test
node1
BFO:0000001
entity
node2
BFO:0000003
occurrent
node1->node2
node2->node2
node5
BFO:0000015
process
node2->node5
node3
GO:0042221
response to chemical
node4
GO:0009636
response to toxic
substance
node3->node4
node6
GO:0008150
biological_process
node5->node6
node7
GO:0050896
response to stimulus
node6->node7
node7->node3