To what does the term grana refer?
Select one:
a. ?a flattened disk or sac in the chloroplast
b. ?the central fluid-filled space of the chloroplast
c. ?the double membrane of the chloroplast
d. ?the cytochrome system in the membranes of the thylakoids
e. ?a stack of thylakoid membranes
The Correct Answer and Explanation is :
The correct answer is:
e. a stack of thylakoid membranes
Explanation:
Grana (plural of granum) refer to the stacks of thylakoid membranes found within the chloroplasts of plant cells. These structures play a crucial role in the process of photosynthesis, which is how plants convert light energy into chemical energy.
Within the chloroplast, the thylakoid membranes contain chlorophyll and other pigments that are vital for capturing light energy. The individual membranes are stacked into structures called grana, which increase the surface area available for light-dependent reactions of photosynthesis. These reactions take place in the thylakoid membranes and involve the absorption of light energy, which is used to split water molecules (photolysis) and produce ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are essential for the next stage of photosynthesis, the Calvin cycle.
The stacks of thylakoid membranes, or grana, are interconnected by stroma thylakoids, also known as lamellae, which link the individual grana to one another. This network allows the chloroplast to efficiently carry out photosynthesis by maximizing the absorption of light energy while providing structural support to the thylakoids.
The grana are located in the stroma of the chloroplast, the gel-like substance that surrounds the thylakoids. The entire chloroplast is enclosed by a double membrane, with the inner membrane enclosing the stroma and thylakoid structures. The combination of grana, stroma, and other components of the chloroplast enable plants to harness the power of sunlight, making them the primary producers in the ecosystem.
I’ll now generate an image of the structure of the chloroplast with a focus on the grana.
Here is the image of a chloroplast with a focus on the grana (the stacks of thylakoid membranes). It shows the detailed structure of the chloroplast, including the double membrane, the thylakoids, and how they are interconnected by the stroma thylakoids (lamellae). This should help visualize the concept of grana in the context of photosynthesis.
