The process of growing plants in a sterile nutrient medium under controlled conditions is called:
A. Hybridization
B. Tissue culture
C. Cloning
D. Genetic engineering
Answer: Option B
Solution (By JKSSB Mock Tests)
Tissue culture is a technique where plant cells, tissues, or organs are grown on a synthetic nutrient medium (like MS medium) under aseptic conditions to regenerate whole plants. It exploits totipotency. It is used for micropropagation, production of disease-free plants, and conservation. Cloning produces genetically identical individuals, genetic engineering alters DNA, hybridization crosses different varieties.
Explanation:
Abscisic acid (ABA) is known as the stress hormone because it plays a crucial role in plant responses to environmental stresses, particularly drought. It induces the closure of stomata to reduce water loss (transpiration) and also inhibits seed germination and growth, helping the plant survive adverse conditions.
Explanation:
Fungal cell walls contain chitin, a polymer of N-acetylglucosamine, which also forms the exoskeleton of arthropods. Plant cell walls are primarily cellulose, bacterial cell walls contain peptidoglycan (except Mycoplasma). Hemicellulose is a component of plant cell walls along with cellulose. Chitin provides structural strength and rigidity to fungi.
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.
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