Why is it necessary to add a day to the calendar every four years? A. The rotation of the Earth is actually 24 hours and 6 seconds.
B. The revolution of the Earth is actually 365.25 days not 365 days.
C. The Earth's orbit is elliptical and not circular.
D. The Earth's axis is tilted and slows its rotation.

Which of the following is true of metabolism in its entirety in all organisms? a) metabolism depends on a constant supply of energy from food. b) metabolism uses all of an organism's resources. c) metabolism consists of all the energy transformation reactions in an organism. d) metabolism manages the increase of entropy in an organism.