Cyanobacteria are photosynthetic prokaryotes. Which of the following cell structures are absent in cyanobacteria?

• I. Cell membrane
• II. Nucleus
• III. Ribosomes

(a) I only

(b) II only

(c) III only

(d) I and II only

(e) I and III only

Cyanobacteria are indeed fascinating organisms known for their ability to perform photosynthesis. When considering the cell structures that are absent in cyanobacteria, we can analyze the options provided:

Cell Structures in Cyanobacteria

• Cell Membrane: Cyanobacteria do have a cell membrane, so this structure is present.
• Nucleus: Being prokaryotes, cyanobacteria lack a true nucleus.
• Ribosomes: Cyanobacteria contain ribosomes, which are essential for protein synthesis.

Correct Answer

Based on this information, the structure that is absent in cyanobacteria is the nucleus. Therefore, the correct answer is:

(b) II only