Question

13 multiple choice 1 point
what type of bond forms the backbone of each dna strand?
ionic bonds
hydrogen bonds
covalent bonds
van der waals forces
14 multiple choice 1 point
which of the following protects chromosomes from losing valuable genetic information?
telomerase
dna ligase
mismatch repair
dna polymerase ii
15 multiple choice 1 point
gene expression refers to what process?
the process of transcribing dna into rna and translating rna into chromatin
the process of transcribing dna into rna and translating rna into protein
the process of transcribing rna into dna and translating dna into protein
reverse transcription of rna from dna

Explanation:

• Question 13: DNA strands' backbone is formed by covalent bonds (phosphodiester bonds) between nucleotides. Ionic bonds are not involved in this backbone. Hydrogen bonds are between complementary bases (not the backbone). Van der Waals forces are too weak for this structural role.
• Question 14: Telomerase adds repetitive DNA sequences (telomeres) at chromosome ends, protecting against loss of genetic information. DNA ligase joins DNA fragments. Mismatch repair fixes errors in base - pairing. DNA polymerase II is involved in DNA repair and replication but not specifically in protecting chromosome ends.
• Question 15: Gene expression is the process of transcribing DNA into RNA (usually mRNA) and then translating that RNA into protein. Chromatin is a complex of DNA and proteins in the nucleus, not the end - product of translation. Transcribing RNA into DNA is reverse transcription (not the normal gene expression pathway).

Answer:

1. covalent bonds
2. telomerase
3. the process of transcribing DNA into RNA and translating RNA into protein