Question Detail
Question
The distinctive blue-green color often seen in hornworts is attributed to the presence of which organism within their mucilage-filled cavities?
Correct Answer
Option C is the correct answer.
Detailed Explanation
Page 21 states that hornwort gametophytes often have mucilage-filled cavities invaded by 'free-living cyanobacteria (especially Nostoc). The presence of cyanobacteria growing inside the thallus give the hornwort a distinctive blue-green color.'
Hint
Look for the symbiotic relationship mentioned for hornworts and its effect on color.