MCAT Biology Final Study
Practice Questions with Latest
2025-2026 Correct Answers
GRADED A+
Central Dogma
- ANS - DNA → RNA → Protein
Purines
- which bases?
- how many rings?
- ANS -
Pyrimidines
- which bases?
- how many rings?
- ANS - Remember: "Pyrimidine" has a "y" in it; so does
"cytosine" and "thymine."
,Phosphodiester Bond
- ANS - Joins one nucleotide to the next; between the 3rd C of
one ribose and the 5th C of the other to create the sugar-
phosphate backbone
Directionality of DNA (convention)
- ANS - 5' → 3'
(but strands are antiparallel, so other strand is opposite)
3' of DNA attached to ...
- ANS - OH
5' of DNA attached to ...
- ANS - Phosphate group
DNA composition
- ANS - 1. Phosphate group
2. 5-Carbon sugar
3. Nitrogenous base (A, T, G, C)
Which nitrogenous bases form 2 hydrogen bonds?
- ANS - A, T
,Which nitrogenous bases form 3 hydrogen bonds?
- ANS - G, C
Replisome
- ANS - Proteins that govern the replication process
Origin of replication
- ANS - Where replication begins. Prokaryotes have 1;
eukaryotes have many on each chromosome
DNA synthesis: direction of synthesis
- ANS - 5' → 3'
(the DNA is read 3' → 5')
Steps of replication (5)
- ANS - 1. Helicase unzips double helix
2. RNA polymerase builds a primer
3. DNA polymerase adds leading/lagging strands
4. Primers removed
5. Okazaki fragments joined
RNA vs. DNA: differences
- ANS - RNA:
, - C2 is oxygenated (has OH)
- Single stranded
- Uses uracil instead of thymine
- Can move through nuclear pores out of nucleus
DNA
- C2 is deoxygenaged (has H)
- Double stranded (double helix)
- Uses thymine
- Stuck in the nucleus
Transcription
- ANS - Process of making RNA (rRNA, mRNA, tRNA)
Promoter
- ANS - Required for transcription. Sequence of DNA
nucleotides that signals beginning point for transcription.
Primer
- ANS - Required for DNA replication
Consensus sequence
- ANS - Most common promoter sequences; closer the DNA
Practice Questions with Latest
2025-2026 Correct Answers
GRADED A+
Central Dogma
- ANS - DNA → RNA → Protein
Purines
- which bases?
- how many rings?
- ANS -
Pyrimidines
- which bases?
- how many rings?
- ANS - Remember: "Pyrimidine" has a "y" in it; so does
"cytosine" and "thymine."
,Phosphodiester Bond
- ANS - Joins one nucleotide to the next; between the 3rd C of
one ribose and the 5th C of the other to create the sugar-
phosphate backbone
Directionality of DNA (convention)
- ANS - 5' → 3'
(but strands are antiparallel, so other strand is opposite)
3' of DNA attached to ...
- ANS - OH
5' of DNA attached to ...
- ANS - Phosphate group
DNA composition
- ANS - 1. Phosphate group
2. 5-Carbon sugar
3. Nitrogenous base (A, T, G, C)
Which nitrogenous bases form 2 hydrogen bonds?
- ANS - A, T
,Which nitrogenous bases form 3 hydrogen bonds?
- ANS - G, C
Replisome
- ANS - Proteins that govern the replication process
Origin of replication
- ANS - Where replication begins. Prokaryotes have 1;
eukaryotes have many on each chromosome
DNA synthesis: direction of synthesis
- ANS - 5' → 3'
(the DNA is read 3' → 5')
Steps of replication (5)
- ANS - 1. Helicase unzips double helix
2. RNA polymerase builds a primer
3. DNA polymerase adds leading/lagging strands
4. Primers removed
5. Okazaki fragments joined
RNA vs. DNA: differences
- ANS - RNA:
, - C2 is oxygenated (has OH)
- Single stranded
- Uses uracil instead of thymine
- Can move through nuclear pores out of nucleus
DNA
- C2 is deoxygenaged (has H)
- Double stranded (double helix)
- Uses thymine
- Stuck in the nucleus
Transcription
- ANS - Process of making RNA (rRNA, mRNA, tRNA)
Promoter
- ANS - Required for transcription. Sequence of DNA
nucleotides that signals beginning point for transcription.
Primer
- ANS - Required for DNA replication
Consensus sequence
- ANS - Most common promoter sequences; closer the DNA
