BIO 2A03 FINAL EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026

BIO 2A03 FINAL EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 Purpose of mitochondrial respiration - Answers To supply the ATP needed for cellular functions External Respiration - Answers The movement of oxygen from the environment into the cell and carbon dioxide out Internal Respiration - Answers The metabolic process of cellular respiration occurring within the mitochondria The Oxygen Cascade - Answers The sequential series of steps moving oxygen from the environment to the mitochondria including ventilation diffusion circulation tissue perfusion and cellular utilization Why small animals can rely on simple diffusion - Answers Because they have a large Surface Area to Volume (SA:V) ratio Fick's First Law - Answers Solutes move from high to low concentration across a gradient Fick's Second Law - Answers Diffusion is proportional to surface area and inversely proportional to distance Gills - Answers Evaginations of the body surface used for gas exchange Lungs - Answers Invaginations of the body surface that form an internal cavity for gas exchange Countercurrent Exchange in fish - Answers Water flows in one direction across gills while blood flows in the opposite direction to maintain a constant diffusion gradient Spiracular Breathing in insects - Answers Tracheal system of air-filled tubes bringing oxygen directly to aerobic tissues Spiracles - Answers Openings that control airflow into the trachea control water loss and keep dust out Lung Ventilation in birds - Answers Rely on extensible air sacs and require two full cycles of inhalation and exhalation to move one breath through rigid lungs Crosscurrent Exchange in birds - Answers Air flows in one direction perpendicular to the flow of blood in the parabronchi Conducting Zone of Respiratory Tract - Answers Upper airways and bronchi reinforced with cartilage that conduct air but perform no gas exchange Respiratory Zone of Respiratory Tract - Answers Includes bronchioles and alveoli acting as the site of gas exchange Dalton's Law - Answers Total pressure of a gas mixture is the sum of the partial pressures of its individual gases Boyle's Law - Answers The pressure of a gas is inversely proportional to the volume of its container Henry's Law - Answers The concentration of a gas in a liquid is directly proportional to its solubility and its partial pressure Intrapleural Pressure - Answers The pressure within the pleural sac that is always sub-atmospheric (negative) to prevent lung collapse Muscles used in active inhalation - Answers External intercostal muscles and the diaphragm Quiet or resting exhalation - Answers A passive process driven by the elastic recoil of the lungs and chest wall Type II Alveolar Cells - Answers Cells that produce surfactant which reduces surface tension and improves lung compliance Hemoglobin Structure - Answers A tetrameric protein consisting of 4 globin chains and 4 heme groups Hemoglobin Cooperativity - Answers Allosteric modulation where the binding of one O2 molecule changes the shape of the protein making it easier for subsequent O2 molecules to bind Venous Reserve - Answers Blood leaving resting tissues is still 75% saturated with oxygen to ensure availability if demand suddenly increases P50 Value - Answers The partial pressure of oxygen at which the respiratory pigment is 50% saturated Right Shift of Oxygen Equilibrium Curve - Answers Indicates decreased affinity promoting O2 unloading at tissues caused by the Bohr Effect increased temperature and organic phosphates Left Shift of Oxygen Equilibrium Curve - Answers Indicates increased affinity promoting O2 loading at lungs caused by decreased PCO2 increased pH and lower temperatures Fetal Hemoglobin - Answers Insensitive to 2 3-DPG causing a left shift so it can effectively grab O2 from maternal blood Bicarbonate (HCO3-) - Answers The form in which the majority (60%) of CO2 is transported dissolved in blood plasma Carbonic Anhydrase - Answers The enzyme in red blood cells that catalyzes the reversible bicarbonate reaction Central Chemoreceptors - Answers Sensors in the medulla that detect changes in PCO2 and pH within the cerebral spinal fluid Peripheral Chemoreceptors - Answers Sensors in the carotid and aortic arteries that are incredibly sensitive to changes in blood CO2 Aging and Respiration - Answers Elastic tissue deteriorates decreasing lung compliance and chest movements become restricted Anabolic Pathways - Answers Metabolic reactions that build large molecules from small ones and require energy Catabolic Pathways - Answers Metabolic reactions that break down large molecules into small ones and release energy Four stages of animal food processing - Answers Food/Nutrient Sensing Food Capture Mechanical Disruption and Chemical Processing and Assimilation Intracellular Digestion - Answers Used by sponges where water is drawn in by choanocytes and food particles are phagocytosed Four main processes of a one-way GI tract - Answers Digestion Absorption Secretion and Motility Herbivore Dietary Challenge - Answers Cellulose digestion requiring microbial fermentation because animals