Official Answer Key & Detailed Solution
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Correct Answer: Option (C) — 1 and 3
Concept & Option Breakdown
Standard Reference VerifiedStatement 1 is correct: Probiotics comprise beneficial live microorganisms, which include bacteria (such as Lactobacillus and Bifidobacterium) as well as yeasts (such as Saccharomyces boulardii).
Statement 2 is incorrect: Probiotic strains are either identical or closely related to the normal microflora naturally residing in the human gastrointestinal tract.
Statement 3 is correct: Many probiotic bacteria express beta-galactosidase (lactase), which hydrolyzes milk sugar (lactose) into glucose and galactose, aiding lactose digestion.
Absolute expressions such as 'do not naturally occur' are typical indicators of incorrect statements in biology questions. Since probiotics naturally support gut health, it is intuitive that similar organisms already constitute the indigenous gut microbiome.
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