test
node1
GO:0042221
response to chemical
node2
GO:0010035
response to inorganic
substance
node1->node2
node8
GO:0010038
response to metal ion
node2->node8
node3
BFO:0000015
process
node4
GO:0008150
biological_process
node3->node4
node5
GO:0050896
response to stimulus
node4->node5
node5->node1
node6
BFO:0000001
entity
node7
BFO:0000003
occurrent
node6->node7
node7->node3
node7->node7