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.
Prions are made up of:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Protein
Option (1) RNA — Incorrect. An infectious agent made of RNA alone is a viroid. A viroid is a free RNA with no protein coat, and it is smaller than a virus. Prions carry no RNA.
Option (2) DNA — Incorrect. DNA is the genetic material of most organisms and of many viruses. Prions have no DNA, or any other nucleic acid.
Option (3) Protein — Correct. Prions are proteinaceous infectious agents. Each is an abnormally folded protein, with no nucleic acid in it. Prions cause diseases of the brain, such as mad cow disease in cattle.
Option (4) Both RNA and Protein — Incorrect. A nucleic acid inside a protein coat is the make-up of a virus, for example an RNA virus. Prions are made of protein only.
Note: 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.