Read the given passage carefully and answer the questions.
Antibiotics have greatly improved our capacity to treat deadly diseases such as plague, whooping cough (kali khansi), diphtheria (gal ghotu) and leprosy (kusht rog), which used to kill millions all over the globe. Streptokinase produced by the bacterium Streptococcus and modified by genetic engineering is used as a 'clot buster' for removing clots from the blood vessels of patients who have undergone myocardial infarction leading to heart attack. Microbes are diverse-protozoa, bacteria, fungi and microscopic animal and plant viruses, viroids and also prions that are proteinacious infectious agents. The puffed-up appearance of dough is due to the production of CO2 gas. Similarly the dough, which is used for making bread, is fermented using baker's yeast (Saccharomyces cerevisiae). Primary sewage treatment basically involve physical removal of particles - large and small - from the sewage through filtration and sedimentation. These are removed in stages; initially, floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge, and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment. The primary effluent is passed into large aeration tanks, where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs. While growing, these microbes consume the major part of the organic matter in the effluent.
The puffed-up appearance of dough in the baking industry is due to the production of -
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Carbon dioxide
Option (1) Carbon dioxide — Correct. Bread dough is fermented by baker’s yeast (Saccharomyces cerevisiae), and dosa and idli dough by bacteria. These microbes break down the sugars of the dough and release CO2 gas. The gas bubbles stay trapped in the dough and make it puff up.
Option (2) Methane — Incorrect. Methane is made by methanogens, such as Methanobacterium, that grow without oxygen on cellulose material. They live in biogas plants and in the rumen of cattle, not in dough.
Option (3) Carbon monoxide — Incorrect. Carbon monoxide is a poisonous gas given off when fuel burns in too little air. Fermentation does not produce it.
Option (4) Lactic acid — Incorrect. Lactic acid is made by lactic acid bacteria (Lactobacillus), which turn milk into curd. It is an acid that makes food sour. It is not a gas, so it cannot puff up the dough.
Note 1: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
Note 2: A similar question was also asked in CUET (UG) 2026 on 22-05-2026 (Slot 2), and in CUET (UG) 2023 on 23-06-2023 (Slot 3).