1. Environment and Gene Expression

2. Gene Expression The genetic make up of an organism is determined at fertilization. However, the external environment can influence how and which traits are expressed.

3. External Influences on gene expression The Hydrangea petal color is influenced by the soil acidity level. The more acidic the deeper the blue while the more neutral to basic leads to pink.

4. External expression in humans Type 2 Diabetes is an external expression based on the human diet and exercise. People with poor diet and exercise tend to develop diabetes by overworking the pancreas.

5. What is a test cross? Test cross is a punnett square used to determine the genotype of an organism by checking the phenotypes of the offspring. – Always cross with a recessive phenotype. – Trying to determine the genotype of the dominant parent by crossing with a recessive parent.