Question

Deposition of calcareous shell around zygote occurs in

• A. Birds and reptiles
• B. Birds and mammals
• C. Mammals and reptiles
• D. All of the above
  

Answer 1

Answer: (A)

Birds and reptiles

In oviparous animals such as reptiles and birds, fertilised eggs are covered by hard calcareous shell and are laid in a safe place. After incubation period, young ones hatch out. In viviparous animals such as majority of mammals including human beings, the zygote develops into a young one inside the body of the female individual. After a certain growth, young ones are delivered by the female individual. Due to proper care and protection, the chances of survival of young ones are more in viviparous individuals.