Question

Which of the following statements about protists is FALSE (pick one).

	A.	They range from unicellular to large multicellular organisms, but without highly differentiated tissues.
	B.	Some lack cell walls and move using amoeboid motions.
	C.	While it was originally thought that some protists evolved before the endosymbiosis event that provided eukaryotes with mitochondria, it is now thought that these lineages had mitochondria but lost them.
	D.	Some construct hard, long-lasting “shells” using calcium carbonate or cellulose.
	E.	There are 5 monophyletic lineages of protists, all of which together comprise one monophyletic clade.

Answer 1

Ans. Let us go through each of the statement options and see whether they are true or false regarding protists.

(A) They range from unicellular to large multicellular organisms, but without highly differentiated tissues - Protists are eukaryotes that are not plants,animals or fungus, having a defined nucleus enclosed in a membrane.While most of the protists are unicellular like the amoeba,there are few that are multicellular,for example- Green algae which is a group of multicellular protist.However multicellular protists lack highly specialized tissue or organs.

Thus, the statement is TRUE and hence cannot be the answer option.

(B) Some lack cell walls and move using amoeboid motions - While Fungus is a group of protists having cell walls,amoeba is a unicellular protist that lacks cell wall which helps them in free movement.They have a temporary arm-like projections called pseudopods which they use for movement and feeding by retracting them.This crawling like type of movement is called as amoeboid movement and is mostly commonly used mode of movement in eukaryotes.

Thus, the statement is TRUE and hence cannot be the answer option.

(C) While it was originally thought that some protists evolved before the endosymbiosis event that provided eukaryotes with mitochondria, it is now thought that these lineages had mitochondria but lost them - While Molecular and morphological evidences shows that the protists Chlorarachiniophyte are derived from a secondary endosymbiotic event, protists like Paramecium bursaria and Paulinella do not have or lost mitochondria as they enter into endosymbiontic relationship with other algae and bacteria which replaced their missing functionality.

Thus, the statement is TRUE and hence cannot be the answer option.

(D) Some construct hard, long-lasting “shells” using calcium carbonate or cellulose - Unicellular heterotrophic protists like Foraminiferans are those which resembles snails because it exhibits porus shells made up of organic materials hardened with calcium carbonate.These porus shells are called as tests which they use it for housing photosynthetic algae for deriving nutrition.

Thus, the statement is TRUE and hence cannot be the answer option.

(E) There are 5 monophyletic lineages of protists, all of which together comprise one monophyletic clade - Protists evolved from more than one ancestral lineage and hence are Polyphyletic as they do not share a common ancestor.This is mainly because althouth they exhibits the characteristics of both eukaryotic plants as well as animals,their evolution history does not show any resemblance to any immediate common ancestor.Protists are photosynthetic like plants and heterotrophic like animals, but they are neither called as a true plant nor as an animal.

Thus, the statement is FALSE and hence,is the Correct answer option.

Hence, the answer is (E) There are 5 monophyletic lineages of protists, all of which together comprise one monophyletic clade'. which is FALSE.