In order to obtain virus-free plants through tissue culture, the best method is meristem culture. Meristem tissue is the region of the plant where cell division occurs, and it is less likely to harbor viruses compared to other plant tissues.
Therefore, the correct option is (D): meristem culture
Answer the following questions:
(a) [(i)] Explain how some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans but do not kill the Bacillus.
[(ii)] How is the above mechanism exploited for the production of Bt cotton plant by biotechnologists?
(b) [(i)] Explain how the amplification of gene of interest is done using PCR.
[(ii)] State two applications of the desired amplified fragment of DNA.
The basic scheme of the essential steps involved in the process of recombinant DNA technology is summarised below in the form of a flow diagram. Study the given flow diagram and answer the questions that follow.
(a) What is the technical term used for Step 4 in the above process?
(b) Which of the given two combinations of restriction enzyme should be used in Step 1? Justify your answer.
(i) EcoR I to cut the plasmid and Hind III to cut the alien DNA.
(ii) EcoR I to cut both the plasmid and alien DNA.
A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is :
The output (Y) of the given logic implementation is similar to the output of an/a …………. gate.
What is Microalbuminuria ?

In the above represented plasmid an alien piece of DNA is inserted at the EcoRI site. Which of the following strategies will be chosen to select the recombinant colonies?
Human Respiratory System is a compound biological system of organs and tissues that helps in gaseous exchange. The system includes airways, lungs, and blood vessels. Its core function is to introduce oxygen and expel carbon dioxide from the body. The atmospheric air is continuously pumped in and out through a system of pipes which are called the conducting airways. There are a great number of muscles and blood vessels involved in the whole process of respiration.
