Across
- 3. the blood which is circulating through the body of a person or animal
- 5. firmly fixed or established; difficult to change
- 7. an external opening of the nasal cavity in that allows air to enter the lungs
- 8. a molecule in the cell membrane which can receive a neurotransmitter, hormone, or other type of chemical substance
- 11. watery liquid in the mouth which assists in chewing, swallowing and digestion
- 13. a person's awareness or perception of something
- 15. a substance in a living organism which helps chemical reactions happen.
- 16. a hormone that regulates the amount of glucose in the bloodstream
- 18. a countless or extremely great number.
- 19. a simple sugar which is an important energy source for many living organisms
- 20. the branch of biology that deals with the bodily structure of humans, animals, and other living organisms
- 21. a thing made by combining two different elements; a mixture.
Down
- 1. easily evaporate at normal temperatures
- 2. a substance produced in an organism that stimulates specific cells or tissues into action.
- 4. affecting all people or things in the world, or in a group; applicable to all cases.
- 6. a substance which is essential for the growth and maintenance of life
- 9. the act of re-examining something and making changes
- 10. introduce (something) into a passage, cavity, or solid material under pressure.
- 12. not able to be undone or altered.
- 14. the smallest structure and functional unit of an organism
- 17. the branch of biology that deals with the normal functions of living organisms and their parts.