Question

Which of the following shows the relationship between echinoderms and chordates?
A. Balanoglossus
B. Archeopteryx
C. Peripatus
D. None of the above

Answer 1

Hint: Echinoderm is a marine organism that belongs to the phylum Echinodermata. A chordate refers to an animal that belongs to the phylum Chordata and is characterized by the presence of notochord. The relationship between a class or group of animals can be called a connecting link. Connecting links can be defined as the organisms which share different characteristics of two different groups of organisms.

Complete answer:
The organism which possesses characteristics of two systematic classes of species is known as the connecting link. They are referred to as an intermediate or transitional state. The other name or the alternative name for connecting links is missing links. Balanoglossus is a marine organism that shows the relationship between echinoderms and chordates. It can be considered as an evolutionary link between vertebrates and invertebrates. It is a Hemichordate ocean-dwelling acorn worm.
The connecting link between two classes of reptiles and birds is Archaeopteryx. Therefore, option B is the wrong answer.
Peripatus is a connecting link between Arthropoda and annelids as it possesses nephridia for excretion which is also seen in earthworm which belongs to the group Annelida and possess unjointed leg like parapodia which is seen in the arthropods. Thus, it acts as a connecting link between Arthropoda and Annelida. Therefore, option C is an incorrect answer.
So, option A is the correct answer.

Note: Connecting link present between reptiles and mammals is duck-billed platypus. Lungfish is an organism that forms the Connecting link present between fishes and amphibians. Neopilina is an organism that forms the connecting link between Annelida and Mollusca.