11. Which one of the following statements is correct? (UPSC Prelims 2002)
[A] Prions are the smallest free-living cells
[B] The cell wall of Mycoplasmas is made up of amino sugars
[C] Viroids consist of a single-stranded RNA molecule
[D] Rickettsias lack cell wall
Show Answer
Correct Answer: C [Viroids consist of a single-stranded RNA molecule]
Notes:
Viroids are the smallest infectious pathogens known. They are composed solely of a short strand of circular, single-stranded RNA that has no protein coating. All known viroids are inhabitants of higher plants, in which most cause diseases, ranging in economic importance.
12. Pollination by which among the following is called as ornithophily?
[A] Rodents
[B] Aquatic animals
[C] Ants
[D] Birds
Show Answer
Correct Answer: D [Birds]
Notes:
Ornithophily refers to the pollination assisted by the birds. Ornithology is a branch of science which studies about birds. Dr. Salim Ali is a famous Indian ornithologist.
13. Which branch of biology is known for the study of developmental process of organisms?
[A] Genetics
[B] Evolution
[C] Histology
[D] Heredity
Show Answer
Correct Answer: B [Evolution]
Notes:
In branch of biology, the study of developmental process of organisms is known as Evolution. The theory of evolution is based on the idea that all species are related and change slowly over time. Charles Darwin’s theory of evolution states that evolution occurs by natural selection.
14. Chromosome Theory of Inheritance was proposed by __?
[A] Pier Antonio Micheli
[B] Louis Pasteur
[C] Stephen Hales
[D] Thomas Hunt Morgan
Show Answer
Correct Answer: D [Thomas Hunt Morgan]
Notes:
The chromosomal theory of inheritance, or the idea that genes are located on chromosomes, was proposed based on the experiments of Thomas Hunt Morgan.
15. Which of the following biomolecules is more widely distributed in the cell?
[A] Chloroplast
[B] RNA
[C] DNA
[D] Spaherosomes
Show Answer
Correct Answer: B [RNA]
Notes:
DNA and RNA are two types of nucleic acids. DNA is converted into RNA by the process of transcription. The three types of RNA are m-RNA, t-RNA and r-RNA.
16. Plants that reproduce by spores are classified into which of the following?
[A] Bryophytes
[B] Sporophytes
[C] Cryptogams
[D] Thallophytes
Show Answer
Correct Answer: C [Cryptogams]
Notes:
A cryptogam is a plant or plant-like organism that reproduces by spores without flowers or seeds.
17. Into how many subgroups is the plant kingdom classified?
[A] Three
[B] Four
[C] Five
[D] Six
Show Answer
Correct Answer: C [Five]
Notes:
The plant kingdom has been classified into five subgroups: Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, Angiosperms
18. Bacteria used in making of chocolate__?
[A] Lactobacillus bucheri
[B] Lactobacillus cacaonum
[C] monosodium glutamate
[D] Lactobacillus casei
Show Answer
Correct Answer: B [Lactobacillus cacaonum]
Notes:
Lactobacillus cacaonum is a bacteria used in the food packaging industry for making chocolates. Lactobacillus bucheri is helpful in making wine. Lactobacillus casei is used in making cheese. Monosodium glutamate is used in Chinese food to enhance taste.
19. Which of the following is the final step in the synthesis of peptidoglycan?
[A] attachment of a peptide to muramic acid
[B] attaching two amino acids to form a cross-link
[C] attachment of a portion of peptidoglycan to a membrane lipid
[D] binding of penicillin to a membrane protein
Show Answer
Correct Answer: B [attaching two amino acids to form a cross-link]
Notes:
Peptidoglycan or murein is a type of polymer consisting of sugars and amino acids. Attaching two amino acids to form a cross-link is the final step in the synthesis of peptidoglycan.
20. In which of the growing tissues are cytokinins most abundant?
[A] roots
[B] embryos
[C] fruits
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Cytokinins are most abundant in growing tissues – such as roots, embryos and fruits, where cell division is taking place.
