1. Variation

2. Types of variation Variation means differences between species (remember dichotomous key) or differences within a species Types of variation: 1.Continuous variation 2.Discontinuous variation

3. Continuous variation Variation with a continuous range of unit, such as the range of weight from light to heavy. Determined by genes and other factor such as nutrition and activity (environment) Example: length of leaves or stems range of height from shortest to tallest There are no clear divisions between the intermediates

4. Discontinuous variation Variation in a limited number of phenotypes with no intermediates. Example: various human blood type different color of flower ear lobe

5. Inheritance versus Variation Identical twins develop from the same embryo and are genetically identical. However, they are different in many ways! how this is happen?

6. A Mexican hat plant reproduce asexually to make lots of tiny plantlets all around its leaves. How you would investigate the environmental factor that effect the variety of this plant? Inheritance versus Variation

7. Mutations

8. Mutation It is a change in a gene or a chromosome that may cause a change in a phenotypic characteristic Mutation can be harmful but some are beneficial and some have no effect

9. Gene mutation Mutation of the red color eye of a fruit fly into white eyes. It is caused by the changes of gene that no longer coded for the production of the red pigment. Albino, mutation of melanin pigment that responsible to protects skin and eyes from ultra violet light. The gene can mutate and stop produce melanin. This trait is a recessive allele and albino is a homozygous recessive.

10. Gene mutation Sickle cell anemia (SCA) is an inherited disease of the blood. It’s the result of an allele that causes the abnormality form of haemoglobin (C shaped of red blood cell ) which makes it difficult for the red blood cells to carry oxygen.

11. Chromosome Mutation Down syndrome, is a mutation that occurs during meiosis when two of the chromosomes do not separate properly. Instead of the egg having 23 chromosomes there is an extra chromosome. If the egg is fertilised the baby will have 47 chromosome Down’s syndrome affects about 1 in 1000 babies

12. Meiosis KM12

13. Causes of mutation Damage to DNA or failure in the copying process before nuclear division Mutation occur naturally at random but is increased by exposure to radiation, such as: ultra violet, X rays and gamma rays Mutation also increased by some dangerous chemicals, such as: benzpyrine in cigarette smoke.

14. Effect of Mutation Mutation may lead to cancer (as happened after atomic bomb in Japan and the nuclear power station in Chernobyl in the Soviet Union) Mutation on red blood cell and cause heterozygous cause resistance to malaria and since they still have normal red blood cell they do not have problem in transporting oxygen.

15. Natural Selection The process by which organisms that are well adapted to their environment have a greater chance to breed and pass on their genes to the next generation than those that are less well adapted

16. The process of natural selection Variation Over population Competition Adaptation Evolution Search from the Biology book or article to explain how the process above may lead to the natural selection