Chapter 28, Problem 1TY

Summary Introduction

Introduction: Protists are known as the Earth’s first eukaryotes. These eukaryotes are not classified in the plant, animal, or fungal kingdom. Protists are abundant in moist habitats and are microscopic in size. They are informally labeled according to their ecological roles, habitats, and the type of motility.

Answer to Problem 1TY

Correct answer: If an individual is studying the evolution of animal-specific cell-to-cell signaling systems, then the representative species to choose for the observation will be Choanomonada. Hence, the correct answer is option c.

Explanation of Solution

Reason for correct answer:

The Choanomonada belongs to a group of choanoflagellates, which represent the closest living relatives of animals. The evolutionary biologists interested in the origin of animals choose Choanomonada as representative species. These organisms are believed to be the species that have closest association with the multicellular organisms (especially animals). Hence, the representative species to study the animal-specific cell-to-cell signaling system is Choanomonada.

Option c. is given as “Choanomonada”.

Choanomonada are unicellular eukaryotes whose genome is very similar to those of animals. Hence, the correct answer is option (c).

Reasons for incorrect answer:

Option a. is given as, “Rhodophyta”.

Rhodophyta is also known as red algae and they are able to perform photosynthesis. Photosynthesis is a process observed in plants and not in animals. This indicates that Rhodophyta represents a close association with plants. They cannot be used to study the animal-specific cell-to-cell signaling system. Hence, option a. is incorrect.

Option b. is given as, “Discoba”.

Discoba are unicellular eukaryotes with no specific classification. Hence, option b. is incorrect.

Option d. is given as, “Radiolaria”.

Radiolarian lives in an aquatic habitat and they are heterotrophic in nature. They cannot be used to study the evolution of cell-to-cell signaling system as they do not share similarities with the animal cells. Hence, option d. is incorrect.

Option e. is given as, “Chlorophyta”.

Chlorophyta is also referred to as green algae. They contain the same photosynthetic pigments that are present in the plants. Chlorophyta performs photosynthesis and shows a close association with plants and not animals. They cannot be used to study the animal-specific cell-to-cell signaling system. Hence, option e. is incorrect.

Hence, the options a., b., d., and e. are incorrect.

Conclusion

Choanomonada and animals share several genes, and it represents the closest living relative of animals. Hence, it is used as representative species for the animal-specific cell-to-cell signaling studies.