biology life processes

Introduction

  • All living organisms possess common characteristics:

    • Breathing

    • Growing

    • Requiring nutrition

    • Producing offspring

    • Responding to stimuli

  • Vital processes maintain homeostasis and proper body function, referred to as life processes.

  • Life processes are essential and continue even during sleep or inactivity.

  • Includes:

    • Nutrition

    • Photosynthesis

    • Transportation

    • Metabolism

    • Respiration

    • Reproduction

    • Excretion

  • Emphasis on the details of these processes in plants, animals, and humans.

Essentials of Life Processes

  • Maintenance of organisms occurs whether moving, resting, or sleeping.

  • Life processes are essential for maintenance.

  • Examples of life processes:

    • Nutrition

    • Respiration

    • Circulation

    • Excretion

  • Unicellular organisms carry out all processes within a single cell.

  • Multicellular organisms utilize well-developed systems for this purpose.

Nutrition

  • Nutrition: Process of acquiring food needed for organism sustenance.

  • Modes of nutrition:

    • Autotrophic Nutrition:

      • Possessed by plants, algae, some bacteria.

      • Organisms produce their own food via photosynthesis or chemosynthesis.

    • Heterotrophic Nutrition:

      • Present in bacteria, fungi, animals.

      • Derives energy from organic compounds.

      • Subtypes include:

        • Holozoic

        • Saprophytic

        • Parasitic

Autotrophic Nutrition

  • Organisms make their own food:

    • Photoautotrophs: Use sunlight (plants).

    • Chemoautotrophs: Use chemicals (some bacteria).

Photosynthesis

  • Vital process for forming food in plants.

  • Plants utilize sunlight and water.

  • Chlorophyll absorbs light energy, triggering chemical reactions:

    • Splits water into hydrogen and oxygen.

    • Hydrogen reduces carbon dioxide into carbohydrates (glucose).

  • Overall equation:

    • 6CO2 + 6H2O → C6H12O6 + 6O2

Stomata

  • Stomata: Pores on leaves for gas exchange.

  • Dominantly on the leaf's underside, controlled by guard cells.

  • Water content of guard cells regulates the stoma function.

Heterotrophic Nutrition Modes

  • Saprophytic Nutrition:

    • Organisms feed on dead/decaying matter (e.g. Fungi).

    • Digests food externally before absorption.

  • Parasitic Nutrition:

    • Organisms feed off another and often harm it (e.g. Leeches, Ascaris, Cuscuta).

Nutrition in Unicellular Organisms

  • Amoeba:

    • Holozoic – engulfs food via pseudopodia (phagocytosis).

    • Digestion occurs in food vacuoles. Egestion happens through the opening of vacuole.

Nutrition in Paramecium

  • Similar to Amoeba but utilizes cilia for food engulfment.

  • Creates food vacuole that moves via cyclosis.

  • Uses anal pore for expelling undigested matter.

Nutrition in Humans

  • Omnivores: Consume both plant and animal-based foods.

  • Complex nutritional system involving:

    • Alimentary Canal: Long tube from mouth to anus.

    • Stages of Nutrition:

      • Ingestion

      • Digestion

      • Absorption

      • Assimilation

      • Egestion

Alimentary Canal Structure

  • Starts from the mouth and stretches to the anus:

    • Key parts include:

      • Oesophagus

      • Stomach

      • Small intestine

      • Large intestine

Mouth

  • Opening leading to ingestion.

  • Buccal cavity: Contains teeth and tongue, aids in mastication and initiation of digestion.

Teeth

  • Crucial for cutting, shearing, and masticating food.

  • Four layers:

    • Enamel: Hardest part.

    • Dentine: Makes bulk of tooth.

    • Cement: Aligns tooth base.

    • Pulp: Contains nerves and blood vessels.

Oesophagus

  • Muscular tube (25 cm long) that conveys food to the stomach using peristalsis.

Stomach

  • Thick-walled structure receiving food from the oesophagus;

  • Secretes mucus and digestive acids, churning food into chyme.

  • Hydrochloric acid aids in digestion and bacterial elimination.

Small Intestine

  • Longest part of the canal (about 20 feet). Contains regions:

    • Duodenum

    • Jejunum

    • Ileum

  • Villi assist in nutrient absorption and digestion.

Large Intestine

  • Approximately 5 feet long with:

    • Regions: Colon (ascending, transverse, descending) and rectum.

    • Absorbs water and forms stool.

Peristalsis

  • Wave-like muscle contractions in the alimentary canal aid in food movement.

Digestive Glands

  • Include:

    • Salivary glands: Begin digestion in the mouth.

    • Gastric glands: Secrete hydrochloric acid and enzymes.

    • Liver: Produces bile, crucial for fat digestion.

    • Pancreas: Secretes various digestive enzymes.

Enzymes in Digestion

  • Important enzymes contained in pancreatic juice include:

    • Trypsin

    • Amylase

    • Lipase

Holozoic Nutrition Steps

  • Involves:

    • Ingestion

    • Digestion

    • Absorption

    • Assimilation

    • Egestion

Physiology of Digestion

  • Buccal Cavity: Mechanical digestion and salivary amylase initiates starch breakdown.

  • Stomach digests proteins into smaller peptides via pepsin.

  • Small intestine completes digestion; absorption via villi and microvilli.

  • Undigested food enters the large intestine for water absorption and temporary storage.

Digestive Systems Across Animals

  • Variations in digestive systems reflect dietary habits.

