Answer: The frustule.
- A The frustule
- B The capsid
- C The pellicle
- D The mantle
Correct answer: A. The frustule
Explanation: Diatoms have a silica shell of two overlapping halves - the frustule - which resists decay and forms diatomaceous earth.
Whittaker's five-kingdom system (1969) groups all cellular life by cell structure and nutrition; viruses, viroids, and lichens fall outside this system entirely since they aren't independently classifiable as one of the five.
Concept context
Whittaker's five kingdom system covering Monera, Protista, Fungi, plus viruses, viroids, and lichens. A foundational NEET chapter on how living organisms are grouped.