Antigens are proteins that are found on the surface of the pathogen and are viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles. Antigens are usually carried by proteins and polysaccharides, and less frequently, lipids but it also needs to be attached to a large carrier molecule which is usually a protein. When an antigen enters the body, the immune system produces antibodies against it. The Antigen stimulates the immune system to produce antibodies. YOUR WELCOME ;)
The antibodies are very unspecific
For mitosis, two cells are created, and for meiosis, four cells are produced. So the answer is B. Because in mitosis, the chromosome replicates once and divides once. In meiosis, the chromosome replicates once and divides twice. That's why the cell has half of the chromosomes after meiosis.
Indirect methods like mark and recapture become a strong tool to estimate population size or density in species on which it is impossible to apply a direct methods. <em>Because of their biological and ecological characteristics, the Gypsy moth and the Green lizard populations are good examples for which mark and recapture would work well.</em>
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There are different methods to study population density. There are direct methods and indirect methods. Among these last ones, we might find the Mark-Recapture technique.
The Mark-Recapture technique assumes that
- <em>the population is closed during the sampling season, there is no mortality nor natality, </em>
- <em>marks in the individual last the whole sampling season, and they do not affect the marked individual or their behavior. </em>
- <em>marked individuals are randomly distributed in the population, and </em>
- <em>all the individuals have the same probability of being sampled.</em>
The method consists of capturing a sample of individuals belonging to the population under study. After capturing the individuals, the researcher marks and releases them again. The third step is to sample again: The researcher captures new individuals and counts how many of them are marked. These marked individuals belong to the first sample.
Indirect methods like this become a strong tool to estimate population size or density in species on which it is impossible to apply a direct method such as <em>counting individuals</em>.
For instance, if we need to estimate insects population density (<u><em>Gypsy moth population</em></u>) or reptiles population density (<u><em>Green lizard population</em></u>) because of their biological and ecological characteristics, the best way of doing it is by applying indirect methods. <em>These species characterize as small-sized, fast to escape, they can hide in small inaccessible places, they have nocturnal habits, their reproductive rate is too high, and their distribution rate is wide. </em>Among many other characteristics, their population density can not be estimated by direct methods. Mark-Recapture technique is the most suitable one.
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