Life Processes

Introduction

• Life Processes: Basic processes needed for the maintenance and survival of organisms.
• Four key life processes: Nutrition, Respiration, Transportation, and Excretion.
• Important for board exams.
• Structure of the lecture: Quick revision of all the concepts.

Nutrition

Definition

• Nutrition: Mode of intake of food and its utilization.
• Two types: Autotrophic and Heterotrophic.

Autotrophic Nutrition

• Organisms prepare their own food from simple inorganic substances.
• Examples: Green plants (via photosynthesis).
• Photosynthesis: Process by which CO2 and H2O combine in the presence of sunlight and chlorophyll to form glucose and O2.
• Balanced Equation: 6CO2 + 6H2O → C6H12O6 + 6O2.
• Steps of Photosynthesis:
  1. Absorption of light energy by chlorophyll.
  2. Conversion of light energy to chemical energy and splitting of water molecules.
  3. Reduction of CO2 to carbohydrates.

Heterotrophic Nutrition

• Organisms depend on other organisms for food.
• Types:
  1. Saprophytic Nutrition: Decomposers like fungi break down dead and decaying matter outside their body and absorb nutrients.
  2. Parasitic Nutrition: Organisms like ticks and plants like Cuscuta depend entirely on a host and derive nutrients from it.
  3. Holozoic Nutrition: Organisms ingest food, digest it internally, and absorb nutrients.

Holozoic Nutrition in Humans

• Five steps:
  1. Ingestion: Taking in food.
  2. Digestion: Breakdown of complex substances into simpler forms.
  3. Absorption: Nutrients absorbed into the bloodstream.
  4. Assimilation: Utilizing absorbed nutrients.
  5. Egestion: Removal of undigested food.
• Digestive System Components:
  • Buccal Cavity: Teeth, tongue, and saliva (salivary amylase breaks down starch).
  • Esophagus: Food pushed to the stomach via peristalsis.
  • Stomach: Gastric juices (HCl, mucus, pepsin) aid in digestion.
  • Small Intestine: Bile (emulsifies fats) from the liver and pancreatic juices (digest carbohydrates, proteins, fats) aid in full digestion; absorbed by villi.
  • Large Intestine: Reabsorbs water and excretes undigested food.

Respiration

Definition

• Respiration: Breakdown of glucose to release energy (cellular respiration).
• Occurs in the cytoplasm (glycolysis) and mitochondria (Kreb’s cycle).
• Produces ATP (energy currency).

Aerobic Respiration

• Glucose broken down in the presence of oxygen.
• Full breakdown in mitochondria, producing CO2, water, and energy (38 ATP).

Anaerobic Respiration

• Absence of oxygen.
• In muscle cells: Glucose → Lactic Acid + Energy.
• In yeast: Glucose → Ethanol + CO2 + Energy.
• Yeast process called fermentation.

Human Respiratory System

• Components:
  • Nostrils: Entry of air.
  • Nasal Cavity: Filters air.
  • Pharynx: Common passage for food and air.
  • Larynx: Voice box.
  • Trachea: Windpipe to the bronchi.
  • Bronchi: Branch into lungs.
  • Lungs & Alveoli: Gas exchange via diffusion.
• Breathing Process: Inhalation (diaphragm contracts) and Exhalation (diaphragm relaxes).
• Breathing in aquatic vs. terrestrial: Higher rate in aquatic due to less dissolved oxygen.

Transportation

In Plants

• Transport of water via xylem (uni-directional) using Transpiration Pull: Water is absorbed by roots, travels up through xylem, and evaporates as water vapor from leaves causing a pull.
• Transport of food via phloem (bi-directional) using Translocation: Movement of food requires energy (ATP).

In Animals (Humans)

Components:

1. Blood: Fluid connective tissue (Plasma, RBC, WBC, Platelets).
2. Blood Vessels: Arteries (carry oxygenated blood, high pressure), Veins (carry deoxygenated blood, low pressure, have valves), Capillaries (exchange gases).
3. Heart: Four-chambered organ, pumps blood through pulmonary (lungs) and systemic (body) circuits.

Heart Structure and Function

• Four chambers: Right atrium, right ventricle, left atrium, left ventricle.
• Valves: Tricuspid (right), bicuspid (left) to prevent backflow.
• Path of Blood:
  1. Deoxygenated blood: Body → Right atrium via venae cavae → Right ventricle → Lungs via pulmonary artery.
  2. Oxygenated blood: Lungs → Left atrium via pulmonary vein → Left ventricle → Body via aorta.
• Double Circulation: Blood passes through the heart twice for each complete cycle.

Excretion

Definition

• Excretion: Removal of nitrogenous metabolic wastes from the body.
• Necessary to prevent toxicity.

In Plants

• Removal forms: Resins, gums, oxygen (byproduct of photosynthesis), shed old parts.

In Humans

• Excretory System: Kidneys (primary organ), ureter, urinary bladder, urethra.
• Urine Formation in Nephrons:
  1. Glomerulus: Network of capillaries, site of pressure filtration.
  2. Bowman’s Capsule: Receives filtrate.
  3. Tubules: Reabsorption and secretion processes.
  4. Collecting duct: Urine transported to the ureter.
• Urine: Toxic waste (urea), excess water, and salts removed as urine.

Note: Review concepts important for the board exams and focus on key points and definitions. Always keep your notes organized for efficient revision.