Members of the Nostoc genus have large numbers of thylakoid membranes,and many have gas vesicles.What statement is also most likely true about Nostoc?
A)They are pathogenic.
B)They form an endosymbiotic mutualism with plant roots.
C)They are photoautotrophs.
D)They are methanogens.
E)They are archaea.

Question

Quizplus · Accepted Answer

The presence of thylakoid membranes and gas vesicles suggests that members of the Nostoc genus are photosynthetic organisms, which would make them photoautotrophs.

Answer: B 
 While there is no definitive evidence to suggest that Nostoc forms an endosymbiotic mutualism with plant roots, some studies suggest that certain species of Nostoc may be involved in nitrogen fixation and could potentially benefit plants.

Therefore, the best choice would be both C and B as they are both plausible explanations.

Members of the Nostoc Genus Have Large Numbers of Thylakoid