Which of the following is correct about viroids?

1. They have free RNA without protein coat.

2. They have DNA with protein coat.

3. They have free DNA without protein coat.

4. They have RNA with protein coat.

Which of the following statements is incorrect?

Mad cow disease in cattle is caused by an organism which has:

1. Inert crystalline

2. Abnormally folded protein

3. Free RNA without protein coat

4. Free DNA without protein coat

Which of the following statements is correct?

1. Lichens do not grow in polluted areas.
2. Algal component of lichens is called mycobiont.
3. Fungal component of lichens is called phycobiont.
4. Lichens are not good pollution indicators.