Nutrition and Respiration

  • Life Processes Defined: Fundamental processes necessary for an organism’s survival and maintenance (e.g., nutrition, respiration, transport, excretion).

  • Nutrition:

    • Autotrophic Nutrition: Organisms synthesize their own food (e.g., plants, cyanobacteria).

      • Photosynthesis: Process of converting light energy into chemical energy.

        • Equation: 6CO2​+6H2​OLight Energy​C6​H12​O6​+6O2​

        • Site: Chloroplasts (contain chlorophyll).

        • Events:

          • Light-dependent reactions: Absorption of light energy by chlorophyll, conversion of light energy to chemical energy (ATP, NADPH), water splitting (H2​O→O2​,H+,e−).

          • Light-independent reactions (Calvin cycle): Reduction of CO2​ to carbohydrates using ATP and NADPH.

        • Stomata: Tiny pores on leaves facilitating CO2​ intake and O2​/water vapor release. Guard cells regulate opening/closing.

    • Heterotrophic Nutrition: Organisms obtain food from others.

      • Types: Saprophytic (dead/decaying matter), Parasitic (living host), Holozoic (ingestion).

      • Holozoic Nutrition in Amoeba: Phagocytosis (pseudopodia engulf food), food vacuole formation, digestion by enzymes, absorption, egestion.

      • Holozoic Nutrition in Humans:

        • Alimentary Canal: Mouth → Pharynx → Esophagus → Stomach → Small Intestine → Large Intestine → Anus.

        • Digestive Glands: Salivary glands, gastric glands, liver, pancreas, intestinal glands.

        • Key Enzymes/Processes:

          • Mouth: Salivary amylase (starch digestion).

          • Stomach: Gastric glands secrete HCl (acidic medium, kills germs, activates pepsin), Pepsin (protein digestion).

          • Small Intestine: Site of complete digestion and absorption.

            • Liver: Bile (emulsifies fats).

            • Pancreas: Pancreatic amylase (starch), Trypsin (protein), Lipase (fats).

            • Intestinal Juice: Peptidases (peptides to amino acids), Sucrase/Lactase/Maltase (disaccharides to monosaccharides), Intestinal lipase.

        • Absorption: Villi and microvilli increase surface area in small intestine.

        • Large Intestine: Water absorption, waste formation.

  • Respiration: Process of releasing energy from food.

    • Types:

      • Aerobic Respiration: In presence of oxygen.

        • Glucose → Pyruvate (cytoplasm) → CO2​+H2​O+Energy (mitochondria). High ATP yield.

        • Equation: C6​H12​O6​+6O2​→6CO2​+6H2​O+Energy (38 ATP)

      • Anaerobic Respiration: In absence of oxygen.

        • Fermentation (Yeast): Glucose → Pyruvate → Ethanol + CO2​ + Energy.

        • Lactic Acid Formation (Muscle Cells): Glucose → Pyruvate → Lactic Acid + Energy. (Occurs during vigorous exercise, leads to cramps).

    • Respiration in Plants: Gaseous exchange via stomata (leaves), lenticels (stems), general root surface. Occurs 24/7, but photosynthesis dominates during day.

    • Respiration in Animals:

      • Aquatic Organisms (e.g., Fish): Gills absorb dissolved oxygen from water. Faster breathing rate due to lower dissolved O2​.

      • Terrestrial Organisms (e.g., Humans): Lungs for gaseous exchange.

        • Human Respiratory System: Nostrils → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.

        • Alveoli: Thin-walled, richly vascularized sacs for efficient gaseous exchange (diffusion of O2​ into blood, CO2​ out).

        • Mechanism: Inhalation (diaphragm contracts, ribs lift, volume increases, pressure decreases, air rushes in); Exhalation (diaphragm relaxes, ribs lower, volume decreases, pressure increases, air rushes out).

        • Transportation of Gases: O2​ transported by hemoglobin in RBCs. CO2​ transported

        • largely as bicarbonate ions in plasma.

\(ΔK = -\frac{m_1m_2}{2(m_1+m_2)}(v_{1i}-v_{2i})^2\).

