Cambridge Pre-U Biology (Principal Subject) Syllabus

Biology (Principal Subject) syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Biology (Principal Subject) in Cambridge Pre-U, not a summary of it.

1. 1

   Cells and Biological Molecules

   4 topics

   • Cell Structure
     • Prokaryotic and eukaryotic cells
     • Organelles and their functions
     • Microscopy and magnification
   • Biological Molecules
     • Carbohydrates, lipids and proteins
     • Water and inorganic ions
     • Nucleic acids DNA and RNA
   • Enzymes
     • Enzyme action and specificity
     • Factors affecting enzyme activity
     • Inhibition mechanisms
   • Membranes and Transport
     • Fluid mosaic model
     • Diffusion, osmosis and active transport
2. 2

   Physiology and Exchange

   4 topics

   • Gas Exchange
     • Exchange surfaces and ventilation
     • Gas exchange in mammals, insects and plants
   • Transport Systems
     • The mammalian circulatory system and heart
     • Haemoglobin and oxygen dissociation
     • Transport in plants: xylem and phloem
   • Homeostasis
     • Negative feedback and control of blood glucose
     • Thermoregulation and osmoregulation
     • The kidney and excretion
   • Coordination and Response
     • Nervous coordination and synapses
     • Hormonal control
     • Muscle structure and contraction
3. 3

   Genetics and Evolution

   5 topics

   • DNA and Protein Synthesis
     • DNA replication
     • Transcription and translation
     • The genetic code and mutations
   • Cell Division
     • Mitosis and the cell cycle
     • Meiosis and genetic variation
   • Inheritance
     • Monohybrid and dihybrid crosses
     • Sex linkage and codominance
     • Gene mutation and chromosome mutations
   • Evolution and Selection
     • Natural selection and adaptation
     • Speciation and isolation mechanisms
     • Genetic drift and the Hardy-Weinberg principle
   • Biotechnology
     • Recombinant DNA technology
     • Polymerase chain reaction and gene sequencing
4. 4

   Energy and Ecosystems

   4 topics

   • Photosynthesis
     • Light-dependent reactions
     • The Calvin cycle
     • Limiting factors
   • Respiration
     • Glycolysis and the link reaction
     • Krebs cycle and oxidative phosphorylation
     • Anaerobic respiration
   • Ecology
     • Energy flow and trophic levels
     • Nutrient cycles: carbon and nitrogen
     • Population dynamics and succession
   • Human Impact and Conservation
     • Biodiversity and its measurement
     • Climate change and pollution
     • Conservation strategies

Biology (Principal Subject) flashcards for Cambridge Pre-U

20 of 66 cards from the Biology (Principal Subject) deck — real questions with worked answers.

1. What is the magnification formula relating image size, actual size, and magnification?

   $$\text{magnification} = \frac{\text{image size}}{\text{actual size}}$$ It is a ratio with no units.

2. Convert: how many micrometres ($\mu m$) and nanometres ($nm$) are in 1 millimetre?

   $1\ mm = 10^{3}\ \mu m = 10^{6}\ nm$. Also $1\ \mu m = 10^{3}\ nm = 10^{-6}\ m$.

3. State the function of the rough endoplasmic reticulum versus the smooth endoplasmic reticulum.

   Rough ER (ribosome-studded) synthesises and transports proteins; smooth ER synthesises lipids and steroids and stores/releases calcium ions.

4. List the key differences between prokaryotic and eukaryotic cells (3 points).

   Prokaryotes: no membrane-bound nucleus (circular DNA free in cytoplasm), 70S ribosomes, no membrane-bound organelles. Eukaryotes: true nucleus, 80S ribosomes, membrane-bound organelles (mitochondria, ER, etc.).

5. Why is resolution, not magnification, the limiting factor of the light microscope, and what is its approximate limit?

   Resolution is the ability to distinguish two close points as separate; the light microscope is limited by the wavelength of visible light to about $200\ nm$ ($0.2\ \mu m$), so greater magnification just gives empty (blurred) enlargement.

