Which of the following is known as the energy currency of the cell in biology?

The breathing cycle is an essential process for the exchange of gases. Justify this statement.

There are five animals $P$, $Q$, $R$, $S$ and $T$. The animal $P$ always lives in water and has gills for breathing. The animal $Q$ can stay in water as well as on land and can breathe through both, moist skin and lungs. The animal $R$ lives in soil and breathes only through its skin. The animal $S$ lives on land and breathes through spiracles and tracheae. The animal $T$ lives in water and breathes through its cell membrane. Identify the animals:
$(a)$ Which of the animals could be $Amoeba$?
$(b)$ Which of the animals could be frog?
$(c)$ Which animal could be fish?
$(d)$ Which animal could be grasshopper?
$(e)$ Which animal could be earthworm?

The correct sequence of anaerobic reactions in yeast is:

Which gases are exchanged in your lungs?

The portion of the human respiratory tract known as the sound box is: