State reasons for the following:
$(a)$ Tapeworm does not have a digestive tract.
$(b)$ Frogs use both skin and lungs for breathing.
$(c)$ Birds have pneumatic/hollow bones.

(N/A) Tapeworms are endoparasites that live in the intestine of the host. They lack a digestive tract because they absorb pre-digested nutrients directly from the host's intestine through their body surface.
$(b)$ Frogs exhibit cutaneous respiration through their moist skin when submerged in water and pulmonary respiration using lungs when they are on land.
$(c)$ Birds possess pneumatic (hollow) bones to reduce their body weight,which is an essential adaptation for flight,allowing them to remain buoyant and fly efficiently.