11. Why there are more anti-bacterial drugs than anti-viral drugs? (UPSC Prelims 1989)
[A] Bacterial diseases are intra-cellular
[B] Viral diseases are intra-cellular
[C] Virus is smaller than bacteria
[D] Drugs can penetrate bacteria more effectively
Show Answer
Correct Answer: B [Viral diseases are intra-cellular]
Notes:
Viruses infect all sorts of cells, from bacteria to human cells, but for the most part tend to be host specific. For example, the tobacco mosaic virus infects certain plants; the rabies virus infects only mammals; and the AIDS virus, HIV, infects only certain human blood cells.
12. In Mycorrhiza, symbiotic association occurs between which of the following organisms? (UPSC Prelims 1990)
[A] Bacteria and roots of higher plants
[B] Algae and roofs of orchids
[C] Fungi and roots of higher plants
[D] Protozoa and roots of higher plants
Show Answer
Correct Answer: C [Fungi and roots of higher plants]
Notes:
Mycorrhiza is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant’s rhizosphere, its root system.
13. Which of the following is the name given to the cellular and molecular control of programmed cell death? (UPSC Prelims 2001)
[A] Apoptosis
[B] Ageing
[C] Degeneration
[D] Necrosis
Show Answer
Correct Answer: A [Apoptosis]
Notes:
• Apoptosis is the process of programmed cell death in multicellular organisms. Apoptosis occurs during normal cell turnover, development and in immune system.
• Ageing is the accumulation of changes.
• Degeneration is the deterioration of a tissue or an organ in which its function is diminished or its structure impaired.
• Necrosis is the disorganized break down of flesh in some part of the body of multicellular organism.
14. Among living organisms, which one of the following is the most responsible factor for bringing about the origin of a new species? (UPSC Prelims 2002)
[A] Isolation
[B] Mutation
[C] Natural Selection
[D] Sexual Reproduction
Show Answer
Correct Answer: A [Isolation]
Notes:
Origin of new species depends on isolation of gene flow between new species and develops significant genetic divergence.
15. When one gene controls two or more different characters simultaneously, the phenomenon is known by which of the following names? (UPSC Prelims 2002)
[A] Apomixis
[B] Pleiotropy
[C] Polyploidy
[D] Polyteny
Show Answer
Correct Answer: B [Pleiotropy]
Notes:
• Polyploidy occurs in cells and organisms when there are more than two paired (homologous) set of chromosome founds which controls more than one characters simultaneously.
• Apomixis is the process of asexual reproduction in which the embryo grows from egg cells without being fertilized.
• Pleiotropy occurs when a single gene influences multiple phenotypic traits.
• Polytene is a giant chromosome found in some two-winged flies.
16. What is the famous Bombyx Mori, a variety of?
[A] Honeybee
[B] Cotton
[C] Earthworm
[D] Silk
Show Answer
Correct Answer: D [Silk]
Notes:
Sericulture – It refers to the rearing of silk worms and obtaining silk from them. It involves raising a feed crop, chiefly mulberry leaves, and tending to silk worms and obtaining silk fibre from the cocoons produced by the worms.
Varieties – There are a number of varieties of worm reared for silk production, the most important variety being Bombyx mori.
17. Viruses are usually divided into several large groups based mainly on?
[A] nature of the host
[B] nucleic acid characteristics
[C] capsid symmetry
[D] diameter of the viroin or nucleocapsid
Show Answer
Correct Answer: A [nature of the host]
Notes:
Viruses are usually divided into several large groups based mainly on nature of the host. A virus is an infectious agent of small size and simple structure that can multiply only in living cells of animals, plants or bacteria.
18. Which of the following can affect proteins and nucleic acids, but not viruses?
[A] Denaturation
[B] Enzyme treatment
[C] Pressure
[D] All of these
Show Answer
Correct Answer: D [All of these]
Notes:
Because it affects proteins upon denaturation, this nuclease enzymes affect nucleic acids and the pressure will affect the structure but not the virus.
19. Cycas, pinus, Thuja, Cedrus, Abies, Larix are some of the examples of __?
[A] gymnosperms
[B] Phaeophytes
[C] Bryophytes
[D] None of these
Show Answer
Correct Answer: A [gymnosperms]
Notes:
Cycas, pinus, Thuja, Cedrus, Abies, Larix are some of the examples of gymnosperms.
20. What is the arrangement of ovules inside the ovary called?
[A] Aestivation
[B] Placentation
[C]
Hibernation
[D] Fragmentation
Show Answer
Correct Answer: B [Placentation]
Notes:
The arrangements of ovules within the ovary are known as placentation.
