Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): The thickness of the ozone layer is measured in Dobson Units (DU).

Reason (R): The ozone layer is found in the Troposphere and protects us from harmful UV-B radiation.

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#Question id: 38805

#Plant Biotechnology

Q. Which of the following is a significant drawback of using thermotherapy on whole plants?

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#Question id: 38806

#Plant Biotechnology

Q. Thermotherapy is noted to be effective against which specific types of pathogens? 

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#Question id: 38807

#Plant Biotechnology

Q. Why might a plant that survives thermotherapy be at a disadvantage later on?

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#Question id: 38808

#Plant Biotechnology

Q. Assertion (A):Thermotherapy combined with meristem (shoot-tip) culture is more effective than either method alone for eliminating certain plant viruses.

Reason (R): Some viruses such as Potato virus S (PVS) and Potato virus X (PVX) can only be eliminated when heat treatment is followed by shoot-tip culture, and larger shoot tips taken from heat-treated plants show better survival.

Choose the correct option:

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#Question id: 38809

#Plant Biotechnology

Q. Assertion (A): Prolonged cold treatment followed by shoot-tip culture can successfully eliminate plant viruses.

Reason (R):Exposure of chrysanthemum plants to 5°C for several months increased the proportion of virus-free plants for both chrysanthemum stunt virus and chrysanthemum chlorotic mottle virus.

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#Question id: 38810

#Plant Biotechnology

Q. Assertion (A):Increasing the duration of cryotherapy improves virus elimination efficiency.

Reason (R):Extending cold treatment at 5°C from 4 months to 9.5 months increased virus-free frequencies for both CSV and CCMV.