Answer:
Pneumotaxic centre in the pons region of the brain can moderate functions of the respiratory rhythm centre. Neural signals from this centre can reduce the duration of inspiration and thereby alter the respiratory rate. A chemosensltive area is situated adjacent to the rhythm centre to make necessary adjustments in the respiratory process. Receptors associated with aortic arch and carotid artery also can recognise changes in CO
2
and H+ concentration and send necessary signals to the rhythm centre for remedial actions. The role of oxygen in the regulation of respiratory rhythm is quite insignificant.
So, the correct answer is 'Both Assertion and Reason are correct and Reason is the correct explanation for Assertion'.
Explanation:
<span>Certain enzymes and other chemicals including antibodies are created by immune cells. The white blood cells surround the bacteria or other infectious material and release the chemicals and enzymes into the bloodstream.</span>
The correct answers are:
b. Human influenza a virus evolves escape variants, resulting in a distinctive cactus-shaped phylogeny.
All types of Human influenza viruses evolve to escape immunity induced by prior infections and vaccinations.
c. Measles experiences strong selection for escape variants, resulting in a phylogeny similar to a nonpathogenic species.
As a result of measles infection, specific antibody and CD4 and CD8 T cell responses are generated and contribute to virus clearance and protection from reinfection.