In immunology two types of immune response are described depending on whether there is prior contact with the antigen.
• At this first contact, only lymphocytes with receptors specific to the antigen in question are stimulated and lead to the production of antibodies capable of neutralizing it. The lymphocytes capable of recognizing a specific antigen are very few and the production of antibodies - of low intensity and limited duration - is detectable only after a period of latency of several days. This is called the primary response. The specificity of the resulting seropositivity, however, makes it possible to detect contamination (seroconversion).
• Upon re-contact with an antigen that has already triggered a primary response, specific antibody production is found to increase rapidly after a short latency period. The secretion of IgG then reaches levels much higher than those observed during the primary response, while that of IgM is of the same order. This early and intense response, called secondary response, most often results in the destruction of infectious agents before any clinical sign.
• Many centuries before the discovery of microbes, it was noted that people who developed a contagious disease without death were then specifically immunized against the disease, without being protected against others.
• The ability to react appropriately to an already received stimulus supposes the existence of a memory. The immune memory is based on the existence of memory B and T lymphocytes, resulting from the clonal expansion due to the first contact with the antigen. Their lifespan is significantly higher than that of other lymphocytes and their high reactivity gives its rapid and intense character to the secondary response.
False, Darwin was just the most famous one to do it.
Answer:
Endangered
Explanation:
Endangered species are organisms that are at risk of extinction if deliberate efforts are not made to conserve them due to a rapid decrease in their population.
<em>Hence, if a marine biologist writes an article about saving whales and labels them as </em><em>endangered species</em><em>, all efforts should be geared towards saving the animals lest they go extinct and leave a vacuum in the functioning of the ecosystem. Every species have the critical roles they play in the functioning of the ecosystem and the extinction of any particular species represents a loss that might not be replaceable. </em>
Answer:
46 chromosomes
or 23 pair of chromosomes but as u asked single it will be 46 chromosomes
