I think it’s sperm for your question
There is the digestive system is used to help you digest food.
The respiratory system that lets us use and brain oxygen.
Lastly, the circulatory system which allows our bodies to have flowing blood.
Answer:
here it is , plz mark me as brainliest
Explanation:
The relative importance of food supply and predation as determinants of animal population density is a topic of enduring debate among ecologists. ... In the 148 experiments recorded, food supplementation had an overall positive and significant effect, increasing population densities by 1·5‐fold.
The best answer is B - Proteins.
Proteins make up enzymes, or to put it another way enzymes are made up of protein. It is enzymes that speed up the chemical reactions. Enzymes are organic catalysts, substances that speed up a (biochemical) reaction but do not take part in the reaction and remain unchanged at the end of the reaction.
In man, there are many enzymes. The majority of these are found in the digestive system where they greatly aid the process of food breakdown from complex molecules to simple molecules. Examples include salivary amylase found in saliva, which begins the gradual breaking down of starch into glucose right from the moment food is placed in the mouth and mixed with saliva. Pepsin in the stomach breaks down protein.