\(\theta_1+\theta_2=90^\circ\)).

This MCQ module is based on: Nutrition and Respiration

This assessment will be based on: Nutrition and Respiration

Hypothetical Experiment: Investigating the Efficiency of Gaseous Exchange in Different Respiratory Surfaces

  • Objective: To quantitatively compare the rates of oxygen uptake and carbon dioxide release across different simulated respiratory surfaces, emphasizing adaptations for efficiency.

  • Materials:

    • Setup 1 (Simulating Alveolus): Thin, moist, semi-permeable membrane (e.g., dialysis tubing or egg membrane) stretched over a petri dish, connected to a small oxygen sensor and a CO2​ sensor. A circulatory fluid (simulated blood plasma with a pH indicator) on the other side.

    • Setup 2 (Simulating Fish Gill Lamellae): Multiple thin, highly folded semi-permeable membranes submerged in oxygenated water, with a similar sensor setup.

    • Setup 3 (Simulating Plant Stomata): A potted plant leaf coated with a substance to vary stomatal opening (e.g., ABA solution to close, light to open), connected to gas sensors in a sealed chamber.

    • Oxygen and CO2​ gas cylinders, peristaltic pumps, data logger.

  • Procedure:

    1. Alveolus Simulation: Introduce a fixed volume of “atmospheric air” (high O2​, low CO2​) to one side of the membrane. Circulate simulated blood (low O2​, high CO2​, slightly acidic) on the other side. Monitor gas levels over time and pH changes in the “blood.”

    2. Gill Simulation: Submerge the gill model in a continuously flowing stream of oxygenated water. Circulate “blood” through the gill lamellae. Monitor gas levels.

    3. Stomata Simulation: Place the leaf in the sealed chamber. Vary light intensity and measure O2​ and CO2​ changes in the chamber, correlating with stomatal opening (observed under microscope).

  • Expected Observations:

    • Alveolus: Rapid decrease in O2​ on air side, rapid increase in CO2​ on air side, and concurrent changes in blood side, indicating efficient bidirectional diffusion. pH of “blood” would slightly increase as CO2​ diffuses out.

    • Gill: Continuous and efficient O2​ uptake from water and CO2​ release, demonstrating counter-current exchange principles if flow rates are optimized.

    • Stomata: Net O2​ release and CO2​ uptake in light; net O2​ uptake and CO2​ release in dark (respiration). Stomatal opening/closing directly affects gas exchange rates.

  • Theoretical Outcomes & Advanced Concepts:

    • Fick’s Law of Diffusion: Quantitatively analyze how surface area, thickness of membrane, and concentration gradient affect diffusion rates in each setup.

      • Rate of Diffusion ∝Thickness of MembraneSurface Area×Concentration Gradient​

    • Partial Pressures: Relate the observed gas exchange to differences in partial pressures of O2​ and CO2​ across the membranes.

    • Counter-Current Exchange (Gills): Explain how the opposite flow of water and blood maximizes the concentration gradient along the entire length of the gill lamella, leading to highly efficient oxygen extraction.

    • Buffering Capacity of Blood: Explain how the change in pH in the “blood” (due to CO2​ levels) relates to the carbonic acid-bicarbonate buffer system.

    • Regulation of Stomatal Opening: Discuss how environmental factors (light, CO2​ concentration, water availability) influence guard cell turgidity and thus stomatal pore size, linking to water conservation.

  • Real-Life Connections:

    • Respiratory Diseases: How conditions like emphysema (reduced alveolar surface area) or asthma (bronchial constriction) impair gas exchange.

    • Altitude Sickness: The physiological adaptations and challenges associated with lower partial pressures of O2​ at high altitudes.

    • Aquaculture: Designing efficient aeration systems for fish farms based on gill efficiency.

    • Agricultural Productivity: How optimizing stomatal function (e.g., drought-resistant crops) can improve crop yield by balancing photosynthesis and transpiration.

    • Eutrophication: Impact of reduced dissolved oxygen in aquatic environments on aquatic life due to impaired gill function.

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