Digestive System Processes

Free Response

Explain why some dietary lipid is a necessary part of a balanced diet.


Lipids add flavor to food and promote a sense of satiety or fullness. Fatty foods are sources of high energy; one gram of lipid contains nine calories. Lipids are also required in the diet to aid the absorption of lipid-soluble vitamins and for the production of lipid-soluble hormones.

The gut microbiome (the bacterial colonies in the intestines) have become a popular area of study in biomedical research. How could varying gut microbiomes impact a person’s nutrition?


The gut microbiome includes all the bacteria that aid in chemical digestion in the intestines. Changing its composition can change the way that food is digested since not all bacteria have the same macromolecule-digesting enzymes. Additionally, changes in gut microbiome can lead to the establishment of pathogenic bacteria populations that cause inflammation in the gut or other disease.

Many mammals become ill if they drink milk as adults even though they could consume it as babies. What causes this digestive issue?


As mammals wean from their mothers they stop drinking milk. Since they stop consuming the sugar lactose their bodies conserve resources by no longer making the enzyme lactase. If the animals then consume lactose at some point in the future their digestive system cannot break the lactose molecules into glucose and galactose for absorption. When gut bacteria further along the digestive tract interact with the lactose molecules it causes symptoms of lactose intolerance.