According to the cost / benefit model of carnivory proposed by Givnish carnivorous plants occur in an environment with excessive amounts of water and light, but poor in nutrients. In other environments the cost of producing traps would exceed the benefits gained from prey. In terms of photosynthesis, cost represents increased energy requirements for dark respiration (R_D) and the reduction in the rate of net photosynthesis (A_N) in traps. Benefit is an increased uptake of nutrients, especially nitrogen. Species of the genus Nepenthes belong to the group of carnivorous plants with leaves that are composed from assimilation part and passive pitcher trap. This allows us to compare aspects of photosynthesis in both parts separately. The principal aim of this thesis was to assess photosynthetic activity of the traps and assimilation leaves in plants of the genus Nepenthes, together with the detection of important proteins involved in photosynthesis. Our results confirmed the low efficiency of photosynthesis in traps compared with leaves, which is in accordance with the Givnishs model. It also appears that the primary processes of photosynthesis are reduced by much less degree than the secondary. We tested also the effect of N and P on the induction of enzymatic activities. The absence of significant induction of enzymatic activity of the digestion fluid is probably due to a large volume of fluid in traps. This strategy allows continuous digestion, nutrient uptake and constitutive enzyme production in Nepenthes.