Question

2. Traditionally, protists were classified in kingdom Protista. How has the classification of protists changed? 3. Relate Cause and Effect What is a major reason why scientists need to reclassify protists? 4. Apply Concepts What three kingdoms arose from protist ancestors? 5. Write to Learn Scientists say that we should not look for the earliest ancestors of animals among modern-day protists. Write a short paragraph that explains why.

Answer 1

Protists are the eukaryotes which are neither plants, animals nor fungi. But they are plant-like, fungi-like and animal-like organisms.  It is difficult to classify all the protists in one kingdom Protista because of their numerous diversified traits. There are a few parasites, predators and also producers among the protists. Some have a cell wall, while others have a cell membrane. Mode of locomotion can be flagella, cilia or the pseudopodia. The best example is the Euglena exhibiting both plant and animal like characteristics in having a chloroplast performing photosynthesis and exhibiting locomotion by flagella. These diversified traits made the scientists to reclassify the protists. The kingdoms which arose from protist ancestors include the kingdom animalia, plantae and mycota sharing common characteristic features with their ancestor. Scientists say that we should not look for the earliest ancestors of animals among modern-day protists because, the modern day protists have gone through a process of evolution which makes them different from their early ancestors. The gradual changes during the course of evolution has made them different from their ancestors with respect to their structure, adaptations and also the genetic composition.