What is the estimated total range of known plants, animals, and insects?

• A. 1-10 million
• B. 10-100 million
• C. 100-200 million
• D. 1-2 billion

Answer: (B)

Diversity on Earth is vast and not fully cataloged, especially among insects in tropical regions. We’ve described about 1.5–2 million species, but many more are believed to exist that scientists have yet to document. Because of this large unknown portion, the total number of plant, animal, and insect species is estimated to lie in the tens of millions, commonly cited as roughly ten to one hundred million. The lower end would already surpass what’s described, while the upper end stays within plausible bounds for multicellular life. A range like ten to one hundred million best captures this uncertainty and scale.