Competitive Exams: Botany MCQs (Practice-Test 97 of 104)

  1. Which one of the following plants has dimorphic chloroplasts in its leaves?

    1. Zea mays

    2. Triticum aestivum

    3. Oryza sativa

    4. Nicotiana tabaccum

  2. Consider the following events in the photochemical conversion of light energy into chemical energy by chlorophyll during photosynthesis:

    1. Charge separation

    2. Absorption of a quantum of energy

    3. Ejection of electron

    4. Transfer of light energy

    The correct sequence of these events is

    1. 4, 2, 1, 3

    2. 4, 2, 3, 1

    3. 2, 4, 1, 3

    4. 2, 4, 3, 1

  3. Which one of the following compounds in the photosynthetic electron transport chain contains copper?

    1. Cytochrome

    2. Ferredoxin

    3. Plastoquinone

    4. Plastocyanin

  4. On storage, the sweetness of corn is lost due to conversion of soluble sugars into polysaccharide. If corn is immersed after harvest in boiling water and cooled, the sweetness remains because the

    1. Polysaccharide is re-converted into soluble sugars

    2. Concentration of sugar increases due to heating

    3. Conversion of sugars to polysaccharide stops

    4. Enzymes responsible for the conversion are destroyed

  5. Which one of the following statements correctly disguises Nitrosamines and Nitrobacter?

    1. Nitrosamines is nitrifying bacterium whereas Nitrobacteria is a denitrifying bacterium

    2. Nitrosamines oxidizes ammonia to nitrite while Nitrobacteria oxidizes nitrite to nitrate

    3. Nitrosamines fixes atmospheric nitrogen into ammonia while Nitrobacteria oxidizes ammonia to nitrate

    4. Nitrosamines is responsible for amino acid synthesis while Nitrobacteria is responsible for protein synthesis.

  6. The following compounds are intermediates in the pathway of photorespiration:

    1. Phosphoglycolate

    2. Glyxylate

    3. Serine

    4. Glycine

    The correct sequence of their appearance in the pathway is

    1. 1, 2, 3, 4

    2. 2, 1, 3, 4

    3. 1, 2, 4, 3

    4. 2, 1, 4, 3

  7. Trios phosphate dehydrogenises in glycol sis and Calvin cycle are NOT exactly identical enzymes because

    1. These are separated compartmentally

    2. Glycols takes place both in light and darkness while Calvin cycle does not require light

    3. In glycol sis, it is NAD-linked, while in Calvin cycle, it is NADP-linked

    4. In glycol sis it is associated with catabolic reactions, while in Calvin cycle it is associated with anabolism

  8. A competitive enzyme inhibitor

    1. Alters the Vmax but does not alter the Km of the enzyme

    2. Alters the Km but does not alter the Vmax of the enzyme

    3. Alters both Km and vmax of the enzyme

    4. Does not alter either the Km or Vmax of the enzyme

  9. Consider the following statements about enzymes:

    1. Most enzymes arc pertinacious, although some are RNA molecules.

    2. The specificity of an enzyme is due to its well-defamed three-dimensional structure and the active site present in it.

    3. Prosthetic group is loosely bound to the apoenzyme part of the enzyme.

    4. Portions, prosthetic group and apoenzyme are enzymatic ally inactive when separated from each other.

    Of these statements.

    1. 1, 2 and 3 are correct

    2. 1, 3 and 4 are correct

    3. 1, 2 and 4 are correct

    4. 2, 3 and 4 are correct

  10. Which one of the following statements about protein synthesis in a eukaryotic cell is true?

    1. Fornicated tRNA is important for initiation of translation

    2. Cycloheximide blocks elongation during translation

    3. Single in mRNAs specify for more than one gene product

    4. Erythromycin inhibits elongation during translation

  11. Which of the following statements are true of all tRNAs?

    1. The 5'-end is phosphorylated.

    2. They are single chains.

    3. The antic Odon loop is identical.

    4. The 3'-end base sequence is CCA.

    Select the correct answer

    1. 1, 2 and 3

    2. 1, 3 and 4

    3. 1, 2 and 4

    4. 2, 3 and 4

  12. The function of end nuclease is to

    1. Nick the DNA molecule at the terminal end

    2. Nick the DNA molecule in the middle

    3. Nick the reverse transcriptase

    4. Terminate elongation of Okazaki fragments

  13. To start the transcription process, a specific factor called the sigma (s) factor is required. Its function is to

    1. Help RNA polymerase to start transcription

    2. Help binding of RNA polymerase to DNA template

    3. Help binding of rho (stop) factor

    4. Act as a stop signal

  14. RNA is structurally susceptible to chemical and enzymatic degradation because of

    1. The presence of uracil

    2. The absence of thymine

    3. The presence of a hydroxyl group

    4. Ribofuranose ring structure

  15. Which one of the following is a secondary metabolite?

    1. Ribulose

    2. Glycerol

    3. Metabolic acid

    4. Cholesterol