HUMAN SYSTEMS QUESTION 1979: L. PETERSON/AP BIOLOGY Describe the structure and function of the stomach, pancreas, and small intestine as digestive and endocrine organs in the human. (For each organ, include the relevant cell types and their functions.) STANDARDS: [1 point for each statement unless otherwise indicated] Stomach (max. 7 points) STRUCTURE: Regions = cardiac, fundic, pyloric / pyloric sphincter (1 pt. for 2 of 3) Layers of muscle; thick walls Presence of RUGAE (cellular composition = histology) DIGESTIVE FUNCTION: Mention chief cells and parietal cells OR Name and function of chief cells - secrete renin, lipase, pepsinogen Name and function of parietal cells - secrete HCl Presence of mucous coat protects the stomach Function of HCl = aids protein digestion OR converts pepsinogen to pepsin Pepsin - produced in inactive form to protect OR its function in protein digestion Churning aids mechanical digestion Absorption of alcohol, etc. in stomach ENDOCRINE FUNCTION: Name and function of gastrin = stimulates production of digestive juice Presence of Food = stimulus for gastrin release Factors such as stress effects gastrin/stomach function Small Intestine (max. 7 points) STRUCTURE: Increased surface area by folds or villi or microvilli Structure of villi = blood vessels, lymph Regions = duodenum, jejeunum, ileum DIGESTIVE FUNCTION: Name 3 enzymes from intestinal glands (peptidases, sucrases, enterokinase, lipase, amylase, nuclease) Function of each enzyme (max. 2) Bile released in small amounts plus: a) produced in the liver or b) stored in gall bladder or c) emulsifier Site of most absorption Mechanical absorption of long fatty acids Peristalsis Change in pH ENDOCRINE FUNCTION: Secretin /function = stimulates release of alkaline secretions by pancreas Enterogasterone /function = inhibits stomach Cholecystokinin /function = stimulates gall bladder to release bile Pancreozymin /function = stimulates pancrease to secrete digestive enzymes Enterokinin /function = stimulates intestinal glands to secrete enzymes Pancreas (max. 7 points) STRUCTURE: Connects to small intestine by pancreatic duct Comprised of exocrine and endocrine cells DIGESTIVE FUNCTION: Secretion of pancreatic juice and digestive function of enzyme mixture OR Name 3 enzymes in pancreatic juice: amylase, trypsinogen, chymotrypsin, carboxypeptidase, lipase Function of each pancreatic enzyme (max. 2) Secretion of bicarbonate ions to neutralize ENDOCRINE FUNCTION: Mention of Islets of Langerhans - function in glucose metabolism Alpha cells secrete glucagon Glucagon stimulates liver to convert glycogen to glucose Beta cells secrete insulin Insulin stimulates uptake of glucose by cells HUMAN SYSTEMS QUESTION 1982 L. PETERSON/AP BIOLOGY Describe the following mechanisms of response to foreign materials in the human body. a. The antigen-antibody response to a skin graft from another person. b. The reactions of the body leading to inflammation of a wound infected by bacteria. STANDARDS: [1 point for each statement] * = additional points occasionally encountered ANTIGENS- REJECTION Recognition as foreign antigens Rejection by Immune System Antigens on surface of graft cells *Surface glycoproteins as Antigens Antigens stimulate Antibody production or T-cells ANTIBODIES Lymphocytes - B Lymphocytes B Lymphocytes (Antigen Exposure) -> Plasma Cells Plasma cells synthesize Antibodies *Antibodies are Globulins (Immunoglobulins) Types = IgG, A, M, D, E Antibodies are proteins Antibodies remain in circulatory system Antibody structure Antibodies circulate to sites needed Antibodies precipitate Antigens or complex w/Antigens Antibodies make Antigens susceptible to phagocytosis by WBCs Antibody variability due to genes / Clonal Selection Theory Antibody specificity - broad/narrow Antibodies important in both graft rejection and in fighting bacteria, etc. T - CELLS T -cells involved in cell mediated immunity Lymphocytes -> T -cells *T -cells: thymus involvement as "helper" cells COMPATIBILITY Tissues / Graft must be compatible / Tissue matching Blood groups as examples of compatibility Genetic basis of compatibility *Tolerance / Immunosuppression MEMORY Memory cells Secondary Response *Complement = serum proteins acts by Antibody-Antigen Complex complement inactivates or kills bacteria WBCS WBCs invade inflection site - destroy bacteria or wall-off Phagocytosis *WBCs types: neutrophils, basophils, eosinophils, monocytes; lysosomes in phagocytic WBCs macrophages WBCs