WBI15 Respiration, Internal Environment, Coordination and Gene Technology

Lessons in WBI15

1. Respiration overview and glycolysis
   Respiration releases energy in many enzyme-controlled steps. Glycolysis (cytoplasm): glucose phosphorylated (2 ATP), split into 2 triose phosphate, oxidised to
2. The link reaction and the Krebs cycle
   Link reaction (matrix): pyruvate decarboxylated and dehydrogenated, joins coenzyme A to make acetyl CoA. Krebs cycle: acetyl CoA + oxaloacetate → citrate; per t
3. Oxidative phosphorylation and chemiosmosis
   Reduced NAD and FAD give H to the electron transport chain; electrons pass along carriers, energy pumps H+ into the intermembrane space; H+ flows back through A
4. Lactate after exercise and respiratory quotient
   Lactate goes to the liver, where it is oxidised to pyruvate or converted to glucose and glycogen, using extra oxygen after exercise. RQ = CO2 produced / O2 used
5. Core practical 15: yeast respiration with a redox indicator
   A redox indicator (TTC colourless to red, methylene blue blue to colourless) accepts hydrogen from dehydrogenases. Time the colour change; rate = 1/time. Use bo
6. Core practical 16: respirometers and RQ
   KOH or soda lime absorbs CO2, so fluid movement shows O2 uptake: V = πr²l. Without absorber, movement = O2 used - CO2 produced. RQ = (x - y) / x. Use a control
7. Muscles, joints and muscle fibre types
   Tendons: muscle to bone; ligaments: bone to bone. Muscles pull, so work in antagonistic pairs (flexor and extensor). Fibre: sarcolemma, T-tubules, sarcoplasmic
8. The sliding filament theory
   Impulse → Ca2+ released from sarcoplasmic reticulum → binds troponin → tropomyosin moves → myosin heads bind actin, power stroke → ATP detaches heads and recock
9. Control of the heartbeat and ECGs
   SAN (pacemaker) → atria contract → AVN delay → bundle of His → Purkyne fibres → ventricles contract from the apex. ECG: P = atrial depolarisation, QRS = ventric
10. Cardiac output and control of heart rate and breathing
    Cardiac output = stroke volume x heart rate; ventilation = tidal volume x breathing rate. The medulla's cardiovascular centre speeds the heart via sympathetic n
11. Core practical 17: spirometer traces and exercise
    Breathing into a spirometer with soda lime gives a falling trace. Tidal volume = height of a normal breath; breathing rate = peaks per minute; O2 consumption =
12. Homeostasis, feedback and thermoregulation
    Homeostasis is a dynamic equilibrium kept by negative feedback (receptor, control centre, effector reverse a change). Positive feedback amplifies change (action
13. The kidney: structure, ultrafiltration and reabsorption
    Deamination in the liver makes urea. Ultrafiltration: high pressure in the glomerulus forces small molecules through endothelium, basement membrane and podocyte
14. ADH and control of water balance
    Osmoreceptors in the hypothalamus detect low blood water potential; ADH (made in the hypothalamus) is released from the posterior pituitary; it causes aquaporin
15. Adrenaline, hormones and gene switching
    Adrenaline prepares for fight or flight (faster heart and breathing, glucose release, blood to muscles). Transcription factors bind promoters to switch genes on
16. Neurones, reflex arcs and the nervous system
    Sensory neurones carry impulses to the CNS, relay neurones link, motor neurones go to effectors. Schwann cells form myelin. Reflex arc: receptor, sensory, relay
17. Resting potential, action potentials and saltatory conduction
    Resting potential about -70 mV (Na+/K+ pump 3 out, 2 in; K+ leaks out). Action potential: Na+ channels open at threshold (about -55 mV), depolarise to about +40
18. Synapses, the pupil reflex and habituation
    Action potential → Ca2+ in → vesicles release ACh → ACh binds postsynaptic receptors → Na+ in, depolarisation → acetylcholinesterase breaks down ACh. Bright lig
19. Drugs, synapses and brain chemistry
    Nicotine mimics ACh; lidocaine blocks Na+ channels (local anaesthetic); cobra toxin blocks ACh receptors (paralysis); L-DOPA becomes dopamine (Parkinson's); MDM
20. How rod cells detect light
    Dark: Na+ channels open, rod depolarised (about -40 mV), releases inhibitory glutamate. Light: cis-retinal → trans-retinal, rhodopsin bleaches, Na+ channels clo
21. Plant responses: phytochrome, auxin and gibberellin
    Phytochrome: Pr absorbs red (about 660 nm) → Pfr; Pfr absorbs far-red (about 730 nm) → Pr; Pfr is active and alters transcription (germination, flowering, elong
22. Core practical 18: gibberellin and amylase in cereal grains
    Embryo-free half grains are soaked in GA, placed on starch agar, then flooded with iodine: clear halos show amylase activity. Higher GA gives larger halos. Area
23. The brain and brain imaging
    Cerebrum: thought, memory, language, voluntary movement. Hypothalamus: homeostasis, controls pituitary. Cerebellum: balance and coordination. Medulla: heart rat
24. Recombinant DNA and producing drugs with GMOs
    Restriction endonucleases cut at recognition sequences, giving sticky ends; the same enzyme cuts the vector; DNA ligase forms phosphodiester bonds. Insert DNA w
25. Microarrays, bioinformatics and the GM debate
    Microarray: labelled cDNA from a cell's mRNA hybridises to DNA probes; fluorescent spots show active genes. Bioinformatics: software to store and analyse sequen

Next exams for WBI15

• January 2027: Wed 20 Jan 2027, morning, 1h 45m
• Summer 2027: Fri 4 Jun 2027, morning, 1h 45m

From Pearson's final timetables. All exam dates. Always confirm your entries with your exams officer.