Read the definitions carefully and select the correct words.
1. very different from usual in a way that seems strange, worrying, wrong, or dangerous
2. if a problem or difficult situation arises, it begins to happen
3. the smallest part of a living thing that can exist independently
4. a fault or a lack of something that means that something or someone is not perfect
5. not made properly, or not working properly
6. not working properly, or not made correctly
7. a quality or illness that is hereditary is passed from a parent to a child before the child is born
8. the process by which mental and physical qualities are passed from a parent to a child before the child is born
9. the system by which your body protects itself against disease
10. the state of being immune to a disease
11. to put something inside or into something else
12. the act of putting something inside something else
13. a limit on what somebody/something can do or how good they or it can be
14. living or existing for a long time
15. relating to molecules
16. the smallest unit into which any substance can be divided without losing its own chemical nature, usually consisting of two or more atoms
17. if an animal or plant mutates, it becomes different from others of the same kind, because of a change in its genetic structure
18. a change in the genetic structure of an animal or plant that makes it different from others of the same kind
19. to happen
20. happening or done very quickly and in a very short time
21. very quickly and in a very short time
22. existing or happening for only a short time
23. the treatment of an illness or injury over a fairly long period of time
24. a single thing, person or group that is complete by itself but can also form part of something larger