Question

Choose the correct statement
A. All reptiles have a three-chambered heart
B. All Pisces have gills covered by an operculum
C. All mammals are viviparous.
D. All cyclostomes do not possess jaws and paired fins.

Answer 1

Hint: There are different chambers of the heart which can be one, two, three, and four chambers. There are atria and ventricles in a heart which helps in pumping the blood from the heart to various body parts of an organism.

Complete answer:
All reptiles have three-chambered hearts except for crocodiles which have four-chambered hearts. There are two atria and one ventricle in the heart of reptiles which help in pumping blood to all bodies. This makes the first statement incorrect.
Members of Osteichthyes have gills covered by operculum while members of Chondrichthyes lack operculum covering their gills. This operculum helps to cover the gills to prevent the entering of food in them. This makes the second statement incorrect.
All mammals are not viviparous because there are some species of Echidna and Platypus which are oviparous. Other than these all other organisms which fall under mammals are viviparous as they give birth to young ones. This makes the third statement incorrect.
All cyclostomes lack jaws and paired fins and are included in the paraphyletic superclass Agnatha which also includes various groups of extinct armored fishes called ostracoderms. The cyclostomes are organisms of kingdom Animalia and phylum chordate.

Hence, the correct option is D. All cyclostomes do not possess jaws and paired fins.

Note:
Many biologists disagree with the idea of whether cyclostomes are a clade. The vertebrate hypothesis holds that lampreys are more closely related to gnathostomes as compared to the hagfish. The cyclostomes hypothesis holds that lampreys and hagfishes are more closely related making Cyclostomata monophyletic.