Passage

Passage – 2 In a study, scientists compared the microbiomes of poorly nourished and well nourished infants and young children. Gut microbes were isolated from faecal samples of malnourished and healthy children. The microbiome was “immature” and less diverse in malnourished children compared to the better developed “mature” microbiome found in healthy children of the same age. According to some studies, the chemical composition of mother's milk has shown the presence of a modified sugar (sialylated oligosaccharides). This is not utilized by the baby for its own nutrition. However, the bacteria constituting the infant's microbiome thrive on this sugar which serves as their food. Malnourished mothers have low levels of this sugar in their milk. Consequently, the microbiomes of their infants fail to mature. That in turn, leads to malnourished babies.

On the basis of the above passage, the following assumptions have been made : 1. Processed probiotic foods are a solution to treat the children suffering from malnutrition due to immature gut bacteria composition. 2. The babies of malnourished mothers generally tend to be malnourished. Which of the above assumptions is/are valid?

(a) 1 only
(b) 2 only ✓ UPSC's answer
(c) Both 1 and 2
(d) Neither 1 nor 2

Why the answer is (b)

• Assumption 2 is valid because the passage explicitly states that malnourished mothers have low levels of sialylated oligosaccharides in their milk, which prevents the infant's microbiome from maturing, leading to malnourished babies.

• The passage establishes a direct causal link: malnourished mother -> low sugar in milk -> immature microbiome -> malnourished baby.

• Assumption 1 is invalid because the passage does not mention 'processed probiotic foods' as a treatment or solution.

• The passage only explains the biological mechanism of how malnutrition is transmitted via the microbiome, not therapeutic interventions.

• Therefore, only Assumption 2 is supported by the text, making option (b) the correct answer.

Why the other options are wrong

(a) 1 only: Assumption 1 is not mentioned in the passage, and Assumption 2 is valid, so '1 only' is incorrect.
(c) Both 1 and 2: Assumption 1 is not supported by the passage, so 'Both 1 and 2' is incorrect.
(d) Neither 1 nor 2: Assumption 2 is directly supported by the passage, so 'Neither 1 nor 2' is incorrect.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2019, held on 2 June 2019. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.