8A Evaluating Data on Phenotypes

Question 1

Overeating influence on phenotypes

Answer 1

Overeating was thought to be caused only by environmental factors like increased availability of food

It was later discovered that food consumption increases dopamine levels in animals once enough dopamine was released people would stop eating

Researches discovered that people with one particular allele had 30% fewer dopamine receptors

These people were more likely to overeat

Based on this evidence scientists now think that overeating has both environmental and genetic causes

Question 2

Antioxidants influence on phenotypes

Answer 2

Many foods in our diet eg berries contain antioxidants which are compounds that are thought to play a role in preventing chronic diseases
Scientists thought that the berries produced by different species of plant contain different levels of antioxidants due to genetic factors

But experiments that were carried out to see if environmental conditions affected antioxidant levels found that environmental conditions caused a great deal of variation .

Scientists now believe that antioxidant levels in berries are due to both genetic and environmental factors