DEFINE?
a) viroids
b) prions
c) lichens
Answers
(a) Viroid, an infectious particle smaller than any of the known viruses, an agent of certain plant diseases. The particle consists only of an extremely small circular RNA (ribonucleic acid) molecule, lacking the protein coat of a virus. ... Whether viroids occur in animal cells is still uncertain.
(b) A prion is a type of protein that can cause disease in animals and humans by triggering normally healthy proteins in the brain to fold abnormally. The prion mode of action is very different to bacteria and viruses as they are simply proteins, devoid of any genetic material.
(c) Lichens are compound plants as algae and fungi live together in close association, as a result of which both are benefited. This relationship is called symbiosis. They occur as greyish green growths on rocks, bark of the tree or on the ground.
Answer:
A viroid is an infective single-stranded circular RNA particle without any protective shell a la a virus. Viroids infect plants. ... A prion is a misfolded infectious protein that can be transmitted from one host to another.
Lichens are a complex life form that is a symbiotic partnership of two separate organisms, a fungus and an alga. ... The alga can be either a green alga or a blue-green alga, otherwise known as cyanobacteria. Many lichens will have both types of algae.
Explanation: