Biology Revision Y9

5. Variation The differences among individuals due to different environments
7. All the possible versions of genes
9. When an individuals has two of the same allele either dominant or recessive
11. When a species completely disappears
12. Variation When traits have clear separate categories
14. A strand of DNA. They are found in the nucleus. 46 chromosomes(23 from each parent)
17. The appearance of the organisms ( physical appearance)
18. All about protecting nature and species from extinction
19. Variation Differences between individuals within a species. It can be continuous or discontinuous.
20. A doubled stranded helix shaped molecule made of things called nucleotides
21. Refers to the trait that is masked when a dominant allele is present

1. It is the characteristic
2. Selection A process by which a species changes over time in response to changes in the environment
3. A length of DNA that codes for a trait
4. Having two different alleles for a fruit
6. The adjustment of organisms to their environment in order to improve their chances at survival in that environment
8. Tells you the alleles that lead to this appearance
10. Variation When traits fall into range with no distant categories
13. A building block of DNA AND RNA(molecules)
15. A group of living organisms that can interbreed to produce fertile offspring
16. The cell's control centre, housing DNA