Which sequence lists the levels of organization in the human body from simplest to most complex? OPTIONS:
- organ system -> tissue -> cell -> organ
- tissue -> cell -> organ -> organ system
- organ -> organ system -> tissue -> cell
- cell -> tissue -> organ -> organ system
A: cell -> tissue -> organ -> organ system

Which of the following organisms produces energy from sunlight? OPTIONS:
- worm
- rabbit
- hawk
- grass
A: grass

Which adaptation allows a walrus to stay warm in cold water? OPTIONS:
- reddish coat
- bristly mustache
- wrinkled skin
- thick layer of blubber
A: thick layer of blubber

Which of the following is formed immediately after fertilization? OPTIONS:
- egg
- sperm
- zygote
- embryo
A:
zygote