AP BIOLOGY

Detailed explanation-1: -Double line shows the full participation and single line shows partial participation and it is also known as minimum cardinality.

Detailed explanation-2: -Total participation is represented by double lines. Partial participation − Not all entities are involved in the relationship.

Detailed explanation-3: -A double line graph is a line graph with two lines connecting points to show a continuous change. Just like a line graph, the lines can ascend and descend in a double line graph. A double line graph has two axes.

Detailed explanation-4: -Total participation means that every entity in the set is involved in the relationship, e.g., each student must be guided by a professor (there are no students who are not guided by any professor). In the Chen notation, this kind of relation is depicted as a double line.

Detailed explanation-5: -A double line graph is used to compare the changes or the growth in two trends over a period of time. It is preferred to use double line graphs in case of continuous data. For example, if you want to compare the changes in the growth in sales of two companies from the year 2000 to 2020, you can use double line graphs.