Describe, referring to named parts of the nervous system, the pathway that enabled the scientist to detect that the powder tasted bitter.
The scientist who poured the powder did not notice any bitter taste. It was later discovered that inheritance of two different forms of the same gene determines whether a person can detect a bitter taste from PTC or not. State the term used for different forms of the same gene.
A few years later, it was discovered that environmental factors lead people to detect a range of different bitter-taste strengths from PTC. State the type of variation now known to be shown by this characteristic.
State the trophic level that plants occupy in a food web.
State the term for animals that feed only on plants.
Suggest why animals that eat only plants have fewer genes that enable them to detect chemicals that taste bitter than animals that eat both plants and animals.