Question

in dna replication,
○ 23 copies are made of each chromosome.
○ the chromosome is copied to rna, which is then copied to dna for a new chromosome.
○ one new copy is made of each chromosome, and the original chromosome remains intact.
○ two copies are made of each chromosome, and each copy contains one of the dna strands from the original chromosome.
○ two new copies are made of each chromosome, and the original chromosome is destroyed.

Explanation:

To solve this, we analyze each option based on DNA replication (semi - conservative replication) principles:

1. Option 1: Humans have 23 pairs of chromosomes, and DNA replication doesn't make 23 copies of each chromosome. So this is wrong.
2. Option 2: DNA replication produces DNA, not via an RNA intermediate (that's transcription - translation for protein synthesis). So this is wrong.
3. Option 3: DNA replication is semi - conservative, not a single new copy with the original intact. So this is wrong.
4. Option 4: In semi - conservative replication, the double - stranded DNA unwinds, and each strand serves as a template. So two copies (daughter DNA) are made, each with one original strand and one new strand. This matches the process.
5. Option 5: The original chromosome (DNA) isn't destroyed; it's conserved in the daughter DNA. So this is wrong.

Answer:

D. two copies are made of each chromosome, and each copy contains one of the DNA strands from the original chromosome.