Biology 101: Introduction to Digestion and Excretion

Explore macronutrients like carbohydrates, proteins, and fats and how they supply energy. Learn about micronutrients—vitamins and minerals—and their roles, sources, and common deficiencies.

Explore how minerals like iron support hemoglobin and oxygen transport, calcium and phosphorus build bones, sodium regulates blood pressure and nerve impulses, and water underpins digestion and temperature control.

Examine the structure and function of the human dentition, including incisors, canines, premolars, and molars, and how enamel, dentine, and pulp relate to decay and care through brushing and fluoride.

Enzymes, made of proteins, act as biological catalysts that speed up specific reactions at an active site with a lock-and-key substrate fit, while temperature and pH govern their activity.

Explore the human digestive system, from mouth and peristalsis to stomach enzymes like amylase and pepsin, pancreatic juice, bile emulsification, and nutrient absorption in villi.

Explore the digestive system of pigs and rabbits, detailing mouth, esophagus, rumen-like stomach stages, regurgitation, cellulose digestion by gut bacteria, and ileum absorption.

Defines excretion as removing metabolic wastes and outlines how kidneys and nephrons filter blood, reabsorb essentials, and produce urine via proximal tubule, loop of Henle, distal tubule, and collecting duct.

Trace amino acids from digested proteins to the liver, where deamination forms ammonia and converts to urea for excretion, and observe plant ammonia-to-urea excretion.

Explore osmoregulation via hypothalamus and pituitary controlling antidiuretic hormone to kidneys, balancing water and urine concentration, and learn plant and animal food storage, including starch and glycogen.

Explore excretion through sample questions and connect digestion to waste elimination in the human body.

Explore the respiratory system’s structure and adaptations, from nose to alveoli, including inhalation and exhalation, epiglottis function, gaseous exchange, diffusion on a vast lung surface, and mucus and cilia defenses.

Explore how inhalation expands the chest and air moves by diffusion through moist alveoli, where oxygen binds to hemoglobin to form oxy hemoglobin and carbon dioxide diffuses out.

Explore respiration in mitochondria that releases energy from glucose, forms carbon dioxide and water, and stores energy as ATP; aerobic and anaerobic differ, with anaerobic producing ethanol or lactic acid.