Typhoid fever is a life-threatening systemic infection caused by the bacterium Salmonella typhi. It is transmitted through contaminated food and water. Symptoms include sustained high fever, headache, abdominal pain, and sometimes a rash. The Widal test is a common diagnostic test for typhoid. S. pneumoniae causes pneumonia, and V. cholerae causes cholera.
Consider the following statements about the human heart:
1. The bicuspid valve is on the left side.
2. The tricuspid valve is on the right side.
3. The pulmonary valve prevents backflow into the right ventricle.
Which of the above is/are correct?
Explanation:
HIV is a retrovirus with two copies of single-stranded RNA as its genome. It uses reverse transcriptase to convert RNA into DNA upon infection. Double-stranded DNA is typical of many organisms. Single-stranded DNA viruses exist (e.g., parvovirus). Double-stranded RNA viruses include rotavirus. The viral RNA genome enables integration into host DNA via a DNA intermediate.
Explanation:
Monocots are less susceptible to Agrobacterium-mediated transformation using Ti plasmid. Therefore, direct gene transfer methods like particle bombardment (biolistics) are commonly used. The gene gun shoots DNA-coated gold or tungsten particles into plant cells. Ti plasmid works well for dicots. Bacteriophage and cosmids are for bacterial cloning.
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