MDCAT Biology: The 10 Topics That Appear Every Single Year
These 10 Biology topics have appeared in every MDCAT past paper for the last 7 years. Master them first and you will secure at least 55 of your 80 Biology marks.
Roughly 70% of Biology MCQs come from the same recurring topics year after year. Here are the ten you cannot afford to skip.
1. Cell Membrane Structure and Transport
Fluid mosaic model, phospholipid bilayer, differences between simple diffusion, facilitated diffusion, osmosis, and active transport. Know the Na+/K+ pump and why it is electrogenic.
2. DNA Structure, Replication, and Repair
Chargaff's rules, antiparallel double helix, semiconservative replication, roles of helicase, primase, DNA polymerase III, and ligase.
3. Protein Synthesis
Promoter to transcription to mRNA processing to translation. Understand codons, anticodons, start and stop codons, and degeneracy of the genetic code.
4. Enzyme Kinetics
Michaelis-Menten kinetics, Vmax, Km, competitive vs non-competitive inhibition, effect of temperature and pH on enzyme activity.
5. Cell Division: Mitosis and Meiosis
Know every phase. Focus on crossing over at prophase I, independent assortment, non-disjunction and its consequences (Down syndrome, Turner syndrome, Klinefelter syndrome).
6. Human Digestive System
Path of food, role of each enzyme (amylase, pepsin, trypsin, lipase), function of bile, structure of villi for absorption, hepatic portal system.
7. Respiratory System and Gas Exchange
Mechanism of breathing, oxygen-haemoglobin dissociation curve, Bohr effect, CO2 transport as bicarbonate. Tidal volume, vital capacity, residual volume.
8. Nervous System and Nerve Impulse
Resting membrane potential, action potential, all-or-none law, synaptic transmission, reflex arc. Myelinated vs unmyelinated fibres.
9. Genetics: Mendelian Laws and Beyond
Monohybrid and dihybrid crosses, codominance, incomplete dominance, epistasis, sex-linked inheritance (haemophilia, colour blindness). Practice Punnett squares for every type.
10. Homeostasis and the Kidney
Structure of the nephron, glomerular filtration, selective reabsorption, loop of Henle, ADH and the collecting duct, renin-angiotensin-aldosterone system.