Can you help me with both please

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

Ayoung boy has been found and police are trying to locate his family they take a dna sample from him and begin collec dna samples from families who have missing children if police use dna samples only from the fathers, which type of dn technology can they use to identify the boy's parent? y-chromosome analysis omtdna (mitochondrial dna) analysis vntrs (variable tandem repeats) o pcr (polymerase chain reaction) analysis

Rachel ate a piece of fruit and happened to drop the seeds in her backyard. after a few weeks, she saw a small plant with flowers growing in the backyard. which group does this plant belong to? a. angiosperms b. gymnosperms c. pteridophytes d. bryophytes e. chytrids