Plans to merge the Institute of Biology with the Biosciences Federation - to create a "single powerful voice for British biology" - have raised concerns among biologists.
Members of the institute say that the merger could threaten the grassroots structure of their organisation.
The Institute of Biology represents about 14,000 bioscientists while the Biosciences Federation is an umbrella body that represents 44 specialist organisations ranging from the Society for Applied Microbiology to the multinational drug company AstraZeneca.
A merger was first mooted last month on the grounds that a single organisation would be much more effective at promoting biosciences among politicians and opinion-formers who are "ill disposed" to listen to multiple voices. Plans are now being progressed.
"People are having difficulty understanding how you mesh the IoB and the BSF together," said Patrick Dunlop, a researcher at the University of Ulster and honourable secretary of the Northern Ireland branch of the IoB. "It would be better if there were a single voice for British biology, but how that happens is being debated."
The difficulty, he said, was that while the IoB had a strong "branch structure" the composition of the BSF was much more London-centric and "top down".
"IoB members are reluctant to give anything away but can see the potential," he explained.
The issue is also understood to be highly sensitive because of the history of the organisations. First the UK Life Sciences Committee was formed in 1996 and then the Biosciences Federation in 2002 after the IoB was not seen to be properly representing the interests of the whole biosciences community. Members of the IoB now fear a takeover.
"The institute has been going a long time - the BSF is newer - and therein lies a lot of the problems," said an IoB branch committee member who declined to be named.
The chairman of the BSF, Dame Nancy Rothwell, said that the intention was to retain the branch structure of the IoB, adding that the vision was for an "equal and complementary partnership".
The organisations hope to merge by mid-2009 if members consent.