Answer:
Chemicals that are secreted from antigen-presenting cells then activate helper T cells.
Explanation:
Answer:
Some viruses are hard to treat because sometimes it’s not the virus that makes us sick; it’s our immune system.
Explanation:
The development of resistance to the disease has taken different courses. In Australia, the virus initially killed rabbits very quickly – about 4 days after infection. This gave little time for the infection to spread. However, a less virulent form of the virus then became prevalent there, which spread more effectively by being less lethal. In Europe, many rabbits are genetically resistant to the original virus that was spread. The survival rate of diseased rabbits has now increased to 35%, while in the 1950s it was near zero.[15]
Hares are not affected by Myxomatosis, but can act as vectors.<span>[16</span>
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Answer:
a. most genes encode one polypeptide and can be operationally defined by the complementation test
Explanation:
Genes are the stretch of DNA that code for specific polypeptides. In general, one gene codes for the only polypeptide.
Genes are defined by complementation tests which in turn tell if two mutations have occurred in the alleles of the same gene or different gene.
For the purpose, an organism with the homozygous genotype for one recessive mutation is crossed with an organism having the homozygous recessive genotype for another mutation.
If the two mutations are in the same gene, the progeny would show the mutant phenotype. On the other hand, if two mutations are in different genes, the progeny would exhibit normal phenotype.
