The hardest part in the animal body is

In mammals,the scent-producing glands are known as:

Which gland in mammals secretes odoriferous substances?

Identify the correctly matched pair/pairs of the germ layers and their derivatives.
$A$. Ectoderm-Epidermis
$B$. Endoderm-Dermis
$C$. Mesoderm-Muscles
$D$. Mesoderm-Notochord
$E$. Endoderm-Enamel of teeth

In both vertebrates and invertebrates,the gut develops from the .......

Organs and organ systems are formed by the organization of which of the following?