Fungi were once classified as plants, but molecular data has shown that fungi are more closely related to animals than plants. Compare and contrast fungi to both plants and animals.

Question

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Answer 1

Answers may vary. Fungi were once classified as plants because they are nonmotile and their cells have cell walls. Upon closer examination, we find that fungal cell walls contain chitin, whereas plant cells walls contain mostly cellulose. Both are polymers of glucose, but chitin has nitrogen groups attached to the glucose molecules. Unlike plants, which are photoautotrophs, fungi are heterotrophic like animals. In contrast to animals that are heterotrophic by ingestion, fungi are heterotrophic by absorption. They secrete enzymes, which digest organic molecules externally. The fungus then absorbs the smaller molecules. Most fungi, like plants, are nonmotile. An exception are the chytrids which have a motile zoospore. It is believed that animals and fungi evolved from a flagellated protist.