from marrow bacterial presence -> WBC production PUS/FLUIDS Pus = WBCs, Dead Cells, etc, Fluids, plasma -> swelling Inflammed area = hot (kills bacteria) Lymphatic System Filters CLOT Clot walls-off inflammed area Clotting Mechanism - some detail DILATION Dilation of Blood Vessels increases circulation; WBCs *Histamines -> Dilation Histamines from mast cells CHEMOTAXIS WBCs accumulate /"message" calls WBCs to inflammed site *Kinin - chemotactic or increases dilation HUMAN SYSTEMS QUESTION 1983 L. PETERSON/AP BIOLOGY Describe the structure of a mammalian respiratory system. Include in your discussion the mechanisms of inspiration and expiration. STANDARDS: 21 points possible - max. = 15 [must include description &/or function to get point] DESCRIPTION - STRUCTURE 1 - Nasal Chambers - hard/soft palate, cilia, mucous membranes Sinuses - air spaces, sensory receptors 1 - Pharynx - eustachian tube, tonsils 1 - Larynx - vocal cords, epiglottis 1 - Trachea - cartilaginous rings 1 - Bronchial tree - bronchioles 1 - Lungs - pleural membranes 1 - Alveoli - site of gas exchange, thin-walled 1 or 2: 2 - Sequential Listing of 5 or more portions of system 1 - Incorrect sequence or less than 5 organs MECHANISMS - INSPIRATION 1 - Diaphragm - contraction, goes down 1 - Intercostal muscles 1 - Thoracic cage - outward and upward 1 - Negative pressure (Concept) MECHANISMS - EXPIRATION 1 - Passive recoil (Concept) 1 - Thoracic and abdominal muscles 1 - Thoracic cage - downward and inward 1 - Diaphragm - goes upward NEURAL CONTROL 1 - Medulla 1 - Inspiratory center 1 - Expiratory neuron, inhibition 1 - pH HUMAN SYSTEMS QUESTION 1984 L. PETERSON/AP BIOLOGY Discuss the sources and actions of each of the following pairs of hormones in humans and describe the feedback mechanisms that control their release. a. Insulin..glucagon b. Parathyroid hormone..calcitonin c. Thyrotropin (TSH)..thyroxine (T4) STANDARDS: Maximum of any 6 points on each of three sections. Must answer all three sections of exam to score 15. Discretionary point on adequate discussion of feedback loop and/or homeostasis. INSULIN/GLUCAGON SECTION INSULIN: SOURCE 2 - Beta cells of pancreas 1 - Pancreas or Islets of Langerhans ACTION 1 - Lowers blood sugar 1 - Promotes glucose oxidation in cells 1 - Glycogen synthesis (liver and muscle) RELEASE 1 - Chemical - blood glucose level 1 - Hormonal - secretin, gastrin, etc. 1 - Neural - Acetylcholine (parasympathetic) stimulates GLUCAGON: SOURCE 2 - Alpha cells of pancreas 1 - Pancreas or Islets of Langerhans ACTION 1 - Increases blood glucose 1 - Stimulates glycogen -> glucose (liver) 1 - Synthesis of glucose from amino acids and fatty acids RELEASE 1 - Level of blood glucose, i.e. low glucose / increases glucagon 1 - Neural - Autonomic system PARATHYROID HORMONE/CALCITONIN SECTION PARATHYROID HORMONE: SOURCE 1 - Parathyroid gland on posterior surface of thyroid ACTION 1 - Control of Ca (inc.) and P (dec.) level 1 - Acts on bones, kidneys, and intestine 1 - Increases activity of osteoclasts (Ca and P bone -> blood) 1 - Kidney Ca reabsorbed, P excreted RELEASE 1 - Blood Ca low, PTH high (vice-versa) CALCITONIN: SOURCE 1 - Cells in thyroid gland ACTION 1 - Decreases osteoclast activity 1 - Inhibits release of Ca and P from bone 1 - Lowers blood Ca and P RELEASE 1 - Increased blood Ca causes increase in Calcitonin THYROTROPIN/THYROXINE SECTION THYROTROPIN SOURCE 1 - Anterior Pituitary ACTION 1 - Stimulates thyroid hormone synthesis and secretion 1 - Increases iodide binding, T3, T4 synthesis 1 - T3, T4 release RELEASE 1 - Thyroid Hormone level decreases, TSH increases (vice-versa) THYROID HORMONE SOURCE 1 - Follicles of thyroid gland or thyroid gland ACTION 1 - Maintains metabolic level 1 - Increases O2 consumption 1 - Maintains normal development and function RELEASE 1 - Neural via hypothalamus (low thyroid hormone, increases TSH) 1 - TSH feedback (thyroid and anterior pituitary HUMAN SYSTEMS QUESTION 1985 L. PETERSON/AP BIOLOGY Describe the anatomical and functional similarities and differences within each of the following pairs of structures. a. Artery..vein b. Small intestine..colon c. Skeletal muscle..cardiac muscle d. Anterior pituitary..posterior pituitary STANDARDS: 15 point maximum - must answer all four parts for 15 A. ARTERY-VEIN (7 points possible - 4 points maximum) 1 - Wall thickness or lumen - relate to blood pressure 1 - 3 layers identify or elaborate 1 - Valves in veins - function 1 - Direction of flow 1 - O2/CO2 concentration - mention of pulmonary circulation 1 - Capillary relationship - hydrostatic or osmotic pressure 1 - Pulsating/elasticity - explanation of pressure B. SMALL INTESTINE-COLON (8 points possible - 4 points maximum) 1 - Villi - function - increase in absorption 1 - Length - diameter - size comparison or elaboration 1 - Glands of intestine - Digestive vs. mucous 1 - Regions - elaboration 1 - Smooth muscle - peristalsis 1 - Three tissue layers - elaboration 1 - Absorption - food materials, water, salts, mention of surface area 1 - Flora - comparison/explanation C. SKELETAL-CARDIAC MUSCLE (7 points possible - 4 points maximum) 1 - Location - explanation 1 - Nervous control - voluntary/involuntary 2 - Appearance - Similarities ex. striations / actin-myosin, etc. Differences ex. discs / branching, etc. 3 - Physiology (Comparisons) ex. contraction / refraction / ions / specific nerves / nodes, etc. D. ANTERIOR-POSTERIOR PITUITARY (8 points possible - 4 points maximum) 1 - Origin - mouth - brain 1 - Location - hypothalamus - connection to brain 1 - Control - anterior/hormonal; posterior/nervous 2 - Hormones (list and explain 2 or more) 6 anterior: FSH, LH, ACTH, TSH, somatotropin, prolactin 2 posterior: ADH, oxytocin 1- Anterior production / Posterior storage 1- Endocrine - elaboration or definition 1- Feedback mechanism HUMAN SYSTEMS QUESTION 1986: L. PETERSON/AP BIOLOGY Describe the processes of fat and protein digestion and product absorption as they occur in the human stomach and small intestine. Include a discussion of the enzymatic reactions involved. STANDARDS: STOMACH: GENERAL POINTS 1 - no absorption in the stomach 1 - mechanical breakdown occurs in the stomach 1 - protection of the stomach 1 - chyme (definition) 1 - chyme is in stomach for several hours (implied) 1 - mention of the stomach being acidic due to HCl 1 - parietal cells produce HCl / chief cells produce pepsinogen 1 - gastrin (hormone) 1 - hydrolysis (definition) PROTEIN POINTS 1 - HCl - pepsinogen -> pepsin 1 - pepsin--protein -> polypeptide FAT POINTS 1 - very little digestion of fat in the stomach SMALL INTESTINE: GENERAL POINTS 1 - pH becomes more basic 1 - secretin (hormone) ABSORPTION 1 - occurs in small intestine 1 - microvilli 1 - villi 1 - increase surface area 1 - amino acids -> capillary or amino acid absorption products 1 - amino acids 1 - fatty acids -> lacteals or lymphatic 1 - glycerol -> capillaries 1 - fatty acids by diffusion PROTEIN POINTS 1 - trypsinogen/trypsin 1 - chymotrypsinogen/chymotrypsin 1 - peptidase/di/tripeptidase 1 - endopeptidase (within molecule) 1 - exopeptidase (terminal end of molecule) 1 - protease 1 - pancreas / intestinal gland 1 - protein/polypeptide -> amino acid FAT POINTS 1 - bile (liver - gall bladder) 1 - cholecystokinin (hormone) 1 - emulsify (definition) 1 - lipase/pancreas 1 - lipase function: lipids -> fatty acids and glycerol 1 - Na bicarbonate HUMAN SYSTEMS QUESTION 1986: L. PETERSON/AP BIOLOGY Beginning at the presynaptic membrane of the neuromuscular junction, describe the physical and biochemical events involved in the contraction of a skeletal muscle fiber. Include the structure of the fiber in your discussion. STANDARDS: Presynaptic (must be a motor neuron) 1 - Nature of impulse +++ --- 1 - Increase of permeability of Ca 2+ 1 - Movement of vesicles 1 - Fusion of vesicles with membrane 1 - Transmitter release 1 - Acetylcholine 1 - Diffusion of transmitter (20 nm) 1 - Cholinesterase 1 - Motor end plate or terminal bouton Postsynaptic (muscle be a muscle fiber) A. Transmitter Effects 1 - Specific receptor sites 1 - Causes depolarization/action potential 1 - Action potential sweeps fiber membrane/T. tubules 1 - Release of Ca 2+ from Sarcoplasmic reticulum (T. cisternae) B. Calcium Effects 1 - Calcium floods sarcomere 1 - Calcium binds to troponin 1 - Bound troponin displaces tropomyosin 1 - Calcium returned by active transport (Ca2+ pump) C. Actinomyosin Complex 1 - Binding sites actin exposed by tropomyosin displacement 1 - Myosin cross bridges bind actin 1 - ATP used 1 - Power stroke, recovery flip 1 - ATP needed to separate actin-myosin 1 - Rigor Mortis D. Other 1 - Sliding Filament Theory 1 - Diagram/explanation contracted muscle 1 - Muscle twitch, tetany, fatigue 1 - Lactic acid, O2 debt 1 - Creatine phosphate--ATP Muscle Fiber Structure 1 - Definition 1 - Characteristics 2 - Striations, banding multi-nucleated, many mitochondria 1 - Myofibrils (as sub-units) 1 - Sarcomere (as unit of myofibril) 