Graduate Medical School Admissions Test (GAMSAT) Section III: Biological Sciences Syllabus

Section III: Biological Sciences syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Section III: Biological Sciences in Graduate Medical School Admissions Test (GAMSAT), not a summary of it.

1. 1

   Cell Biology and Molecular Biology

   4 topics

   • Cell structure and organelles
     • Prokaryotic vs eukaryotic cells
     • Membrane structure and transport
     • Functions of organelles
   • Cellular respiration and energy
     • Glycolysis, Krebs cycle and electron transport
     • ATP and energy currency
     • Aerobic vs anaerobic metabolism
   • DNA, RNA and protein synthesis
     • Replication, transcription and translation
     • The genetic code
     • Gene regulation
   • Enzymes and biochemical pathways
     • Enzyme kinetics and inhibition
     • Regulation of metabolic pathways
2. 2

   Genetics and Inheritance

   5 topics

   • Mendelian genetics
     • Monohybrid and dihybrid crosses
     • Dominance, recessiveness and Punnett squares
   • Chromosomes and cell division
     • Mitosis and meiosis
     • Chromosomal abnormalities
   • Patterns of inheritance
     • Sex linkage and pedigrees
     • Codominance and incomplete dominance
   • Mutation and genetic variation
   • Population genetics basics
3. 3

   Human Physiology and Body Systems

   5 topics

   • Circulatory and respiratory systems
     • Heart structure and the cardiac cycle
     • Gas exchange and oxygen transport
   • Nervous and endocrine systems
     • Neuron structure and action potentials
     • Synaptic transmission
     • Hormonal regulation and feedback
   • Digestive and excretory systems
     • Digestion and absorption
     • Kidney function and osmoregulation
   • Homeostasis and regulation
     • Negative feedback control
     • Thermoregulation and blood glucose control
   • Immune system and defence
4. 4

   Reproduction, Development and Ecology

   4 topics

   • Human reproduction
     • Gametogenesis and fertilisation
     • Hormonal control of reproduction
   • Evolution and natural selection
     • Mechanisms of evolutionary change
     • Evidence for evolution
   • Ecology and ecosystems
     • Energy flow and nutrient cycles
     • Population dynamics
   • Microbiology and disease

Section III: Biological Sciences flashcards for Graduate Medical School Admissions Test (GAMSAT)

24 of 55 cards from the Section III: Biological Sciences deck — real questions with worked answers.

1. What is the function of the nucleus in a eukaryotic cell?

   It stores the cell's genetic material (DNA) as chromatin, controls gene expression, and is the site of DNA replication and transcription (RNA synthesis).

2. Which organelle is the site of aerobic respiration and ATP production, and why is it called semi-autonomous?

   The mitochondrion. It is semi-autonomous because it contains its own circular DNA and ribosomes (70S), allowing it to replicate independently, consistent with the endosymbiotic theory.

3. Distinguish the roles of rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).

   RER has ribosomes and synthesises/folds proteins for secretion or membranes; SER lacks ribosomes and synthesises lipids/steroids, metabolises drugs, and stores $\ce{Ca^2+}$.

4. What is the function of the Golgi apparatus?

   It modifies, sorts, packages, and ships proteins and lipids (e.g. glycosylation) into vesicles for secretion or delivery to other organelles, including lysosome formation.

5. Compare the cell walls and key structural features of prokaryotic and eukaryotic cells.

   Prokaryotes have no membrane-bound nucleus or organelles, 70S ribosomes, and a peptidoglycan wall (bacteria); eukaryotes have a true nucleus, membrane-bound organelles, 80S ribosomes, and (in plants) a cellulose wall.

6. Write the overall balanced equation for aerobic cellular respiration of glucose.

   $$\ce{C6H12O6 + 6O2 -> 6CO2 + 6H2O}$$ releasing energy stored as ATP (theoretical maximum $\approx 38$, typically $\approx 30\text{–}32$ ATP per glucose).

7. Name the four stages of aerobic respiration and where each occurs in the cell.

   Glycolysis (cytoplasm), pyruvate oxidation/link reaction (mitochondrial matrix), Krebs/citric acid cycle (matrix), and oxidative phosphorylation via the electron transport chain (inner mitochondrial membrane).

