Answer:
Ecosystems are closed systems
Explanation:
This answer (Ecosystems are closed systems) is false because ecosystems are open systems by nature.
The steps need to be arranged as follows:
1. S.aureus grow at low density on skin surface.
2. S.aureus enter tissue through a wound.
3. S.aureus grow to high density inside the tissue.
4. S.aureus sense quorum through only the Agr pathway.
5. S.aureus secrete toxin.
S.aureus is a bacterium which can be found in the normal flora of the body, however, under specific conditions, it can become pathogenic and cause skin and respiratory infections and food poisoning. Quorum sensing is a method used by bacteria for cell-to-cell communication and coordination of their colonization. Bacteria secrete signalling molecules to communicate and as the population grows so does the concentration of the signalling molecules. When the signalling molecules reach a specific concentration, then the expression of a specific gene is triggered. This gene is agr and it regulates the secretion of toxins which constitute the pathogenic mechanism of the bacterium.
Answer: D. reduces the activation energy for the reaction it catalyzes.
Explanation:
The enzyme amylase is the enzyme which functions optimally in the environment. The enzyme amylase in the saliva functions in break down of starch which is a polysaccharide into small sugars. In this situation, the amylase is the enzyme and the starch is the substrate also the small sugar molecules are the products.
When the enzyme amylase binds to the substrate, then enzyme-substrate complex forms. The formation of this complex lowers the activation energy of the reaction and promotes the rapid progression of the reaction.