1 - Sarcoplasmic reticulum (cell membrane, etc.) (terminal cisternae) 1 - T. tubules (cell membrane connection, etc.) 1 - Banding Pattern (explain or diagram) 1 - Actin/myosin (protein or thin, thick, etc.) 1 - Actin a globular protein 1 - Myosin a linear protein w/cross bridges 1 - Troponin/tropomyosin associated with actin HUMAN SYSTEMS QUESTION 1987: L. PETERSON/AP BIOLOGY Discuss the exchange of oxygen and carbon dioxide that occur at the alveoli and muscle cells of mammals. Include in your answer a description of the transport of these gases in the blood. STANDARDS: EXCHANGE (8 points max.) 1 - O2/CO2 diffusion or correct direction of O2/CO2 gas movement 1 - concentration gradient or explanation 1 - Alveoli/membrane characteristics (large surface area, or thin-walled, or "grape clusters", or sacs, or surrounded by capillaries) 1 - moist surface necessary for exchange 1 - interstitial fluid role in transport 1 - P O2/CO2 description 1 - Illustrated curve on graph or explanation 100 mm Hg lungs 40 mm Hg muscles (rest) 20 mm Hg muscles (exercise) 1 - temperature effects 1 - further explanation as: (tissues) higher temperatures -> less affinity OR (lungs) lower temperatures -> more affinity OR graph 1 - CO2 in plasma lowers pH of blood 1 - Bohr effect - acidity affects affinity of Hb for O2 1- example lower pH -> less affinity higher pH -> more affinity OR graph 1 - myoglobin in muscle stores O2 (greater affinity for O2) 1 - air is approximately 20% oxygen 1 - other hemoglobin adaptations, such as: (maternal-fetal or low altitude-high altitude) TRANSPORT (8 points max.) OXYGEN 1 - carried by hemoglobin or in red blood cell 1 - hemoglobin found in red blood cell 1 - hemoglobin characteristics such as: protein, or 4 subgroups, or Heme, or iron and porphyrin ring 1 - Hb cooperativity (allosteric) - one O2 increases affinity for others S-shaped curve 1 - CO can compete with O2 for Hb binding site CARBON DIOXIDE - 1 - majority carried as bicarbonate ions (HCO3) 1 - enzyme carbonic anhydrase speeds reaction - 1 - CO2 + H2O <--> H2CO3 <--> H+ + HCO3 1 -some CO2 carried aqueously (dissolved) 1- some CO2 carried by Hb (on a different site - does not compete with O2) 1 - Hb picks up H+ ions to buffer blood CIRCULATORY TRANSPORT PATHWAY 1 - from alveolus to muscle cell (pulmonary vein -> left atrium -> left ventricle -> artery -> capillary) 1 - from muscle cell to alveolus (capillary -> vein -> right atrium -> right ventricle -> pulmonary artery) HUMAN SYSTEMS QUESTION 1989: L. PETERSON/AP BIOLOGY Describe negative and positive feedback loops, and discuss how feedback mechanisms regulate each of the following: a. The menstrual cycle in a nonpregnant human female b. Blood glucose levels in humans STANDARDS: Introduction: (describe -/+ feedback loops) 1 pt 1. Definition as an overview of the process: Control mechanism which is regulated through the effect it brings about. 1 + 1 pts 2. Negative feedback: Endproduct acts as an inhibitor of pathway (stimulatory-inhibitory). Seek terms such as inhibit/turn off. Examples: ACTH -> cortisol -> feedback; Lac operon; thermostat metaphor; CO2 respiration, etc. 1 + 1 pts 3. Positive feedback: change in variable amplifies the pathway (stimulatory-stimulatory). Seek terms such as turn on/stimulate/induce. Examples: Oxytocin/birth; LH surge; trypsinogen/trypsin; neural membrane permeability; mating process; sound amplification metaphor; etc. [one point for definition and one point for example] Note: these points might be embedded in Parts A and B. Total of 3 points maximum for introduction out of 5 points possible. Part A: Menstrual Cycle 1 pt 1. Primary function of the cycle as an overall concept: production of gamete and preparation of the uterus. A borad interpretation OK. 1 + 1 + 1 pts 2. Hormones and interactions: look for information that suggests cause and effect and a pathway. Items a-c are complete examples. To earn a point, three targets, hormones, and sources must be given in a logical sequence. Wrong information will void a string of three. The goal is to find physiological relationships and not just terms. a. GnRH (hypothalamus) -> FSH (pituitary) -> estrogen (ovary) -> endometrium b. GnRH (hypothalamus) -> LH (pituitary) -> progesterone (corpus luteum) -> endometrium c. estrogen -> LH surge -> ovulation Research on the regulation of the menstrual cycle is rapidly evolving and textbooks can reflect different philosophies or progress of research. 