Nutrition: Autotrophs, Heterotrophs, and Digestion
T.9: Nutrition
Nutrition is the process where organisms exchange matter and energy with their environment. Based on nutrition, organisms are classified as:
Autotrophs
Use inorganic matter to create organic matter. They obtain energy from:
- Photosynthesis (light energy, e.g., algae, plants)
- Chemosynthesis (energy from oxidation, e.g., some bacteria)
Heterotrophs
Obtain energy from organic compounds produced by other organisms (e.g., animals, fungi, bacteria).
Nutrition Process
Ingestion: Animals incorporate organic matter through food; plants incorporate inorganic matter through absorption.
Digestion: Animals break down organic molecules into smaller ones for cellular absorption.
Gas Exchange: Exchange of oxygen and carbon dioxide (respiratory system).
Transportation: Distribution of nutrients (circulatory system).
Metabolism: Transformation of energy for cellular use.
Excretion: Elimination of waste products.
Nutrient Incorporation
Thallophytic Organization (Algae)
Nutrients are absorbed through cell membranes.
Cormophytic Organization (Higher Plants)
Specialized structures for absorption and transport:
- Roots: Absorb inorganic compounds.
- Leaves: Photosynthesis occurs here.
- Stem: Transports substances between roots and leaves.
Water and Mineral Incorporation:
- Water enters roots via osmosis.
- Minerals enter via active transport.
Root Structure
- Epidermis: Protects internal tissues.
- Cortex: Stores substances.
- Endodermis: Controls water flow.
- Pericycle: Gives rise to lateral roots.
- Stele: Contains xylem and phloem.
Transport of Raw Sap
Xylem transports water and minerals upwards.
Tension-Adhesion-Cohesion Mechanism:
- Root Pressure: Water molecules push sap upwards.
- Transpiration: Water evaporation in leaves creates suction.
- Tension-Cohesion: Water molecules stick together, aiding upward movement.
Gas Exchange in Plants
Plants need oxygen for respiration and carbon dioxide for photosynthesis.
- Stomata: Main entry point for gases.
- Root Hairs: Absorb dissolved gases.
- Lenticels: Openings in woody stems.
Stomata Opening and Closing
Regulated by potassium ion concentration, light, and temperature.
Leaf Structure for Photosynthesis
- Parenchyma: Contains chloroplasts.
- Conductive Tissues: Xylem and phloem.
Importance of Photosynthesis
Converts inorganic matter into organic matter and light energy into chemical energy.
Transport of Elaborated Sap
Phloem transports sugars and amino acids from leaves to other plant parts.
Other Forms of Nutrition
- Symbiotic Plants: Rhizobia and mycorrhizae.
- Parasitic Plants: Use haustoria.
- Carnivorous Plants: Trap and digest insects.
Metabolism
Chemical transformations of matter and energy.
- Anabolism: Synthesis of complex substances (e.g., photosynthesis).
- Catabolism: Breakdown of complex substances (e.g., cellular respiration).
T.10: Digestive Process
Transformations of food in the digestive system.
Stages: Ingestion, digestion, absorption, egestion.
Systems Involved: Digestive, circulatory, respiratory, excretory.
Digestive System Models
- Gastrovascular Cavity: Single opening (mouth/anus).
- Digestive Tube: Two openings (mouth and anus).
Digestion in Invertebrates
Common structures: tube, mouth, pharynx, esophagus, stomach, intestine.
Digestion in Vertebrates
Digestive tube with associated glands (salivary, pancreas, liver).
Ingestion Types
- Passive Ingestion: In aquatic animals.
- Active Ingestion: Involves capturing and restraining food.
Digestion Types
- Intracellular: Inside cells (e.g., sponges).
- Mixed: Both intracellular and extracellular (e.g., cnidarians).
- Extracellular: Outside cells (mechanical and chemical).
Digestion in Humans
Mouth: Mechanical (chewing) and chemical (saliva) digestion.
Gastric Digestion: Mechanical (stomach contractions) and chemical (gastric juice).
Intestinal Digestion: Completion of digestion in the small intestine.
Nutrient Transport
Circulatory System: Distributes nutrients and oxygen.
- Transport Fluid: Hemolymph or blood.
- Blood Vessels: Arteries, veins, capillaries.
- Heart: Pumps blood.
Circulatory System Types
- Open: Blood flows into sinuses.
- Closed: Blood remains within vessels.
Cardiac Cycle
Systole (contraction) and diastole (relaxation).
External Signs
- Heart Sounds: Due to valve closure.
- Heartbeat: Ventricular contractions.
- Pulse: Rhythmic expansion of arteries.
- Blood Pressure: Systolic and diastolic pressure.