Final answer:
The plastids in the protoplast of diatoms are yellow-brown or brown in color due to the presence of chlorophyll c. Diatoms are unicellular photosynthetic algae with glassy cell walls made of silica.
Step-by-step explanation:
The plastids in the protoplast of diatoms are typically yellow-brown or brown in color.
These plastids contain chlorophyll c in addition to chlorophyll a, which gives the diatoms their distinctive coloration.
Diatoms are unicellular photosynthetic algae that form intricate glassy cell walls made of silica.