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Biological Molecules MCQs for MDCAT Practice

Biology section, Biological Molecules chapter. Up to eight free sample questions, each with the correct answer and a worked explanation. The full chapter opens in the app.

The bank has 2,319 active questions on this chapter. Your first 500 practice attempts are free, and every attempt includes a worked explanation.

  1. Question 1
    Phosphatidic acid is composed of:
    • 2 glycerol, 2 fatty acids & 1 phosphoric acid
    • 2 glycerol, 1 fatty acids & 1 phosphoric acid
    • 1 glycerol, 2 fatty acids & 1 phosphoric acid (correct answer)
    • 2 glycerol, 1 fatty acids & 2 phosphoric acid
    Correct answer: C
    Phosphatidic acid, a key phospholipid precursor, is formed from one glycerol molecule esterified with two fatty acids and one phosphate group.
  2. Question 2
    Poly A tail:
    • Core enzyme
    • U ribonucleotide
    • 3' end (correct answer)
    • Sigma factor
    Correct answer: C
    The Poly-A tail, a crucial post-transcriptional modification in eukaryotes, is added to the 3' end of mRNA, enhancing its stability and translation.
  3. Question 3
    In the ground state of a cobalt atom there are _______ unpaired electrons and the atom is _______.
    • 5, paramagnetic
    • 2, diamagnetic
    • 0, diamagnetic
    • 3, paramagnetic (correct answer)
    Correct answer: D
    Determine unpaired electrons in Cobalt's ground state to classify it as paramagnetic or diamagnetic, testing electron configuration and magnetic properties.
  4. Question 4
    The DNA of an elephant and the DNA of a cherry tree will probably differ in all of the following respects EXCEPT the:
    • Kinds of genes for which the DNA codes
    • Number of DNA molecules
    • Length of DNA molecules
    • Kinds of nucleotides utilized in forming DNA (correct answer)
    Correct answer: D
    DNA's fundamental building blocks are universal, meaning elephants and cherry trees use the same nucleotides, unlike their genes, chromosome numbers, or lengths.
  5. Question 5
    Which one of the following is a correct sequence in biological methods?
    • Observations - Hypothesis - Law - Theory
    • Observations - Hypothesis - Deduction - Experimentation (correct answer)
    • Hypothesis - Observations - Deduction - Experimentation
    • Law - Theory - Deduction - Observations
    Correct answer: B
    Master the scientific method's logical flow: from initial observations and hypothesis formation to experimental testing and deduction.
  6. Question 6
    The data presented by Erwin Chargaff suggested that:
    Diagram for this question, with no written description.
    • Adenine and Guanine are equal
    • Guanine and thymine are equal
    • Adenine and cytosine are equal
    • Adenine and thymine are equal and so are cytosine and guanine (correct answer)
    Correct answer: D
    Chargaff's rules reveal the base pairing principles in DNA: A pairs with T, and G pairs with C, forming the double helix structure.
  7. Question 7
    Among the following edible fishes, which one is a marine fish having a rich source of omega­-3 fatty acids?
    • Mystus
    • Mangur
    • Mrigala
    • Mackerel (correct answer)
    Correct answer: D
    Identify the marine fish rich in omega-3 fatty acids among common edible options, highlighting Mackerel's nutritional significance.
  8. Question 8
    A haemoglobin molecule consists of ____ amino acids:
    • 874
    • 474
    • 674
    • 574 (correct answer)
    Correct answer: D
    Master the precise amino acid count of human haemoglobin, a key protein in oxygen transport, to ace MDCAT questions on protein structure.

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Read the full Biological Molecules chapter notes: Biological Molecules notes. Or browse every chapter.