I believe the correct answer is "Carbon dioxide"
D. population and nutrients
Answer:
population density is the answer of the question
Answer: The upper gastrointestinal tracts organs consist Esophagus, stomach and duodenum.
Explanation:
Gastrointestinal tracts is a organ system found in human beings and other animals that deals with intake of food, digestion of food, adsorbing nutrients from the digested food and expelling or excreting the waste products and undigested food.
The gastrointestinal tracts is divided into two, the upper and lower gastrointestinal tracts. The upper gastrointestinal tracts organs consist of Esophagus, stomach and duodenum while the lower gastrointestinal tracts consist of the large and small intestine. The structures include anus, colon,rectum,caecum.
Molecules with similar shapes have similar biological effects, because shape (structure) dictates effects (functions).