lack the enzymes to break it down naturally Avian Crop - Answers An outpocketing of the esophagus used for food storage Avian Proventriculus - Answers The first bird stomach acting as the glandular stomach by secreting digestive juices Avian Gizzard - Answers The second bird stomach which is highly muscular and grinds food often using swallowed stones Coprophagy - Answers The practice of eating special nutrient-rich droppings (cecotropes) to digest material a second time seen in pseudo-ruminants like rabbits Rumen and Reticulum - Answers The first compartments of a ruminant stomach that house fermentative bacteria to break down cellulose Abomasum - Answers The true glandular stomach of a ruminant that secretes acidic digestive enzymes Advantages of a one-way GI tract - Answers Allows for continuous movement of food different isolated compartments with varying pH and simultaneous digestion and absorption Buccal Phase - Answers Voluntary movement where the tongue pushes the bolus to the back of the mouth Pharyngeal Phase - Answers The uvula and epiglottis block the nasal passage and trachea allowing the bolus to move into the esophagus Esophageal Phase - Answers Peristalsis pushes the bolus down the esophagus Lower Esophageal Sphincter - Answers The gateway the bolus passes through to enter the stomach Mucosa - Answers The innermost GI mucous membrane containing enterocytes responsible for absorption Submucosa - Answers GI layer containing glands blood vessels and the submucosal nerve plexus Muscularis Externa - Answers GI muscle layer containing circular and longitudinal smooth muscle for motility and the myenteric nerve plexus Serosa - Answers The outermost protective layer of the GI tract Enteric Nervous System - Answers Made up of the submucosal and myenteric plexuses Stomach Storage Capacity - Answers Can distend up to 50 times its empty size holding up to 1.5 L Chyme - Answers The mixture of food and gastric juices formed in the stomach Four Main Stomach Functions - Answers Storage of ingested food mechanical breakdown chemical breakdown and production of intrinsic factor Intrinsic Factor - Answers Produced by the stomach and crucial for Vitamin B12 absorption Chief Cells - Answers Gastric cells that secrete pepsinogen Parietal Cells - Answers Gastric cells that secrete H+ to form hydrochloric acid Enteroendocrine (G) Cells - Answers Gastric cells that secrete the hormone gastrin Mucous Neck Cells - Answers Gastric cells that secrete mucus to protect the stomach lining Cephalic Phase - Answers Gastric regulation triggered by the sight smell or thought of food resulting in increased gastric juice production Gastric Phase - Answers Gastric regulation triggered by food arriving in the stomach resulting in massive acid secretion and intense mixing waves Intestinal Phase - Answers Gastric regulation triggered when acidic chyme enters the duodenum to control the rate of gastric emptying Enterogastric Reflex - Answers Stretch in the duodenum inhibits gastrin production and slows stomach contractions so the small intestine is not overwhelmed Gastrin - Answers Hormone that stimulates gastric acid production and mixing movements GIP (Gastric Inhibitory Peptide) - Answers Hormone that inhibits gastric secretions and stimulates insulin release from the pancreas Secretin - Answers Hormone that stimulates the pancreas to release water and bicarbonate and stimulates bile production CCK (Cholecystokinin) - Answers Hormone that stimulates the gallbladder to eject bile stimulates the release of pancreatic enzymes and reduces appetite VIP (Vasoactive Intestinal Peptide) - Answers Hormone that dilates intestinal capillaries to improve nutrient absorption and inhibits stomach acid Liver Digestive Function - Answers Produces bile Gallbladder Function - Answers Stores and concentrates bile containing phospholipids and bile salts Pancreatic Duct Cells - Answers Secrete an aqueous bicarbonate solution to neutralize stomach acid Pancreatic Acinar Cells - Answers Secrete inactive digestive enzymes like amylase proteases and lipases Three Zones of the Small Intestine - Answers Duodenum Jejunum and Ileum Duodenum - Answers Small intestine zone that receives chyme pancreatic juice and bile Jejunum - Answers The primary site of nutrient absorption in the small intestine Small Intestine Surface Area Amplification - Answers Achieved via gut length circular folds villi and microvilli Peristalsis Mechanism - Answers Circular muscles contract behind the food mass and longitudinal muscles contract ahead of it to propel the bolus forward Large Intestine Anatomy - Answers Cecum ascending colon transverse colon descending colon sigmoid colon and rectum Large Intestine Function - Answers Absorbs water and inorganic ions and stores indigestible material and bacteria Enterocytes - Answers The primary absorptive mucosal cells containing microvilli Goblet Cells - Answers Intestinal mucosal cells that secrete protective mucus Paneth Cells - Answers Intestinal mucosal cells that secrete antimicrobial molecules for immune defense Protein Digestion Pathway - Answers Proteins to large polypeptides to dipeptides to amino acids Protein Digestion