Q: Like animals, cyanobacteria possess what kind of biological rhythm? Choices: - brain rhythm - music rhythm - variable rhythm - circadian rhythm A:
circadian rhythm

Q: The brain and spinal cord are part of what system? Choices: - cardiovascular system - digestive system - immune system - central nervous system A:
central nervous system

Q: Q: Although they differ vastly in hardness, pencil lead and diamonds both contain what element? Choices: - graphite - hydrogen - oxygen - carbon A:
A: carbon

Question: Q: Which systems work together to provide cells with the oxygen they need for cellular respiration? Choices: - muscular and lymph systems - circulatory and digestive systems - respiratory and lymph systems - respiratory and circulatory systems A:
Answer: respiratory and circulatory systems

*Question*
Q: What phenomenon is crowding out other species and making all the other causes of extinction worse? Choices: - climate change - human suburbanization - migration - human overpopulation A:
**Answer**
human overpopulation

*Question*
Q: Nerves of the hands, arms, feet, legs, and trunk are part of what system? Choices: - urinary system - circulatory system - cardiovascular system - peripheral nervous system A:
**Answer**
peripheral nervous system