1.Explain how Toxoplasma gondii is the most successful parasite in the world.  Explain the roles of definite and intermediate hosts, including the roles of cats and undercooked meat.  Be sure to include trophozoites, encystment and excystment.

What advantageous uses have viruses been shown to have? The activities of viral genes mimic those of host genes so they are useful for studying mechanisms of DNA replication and gene expression in their much more complex hosts. O Bacteria-killing viruses may play an increasing role in the war against bacterial pathogens. O All are correct. They can be used as a means to introduce foreign genes into human cells, which may serve as a basis for treatment of human diseases by gene therapy. O Insect-killing viruses may play an increasing role in the war against insect pests.

Select only the true statements about soil bacteriophages ahead: -Phages help on increasing soil biodiversity -Phages are nnonself replicating living infectious agents -Phages prevents low-generation-time- species from becoming dominant - Phages can infect protozoa -Phages are important in bacteria lateral gene transfer

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