Q 01/05

Which base does RNA use in place of DNA's thymine?

A) Uracil

B) Guanine

C) Cytosine

D) Inosine

Answer · why

A) Uracil

Thymine is just uracil with a methyl group added, which makes DNA more stable and easier to proofread.

Q 02/05

Which feature of the ribose sugar chemically distinguishes RNA from DNA?

A) A 5' phosphate

B) A 2' hydroxyl group

C) A methylated 3' carbon

D) A pyranose ring

Answer · why

B) A 2' hydroxyl group

That extra –OH makes RNA more reactive and pushes its helices into the A-form rather than DNA's B-form.

Q 03/05

Which two RNA bases are purines?

A) Adenine and guanine

B) Cytosine and uracil

C) Adenine and uracil

D) Guanine and cytosine

Answer · why

A) Adenine and guanine

Purines have a double ring; the single-ring pyrimidines in RNA are cytosine and uracil.

Q 04/05

Who discovered nucleic acids in 1868 and called the material 'nuclein'?

A) Phoebus Levene

B) Friedrich Miescher

C) Albrecht Kossel

D) Erwin Chargaff

Answer · why

B) Friedrich Miescher

He isolated it from pus-soaked bandages collected from a surgical clinic in Tübingen.

Q 05/05

Which type of RNA makes up about 80% of the RNA in most cells?

A) Messenger RNA

B) Transfer RNA

C) MicroRNA

D) Ribosomal RNA

Answer · why

D) Ribosomal RNA

It is never translated into protein itself, yet it forms the catalytic core of every ribosome.