The answer is
D. another natural disturbance
The significance of the spore formation during the reproductive cycle of the bacterium is that, it provide a defensive strategy against hostile and unfavorable conditions. The spore formation allows the bacterium to reproduce and spread even when the conditions are not favorable. The spore formation also make it possible for the bacterium to remain dormant over a long period of time during unfavorable conditions, waiting for the right conditions to become active again.
Answer: (<u>Note</u>: You will find the image with the highlighted structure in the attached file)
Peyer's patches (aggregated lymphoid nodules)
Explanation:
Peyer's patches are anatomical regions located under the mucosa of the gastrointestinal tract, specifically in the lamina propria of the thin intestine. These patches are nodules or cumulus of lymphatic tissue and other accessory cells, and this is why they represent a huge part of the mucosa´s immunity system.
Peyer's patches belong to the group of lymphoid tissue associated with the intestine, composed of lymphoid follicles distributed along the gastrointestinal tract.
A lymphoid follicle is a cumulus or aggregate of lymphoid cells that do not have a well-defined structure nor organization. In general, these follicles are isolated from each other in the intestine. But in the terminal ileum (The last portion of the thin intestine) they get so close that they might form a plaque. The Peyer´s patches are formed principally by lymphocytes B that synthesize immunoglobulin A, which has an important role in immunity.
Answer:
Disulfide linkage/bond
Explanation:
The tertiary and quarternary structure of the protein is stabilized by Disulfide linkage which is formed between two thiol groups in the protein. 2-mercaptoethanol is a reducing agent that breaks this disulfide bond.
A protein becomes denature when it loses its native configuration and becomes inactive. So as 2-mercaptoethanol breaks disulfide bond in protein it looses its native configuration and becomes denatured. 2-mercaptoethanol is used in SDS-PAGE to separate protein subunits. Therefore the correct answer is Disulfide linkage/bond.