1 or 2 pts 3. Negative feedback results on hypothalamus/pituitary. Estrogen/progesterone inhibits FSH and LH production at the GnRH (hypothalamus) and pituitary level. If no choriogonadotropic hormone -> estrogen/progesterone levels drop and endometrium stimulus no longer supported - > endometrium lost as cycle begins again and FSH and LH released from inhibition. [2 points for completeness] 1 pt 4. Positive feedback: estrogen -> LH surge. Note: estrogen can be both inhibitory and stimulatory on the hypothalamus/pituitary. Total of 5 points maximum for Part A out of 7 points possible. Part B: Blood Sugar 1 pt 1. Concept of homeostasis, equilibrium, and/or maintenance of glucose level. 1 pts 2. Concept of antagonistic relationship of glucagon and insulin. 1 + 1 pts 3a. Low blood glucose -> glucagon release -> glycogen converted to glucose/ glucose mobilized from liver to blood or alpha cells in pancreas release glucagon 1 + 1 pts 3b. High blood glucose -> insulin release - glucose mobilized into cells -> lower blood levels/glucose mobilized into liver or muscle or beta cells of pancreas release insulin 1 pt 4. Alternate loops of blood glucose levels (only one point possible here): a. adrenalin, noradrenalin b. ACTH, cortisol c. somatostatin Total of 5 points maximum for Part B out of 7 points possible. HUMAN SYSTEMS QUESTIONS: 1991 L. PETERSON/AP BIOLOGY The graph below shows the response of the human immune system to an antigen. Use this graph to answer part a and part b in this question. a. Describe the events that occur during period I as the immune system responds to the initial exposure to the antigen. b. Describe the events that occur during period II following a second exposure to the same antigen. Period I Period II Antibody Titer in Antigen Antigen Serum Injected Injected 0 40 80 120 160 200 240 280 Time in Days c. Explain how infection by the AIDS virus (HIV) affects the function of both T and B lymphocytes. STANDARDS: The question as represented on the graph is predicated on a "humoral response". That approach is reflected in the standards. The capitalized term in the concept that receives the point (column left). The information in the right column expresses a perfect response, i.e. specific information. The point can be gained with general information as long as it is in context. Part A. Max at four points __OVERVIEW _ clonal selection theory _ humoral response __RECOGNITION _ Ag bind with appropriate cell receptor; B cell response to T cell (T cell signaling) __PROLIFERATION _ B cells divide (and differentiate) _ B cells produce plasma cells (effectors), memory cells __AB PRODUCTION _ B cells produce antibody (to epitope of Ag) _ Antibody specificity to Ag __AB CHARACTERS _ Ab types (IgM, IgE, IgA, IgG), structure of Ab _ Ab switching (between types) __GRAPH _ dynamics of response (lag, exponential, plateau, decline) _ reasons for decline (suppression, turnover, Ag binding) __OTHER _ factors affecting time scale, degree of response (such as) _ Ag presentation (macrophage to T cell) (HLA compt. cell) _ IgD strip from B cell Part B. Max at four points __SPEED _ near immediate response __MEMORY _ memory B cell fast response, stronger response __GRAPH _ short lag, fast rise, extended plateau, slow decline __QUANTITY _ high Ab titer, 10-100 fold increase __QUALITY _ greater binding affinity _ more discrimination _ not IgM response (rather IgG, A, E) __OTHER _ basis for vaccination (such as) _ location of memory cell (lymphoid tissue) Part C. Max at four points __INFECTIVITY _ T cells but not B cells _ T4 cells of CD4+, or T helper (TH) or effector T __CELL DEATH _ decreased T cell population _ loss of T cell function (loss of CMI, loss of cytotoxicity, decreased lymphokines) __CONSEQUENCES _ decreased B cell proliferation (such decrease leads to a decrease of overall immunity) _ loss of T cell signalling to B cell __VIRAL INTERACT I _ viral glycoproteins (gp 120, 41) bind to CD4 sites on T4 cell _ receptor mediated endocytosis (RME) __VIRAL INTERACT II _ reverse transcription incorporation of viral genome into lymphocyte genome _ budding leads to cell disruption (impaired function/death) _ viral latency __OTHER _ infection leads to decreasing low Ab titer (anti HIV titer) (such as) _ Ab produced to HIV forms basis for testing _ mutagenesis of HIV (antigenic drift) _ infected T cells make immunosuppressants HUMAN SYSTEMS QUESTION 1992: L. PETERSON/AP BIOLOGY Biological recognition is important in many processes at the molecular, cellular, and