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.
Population refers to an array of organisms of the similar species, which thrives in a particular geographical region and interbreed. The three main characteristics of a population are density, size, and dispersion.
The density signifies towards how many organisms are thriving in a specific region. The size refers to how big a population is, and dispersion signifies towards the degree of spreading of the particular population.
The heat from hotter object goes to the cooler object. when they reach the same temperature the heat flow will stop.
Answer:
It chloroplast
Explanation:
contains chlorophyll which traps energy from the sun.
Answer:
The correct answer is : The dominant form of the trait shows.
Explanation:
In simple dominance, the attribute related to the prevailing or dominant allele is communicated while the character related to the latent or recessive allele is persecuted or masked. For instance –
Taking a bloom where the dominant allele attribute is red shading and the recessive allele characteristic is white shading. At the point when a posterity of this bloom is created containing one prevailing or dominant allele and one passive allele, its shade would be red simply because just the predominant allele communicates its characteristic.
Thus, the right answer is: The dominant form of the trait shows.
