How does the tilt of Earth's axis and its rotation affect the weather?
OPTIONS:
- The tilt of Earth allows Earth to absorb all of the Sun's radiation as it rotates.
- The tilt allows certain latitudes of Earth to be heated at a greater rate while Earth rotates.
- The tilt of Earth allows Earth to rotate fast enough to allow surface cooling to occur at night.
- The tilt allows energy to be evenly distributed throughout the atmosphere while Earth rotates.

The tilt allows certain latitudes of Earth to be heated at a greater rate while Earth rotates.

Which of the following best describes the purpose of cellular respiration?
OPTIONS:
- to provide energy for cell activities
- to produce sugar for storage in cells
- to release oxygen for breathing
- to supply carbon dioxide for photosynthesis

to provide energy for cell activities

In a desert environment, cactus wrens often build their nests in cholla cacti to avoid predators. This behavior does not hurt the cacti. Which type of relationship do cactus wrens and cholla cacti demonstrate?
OPTIONS:
- competitive
- commensalism
- mutualism
- parasitism
commensalism