What is used to find true north on a compass

Which of these serves as a reference for comparison during a scientific investigation? a)outcome variable (dependent variable) b) test variable (independent variable) c)control group d)hypothesis

My question says on my assignment. read the following scenarios and decide which of the properties of life are being described. the first one is. katherine stopped on the way to school to grab some donuts. 2. because a dog cannot sweat, it has to pant in order to stay cool. 3. an elephant trun had no bone but 4,000 muscles. i have no idea what i am supposed to anwer. i can't find the answer in my notes or book that i can understand anyway

If assuming tasting ptc as a simple gene trait,what other genotype would you select to put in this missing genotype box that could result in this phenotype