Question

the chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?
cyanobacteria → green algae → fungi → land plants
cyanobacteria → red algae → green algae → land plants
red algae → brown algae → green algae → land plants
cyanobacteria → green algae → land plants

Explanation:

To determine the correct evolutionary sequence of land plant chloroplasts, we rely on the endosymbiotic theory and evolutionary relationships. Chloroplasts originated from cyanobacteria (endosymbiosis). Green algae are close relatives of land plants, and the sequence should show cyanobacteria as the origin, followed by green algae leading to land plants. Let's analyze each option:

• Option 1: Fungi are not part of the chloroplast evolutionary lineage for land plants, so this is incorrect.
• Option 2: Red algae are not the direct intermediate between cyanobacteria and green algae in the land plant chloroplast lineage.
• Option 3: Brown algae and the sequence starting with red algae are not correct for land plant chloroplast evolution.
• Option 4: Cyanobacteria (the original endosymbiont) evolved into green algae, and green algae are the direct ancestors of land plants in terms of chloroplast evolution.

Answer:

D. cyanobacteria → green algae → land plants