organismal levels. Select three of the following, and for each of the three that you have chosen, explain how the process of recognition occurs and give an example. a. Organisms recognize others as members of their own species. b. Neurotransmitters are recognized in the synapse. c. Antigens trigger antibody responses. d. Nucleic acids are complementary. e. Target cells respond to specific hormones. STANDARDS: 4 POINTS MAXIMUM FOR EACH PART (A - E) a) Organisms recognize others as members of their own species. ___ Definition (1 point) ___ Importance of Species Recognition/Definition of Species/Reproductive Isolation prezygotic (3 points) ___ Mechanisms (2 points) ___ Visual/Auditory/Chemical/Tactile/[Multiple/Ritual/Behavioral] Recognition is Innate or Learned (Imprinting) (1 point) ___ Example (1 point) Visual - birds, fruit flies Auditory - birds, whales, frogs, insects Chemical - moths, voles Tactile - fruit flies, octopods Multiple - albatross, butterflies, fruit flies, people, dove Imprinting - ducks, goats b) Neurotransmitters are recognized in the synapse ___ Definition (1 point) ___ Neurotransmitter is a chemical messenger Synapse definition ___ Mechanisms (1 point each) Neurotransmitter binds to receptor on postsynaptic membrane Receptor is a protein ___ "Lock and Key" Concept (3 points) Enzymatic recognition and degradation of Neurotransmitter Reabsorption of Neurotransmitter by presynaptic membrane Presynaptic/Postsynaptic Events (1 point for any one) ___ Stimulus (impulse, depolarization, signal, action potential) travels from presynaptic membrane (axon terminus, synaptic knob), Membrane channels opened (calcium channels, ion channels, calcium goes in), Neurotransmitter released from presynaptic neuron (synaptic vesicle) Neurotransmitter diffuses across synapse/synaptic cleft Neurotransmitter binding alters permeability Depolarizes and/or hyperpolarizes postsynaptic membrane (creates EPSP-[excitatory postsynaptic potential]/creates IPSP-[inhibitory postsynaptic potential]) / Opening ion channels Change membrane potential (towards or away from threshold) Alter metabolism inside postsynaptic cell (2nd messenger, cAMP) Reversible binding of Neurotransmitter Examples (1 point) ___ Acetylcholine (ACh) Synapse Types GABA Acetylcholinesterase (AChE) Norepinephrine Catecholamines, L-dopa Dopamine and Serotonin - Biogenic Amines Endorphins/Enkephalins - Neuropeptides c) Antigens trigger antigody response ___ Definitions (1 point for either) Antigen (Ag) - foreign substance/non-self Antibody (Ab) - defensive protein produced in response to Ag - structure (2 heavy and 2 light polypeptide chains) Processes (1 point for each) ___ Selection of B cell highly specific B cell surface Ab binds Ag to activate B cell -- plasma cell and memory cell clones Secondary response description Ag-Ab complex - amino acid sequence of light and heavy chains of hypervariable regions at N-terminus Specific site of Ag binding with Ab (Ab binding with Ag) Receptors on B cells and capping Free Ag with Ab T-cell dependent activation of B cells - Macrophage (Ag Presenting Cell) activates Interleukins to activate Helper T cells and B cells Generation of Ab diversity Examples of Antigens or Resultant Antibodies (1 point) ___ IgG, IgM, IgA, IgD, IgE Bacterial cells, viruses, fungi, protozoa, allergens (pollen, dust, dander), grafts (HLA), Heterologous Ag (RBCs), Self Antigens d) Nucleic acids are complementary Definitions (1 point) ___ DNA and RNA are nucleic acids Nucleic acids are polymers of nucleotides Nucleotide = sugar (deoxyribose and ribose), phosphate, nitrogenous base Mechanisms (1 point for each) ___ A with T or U, C with G or Chargaff's Rules Pyrimidine with Purine or Single ring with Double ring 2 Hydrogen Bonds with A+T/U and 3 Hydrogen Bonds with G+C or H bonds Antiparallel orientation 5'---3'/3'---5' Template requirement or semiconservative replication mechanism Primers DNA/RNA polymerase requirements Elongation/Initiation Factors Divalent Cations Examples (1 point) ___ Replication of DNA (2 strands of dsDNA are complementary) Transcription of DNA into mRNA, tRNA, rRNA Translation - mRNA-tRNA (codon/anticodon complementarity) Hybridization - DNA-DNA/DNA-RNA/Probes e) Target cells respond to specific hormones Definition (1 point for each) Hormone - chemical messenger released to travel to cause specific biological response within organism, effective at low concentration Protein hormone/receptor at cell surface (doesn't get