Question

What is true about Nereis, scorpion, cockroach and silverfish?
A. They all possess a dorsal heart.
B. None of them is aquatic.
C. They all belong to the same phylum.
D. They all have joined paired appendages.

Answer 1

Hint: In order to derive the correct answer, you must first know where each of these organisms thrive. For example, do silverfish and scorpion belong to the same phylum? Or are they all aquatic? Fishes generally have gills. Do each of the other organisms mentioned above have gills? Moreover, jointed and paired appendages are present in phylum arthropoda. Do silverfish have appendages? These questions itself are the hints that will help you answer.

Complete answer:
Let us examine each of the options given above.
1. Presence of dorsal heart- Nereis, scorpion, cockroach and silverfish all possess a dorsal heart.
  2. Aquatic nature-Nereis thrives in aquatic conditions. Silverfish, scorpion and cockroach are terrestrial.
3. Phylum- Nereis belong to the phylum Annelida. Whereas scorpion, silverfish and cockroach all belong to phylum Arthropoda.
4. Jointed and paired appendages- Except scorpion, silverfish and cockroach ,Nereis does not have jointed and paired appendages.

Thus, the correct option is A They all possess dorsal hearts.

Note:
Nereis is a genus of polychaete worms that are mostly aquatic. Silverfish is a wingless insect which derives its name from the silvery colour of its body and also due to the fish-like movements of its body. Scorpions are predatory arachnids that are well known for their venomous sting. Lastly cockroaches are insects that have been around for more than 200 million years. They are the true representation of the fittest animals giving meaning to the phrase survival of the fittest.By dorsal we mean the backside of the body of an organism.In the organisms mentioned above,their heart lies at the back of their bodies.