1. The ______ is the outermost layer of the Earth.

2. A ______ is a substance that speeds up a chemical reaction without being consumed.

3. A ______ is a type of energy associated with motion.

4. A ______ is a type of cell division that results in two identical daughter cells.

5. The ______ is the organ in the body responsible for pumping blood.

6. A ______ is a scientific instrument used to observe distant celestial objects.

7. The ______ is a measure of the amount of matter in an object.

8. The ______ is the scientific study of matter and its interactions.

9. A ______ is a group of similar organisms that can reproduce and produce fertile offspring.

10. The ______ is the force that attracts objects toward the center of the Earth.

11. A ______ is a natural satellite that orbits a planet.

12. The ______ is the name of the galaxy that contains our solar system.

13. A ______ is a form of energy transfer that occurs through electromagnetic waves.

14. The ______ is the process by which plants make their own food using sunlight.

15. A ______ is a type of rock formed from the cooling and solidification of magma or lava.

16. The ______ is the layer of gases surrounding the Earth.

17. The ______ is a unit of measurement for energy.

18. A ______ is a small unit of life that is the basic building block of all living organisms.