in) Steroid hormone /receptor inside cell (does get in) Recognition of hormone is to specific receptor (specific proteins) Protein hormone involves 2nd messenger (cAMP, etc.) Steroid hormone affects transcription Examples (1 point each) Any hormone/target or effect (no pheromones, allomones, attractants) HUMAN SYSTEMS QUESTION 1992: L.PETERSON/AP BIOLOGY Survival depends on the ability of an organism to respond to changes in its environment. Some plants flower in response to changes in day length. Some mammals may run or fight when frightened. For both of these examples, describe the physiological mechanisms involved in the response. STANDARDS: FIGHT OR FLIGHT RESPONSE ADAPTIVE __ Turn on needed systems - turn off those not needed; Understanding of Acute vs Chronic response - above and beyond statements in question MECHANISM __ Description of nerve pathway - (sensory-associative-motor) __ Sympathetic nervous system (autonomic) - activation __ Sympathetic system innervates adrenal medulla __ Inhibition of parasympathetic by sympathetic __ Parasympathetic - counters sympathetic, return to normal homeostasis; acetylcholine = neurotransmitter __ Epinephrine - adrenalin (cause and effect) __ Norepinephrine - noradrenalin (cause and effect) __ Source - Adrenalin from adrenal medulla (gland) __ Source - Noradrenalin from adrenal medulla and/or sympathetic nerve endings __ Receptor molecules on cell membranes __ Use of cAMP (second messenger) to elicit intracellular response __ Brief vs. sustained - contrasted (initial = sympathetic vs long = adrenal) __ Chemical structure of adrenalin/noradrenalin EFFECT 2 MAX - target tissues and effects __ a. pupillary muscles of eye - dilates pupils b. inhibits salivation c. bronchi of lungs - relaxes d. increases respiratory rate e. heart muscle - accelerates pulse, strengthens contraction f. piloerection - muscles attached to hair follicles g. liver - breaks down glycogen - stimulates release of glucose h. digestive tract - decreases digestive activities - peristalsis i. stomach, small intestine, pancreas - inhibits secretion of digestive enzymes j. stimulates release of fatty acids from fat cells k. peripheral circulation - vessels constrict l. inhibit sex structures m. relax bladder - bowels n. decreased sensation of pain o. "superhuman" MAXIMUM - 7 points for this section HUMAN SYSTEMS QUESTION 1993: L. PETERSON/AP BIOLOGY Many physiological changes occur during exercise. (a) Design a controlled experiment to test the hypothesis that an exercise session causes short-term increases in heart rate and breathing rate in humans. (b) Explain how at least three organ systems are affected by this increased physical activity and discuss interactions among these systems. STANDARDS: This question was composed of two discrete parts. In part (a) students needed to demonstrate an undertanding of basic experimental protocol. A maximum of 6 points was set for this section to be determined from four protocol points, and single points for verification, understanding of a control, and the understanding of what short-term increase means in relation to exercise. In part (b) students were expected to utilize broader conceptual tehemes. Points were awarded for an effect that was clearly the result of exercise. Points were given for an interaction if the student demonstrated proper effects in each system under consideration and a mechanism (how) to connect each system. (See model at the end of the standard list). A maximum of 6 points was set for this section. (a) Experiment (Maximum of 6 points) 1 + 1 - How to measure heart rate (i.e. pulse rate) and/or breathing rate (i.e. breaths/minute) __ What exercise (mode, intensity, duration) __ When measured (before, during, after) or how long - time function __ Repeatibility - Verification (i.e. large group size, repeated test) __ Description of control vs. experimental group (2 groups only if variables controlled (or same subjects) __ Understanding of Short-term - return to homeostatic conditions. (b) Discussion of at least three organ systems affected and their associated interactions (Maximum of 6 points) SYSTEM EFFECT (one/system) INTERACTIONS Muscular Decrease intracellular ATP, Effects of PCO2, H+ concentration, glycogen and O2 stores PO2 on receptors in Medulla, Pons, Increase ATP, nutrient, O2 Aortic, Carotid bodies and demands / use subsequent effects on circulatory Increase production CO2 and respiratory activity. Lactic acid Capillary beds dilated - muscles. Increased heat Capillary beds dilated - skin, heat loss, etc. Respiratory Increased gas exchange Receptors (aortic, carotid, medulla, Tidal volume, ventilation, pons, stretch). diffusion capacity O2 to cells. Circulatory Stroke volume increased Blood travels faster/volume to Flow rate increased deliver O2 - nutrients. Cardiac output increased Capillary beds to muscles dilate, Blood pressure increased those to splanchnic, renal areas constricted. Capillary beds to skin dilate - heat loss. Nervous Medulla - Pons Impulses sent to diaphragm - (pneumotaxic) intercostal, etc. Stretch receptors Sympathetic system stimulated. Increased neurotransmitters Parasympathetic - return to homeostasis. Neuromuscular junction. Endocrine Increased ACTH (ant pit) Stimulates adrenal cortex Increased Adrenaline -steroid production. (adrenal medulla) Stimulates circulatory Increased glucagon (heart, caps, liver). (pancreas) Stimulates glycogenolysis - liver. Excretory Decreased urine output Decreased blood flow to kidneys. Digestive Increased rate of glycogenolysis Provides fuel for activity. Blood diverted away from splanchnic renal areas Integument Increased sweat/glow/flush Capillary beds - heat loss - cooling. System A (How) System B Valid effect -> carries O2 to muscle -> Valid effect i.e. Stroke volume up (etc.) i.e. materials for muscular function Thus for a valid interaction an explanation needs proper effect in both systems. HUMAN SYSTEMS QUESTION 1994: L. PETERSON/AP BIOLOGY Discuss how cellular structures, including the plasma membrane, specialized endoplasmic reticulum, cytoskeletal elements, and mitochondria, function together in the contraction of skeletal muscle cells. To earn credit a student needed to demonstrate an understanding of basic cell anatomy and physiology as they relate specifically to the structure and function to muscle contraction. Standards were established to follow the cellular activities pertinent to muscle contraction from the neuromuscular junction, through contraction, and returning to the non-contractive state. Points were also awarded if the student included information from the neuromuscular junction, demonstrated an exceptional understanding of chronological information from the neuromuscular junction, demonstrated an exceptional understanding of chronological or spatial relationships, or included an elaboration of special features specific to the process of muscle contraction. (2 pts) Neuromuscular junction Action potential of neuron -> neurotransmitter Concept of neurotransmitter (1 pt) Idea of a sarcomere as a functional unit (1 pt) Actin and Myosin in a sarcomere - (well labeled diagram w/text) (2 pts) Plasma membrane / sarcolemma (no point for name alone) Receptor sites for neurotransmitters Change in permeability / Na+ K+ Action potential distributed / depolarization T-tubules (continuous with specialized E.R.) (2 pts) Specialized E.R. - Sarcoplasmic reticulum (no point for name alone) T-tubule (only if not given above) Ca++ release / Calcium is involved with muscle contraction Change in permeability - release of Ca++ Ca++ recaptured into S.R. - contraction ends / active transport (5 pts) Cytoskeletal Elements Actin and myosin (linked to muscle function) microfilaments / myofibrils / myofibrils Actin - thin fiber (protein structure) Troponin (Ca++ interaction exposes active sites) Tropomyosin (is therefore unblocked) Myosin - thick fiber (protein structure) 'clubs' - bridges - paddles for interaction with actin / ATP binding site ATPase site / hydrolysis of ATP Sliding Filament Concept Z line as a protein which separates sarcomeres (needs strong linkage) ATP functions to release mysoin heads from actin sites (2 pts) Mitochondria ATP production - cellular respiration Number of mitochondria is higher in muscle cells due to... Proximity within muscle fiber Chemiosmosis - elegant elaboration of ATP production (2 pts) Other - Rarely Mentioned: Fast twitch / slow twitch (1 pt) Elaboration (1 pt) (FT) - glycogen and anaerobic (ST) - oxidation of glycogen via TCA and thus aerobic All or nothing response Switches to anaerobic respiration after oxygen consumed / Myoglobin Muscles can only contract Rigor mortis (showing that ATP functions in release rather than contractive phase) Muscle cell is a muscle fiber or muscle cell is multinucleate Glycogen storage (mitochondria functions) Creatine phosphate - PO4 replacement (1 pt) Synoptic synchronization - exceptional chronology or spatial relationships