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Free Biological Molecules MCQs with Answers

1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.

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Classification of Biological MoleculesBiological Importance of WaterCarbohydratesProteinsLipidsRibonucleic Acid (RNA)Conjugated MoleculesStructure of DNA
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1,790 questions · page 90 of 90

1781. In Eukaryotes, DNA replication proceeds at the rate of:

  • A. 50 base pairs per second
  • B. 40 base pairs per second
  • C. 20 base pairs per second
  • D. 30 base pairs per second

Explanation: Eukaryotic DNA replication typically occurs at a rate of approximately 50 base pairs per second.

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Correct answer: 50 base pairs per second

1782. The genome of the most animals and higher plants is:

  • A. DNA
  • B. RNA
  • C. Both DNA and RNA
  • D. Either DNA or RNA

Explanation: Plant genome assembly represents the complete genomic sequence of a plant species, which is assembled into chromosomes and other…

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Correct answer: DNA

1783. Replication of DNA occurs during:

  • A. Interphase
  • B. Prophase
  • C. Metaphase
  • D. Anaphase

Explanation: DNA replication occurs during S-stage of interphase.

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Correct answer: Interphase

1784. Phosphodiester linkage is formed between.

  • A. Two nucleotide bases
  • B. Amino acid
  • C. Two sugar
  • D. Nucleotides and phosphates

Explanation: In the polynucleotide, adjacent nucleotides are joined by a phosphodiester linkage, which consists of a phosphate group that links the…

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Correct answer: Nucleotides and phosphates

1785. The number of hydrogen bonds between guanine and cytosine are:

  • A. One
  • B. Two
  • C. Three
  • D. Four

Explanation: The Adenine - Thymine base pair is held together by 2 hydrogen bonds while the Guanine - Cytosine base pair is held together by 3 hydrogen…

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Correct answer: Three

1786. Individuality of every persons is maintained by nucleotide genome sequence difference of:

  • A. 0.1%
  • B. 2%
  • C. 3%
  • D. 5%

Explanation: Human beings share 99.9% of their genome sequence, making 0.1% the portion that accounts for individual genetic differences.

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Correct answer: 0.1%

1787. Which one among the following is double ring structure?

  • A. Cytosine
  • B. Thymine
  • C. Guanine
  • D. Uracil

Explanation: Cytosine, thymine, and guanine are nitrogenous bases found in DNA and RNA.

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Correct answer: Guanine

1788. Purines are _ nitrogenous bases.

  • A. Double ringed
  • B. Single ringed
  • C. Double bond
  • D. Single bond

Explanation: Purines are a type of nitrogenous base found in DNA and RNA, characterized by a double-ring structure.

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Correct answer: Double ringed

1789. Polyhydroxy aldehydes or ketones are known as:

  • A. Carbohydrates
  • B. Proteins
  • C. Lipids
  • D. Vitamins

Explanation: Carbohydrates are defined as polyhydroxy aldehydes or ketones, or compounds that yield them on hydrolysis.

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Correct answer: Carbohydrates

1790. Sucrose is considered as:

  • A. Monosaccharides
  • B. Disaccharides
  • C. Polysaccharides
  • D. None of these

Explanation: Sucrose is a disaccharide: one glucose unit joined to one fructose unit by a glycosidic bond, with the loss of a molecule of water.

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Correct answer: Disaccharides
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