Which one of the following viruses used to be responsible for highly infectious disease Smallpox ?
- A.Adenovirus
- B.Variola virus
- C.Aichi virus
- D.Coxsackie virus
Correct answer
Explanation
The correct answer is B, Variola virus. Smallpox was caused by the variola virus, a large DNA virus of the pox family that spread from person to person through the air.
Smallpox caused fever and a rash of fluid-filled blisters that left deep scars, and killed about three in ten of those infected. In 1796 Edward Jenner showed that material from cowpox protected people from it, which gave the world its first vaccine; the word vaccine comes from vacca, Latin for cow. A worldwide vaccination drive led the World Health Organization to declare smallpox eradicated in 1980. It remains the only human disease wiped out in this way.
A is wrong because adenoviruses mainly cause colds, sore throats and eye infections. C is wrong because the Aichi virus causes stomach upsets and diarrhoea. D is wrong because coxsackie viruses cause hand, foot and mouth disease and some heart infections.
Exam tip: smallpox, variola virus, Jenner's vaccine in 1796, declared eradicated by WHO in 1980.
Practice Questions
View allWhich one of the following features is an indication for modification of stem of a plant?
- A.Presence of 'eye' on potato
- B.'Scale' found in onion
- C.'Tendril' found in pea
- D.'Hair' present in carrot
Show answer
The eyes of a potato are nodes with buds, and only a stem bears nodes and buds, so they prove that the potato is a modified stem.
Read the full explanation →Which one of the following metals is used in the filaments of photo-electric cells that convert light energy into electric energy ?
- A.Tungsten
- B.Copper
- C.Rubidium
- D.Aluminium
Show answer
Rubidium, an alkali metal like caesium, gives off electrons easily when light falls on it, so it is used in photoelectric cells.
Read the full explanation →Tooth enamel is made up of which one of the following calcium compounds ?
- A.Calcium carbonate
- B.Calcium sulphate
- C.Calcium hydroxide
- D.Calcium phosphate
Show answer
Tooth enamel is made mainly of calcium phosphate in the form of a hard crystal called hydroxyapatite. Enamel is the hardest substance in the human body, harder even than bone.
Read the full explanation →After fertilization, the fruit and the seed are produced by
- A.ovule and ovary, respectively
- B.ovary and ovule, respectively
- C.ovary, no ovule required
- D.ovule, no ovary required
Show answer
After fertilisation the ovary of the flower grows into the fruit, and each ovule inside it develops into a seed.
Read the full explanation →Which among the following statements with respect to carbon is/are correct?
1. Carbon forms the basis for all living organisms and many things we use
2. Carbon shows tetra-valency and the property of catenation
3. Carbon forms covalent bonds with itself and other elements
4. Carbon forms compounds containing triple and tetra bonds between carbon atoms
Select the correct answer using the code given below :
- A.1 only
- B.1 and 2 only
- C.1, 2 and 3
- D.2 and 4
Show answer
Statements 1, 2 and 3 are true, but carbon never forms a quadruple, or tetra, bond between two carbon atoms.
Read the full explanation →