Foundational Concepts in Biology
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Questions and Answers

What does the August Krogh Principle emphasize?

  • The value of diverse animal models for studying biological problems. (correct)
  • The importance of genetic engineering in research.
  • The significance of theoretical models in biology.
  • The necessity of using a single species for all experiments.

    • What is characterized by positive allometry?

  • An organ grows faster than the body. (correct)
  • An organ grows slower than the body.
  • An organ grows at the same rate as the body.
  • An organ remains unchanged as the body grows.

    • Which term describes the ability to change phenotype in response to environmental changes?

  • Ontogeny
  • Acclimatization
  • Phenotypic plasticity (correct)
  • Genetic drift

    • What is the primary function of glycogen?

    <p>The storage of energy in cells.</p> Signup and view all the answers

    What occurs during glycolysis?

    <p>Pyruvate, ATP, and NADH are produced.</p> Signup and view all the answers

    Which metabolic pathway is primarily responsible for breaking down fatty acids?

    <p>β-oxidation</p> Signup and view all the answers

    What is a key feature of reversible acclimation?

    <p>It occurs in response to controlled environmental changes.</p> Signup and view all the answers

    What characterizes catabolic pathways?

    <p>They break down molecules for energy release.</p> Signup and view all the answers

    What initiates neurotransmitter release from vesicles in the presynaptic neuron?

    <p>Voltage-gated calcium channels</p> Signup and view all the answers

    What is responsible for maintaining ion concentrations following an action potential?

    <p>Sodium-potassium ATPase pump</p> Signup and view all the answers

    Which statement accurately describes the length constant in nerve fibers?

    <p>It determines how far an action potential can travel</p> Signup and view all the answers

    How do myelinated fibers conduct action potentials differently than unmyelinated fibers?

    <p>They increase resistance and decrease capacitance</p> Signup and view all the answers

    Which type of muscle fiber is primarily utilized for sustained, aerobic activity?

    <p>Red muscle fibers</p> Signup and view all the answers

    What is the role of troponin in muscle contraction?

    <p>Uncovers binding sites on actin after calcium binding</p> Signup and view all the answers

    Which mechanism describes the alteration of the postsynaptic membrane potential due to neurotransmitter binding?

    <p>Post-synaptic potential</p> Signup and view all the answers

    What type of summation refers to simultaneous inputs affecting the postsynaptic potential?

    <p>Spatial summation</p> Signup and view all the answers

    Which characteristic is true about phasic neurons?

    <p>They primarily encode changes in stimulus intensity</p> Signup and view all the answers

    In the context of muscle physiology, what effect does temporal summation have on muscle force production?

    <p>Increases force via successive stimulation</p> Signup and view all the answers

    What is the primary function of the tricarboxylic acid cycle (TAC)?

    <p>Break down acetyl-CoA to produce NADH, FADH2, and GTP</p> Signup and view all the answers

    Which statement correctly describes the role of phosphocreatine in muscle cells?

    <p>It serves as an alternative high-energy phosphate source.</p> Signup and view all the answers

    What does a respiratory quotient (RQ) value near 1.0 indicate?

    <p>Predominantly carbohydrate oxidation</p> Signup and view all the answers

    Which factor influences heat exchange in animals?

    <p>Surface area to volume ratio</p> Signup and view all the answers

    How does the maximum aerobic metabolic rate (VO2max) relate to exercise?

    <p>It reflects the maximum sustainable oxygen consumption during vigorous activity.</p> Signup and view all the answers

    What is the primary role of gut microflora in digestion?

    <p>They break down complex carbohydrates like cellulose.</p> Signup and view all the answers

    What effect does hyperventilation have in high altitude adaptations?

    <p>It enhances oxygen release from hemoglobin.</p> Signup and view all the answers

    What is the basic definition of metabolic rate?

    <p>The amount of energy utilized by an organism over time</p> Signup and view all the answers

    During which condition is iso-osmotic urine typically produced?

    <p>With minimal modification of filtrate</p> Signup and view all the answers

    Which of the following statements about osmotic pressure is correct?

    <p>It represents the pressure required to prevent the movement of water across a membrane.</p> Signup and view all the answers

    What hormonal response is triggered by the Renin-Angiotensin-Aldosterone (RAA) system?

    <p>Enhanced Na+ and water retention in kidneys</p> Signup and view all the answers

    What physiological role does the Bohr effect play?

    <p>It modifies hemoglobin's affinity for oxygen based on pH and CO2 levels.</p> Signup and view all the answers

    What is one of the key functions of the electrical concepts in neural signaling?

    <p>They help maintain a cell's membrane potential through ion distribution.</p> Signup and view all the answers

    Which term describes the phenomenon of hyperpolarization in a neuron?

