RIO BIO 156 CORE EXAMS SET 2025/2026 QUESTIONS AND
ANSWERS GRADED A+
✔✔What is the role of a nucleotide in nucleic acids? - ✔✔Builds DNA and RNA chains
to store and transmit genetic info.
✔✔What are the two main stages of protein synthesis? - ✔✔Transcription and
translation.
✔✔What happens during transcription and where does it occur? - ✔✔DNA → mRNA;
occurs in the nucleus.
✔✔What enzyme is responsible for transcription? - ✔✔RNA polymerase.
✔✔What happens during translation and where does it occur? - ✔✔mRNA → protein;
occurs at the ribosome in the cytoplasm.
✔✔What is the role of ribosomes in translation? - ✔✔Reads mRNA and assembles
amino acids into proteins.
✔✔What molecules are involved in translation? - ✔✔mRNA, tRNA, rRNA, amino acids.
✔✔What is the final product of protein synthesis? - ✔✔A polypeptide (protein).
✔✔How does the sequence of amino acids determine protein function? - ✔✔The
sequence determines how the protein folds and works.
✔✔What is DNA replication? - ✔✔Copying DNA before cell division.
✔✔When and where does it occur? - ✔✔During S phase of interphase; in the nucleus.
✔✔What is the purpose of DNA replication? - ✔✔To ensure each new cell gets a full
DNA copy.
✔✔What are the main steps of DNA replication? - ✔✔Unzip DNA → match new bases
→ seal strands.
✔✔What is the result of DNA replication? - ✔✔Two identical DNA molecules.
✔✔Helicase - ✔✔unzips DNA
✔✔DNA polymerase - ✔✔Adds new bases.
✔✔Ligase - ✔✔Seals gaps between fragments.
, ✔✔Topoisomerase - ✔✔Relieves twisting strain.
✔✔Single-stranded binding proteins - ✔✔Keep strands apart.
✔✔What are Okazaki fragments? - ✔✔Short DNA pieces on the lagging strand.
✔✔Why do they form? - ✔✔DNA is built in opposite directions; lagging strand needs
fragments.
✔✔What are mutations? - ✔✔Changes in the DNA sequence.
✔✔What is a point mutation? - ✔✔Change in one base.
✔✔What is a substitution mutation? - ✔✔One base is replaced with another.
✔✔What are missense, nonsense, and silent mutations? - ✔✔Missense: changes
amino acid
Nonsense: early stop
Silent: no change to protein
✔✔What is a frameshift mutation? - ✔✔Insertion or deletion that shifts the reading
frame.
✔✔How do mutations affect DNA and proteins? - ✔✔Can change protein structure and
function—harmful, helpful, or neutral.
✔✔Why are proteins important? - ✔✔They do most cell functions—enzymes, structure,
hormones, etc.
✔✔Why is DNA important? - ✔✔It holds the instructions to make all proteins.
✔✔Label the parts on a bacterial diagram: - ✔✔DNA - genetic material
Plasmid - small circular DNA
Pili - for attachment and conjugation
Cell membrane - controls entry/exit
Cell wall - protection
Capsule - outer defense layer
Flagella - movement
✔✔Compare prokaryotic vs. eukaryotic genomes: - ✔✔Prokaryotic: circular DNA, no
nucleus.Eukaryotic: linear chromosomes, inside nucleus.
ANSWERS GRADED A+
✔✔What is the role of a nucleotide in nucleic acids? - ✔✔Builds DNA and RNA chains
to store and transmit genetic info.
✔✔What are the two main stages of protein synthesis? - ✔✔Transcription and
translation.
✔✔What happens during transcription and where does it occur? - ✔✔DNA → mRNA;
occurs in the nucleus.
✔✔What enzyme is responsible for transcription? - ✔✔RNA polymerase.
✔✔What happens during translation and where does it occur? - ✔✔mRNA → protein;
occurs at the ribosome in the cytoplasm.
✔✔What is the role of ribosomes in translation? - ✔✔Reads mRNA and assembles
amino acids into proteins.
✔✔What molecules are involved in translation? - ✔✔mRNA, tRNA, rRNA, amino acids.
✔✔What is the final product of protein synthesis? - ✔✔A polypeptide (protein).
✔✔How does the sequence of amino acids determine protein function? - ✔✔The
sequence determines how the protein folds and works.
✔✔What is DNA replication? - ✔✔Copying DNA before cell division.
✔✔When and where does it occur? - ✔✔During S phase of interphase; in the nucleus.
✔✔What is the purpose of DNA replication? - ✔✔To ensure each new cell gets a full
DNA copy.
✔✔What are the main steps of DNA replication? - ✔✔Unzip DNA → match new bases
→ seal strands.
✔✔What is the result of DNA replication? - ✔✔Two identical DNA molecules.
✔✔Helicase - ✔✔unzips DNA
✔✔DNA polymerase - ✔✔Adds new bases.
✔✔Ligase - ✔✔Seals gaps between fragments.
, ✔✔Topoisomerase - ✔✔Relieves twisting strain.
✔✔Single-stranded binding proteins - ✔✔Keep strands apart.
✔✔What are Okazaki fragments? - ✔✔Short DNA pieces on the lagging strand.
✔✔Why do they form? - ✔✔DNA is built in opposite directions; lagging strand needs
fragments.
✔✔What are mutations? - ✔✔Changes in the DNA sequence.
✔✔What is a point mutation? - ✔✔Change in one base.
✔✔What is a substitution mutation? - ✔✔One base is replaced with another.
✔✔What are missense, nonsense, and silent mutations? - ✔✔Missense: changes
amino acid
Nonsense: early stop
Silent: no change to protein
✔✔What is a frameshift mutation? - ✔✔Insertion or deletion that shifts the reading
frame.
✔✔How do mutations affect DNA and proteins? - ✔✔Can change protein structure and
function—harmful, helpful, or neutral.
✔✔Why are proteins important? - ✔✔They do most cell functions—enzymes, structure,
hormones, etc.
✔✔Why is DNA important? - ✔✔It holds the instructions to make all proteins.
✔✔Label the parts on a bacterial diagram: - ✔✔DNA - genetic material
Plasmid - small circular DNA
Pili - for attachment and conjugation
Cell membrane - controls entry/exit
Cell wall - protection
Capsule - outer defense layer
Flagella - movement
✔✔Compare prokaryotic vs. eukaryotic genomes: - ✔✔Prokaryotic: circular DNA, no
nucleus.Eukaryotic: linear chromosomes, inside nucleus.
