Which of the following statements is supported by Chargaff's rule about the composition of DNA?

A:DNA is a single stranded nucleic acid that contains uracil.

B:The number of adenines in a strand of DNA is equal to the number of thymines.

C:The "steps" of the DNA ladder are made of sugar and phosphates.

D:DNA is a complex of RNA wrapped around protein

Why is DNA replication said to be semiconservative?

A:The old cell keeps part of the original DNA during cell division.

B:The new DNA strand can only be constructed in the 3' to 5' direction.

C:The double helix becomes a single strand of DNA.

D:New DNA has one original strand and one replicated strand.

Which of the following is the complimentary DNA strand for the sequence shown below?
ACT GCA
A:ACG TCA

B:ACU GCA

C:UCT GCU

D:TGA CGT

What is the central dogma of molecular biology? Explain its meaning.