Enzymes - Answers Pepsin Trypsin Chymotrypsin Carboxypeptidases and Dipeptidases Amino Acid Absorption - Answers Actively transported into enterocytes via amino acid-Na+ cotransporters Lipid Emulsification - Answers Hydrophobic fats are broken down into small droplets called micelles by bile salts Lipid Digestion Enzymes - Answers Pancreatic lipases break emulsified fats into fatty acids and monoglycerides Chylomicrons - Answers Triglycerides reassembled inside the enterocyte and packaged for transport Lacteals - Answers Lymphatic vessels where chylomicrons enter because they are too large for blood capillaries Carbohydrate Digestion Pathway - Answers Polysaccharides to Disaccharides to Monosaccharides Carbohydrate Digestion Enzymes - Answers Amylase and Disaccharidases like maltase sucrase and lactase Insulin - Answers Hormone secreted by Beta Cells in response to high blood glucose promoting glucose uptake and glycogen synthesis Glucagon - Answers Hormone secreted by Alpha Cells in response to low blood glucose promoting glycogenolysis and gluconeogenesis Ghrelin - Answers Hormone secreted by the stomach that stimulates hunger for short-term regulation Leptin - Answers Hormone secreted by adipose tissue that suppresses appetite for long-term regulation PYY - Answers Hormone secreted by the small intestine after meals that suppresses appetite GLP-1 (Glucagon-like peptide-1) - Answers Released by intestinal L-cells to increase insulin decrease glucagon slow gastric emptying and decrease appetite Short Chain Fatty Acids (SCFAs) - Answers Produced by gut microbiome fermenting dietary fiber to regulate immunity stimulate satiety hormones and safeguard ovarian reserve Ketogenic Diet - Answers High fat very low carb diet shifting primary fuel from glucose to fat and producing ketone bodies Intermittent Fasting - Answers Depletes glycogen stores to force a metabolic switch to fat utilization through timing of food intake Sexual Reproduction Core Concept - Answers Requires two haploid gametes to fuse during fertilization to restore the diploid chromosome number Gametogenesis - Answers The creation of gametes from precursor germ cells via meiosis Internal vs External Fertilization - Answers External releases millions of gametes into water while internal occurs within the reproductive tract offering better embryo protection Anisogamy - Answers The fundamental difference in size and energetic investment between male and female gametes Sperm Gamete Characteristics - Answers Small motile minimal cytoplasm produced continuously in massive numbers with low energetic investment Egg Gamete Characteristics - Answers Large non-motile finite pool with high energetic investment providing maternal DNA cytoplasm mitochondria and nutrients Scrotum - Answers Houses testes outside the body cavity to maintain optimal temperature for sperm production Testes - Answers Site of sperm production within seminiferous tubules and testosterone secretion Epididymis - Answers Site of sperm maturation gaining swimming capacity and storage Vas Deferens - Answers Transports sperm from the epididymis to the ejaculatory duct Male Accessory Glands - Answers Seminal Vesicles Prostate Gland and Bulbourethral Gland which produce seminal fluid Sperm Capacitation - Answers A final maturation process sperm must undergo within the female reproductive tract before they can fertilize an egg Leydig Cells - Answers Located between seminiferous tubules and secrete testosterone Sertoli Cells - Answers Epithelial cells lining seminiferous tubules that secrete luminal fluid provide nutrients and support sperm development Meiotic Progression of Sperm - Answers Spermatogonia to Primary spermatocytes to Secondary spermatocytes to Spermatids Spermiogenesis - Answers Structural transformation of Spermatids into mature Spermatozoa gaining a head midpiece and flagellum HPG Axis Hypothalamus - Answers Secretes Gonadotropin-Releasing Hormone (GnRH) HPG Axis Anterior Pituitary - Answers Stimulated by GnRH to secrete FSH and LH FSH in Males - Answers Stimulates Sertoli cells to release Androgen-Binding Protein (ABP) to keep local testosterone levels high LH in Males - Answers Stimulates Leydig cells to secrete Testosterone Inhibin - Answers Secreted by Sertoli cells to specifically inhibit FSH release via negative feedback Fallopian Tubes - Answers The site of fertilization containing fimbriae to catch the ovulated egg Oogenesis Finite Pool - Answers Females are born with a non-renewable pool of oocytes and most undergo apoptosis called atresia Oogenesis Fetal Development Arrest - Answers All oogonia enter meiosis and arrest in Prophase I as Primary Oocytes Oogenesis Ovulation Arrest - Answers The released Secondary Oocyte is arrested in Metaphase II Completion of Meiosis II in Females - Answers Only occurs if a sperm fertilizes the egg Ovarian Cycle Follicular Phase - Answers Days 1-14 where a dominant Graafian follicle matures and develops a fluid-filled antrum Ovulation Trigger - Answers Caused by an LH surge around Day 14 Ovarian Cycle Luteal Phase - Answers Days 14-28 where the ruptured follicle transforms into the corpus luteum to secrete estrogen and progesterone