In group testing, the task is to determine the distinguished members of a set of objects L by asking subset queries of the form ``does the subset Q of L contain a distinguished object?'' The primary biological application of group testing is for screening libraries of clones with hybridization probes. This is a crucial step in constructing physical maps and for finding genes. Group testing has also been considered for sequencing by hybridization. Another important application includes screening libraries of reagents for useful chemically active zones. This preliminary report discusses some of the constrained group testing problems which arise in biology.

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