Why temperature affects heart rate in ectothermic organisms? If the temperature is within the optimal range for enzyme activity more ATP will be produced and the heart will beat faster due to increased metabolic activity and energy availability.
The phenotype is just a characteristic/trait.
For instance Brown and Green are phenotypes of eye color.
This can also be used in Punnet Squares, and could be displayed as B and G.
B equaling dominant Brown, and G = dominant Green, vice versa to g and b where they are recessive.
Although, I'm not sure about the entirety of this question, when reviewing claims and evidence, check your sources to make sure they are reliable.
