During a controlled experiment, a scientist will isolate and test (D) a single variable. A conclusion, nor a mass of information can be isolated or tested. A control group is the group that would receive a placebo, so testing that would be futile.
The journey of the food through the digestive system will actually digest the food. The rest will be given out as feces.
<h3><u>Explanation:</u></h3>
The digestive system actually consists of digestive tract and Digestive glands. The processes that are associated with digestive system is - ingestion, digestion, absorption, assimilation and egestion.
The food that is taken is first smashed and chewed into a rough bolus by mixing with saliva. The salivary amylase slightly digests the starch into dextrin.
Then the food is engulfed through the oesophagus into stomach. Inside stomach, the food is mixed with an enzyme pepsin and HCl. Pepsin digests the proteins into peptones and peptides. The food is converted into a bolus and transported into duodenum.
In duodenum, there are several enzymes from small intestine and pancreas breaks the fats into fatty acids, proteins into peptides and starch into carbohydrates like glucose. They are absorbed and the undigested substances are left over ad feces.
