3] A scientist is attempting to create a recombinant DNA molecule by combining a plasmid vector and a foreign DNA. A plasmid DNA and a linear DNA of the same size have a single site for the restriction enzyme EcoRI. When cut by the same RE and separated by gel electrophoresis, the plasmid shows one DNA band, and the linear DNA shows two bands.
How does EcoRI differ from an exonuclease?
---------------------------------------------------------------------------------------------------------------------
ISC (CLASS XII) SPECIMEN QUESTION PAPER 2026

Answer the following questions briefly.
Renu was conducting an experiment. She started with a single DNA strand and
ran six cycles of PCR to produce number of molecules of DNA.

Answer the following questions briefly.
When a cross is made between tall plants with yellow seeds (TtYy) and tall
plants with green seeds (Ttyy), what proportions of phenotype in the offspring
could be expected to be tall plants with green seeds?

Answer the following questions briefly.
If the number of chromosomes in an endosperm is 12, then what will be the
number of chromosomes in megaspore mother cell?

Answer the following questions briefly.
Anita is suffering from dry and scaly lesions on various parts of the body. What is
the biological name of the causative fungus?

Answer the following questions briefly.
At what stage of embryonic development, can the zygote be introduced in the
Fallopian tube in ZIFT?

Answer the following questions briefly.
A research scholar isolated a new restriction enzyme from Thermus aquaticus
strain YT3. It was the fourth restriction enzyme discovered from this strain.
Propose a scientifically accurate name for this enzyme using the standard
nomenclature rules.