In the human digestive system, the enzymes $pepsin$ and $trypsin$ are secreted respectively by:

A unicellular animal $P$ having no fixed shape ingests a food particle by forming temporary finger-like projections $Q$. The food particle is engulfed with a little surrounding water to form a temporary stomach $R$ inside it. The chemicals $S$ from surrounding cytoplasm enter into $R$ and break down food into small and soluble molecules by chemical reactions. The digested food is absorbed directly into cytoplasm by the process $T$. The undigested food is thrown out of the body by the rupture of a cell membrane $U$ in a process called $V$.
$(a)$ Name the unicellular animal $P$.
$(b)$ What are $(i)$ $Q$, and (ii) $R$?
$(c)$ Name $(i)$ chemical $S$, and (ii) process $T$.
$(d)$ Name $(i)$ organelle $U$, and (ii) process $V$.

What is the name of the rhythmic muscular contraction and relaxation that moves food through the digestive tract?

What role does bile play in digestion?

When a person puts food in his mouth, teeth cut it into small pieces, chew, and grind it. Glands $A$ in the mouth secrete a substance $B$ which is mixed with the food by the tongue. Substance $B$ contains an enzyme $C$ which starts the digestion of food in the mouth. The slightly digested food from the mouth goes down a tube $D$. The special type of movements $E$ in the walls of tube $D$ push the food into the stomach for further digestion. The stomach wall secretes gastric juice containing three substances $F$, $G$, and $H$. One of the functions of $F$ is to kill bacteria which may enter the stomach with food. Substance $G$ protects the inner lining of the stomach from the damaging effect of substance $F$, whereas substance $H$ is an enzyme for digestion. The partially digested food then enters the small intestine for further digestion.
$(a)$ What are Gland $A$, Substance $B$, and Enzyme $C$?
$(b)$ Name the tube $D$.
$(c)$ What is the movement $E$ known as?
$(d)$ What are $F$, $G$, and $H$?

In which part of the alimentary canal is food finally digested?