Question

Which of the following represents the correct combination without any exception?

• A.
  
  Characteristics - Body covered with feathers; skin moist and glandular; fore - limbs form wings; lungs with air sacs
  Class - Aves
  
• B.
  
  Characteristics - Mammary gland; hair on body; pinnae; two pairs of limbs
  Class - Mammalia
• C. Characteristics - Mouth ventral; gills without operculum; skin with placoid scales; notochord replaced by the vertebral column in adults.
  Class - Chondrichthyes
• D. Characteristics - Sucking and circular mouth; jaws absent, integument without scales; paired appendages
  Class - Cyclostomata

Answer 1

The correct option is C Characteristics - Mouth ventral; gills without operculum; skin with placoid scales; notochord replaced by the vertebral column in adults.

Class - Chondrichthyes
Class Chondrichthyes - Mouth ventral; gills without operculum; skin with placoid scales; notochord replaced by the vertebral column in adults.
Class Mammalia - The external part of the ear is called the "pinna", and only mammals have it. The monotremes (egg-laying mammals -- platypus and echidna) don't have ears with a pinna.
Class Aves - The term moist is usually used to describe amphibian skin. Glandular skin is found in some groups of chordates including amphibians and mammals. The skin of birds is dry except the secretion of the oil glands which keep the feathers in good condition.
Class Cyclostomata - Paired appendages are absent in most cyclostomes.