Which of the following diseases is caused by a protozoan transmitted by the tsetse fly?
A. Yellow fever
B. Malaria
C. Filariasis
D. Sleeping sickness
Answer: Option D
Solution (By JKSSB Mock Tests)
African sleeping sickness (trypanosomiasis) is caused by the protozoan Trypanosoma brucei, transmitted by the tsetse fly (Glossina). Malaria is by Plasmodium (Anopheles mosquito), filariasis by Wuchereria (Culex), yellow fever by a virus (Aedes). Sleeping sickness affects the central nervous system, causing lethargy, coma, and death if untreated.
Explanation:
Pollination is the transfer of pollen from the anther to the stigma of a flower, a prerequisite for fertilization. Fertilization is the fusion of male and female gametes. Germination is seed growth, dispersal is seed spreading.
Explanation:
Robert Hooke observed thin slices of cork under a microscope he designed and saw honeycomb-like compartments which he termed 'cells' in his 1665 book 'Micrographia'. Leeuwenhoek discovered living cells (bacteria, protozoa). Brown discovered the nucleus (1831), and Virchow proposed that all cells arise from pre-existing cells (1855). Hooke's cells were dead, empty cell walls of cork.
Explanation:
The cell cycle consists of interphase (G1, S, G2) and M phase. DNA synthesis or replication occurs during the S (synthesis) phase, resulting in each chromosome having two sister chromatids. G1 is for cell growth and RNA/protein synthesis; G2 is for preparation for mitosis. M phase includes mitosis and cytokinesis. Accurate DNA replication in S phase is crucial for genetic continuity.
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