8. What is the net ATP and NADH yield of glycolysis per glucose molecule?

   Net $2$ ATP (4 produced, 2 consumed), $2$ NADH, and $2$ pyruvate molecules.

9. In oxidative phosphorylation, what is the final electron acceptor and what does chemiosmosis describe?

   Oxygen ($\ce{O2}$) is the final electron acceptor, forming water. Chemiosmosis is the flow of $\ce{H+}$ down their electrochemical gradient through ATP synthase, driving ATP production.

10. What is the equation for anaerobic fermentation in human muscle cells?

    $$\ce{C6H12O6 -> 2C3H6O3}$$ (glucose to lactic acid), regenerating $\ce{NAD+}$ to sustain glycolysis with a net yield of only $2$ ATP.

11. State the central dogma of molecular biology.

    Genetic information flows DNA $\to$ RNA $\to$ protein: DNA is transcribed into mRNA, which is translated into a polypeptide (protein).

12. Describe the base-pairing rules in DNA and RNA.

    In DNA: adenine pairs with thymine ($A\text{–}T$, 2 H-bonds) and guanine with cytosine ($G\text{–}C$, 3 H-bonds). In RNA, uracil replaces thymine, so adenine pairs with uracil ($A\text{–}U$).

13. What happens during transcription and where does it occur in eukaryotes?

    RNA polymerase synthesises a complementary pre-mRNA strand from a DNA template strand in the nucleus; the pre-mRNA is then spliced (introns removed, exons joined), capped, and polyadenylated.

14. Explain the genetic code's properties of degeneracy and the role of codons.

    A codon is a triplet of mRNA bases coding for one amino acid. The code is degenerate because most amino acids are specified by more than one codon, reducing the impact of point mutations.

15. During translation, what are the roles of the start codon and stop codons?

    The start codon $AUG$ initiates translation and codes for methionine; the stop codons $UAA$, $UAG$, and $UGA$ do not code for amino acids and signal termination of the polypeptide chain.

16. What is an enzyme and how does it speed up reactions?

    An enzyme is a biological catalyst (usually a protein) that lowers the activation energy ($E_a$) of a reaction by stabilising the transition state, increasing reaction rate without being consumed.

17. Contrast the lock-and-key and induced-fit models of enzyme action.

    Lock-and-key: the substrate fits a rigid, precisely complementary active site. Induced fit: the active site changes shape upon substrate binding to fit more snugly, improving catalysis.

18. Compare competitive and non-competitive enzyme inhibition in terms of their effect on $V_{max}$ and $K_m$.

    Competitive: inhibitor binds the active site; $V_{max}$ unchanged, $K_m$ increases (can be overcome by more substrate). Non-competitive: inhibitor binds an allosteric site; $V_{max}$ decreases, $K_m$ unchanged.

19. How do temperature and pH affect enzyme activity?

    Each enzyme has an optimum temperature and pH where activity peaks; beyond these, the active site distorts and the enzyme denatures, losing its tertiary structure and function.

20. State Mendel's Law of Segregation.

    Each diploid organism carries two alleles for a gene that separate (segregate) during gamete formation, so each gamete receives only one allele of each pair.

21. State Mendel's Law of Independent Assortment.

    Alleles of different genes segregate independently of one another during gamete formation, provided the genes are on different chromosomes (or far apart on the same chromosome).

22. In a monohybrid cross $Aa \times Aa$, what are the genotypic and phenotypic ratios of the offspring?

    Genotypic ratio $1\,AA : 2\,Aa : 1\,aa$; phenotypic ratio $3$ dominant $: 1$ recessive.

23. What phenotypic ratio is expected in the $F_2$ generation of a dihybrid cross between two heterozygotes ($AaBb \times AaBb$)?

    A $9:3:3:1$ phenotypic ratio.

24. Define genotype, phenotype, homozygous, and heterozygous.

    Genotype: an organism's allele combination. Phenotype: its observable traits. Homozygous: two identical alleles ($AA$ or $aa$). Heterozygous: two different alleles ($Aa$).

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