11. Genetic code is made up by the four-letter alphabet forming the pairs?
[A] A—C, C—A, T—G, G—T
[B] A—G, G—A, C—A, T—C
[C] T—G, G—T, A—C, C—A
[D] A—T, T—A, C—G, G—C
Show Answer
Correct Answer: D [A—T, T—A, C—G, G—C]
Notes:
The four letters designating these bases (A, G, C, and T) are the alphabet of the genetic code. Each rung of the DNA molecule is contains a combination of two of these letters, one jutting out from each side. In this genetic code, A always combines with T, and C with G to make what is called a base pair.
12. Which of the following features of the human immunodeficiency virus (HIV) makes it a living entity?
[A] Excrete in human serum
[B] Disturb host cell respiration
[C] Undergo auto-reproduction
[D] Move from one cell to another
Show Answer
Correct Answer: C [Undergo auto-reproduction]
Notes:
The human immunodeficiency virus is a type of virus called a retrovirus. Like all viruses, human immunodeficiency virus reproduces using the genetic machinery of the cell it infects. With the help of an enzyme called integrase (also produced by HIV), the viral DNA becomes integrated with the cell’s DNA.
13. In Mycorrhiza, symbiotic association occurs between which of the following organisms?
[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.
14. Which of the following is the major component of honey?
[A] Glucose
[B] sucrose
[C] maltose
[D] fructose
Show Answer
Correct Answer: D [fructose]
Notes:
Fructose comprises the major portion of honey – about 82%. The carbohydrates present are the monosaccharides fructose (38.2%) and glucose (31%); and disaccharides (~9%) sucrose, maltose, isomaltose, maltulose, turanose and kojibiose.
15. Which one of the following organisms can serve as a biofertiliser for rice crop?
[A] Blue-green algae
[B] Rhizobium sp
[C] Mycorrhizal fungi
[D] Azotobacter sp
Show Answer
Correct Answer: A [Blue-green algae]
Notes:
Blue green algae is used as a biofertilizer in rice crop. Blue green algae has the nitrogen fixing ability which enhances the production of rice. Blue–green algae are not algae at all, but types of bacteria called cyanobacteria that are normally present in many lakes.
16. Who discovered nucleus of cell wall?
[A] Theodor Boveri
[B] Robert Brown
[C] Albert von Kolliker
[D] Robert Hooke
Show Answer
Correct Answer: B [Robert Brown]
Notes:
Robert Brown discovered the nucleus in the cell in 1831. The nucleus is a protoplasmic body in eukaryotic cells. It is covered by a double membrane that contains the hereditary details.
17. What is the pollination medium in Malacophilous?
[A] bats
[B] water
[C] air
[D] snails
Show Answer
Correct Answer: D [snails]
Notes:
Snails are the pollination medium in Malacophilous. Pollination is the process in which the pollens are transferred from anther to stigma.
18. By which gas do commercial fruit growers control the ripening time of fruits?
[A] Ethane
[B] Argon
[C] Benzene
[D] Ethylene
Show Answer
Correct Answer: D [Ethylene]
Notes:
Ethylene gas is used by commercial fruit growers to control the ripening time of the fruit.
19. Which of the following is similar to autogamy, but requires pollinators?
[A] Geitonogamy
[B] Cleistogamy
[C] Apogamy
[D] Xenogamy
Show Answer
Correct Answer: A [Geitonogamy]
Notes:
Geitonogamy is similar to autogamy but requires pollinators. Autogamy is the pollination of a flower by its own pollens. Same geitonogamy is the pollination of one flower by the pollen grains of another flower on the same plant.
20. What are the major diseases of wheat?
[A] Powdery mildew
[B] Loose smut
[C] Karnal bunt
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Powdery Mildew, Loose Smut, Brown Rust, Striped Rust/Yellow Rust, Black Rust, Flag Smut, Hill Bunt or Stinking Smut, Karnal Bunt, etc. are the major diseases of wheat.
