the other answers
Donate electrons to ATP synthase
Split water to create a high concentration of hydrogen ions
Photosystem II splits water into hydrogen and oxygen. Hydrogen ions accumulate in the thylakoid space, creating an electrochemical concentration gradient. Due to this gradient, hydrogen ions pass through ATP sythase, powering the synthesis of ATP from ADP + Pi.
Example Question #1 : Plant Structures
Which of the following structures is unique to plant cells?
Endoplasmic reticulum
Mitchondria
Chloroplasts
Vacuoles
Lysosomes
Chloroplasts
Chloroplasts are organelles in plant cells that conduct photosynthesis; therefore they are unique to plant cells. All the other mentioned organelles can be found in both animal and plant cells.
Example Question #2 : Plant Biology
Which of the following can be found in plant cells, but not animal cells?
Mitochondria
Chloroplasts
Ribosomes
Cell membrane
Chloroplasts
Chloroplasts, the site of photosynthesis, are only in plant cells and are not found in animal cells. Ribosomes, a cell membrane, and a mitochondria, however, can be found in both animal and plant cells.
The other structure that may be found in plant cells, but not animal cells, is a cell wall.
Example Question #1 : Plant Biology
Where in the chloroplasts does the Calvin Cycle of photosynthesis take place?
Thylakoid membrane
Grana
Thylakoid lumen
Stroma
Intermembrane space
Stroma
The Calvin Cycle occurs in the stroma, the aqueous fluid-filled area of the chloroplast. The stroma can be seen as analogous to the cytoplasm of a cell, in that it is the liquid in which all other substructures reside. The other processes of photosynthesis, the light-dependent reactions, take place in the thylakoid, a membrane-bound substructure within the chloroplast.
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