  • Herbivores have longer canals for cellulose digestion.

  • Carnivores have shorter canals.

Role of Hydrochloric Acid

  • Secreted by gastric glands, with a pH between 1.5 to 3.5:

    • Activates digestive enzymes.

    • Provides an acidic medium needed for protein digestion.

    • Kills ingested bacteria.

    • Prevents food spoilage in the stomach.

Salivary Glands

  • Exocrine glands producing saliva, involved in initial digestion.

  • Three pairs in humans: parotid, submandibular, sublingual.

  • Functions:

    • Protects oral cavity tissues.

    • Aids in digestion and taste sensation.

Heterotrophic Nutrition

  • Organisms depending on others for food.

  • Types include:

    • Herbivores

    • Carnivores

    • Various forms of heterotrophic nutrition.

Glandular Epithelium

  • Glands in the stomach and intestines assist in digestion.

  • Gastric glands secrete mucus, acids, and digestive enzymes.

Villi and Microvilli

  • Located in the small intestine, increase surface area for digestion and absorption.

  • Nutrient absorption occurs via diffusion through villi.

Liver Functions

  • Largest digestive gland, secretes bile, filters blood, detoxifies and processes metabolites, stores glucose, and produces proteins.

Digestive Juices Overview

  • Include pancreatic juice, bile, and intestinal juice; essential for complete digestion.

  • Alkalinity of bile neutralizes stomach acidity for enzyme function.

Water Absorption in Large Intestine

  • Absorbs water and solidifies waste; involves protective functions against microbes.

Introduction to Respiration

  • Broadly refers to gas exchange; critical for energy production.

  • Occurs via different mechanisms in animals and plants.

Human Respiration Process

  • Involves complex structures for breathing, gas exchange, and cellular respiration.

  • Primary organs include the nose, lungs, diaphragm, etc.

Physiology of Respiration

  • Breathing facilitated by diaphragm and intercostal muscles; involves inhalation and exhalation.

Inhalation and Exhalation

  • Inhalation: Air intake rich in oxygen.

  • Exhalation: Release of air rich in carbon dioxide.

Cellular Respiration Overview

  • Set of metabolic reactions converting biochemical energy into ATP.

  • Involves catabolic and anabolic processes; glycolysis and Krebs cycle are key pathways.

Aerobic Respiration

  • Occurs in the presence of oxygen.

  • General equation:

  • Glucose + Oxygen → Carbon Dioxide + Water + Energy

Respiration in Lower Animals

  • Less complex systems; respiration through skin, gills, or trachea.

Anaerobic Respiration in Muscles

  • Occurs without sufficient oxygen, leading to the accumulation of lactic acid.

  • Results in muscle soreness.

ATP - Energy Currency

  • ATP (Adenosine Triphosphate) releases energy when phosphate bonds are broken.

Respiration in Plants

  • Respiration occurs through stomata and lenticels; rates lower than in animals.

Transpiration Process

  • Loss of water vapor from plant aerial parts through stomata, aiding in water transportation.

Need for Lungs

  • Simple organisms utilize diffusion; complex organisms require lungs for efficient gas exchange.

Transportation in Organisms

  • Transportation of air, water, and nutrients is essential.

  • Different mechanisms exist in plants and animals for distribution.

Transportation in Humans

  • Conducted via the circulatory system, comprising blood, vessels, and heart.

Heart Structure

  • Main pumping organ with four chambers: atria and ventricles.

Blood Vessels

  • Types:

    • Arteries: Carry oxygenated blood.

    • Veins: Carry deoxygenated blood.

    • Capillaries: Seat of gaseous exchange.

Blood Pressure

  • Measurement of force of blood against vessel walls; consists of systolic and diastolic measures.

Bleeding and Clotting

  • Occurs from ruptured vessels; halted by platelets and clot formation.

Double Circulation

  • Blood passes through the heart twice during human circulation: pulmonary and systemic circulations.

Transportation in Plants

  • Xylem transports water; phloem transports nutrients and sugars.

Phloem Function

  • Responsible for nutrient translocation; flows bidirectionally for active areas.

Translocation Process

  • Food movement in the phloem by osmosis and pressure gradients.

Xylem Function

  • Unidirectional transport of water from roots to aerial parts of plants.

Root Pressure Mechanism

  • Some forces contribute to water transport including root pressure created by osmotic pressure.

Excretion Overview

  • Removal of metabolic wastes; complex systems in animals and simpler in plants.

Excretion in Unicellular Organisms

  • Waste removal through diffusion or contractile vacuoles, egestion through merging vacuoles with body surface.

Human Excretory System

  • Comprises kidneys, ureters, bladder, and urethra; functions via urine production.

Kidney Functions

  • Main filtration units; regulate fluid balance, ion concentrations, pH, and blood pressure.

Nephron Structure

  • Basic units of kidneys, involved in waste filtration and substance reabsorption; outputs urine.

Haemodialysis

  • Artificial kidney machine to assist in filtering blood when kidneys fail.

Excretion in Plants

  • Gas exchanges via stomata; excess water through transpiration; organic by-products stored.

Case Studies of Plant Excretory Products

  • Examples include oils, latex, and storage of waste in various plant parts.

Frequently Asked Questions

  • Sphygmomanometer: Instrument for measuring blood pressure.

  • Function of Phloem: Transports nutrients in plants.

  • Aerobic vs Fermentation: Aerobic respiration generates more ATP.