Implicit in the stop-and-wait scenarios of Figure 2.19 is the notion that the receiver will retransmit its ACK immediately on receipt of the duplicate data frame. Suppose instead that the receiver keeps its own timer and retransmits its ACK only after the next expected frame has not arrived within the […]

1. What tissue lines the digestive tract? cartilagemuscularconnectiveepithelium 2) Sphincters are only found at the beginning of the stomach.are muscles in longitudinal arrangement.prevent movement of material through the digestive tract.are smooth muscles. 3) A bolus is formed in the stomach.esophagus.small intestine.mouth. 4) During the process of swallowing, the epiglottis closes […]

Butterflies have an X-Y sex determina- tion system that is different from that of flies or humans. Female butterflies may be either XY or XO, while but- terflies with two or more X chromosomes are males. This photograph shows a tiger swal- lowtail gynandro- morph, which is half male (left […]

Under certain conditions, the side chains (R-groups) of aspartic acid and lysine can form an ionic bond with one another. The pK for the ionizing groups on these side chains is 3.86 for aspartic acid and 10.53 for lysine. A) Draw the dominant structure of each of these amino acid […]