Animals get energy for growth and repair from OPTIONS:
- soil
- food
- water
- air
A: food

Which of the following remains constant in Earth's carbon cycle? OPTIONS:
- the total mass of available carbon
- the way organisms use carbon
- the physical state of carbon-containing molecules
- the molecule in which a particular carbon atom is found
A: the total mass of available carbon

Where is most of the mass of the atom located? OPTIONS:
- in the protons
- in the nucleus
- in the neutrons
- in the electrons
A: in the nucleus

Which system of the human body provides protection to most of the major organs? OPTIONS:
- skeletal system
- circulatory system
- respiratory system
- muscular system
A:
skeletal system