Question

Arrange these organisms in ascending order based on their size.

1. Organism causing AIDS
2. Organism causing Typhoid
3. PPLO
4. Plant cell

• A. 1-2-3-4
• B. 1-3-2-4
• C. 4-2-3-1
• D. 1-3-2-4

Answer 1

The correct option is B 1-3-2-4

AIDS is caused by a virus.
Typhoid is caused by bacteria.
PPLO (Pleuropneumonia like Organisms) are the smallest known living cells. These are also called as mycoplasma.

The size of the organisms are given below:
Virus: 0.02 - 0.2 $\mu m$
PPLO: About 0.1 $\mu m$
Typical bacteria: 1-2 $\mu m$
Typical eukaryotic cell (like plant cell): 10-20 $\mu m$

Hence, the correct order is virus < PPLO < bacteria < plant cell (option b).