Why human beings cannot digest callulose?

Why can't human beings digest cellulose?

Amoeba cannot digest

Amoeba cannot digest

Amoeba cannot digest

(A) Cellulose is not digested by human beings. (R) Human beings are not having cellulose digestable enzymes.

Human beings digest cellulose.

Name the disease in which human beings cannot make insulin themselves.

Stomach of human beings mainly digests.........................

We (Human being) cannot hear Infrasonic sound.