Humans cannot digest food without the aid of small single-celled organisms that live in our digestive tract. these small organisms humans digest food by breaking down complex food molecules. which common name is associated with these single-celled organisms that humans digest food?
a) algae
b) bacteria
c) protozoa
d) virus

Bacteria are single-celled organisms that help humans digest food.

Explanation:

The symbiotic association of bacteria and human is of importance in the process of digestion. These bacterias are found in our gut, large intestine and sometimes in small intestine also. These bacteria break down big molecules into useful forms. Bacteria are also responsible for producing vitamin k2 and vitamin B in large intestine. They also help in mobilising of xenobiotics, bile and sterols.

answer: 21

step-by-step explanation:

divide 630 by 30. 30 goes into 630 21 times