Which of the following bacterial diseases is transmitted through the bite of an infected rat flea (Xenopsylla cheopis)? MCQ with Answer and Explanation
Which of the following bacterial diseases is transmitted through the bite of an infected rat flea (Xenopsylla cheopis)?
A. Tuberculosis
B. Leprosy
C. Tetanus
D. Plague
Answer: Option D
Solution (By JKSSB Mock Tests)
Plague is a severe zoonotic bacterial disease caused by Yersinia pestis. It is primarily transmitted to humans through the bite of infected rat fleas, most commonly Xenopsylla cheopis. The disease has three main forms: bubonic (swollen lymph nodes), pneumonic (lungs), and septicemic (blood). Tuberculosis is airborne, leprosy is transmitted via prolonged close contact, and tetanus enters through deep wounds.
Explanation:
Polygenic inheritance is when multiple genes (polygenes) contribute to a single trait, resulting in continuous variation. Human skin color is controlled by at least three genes, showing a spectrum of phenotypes. Pleiotropy is one gene affecting multiple traits. Multiple alleles refer to more than two alleles for a gene (e.g., ABO blood groups). Co-dominance is when both alleles express equally.
Explanation:
Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis. This leads to genetic recombination. Sister chromatid exchange does occur but crossing over specifically refers to the exchange between homologues.
Explanation:
Phycoerythrin absorbs blue-green light, which penetrates deeper water, allowing red algae to photosynthesize at greater depths. Fucoxanthin is in brown algae, chlorophyll b green, carotenoids orange.
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