    <p>More negative membrane potential than resting level</p> Signup and view all the answers

    Study Notes

    Foundational Concepts

    • The August Krogh Principle: A biological problem can be conveniently studied in a specific animal model.
    • Allometry: Studies how organism size relates to part size.
      • Positive allometry (α > 1): Organ growth faster than body.
      • Negative allometry (α < 1): Organ growth slower than body.
    • Physiological Phenotype: Influenced by genotype and environment.
      • Phenotypic plasticity: Changes in phenotype due to environmental factors.
      • Ontogenetic changes: Changes during growth and development.
      • Reversible acclimation: Responses to controlled environmental changes.
      • Acclimatization: Responses to natural environmental variations.
    • Metazoans: Develop from embryos with ectoderm, endoderm, sometimes mesoderm, and reproduce sexually or asexually (sexual reproduction leads to greater variation).
    • Metabolic pathways: Enzyme-catalyzed reactions converting substrates to products.
      • Anabolic pathways: Synthetic.
      • Catabolic pathways: Degradative.
      • Metabolism: Sum of all anabolic and catabolic pathways.

    Cellular Energy and Metabolism

    • Cells store energy in reducing energy and high-energy covalent bonds.
    • Carbohydrates (e.g., glucose): Used for energy and biosynthesis.
      • Polysaccharides (e.g., glycogen): Energy storage.
      • Polysaccharides (e.g., chitin, cellulose): Structural molecules.
      • Glycogenesis: Glycogen synthesis.
      • Glycogenolysis: Glycogen breakdown.
    • Glucose metabolism:
      • Glycolysis (cytoplasm): Anaerobic, produces pyruvate, ATP, NADH.
      • Pyruvate oxidation (mitochondria): Forms acetyl-CoA.
      • NADH oxidation: Redox shuttles transport reducing equivalents to mitochondria.
      • Anaerobic conditions: NADH oxidized to lactate.
    • Lipids (carbon backbone): Energy storage, cell structure, signaling.
      • Fatty acids: Dense energy storage, broken down by β-oxidation in mitochondria.
    • Ketones: Produced from fatty acids when acetyl-CoA can't be fully oxidized; alternative fuel.
    • Tricarboxylic acid cycle (TAC): Breaks down acetyl-CoA, generating NADH, FADH2, GTP.
    • Oxidative phosphorylation (mitochondria): Proton gradient drives ATP synthesis by F1F0ATPase.
    • Phosphocreatine: High-energy phosphate source, especially in muscle.
    • Metabolic rate measurement: 31P-NMR spectroscopy tracks ATP turnover.
    • Respiratory quotient (RQ): Ratio of CO2 production to O2 consumption.
      • RQ near 0.7: Lipid oxidation.
      • RQ near 1.0: Carbohydrate oxidation.

    Whole-Organism Physiology

    • Multicellularity: Specialized cells, tissues, organs, and organ systems arise.
    • Comparative physiology: Examines animal adaptations to environments, evolutionary relationships.
    • Metabolic rate: Energy usage rate.
      • Basal Metabolic Rate (BMR): Minimum metabolic rate in homeotherms at rest.
      • Standard Metabolic Rate (SMR): BMR of poikilotherms at a defined temperature.
      • Resting Metabolic Rate (RMR): Metabolic rate of an animal at rest.
      • Maximum Aerobic Metabolic Rate (VO2max): Maximum sustainable oxygen consumption during exercise.
      • Field Metabolic Rate: Actual metabolic rate in a natural habitat.
    • Scaling of metabolic rate: Whole-animal metabolic rate increases with size, but mass-specific metabolic rate is higher in smaller animals (MR = a (mass)b).
    • Heat fluxes: Metabolism, convection, radiation, evaporation.
      • Evaporative cooling: Depends on water volume and heat of vaporization.
      • Conduction: Depends on thermal conductivity.
    • Surface area to volume ratio: Influences heat exchange.
    • Regional endothermy: Maintains higher temperatures in specific areas via vascular countercurrent heat exchangers.
    • Hypometabolic phases (hibernation, torpor): Reduced metabolic energy demands.

    Thermal Adaptation

    • Thermal tolerance:
      • Eurytherms: Wide temperature tolerance.
      • Stenotherms: Narrow temperature tolerance.
    • Thermogenesis: Heat production (ion pumping, "leaky" membranes). Endotherm plasma membranes leakier than ectotherms.
    • Cold adaptation:
      • Psychrotrophs: Thrive at low temperatures.
      • Cold-adapted enzymes: Flexible structures for maintaining activity.
      • Antifreeze proteins: Prevent ice crystal formation.
      • Freeze-tolerant animals: Control ice crystal growth.

