Q 01/05

DNA is shaped like a twisted ladder. What is that shape called?

A) A double helix

B) A spiral staircase

C) A zigzag

D) A figure eight

Answer · why

A) A double helix

Two long chains coil around each other, and the 'rungs' of the ladder are pairs of chemical letters.

Q 02/05

How many different 'letters', or bases, make up the DNA code?

A) Four

B) Two

C) Ten

D) Twenty-six

Answer · why

A) Four

They are adenine, thymine, cytosine and guanine, usually written A, T, C and G.

Q 03/05

In DNA, the letter A always pairs with which letter?

A) C

B) G

C) T

D) U

Answer · why

C) T

C pairs with G, and the pairs are held together by hydrogen bonds like the rungs of a ladder.

Q 04/05

What do the letters DNA stand for?

A) Double nucleus atom

B) Dynamic natural arrangement

C) Deoxyribonucleic acid

D) Dual nitrogen acid

Answer · why

C) Deoxyribonucleic acid

It is a long word for a long molecule; the 'deoxyribose' part is the sugar in its backbone.

Q 05/05

Besides four bases, each unit of DNA contains a phosphate group and what kind of sugar?

A) Glucose

B) Deoxyribose

C) Fructose

D) Sucrose

Answer · why

B) Deoxyribose

The sugars and phosphates form the two rails of the ladder, and the bases stick out to pair in the middle.