The demand for plastic is continuously growing in various areas of human activity and large amounts of plastic end up in the environment as waste, thus creating a significant environmental challenge. Being non-biodegradable, plastic remains in the environment for a very long time and therefore plastic waste is under a continuous process of degradation that leads to the fragmentation of plastic into smaller parts, from larger plastic debris to micro (MP) and nano (NP) dimension of particles. Plastic particles remain in the land and water environment and in the atmosphere, thus endangering the living world. The dimensions of the plastic and its ability to adsorb toxic organic and inorganic pollutants, as well as the basic structure of the polymer, are key variables in determining the level of plastic toxicity in exposed organisms. Particularly interesting are studies dealing with interactions between MP and metal nanoparticles, especially silver nanoparticles (AgNPs), due to their worldwide distribution in soil, water and air, and their toxicity to most organisms. In our project, we propose innovative research on the interactive effects of MP and AgNP on plants and green algae, key components of every ecosystem and food chain. In the project we will investigate two types of microplastics (PS-MP and PMMA-MP) and AgNPs with two types of coatings (PVP- and CTAB-AgNPs) on the terrestrial plant Allium cepa, aquatic plant Lemna minor, and the green alga Chlorella vulgaris to elucidate the nature of their interactions and what it depends on. Moreover, the innovative approaches to MP localization and detection are proposed. Knowledge about the interactions of MPs and AgNPs is generally very modest, and for plants and green algae there is only one published study so far.