Viruses are obligate parasites because they cannot carry out metabolic processes or reproduce independently. They rely on the cellular machinery of a host organism to replicate and propagate. Viruses are essentially genetic material (either DNA or RNA) enclosed in a protein coat, which is called a capsid (option D is incorrect). Option A is incorrect because viruses lack their own metabolic systems, and option B is incorrect because not all viruses contain both RNA and DNA; they can have one or the other as their genetic material.
So, the correct option is (C): Viruses are obligate parasites
Each of the following characteristics represents a Kingdom proposed by Whittaker. Arrange the following in increasing order of complexity of body organization.
A. Multicellular heterotrophs with cell wall made of chitin.
B. Heterotrophs with tissue/organ/organ system level of body organization.
C. Prokaryotes with cell wall made of polysaccharides and amino acids.
D. Eukaryotic autotrophs with tissue/organ level of body organization.
E. Eukaryotes with cellular body organization.
Choose the correct answer from the options given below:
| List I | List II | ||
| A | Typhoid | I | Fungus |
| B | Leishmaniasis | II | Nematode |
| C | Ringworm | III | Protozoa |
| D | Filariasis | IV | Bacteria |
A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is : 
AB is a part of an electrical circuit (see figure). The potential difference \(V_A - V_B\), at the instant when current \(i = 2\) A and is increasing at a rate of 1 amp/second is: