What is the function of the iris in the eye of a frog?

Which one of the following pairs of structures is correctly matched with their description?

Description	Structures
$a$. Tibia and fibula	Both form parts of knee joint
$b$. Cartilage and cornea	No blood supply but do require oxygen for respiratory need
$c$. Shoulder joint and elbow joint	Ball and socket type of joint
$d$. Premolars and molars	$20$ in all and $3$ rooted

Volkmann's canals are found in:

We swing our arms while walking for $......$.

Match Column $I$ with Column $II$.

Column $I$	Column $II$
$(a)$ Smooth muscle	$(i)$ Myoglobin
$(b)$ Tropomyosin	$(ii)$ Thin filament
$(c)$ Red muscle	$(iii)$ Sutures
$(d)$ Skull	$(iv)$ Involuntary

Write true or false. If false,correct the statement to make it true.
$(a)$ Actin is present in thin filament.
$(b)$ $H$-zone of striated muscle fibre represents both thick and thin filaments.
$(c)$ Human skeleton has $206$ bones.
$(d)$ There are $11$ pairs of ribs in man.
$(e)$ Sternum is present on the ventral side of the body.