[Biological research in space].

The paper presents the results of investigations carried out during the last two decades on various biological objects--microorganisms, plant seeds, insects, higher and lower plants, fish and amphibians--in real and simulation space flights. The paper discusses the current knowledge of the biological role of gravity and possible mechanisms of adaptation to weightlessness as well as the suitability of different biological objects for further space studies. Most experiments conducted in real space flights have lent support to the theoretical studies of the level and limits of weightlessness effects upon biological systems. Analysis of the data obtained in space and ground-bound experiments suggests that molecular processes are indifferent to an altered gravity and that energy metabolism plays an important role in adaptation of biological systems to zero-g.