Memory Anchor:

• Super Challenge:

  Stretch:

  Challenge:

Key Questions:

1. How does the genome and the environment influence the development of phenotype?
   • An organisms genome depends on the alleles that the organism inherits. Dominant characteristics inherited from the parents will be expressed always. If no dominant alleles are present then the recessive ones will be expressed. The environment can also affect certain phenotypes through variations in climate diet, physical accidents, culture and lifestyle.
2. How do differences in the characteristics of individuals occur?
   • Differences in the characteristics of individuals in a population is called variation and may be due to differences in: - the genes they have inherited (genetic causes) - the conditions in which they have developed (environmental causes) - a combination of genes and the environment
3. How much genetic variation is usually within a population?
   • There is usually extensive genetic variation within a population of a species.
4. When is a recessive allele expressed?
   • A recessive allele is only expressed if two copies are present (therefore no dominant allele present).
5. (Biology only) How often do mutations occur and how often do they lead to a new phenotype? What happens when a new phenotype is suited to an environmental change?
   • (Biology only) Mutations occur continuously. Very rarely a mutation will lead to a new phenotype. If the new phenotype is suited to an environmental change it can lead to a relatively rapid change in the species.
6. What is evolution?
   • Evolution is a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.
7. What does the theory of evolution state?
   • The theory of evolution by natural selection states that all species of living things have evolved from simple life forms that first developed more than three billion years ago.
8. How does evolution occur?
   • Evolution occurs through the natural selection of variants that give rise to phenotypes best suited to their environment.
9. How is a new species formed?
   • If two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring they have formed two new species.