Question

Absorption is defined as
A. Elimination of solid waste from the digestive system
B. Breakdown of foods by enzymatic action
C. Passage of nutrients from the gastrointestinal tract into the bloodstream
D. Mechanical breakdown of fat

Answer 1

Hint: Absorption is one of the chief processes taking place in a living body. It is concerned with transportation of a substance from one area to another through thin membranous structures.

Complete Answer
Let's study each of the options given above in detail to find the correct option.
Elimination of solid waste from the digestive system is called excretion. It is the method used by the body to eradicate all unuseful, nitrogenous and harmful substances out of the body. This process is achieved in plants by simple secretion through various porous openings while in animals excretion involves peristaltic movement (rhythmic contraction and relaxation of muscles) of muscles. Therefore, it is clear that nowhere absorption takes place in the entire process. Therefore, option A is an incorrect option.
Breakdown of foods by enzymatic action is another process that takes place in digestion. This process involves breakdown of complex substrates by enzymatic activity. Therefore, it is a chemical process that nowhere includes absorption of any substance. Thus, option B is an incorrect answer.
Passage of nutrients from the gastrointestinal tract into the bloodstream can be deemed as an absorption process because it involves transportation of simple food molecules from gut muscles to concerned breakdown sites. This absorption takes place through small structures called villi that absorbs digested food and moves it to the blood streams.

Therefore, we can say that option C is the correct answer.

Note:
This kind of process is common to both animals and plants. Animals secrete this waste material in both solid and liquid form whereas plants secrete in form of gases (Carbon dioxide, oxygen through photosynthesis) or in liquid form (excess water) through fruits and stems.