The trachea needs to be rigid but the esophagus does not. why is this

In german cockroaches, curved wing (cv) is recessive to normal wing (cv+). bill, who is raising cockroaches in his dorm room, finds that the frequency of the gene for curved wings in his cockroach population is 0.6. in his friend joe’s apartment, the frequency of the gene for curved wings is 0.2. one day joe visits bill in his dorm room, and several cockroaches jump out of joe’s hair and join the population in bill’s room. bill estimates that, now, 10% of the cockroaches in his dorm room are individual roaches that jumped out of joe’s hair. what is the new frequency of curved wings among cockroaches in bill’s room? 0.69 0.4 0.5 0.31 0.20

Arepair man charged $93.06 the price included 2 hours of labor and 40 service charge how much does the repairmen charge per hour for labor?

All but one describes an effect of aging on the digestive system. a) decreased acid secretion b) decreased elasticity of stomach c) capacity to resist damage decreases d) food remains in stomach for less time