Answer:
(a) The characteristics possessed by aves are as follows
These are warm-blooded animals having four-chambered heart. Their body is
divisible into head, neck, trunk and tail. These are flying animals, having
exoskeleton of feathers.
They have modified forelimbs into wings and jaws are
modified into horny toothless beak.
Their bones are light in weight because of air spaces
(pneumatic bones) and the body is streamlined to reduce air resistance during
flight.
Lungs as well as air sacs are present for double respiration.
Oviparous
Animals
Viviparous
Animals
Females
lay fertilized/unfertilized eggs.
Females
give birth to young ones.
The
development of zygote takes place
outside
the female's body.
The
development of zygote takes place inside the female's body.
Females
lay number of eggs in a safe place in the environment but the chances of survival
are less.
Females
deliver few young ones and the chances of survival are more.
Examples
All birds, most of reptiles and egg- laying mammals.
Examples
Mammals except egg-laying mammals.
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