A beaker of pond water containing few specimens of Euglena was placed in a dark room for two weeks. At the end of this period, the specimens of Euglena were...

The specimens of Euglena were still alive after being kept in a dark room for two weeks because they were able to carry out heterotrophic nutrition using holozoic nutrition. Euglena is a unicellular organism that is capable of both autotrophic and heterotrophic modes of nutrition. In the presence of light, it is able to carry out photosynthesis using chloroplasts, just like plants. However, when there is no light, Euglena is able to survive by carrying out holozoic nutrition, which involves engulfing and digesting other small organisms. In this case, since the Euglena specimens were kept in a dark room with no light available for photosynthesis, they must have switched to holozoic nutrition to survive. They were able to feed on other small organisms present in the pond water, which sustained them for the two-week period. Therefore, the correct answer is that the Euglena specimens were able to carry out holozoic nutrition in the absence of light, allowing them to survive for two weeks.