The green organisms collected from the pond by Ricardo may be plants or protists. It is required to key out these organisms so that they can be differentiated. In order to determine whether or not these organisms are plants, he should check for the key features of plants, such as whether or not the organisms do photosynthesis. and whether these organisms are multi-cellular or unicellular.
The protists may also contain chloroplasts and cell wall made up of cellulose. Therefore, testing for the presence of these features will not help in determining whether the collected organisms are plants or not.
Hence, he should check whether the organisms are capable of doing photosynthesis or not.
