Read the following passage carefully and answer the given questions.
The separated DNA fragments can be visualized only after staining the DNA with ethidium bromide followed by exposure to UV radiation. Bright orange colored bands of DNA in ethidium bromide stained gel exposed to UV light can be seen. The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. This step is known as elution. The DNA fragments purified in this way are used in constructing recombinant DNA by joining them with a cloning vector.
The natural polymer used in the agarose gel is extracted from:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Sea weeds
Option (1) Sea weeds — Correct. Agarose is a natural polymer, a large molecule made of many repeating sugar units. It is obtained from seaweeds, which are large marine algae. Its gel forms a fine mesh that sieves the DNA fragments by size.
Option (2) Desert plants — Incorrect. Desert plants are land plants of dry places. Agarose does not come from them; its source is algae of the sea.
Option (3) Soil microbes — Incorrect. Soil microbes give us many useful products, such as antibiotics and enzymes. But agarose is not a microbial product.
Option (4) Vegetable peels — Incorrect. Vegetable peels are kitchen waste of land plants. Agarose is not extracted from them.
Note 1: This passage is taken from NCERT as it is. 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) 2023 on 26-05-2023 (Slot 3).
NCERT Extract:
Restriction Enzymes – …
