Final answer:
Seropositive and seronegative in biology refer to the presence or absence of antibodies in a person's blood serum.
Step-by-step explanation:
In biology, seropositive and seronegative refer to the presence or absence of antibodies in a person's blood serum. When a person is seropositive, it means that antibodies specific to a certain pathogen or antigen are present in their serum. On the other hand, seronegative means that no detectable antibodies are present in the serum.
For example, in a sample of students, if 9 tested positive for Toxoplasma antibodies and 28 tested negative, the percentage of seropositive students would be 24.3% (9 out of 37).