False claim about mRNA nucleotide linkage

Steps:

• Recall mRNA structure: single-stranded RNA polymer of ribonucleotides.
• Check bonding in A: nucleotides link via phosphodiester covalent bonds, not hydrogen bonds.
• Verify sugar in B: ribonucleotides contain ribose.
• Assess base equality in C: A and U amounts vary by gene sequence.
• Compare to DNA in D: mRNA matches coding strand sequence (U for T), complements template.

Why A is correct:

• Hydrogen bonds pair bases internally, but mRNA's sugar-phosphate backbone forms through phosphodiester bonds between 3' OH and 5' phosphate.

Why the others are wrong:

• B: All mRNA nucleotides include ribose sugar as part of RNA composition.
• C: Single-stranded mRNA has sequence-dependent base ratios, not always equal A to U.
• D: Transcription produces mRNA complementary to template DNA, matching the nontemplate (coding) strand.

Final answer: A