    Digestion and Absorption

    • Digestive systems: Differ between monogastric and ruminant species. Gastric glands secrete HCl and digestive enzymes.
    • Gut microflora: Essential for digesting substances (e.g., cellulose).
    • Absorption: Increased surface area by villi. Sugar uptake constraints, glucose/fructose mix more effective.
    • Lipogenesis: Fat synthesis.
    • Lipolysis: Fat breakdown.
    • Hormonal control: Insulin stimulates glucose uptake, lipogenesis, suppresses lipolysis.

    Circulatory and Respiratory Systems

    • Circulatory systems: Closed (mammalian) or open (insect).
    • Gas exchange: Oxygen diffusion into blood, transport by hemoglobin, diffusion into tissues, mitochondrial utilization. Insects use tracheal systems.
    • Respiratory pigments (e.g., hemoglobin, Hb): Cooperative oxygen binding.
      • P50: Partial pressure for 50% heme saturation.
    • Bohr effect: pH, temperature, CO2 affect hemoglobin oxygen affinity.
    • High altitude adaptations: Hyperventilation, increased 2,3-DPG release.
    • Ventilation mechanisms: Axial musculoskeletal oscillations. Bird lungs (parabronchi) unidirectional airflow.
    • Hypoxic Pulmonary Vasoconstriction (HPV): Constricts arterioles in hypoxic environments.

    Osmoregulation and Excretion

    • Osmotic pressure: Pressure needed to offset solute movement across a membrane. Water moves from high to low concentration.
      • Hypotonic solutions: Water intake by cells.
      • Hypertonic solutions: Water loss from cells.
    • Electrolyte balance: Extracellular high Na+, intracellular high K+.
    • Mammalian kidney: Juxtamedullary and cortical nephrons for urine production.
      • Iso-osmotic urine: Little modification.
      • Hyperosmotic urine: Water retention.
      • Hypo-osmotic urine: Water loss.
    • Water storage: Fat is a dense water source. Protein catabolism can provide water.
    • Renin-Angiotensin-Aldosterone (RAA) system: Blood pressure control.
      • Angiotensin II: Vasoconstriction.
      • Aldosterone: Na+ and water retention.
    • Hypertension: Elevated blood pressure due to excessive Na+ intake.

    Electrophysiology and Neural Signaling

    • Electrical concepts: Current (I), voltage (V), resistance (R). Biological systems behave like DC and AC circuits (Ohm’s Law: I=V/R).
    • Membrane potential: Higher intracellular K+. Nernst equation predicts potential for a single ion.
    • Perturbing membrane potential:
      • Hyperpolarization: Current into cell (Vm more negative).
      • Depolarization: Current out of cell (Vm more positive).
    • Action Potential (AP): Threshold stimulus needed for AP; all-or-nothing phenomenon.
    • Hodgkin cycle: Positive feedback cycle with voltage-gated Na+ and K+ channels. Na/K ATPase maintains ion concentrations.
    • Refractory period: Period after AP with lower excitability (absolute and relative periods).
    • Length constant: Distance for signal to decay by 63%. Affected by myelination.
    • Saltatory conduction: Myelin increases resistance, reduces capacitance, AP jumps between nodes of Ranvier.
    • Synaptic transmission:
      • Ligand-gated channels: Ligand binding opens ion channels.
      • Voltage-gated calcium channels: AP causes Ca2+ influx, neurotransmitter release.
      • Post-synaptic potentials (PSPs): Excitatory (EPSP) or inhibitory (IPSP).
      • Signal integration: Spatial and temporal summation at the axon hillock.
    • Synaptic facilitation: Stronger EPSPs after successive stimulation pulses.

    Sensory Systems and Muscle Physiology

    • Sensory receptors: Convert stimuli to membrane potential changes. Types include chemoreceptors, mechanoreceptors, photoreceptors, electroreceptors, magnetoreceptors, and thermoreceptors (classified by location and stimulus).
    • Stimulus encoding: Modality, location, intensity (AP frequency), duration (tonic vs. phasic neurons).
    • Muscle structure: Sarcomeres (actin and myosin).
    • Muscle contraction: APs, T-tubules, calcium release from SR, calcium binding to troponin.
    • Muscle twitch: Single motor neuron stimulation.
    • Temporal summation: Increasing stimulation frequency increases force.
    • Muscle fiber types: Red (fatigue-resistant, aerobic), white (high-power output).
    • Motor unit: Single motor neuron and innervated fibers.
    • Muscle types: Phasic (twitch), tonic (graded potential). Smooth muscles can change shape.
    • Invertebrate muscles: Arthropods use striated muscle in functions vertebrate smooth muscle performs.

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    Description

    This quiz covers the fundamental concepts in biology, including the August Krogh Principle, allometry, physiological phenotypes, and metabolic pathways. It explores the relationships between organism size and structure, the impact of genotype and environment, and the mechanisms of growth and development.

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