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.
Answer:
They are rovers that are made to study Mars. For example, they can analyze the martian soil.
Hope this helps :)
plz mark Brainliest :3
Explanation:
The correct answer is A. 20.2 s
Explanation:
The table shows there were three trials to measure how much time a toy car needs to move 1 meter on different surfaces. Now, to find the average time on a surface simply add the results of the three trials and divide this by number 3 (number of trials). The process to know the average time on dirt is shown below:
20 + 19.2 + 21.5 = 60.7 - Results of each of the trials
60.7 ÷ 3 = 20.2 s - Divide the total by the number of trials
This means the average time for the toy to move on dirt was 20.2s
The answer is B: CGT
According to the base pairing rules, in DNA, adenine
pairs with thymine (A-T), and cytosine pairs with guanine (C-G).
The complementary triplet for GCA is CGT. So, for the DNA segment AGT CAC GCA, the complementary strand will be TCA GTG CGT:
Known strand: <span>AGT CAC GCA</span>
<span>Corresponding strand: TCA GTG CGT</span>
Answer:
good luck on that one... ........... ..
