*Question*
Q: What is the most numerous species on the planet? Choices: - trees - viruses - humans - bacteria A:
**Answer**
bacteria

*Question*
Q: What term describes a drug that has an effect on the central nervous system? Choices: - nonaddictive drug - elemental drug - steroidal drug - psychoactive drug A:
**Answer**
psychoactive drug

*Question*
Q: Some earthworms can also reproduce asexually by fragmentation followed by what? Choices: - fertilization - germination - digestion - regeneration A:
**Answer**
regeneration

*Question*
Q: What is a species that plays an especially important role in it's community called? Choices: - complement - Invasive - Leader - keystone A:
**Answer**
keystone