6. Name the four classes of biological macromolecule and their respective monomers.

   Carbohydrates (monosaccharides), proteins (amino acids), nucleic acids (nucleotides), and lipids (not true polymers; built from glycerol and fatty acids).

7. Describe the formation of a glycosidic bond and the reaction type involved.

   A glycosidic bond forms between two monosaccharides by a condensation reaction, releasing one molecule of water ($\ce{H2O}$). It is broken by hydrolysis.

8. Give the general molecular formula of a monosaccharide and an example of a hexose.

   General formula $(\ce{CH2O})_{n}$; a hexose has $n=6$, e.g. glucose $\ce{C6H12O6}$.

9. Compare the structures of starch (amylose), glycogen, and cellulose.

   Amylose: $\alpha$-glucose, $1\text{-}4$ links, unbranched helix. Glycogen: $\alpha$-glucose, $1\text{-}4$ and $1\text{-}6$ links, highly branched. Cellulose: $\beta$-glucose, $1\text{-}4$ links, straight chains forming H-bonded microfibrils.

10. Distinguish saturated from unsaturated fatty acids.

    Saturated fatty acids have no $\ce{C=C}$ double bonds (single bonds only, straight chains, solid at room temperature); unsaturated have one or more $\ce{C=C}$ double bonds (kinked chains, liquid at room temperature).

11. Name the four levels of protein structure and the bond/interaction that defines each.

    Primary: peptide bonds (amino acid sequence). Secondary: hydrogen bonds ($\alpha$-helix/$\beta$-pleated sheet). Tertiary: hydrogen, ionic, disulfide bonds and hydrophobic interactions. Quaternary: multiple polypeptide subunits held together.

12. State the biochemical test for reducing sugars and a positive result.

    Benedict's test: add Benedict's reagent and heat. Positive result changes from blue to a brick-red precipitate ($\ce{Cu2O}$).

13. What is the biochemical test for proteins and the positive colour change?

    The biuret test: add biuret reagent (\ce{NaOH} plus dilute \ce{CuSO4}); a positive result changes from blue to purple/violet.

14. Define enzyme and explain why enzymes are described as biological catalysts.

    An enzyme is a globular protein that speeds up a reaction by lowering activation energy; it is a biological catalyst because it is not used up and remains chemically unchanged after the reaction.

15. 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 is flexible and changes shape slightly as the substrate binds, moulding around it to form the enzyme-substrate complex.

16. How do competitive and non-competitive inhibitors differ in their action?

    Competitive inhibitors resemble the substrate and bind reversibly to the active site (effect reduced by raising substrate concentration). Non-competitive inhibitors bind to an allosteric site, changing the active site's shape (effect not reversed by adding substrate).

17. Explain the effect of temperature on enzyme activity above the optimum.

    Above the optimum, increasing thermal energy breaks hydrogen and ionic bonds, so the tertiary structure and active site are denatured; the enzyme can no longer bind substrate and the rate falls sharply.

18. State the equation defining the rate of an enzyme-catalysed reaction from a graph.

    $$\text{rate} = \frac{\Delta[\text{product}]}{\Delta t}$$ measured as the gradient of the initial linear portion of the product-versus-time curve.

19. Describe the fluid-mosaic model of the cell-surface membrane.

    A phospholipid bilayer (hydrophilic heads outward, hydrophobic tails inward) in which proteins, cholesterol, glycoproteins and glycolipids are embedded; 'fluid' because phospholipids move laterally, 'mosaic' because of the scattered proteins.

20. Compare diffusion, facilitated diffusion, and active transport.

    Diffusion: passive, down a concentration gradient, no proteins (small/non-polar molecules). Facilitated diffusion: passive, down gradient, via channel/carrier proteins. Active transport: against the gradient, requires ATP and carrier proteins.

See more Biology (Principal Subject) flashcards →

Planning Biology (Principal Subject) for Cambridge Pre-U

Biology (Principal Subject) (Cambridge Pre-U) FAQ