T. O. Diener discovered a

(1) free infectious RNA

(2) free infectious DNA

(3) infectious protein

(4) bacteriophage

Bacterial leaf blight of rice is caused by a species of

(1) Xanthomonas

(2) Pseudomonas

(3) Alternaria

(4) Erwinia

In the light of recent classification of living organisms into three domains of life (bacteria, archaea and eukarya), which one of the following statement is true about archaea?

(1) Archaea resemble eukarya in all respects

(2) Archaea have some novel features that are absent in other prokaryotes and eukaryotes

(3) Archaea completely differ from both prokaryotes and eukaryotes

(4) Archaea completely differ from prokaryotes

Thermococcus, Methanococcus and Methanobacterium exemplify

(1) archaebacteria that contain protein homologous to eukarytic core histones

(2) archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively supercoiled

(3) bacteria whose DNA is relaxed or positively supercoiled but which have a cytoskeleton as well as mitochondria

(4) bacteria that contain a cytoskeleton and ribosomes

Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing microorganism?

(1) Casuarina equisetifolia

(2) Crotolaria juncea

(3) Cycas revoluta

(4) Cicer arietinum

Which of the following is a slime mould?

(1) Rhizopus

(2) Physarum

(3) Thiobacillus

(4) Anabaena

Ergot of rye is caused by a species of:

(1) Phytophthora

(2) Uncinula

(3) Ustilago

(4) Claviceps

True nucleus is absent in

(1) Anabaena

(2) Mucor

(3) Vaucheria

(4) Volvox

Cell wall is absent in

(1) Aspergillus

(2) Funaria

(3) Mycoplasma

(4) Nostoc

Which of the following shows coiled RNA strand and capsomeres?

(1) Polio virus

(2) Tobacco mosaic virus

(3) Measles virus

(4) Retrovirus