Bt cotton is a genetically modified crop that contains a gene from:
A. Pseudomonas fluorescens
B. Escherichia coli
C. Bacillus thuringiensis
D. Agrobacterium tumefaciens
Answer: Option C
Solution (By JKSSB Mock Tests)
Bt cotton is a transgenic crop developed by inserting cry genes (e.g., cryIAc, cryIIAb) from the soil bacterium Bacillus thuringiensis (Bt). These genes code for crystal proteins (Cry proteins) that are toxic to certain insect pests, particularly the cotton bollworm. When the insect ingests the protein, it is activated in its alkaline gut, creating pores in the gut lining, leading to the insect's death.
Explanation:
Edward Jenner developed the first successful smallpox vaccine (1796). Pasteur invented pasteurization and rabies vaccine, not penicillin. Fleming discovered penicillin. Hooke coined the term 'cell' but did not discover bacteria; Leeuwenhoek observed bacteria. Thus, the correct match is Jenner - smallpox vaccine.
Explanation:
Trypsin is a pancreatic protease. Ptyalin is an amylase, pepsinogen requires HCl for activation, sucrase acts on sucrose, lactase on lactose.
Explanation:
Darwin traveled as a naturalist on the HMS Beagle (1831-1836) and made extensive observations, especially in the Galápagos Islands. His observations of finches' beak adaptations led to the concept of natural selection as the mechanism for evolution. 'On the Origin of Species' (1859) laid out his theory. HMS Challenger was an oceanographic expedition. HMS Endeavour was Captain Cook's ship.
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