BioGenius: Guide to Biology Fundamentals | IGCSE

Explore how specialized ciliated cells in the respiratory tract use their cilia to move mucus, clearing dirt, bacteria, and viruses from the lungs.

Understand how nerve cells transmit electrical impulses from the brain to muscles and from sensory organs to the brain, through dendrites, the cell body, the axon, and axon terminals.

Explain how red blood cells transport oxygen from the lungs to body cells, using a bi-concave shape to increase surface area, and lacking nuclei to house more oxygen-absorbing hemoglobin.

Differentiate haploid and diploid cells by chromosome counts; fertilization fuses haploid sperm and ovum to form a diploid zygote, with acrosome enzymes and mitochondrial energy.

Explore specialized plant cells, comparing palisade mesophyll with rectangular chloroplast-rich cells and root hair cells with thin walls and high surface area for water and mineral absorption.

Explore how xylem cells, a dead, lignified vascular tissue, transport water and minerals from roots to leaves, while phloem carries sugars up and down to support photosynthesis.

Levels of organization begin with cells that share shape and function and group into tissues. These tissues form organs, and organs assemble into organ systems that make up the organism.

Explore plant organ systems, including shoot above ground and root below ground, with root xylem and phloem, root hairs, and tubers. Examine leaf tissues: palisade and spongy mesophyll for photosynthesis.

Explore how tissues form organ systems and organs like stomach, lungs, and heart; learn epithelial, nervous, muscular, and connective tissues, plus how thymus, spleen, and bone marrow generate immune cells.

Learn to calculate magnification using the equation magnification equals image size over actual size, and perform unit conversions between centimeter, millimeter, and micrometer by multiplying or dividing.

Understand diffusion, osmosis, and active transport as movement of substances across the cell membrane, driven by concentration gradients. Distinguish passive diffusion and osmosis from active transport across a semi-permeable membrane.

Explore diffusion as a vital mechanism for absorption in intestinal epithelial cells and gas exchange in the lungs, including stomata in leaves, alveoli, and diffusion of oxygen and carbon dioxide.

High temperature and large concentration differences speed diffusion, while increased distance or thick membranes slow it; thin alveolar walls in the lungs maximize diffusion for gas exchange.

Explore osmosis and cell behavior as water moves from high to low potential; animal cells burst in dilute solutions, plant cells become turgid, and animal cells shrink in concentrated solutions.

Active transport uses energy to move substances from low to high concentration. It enables glucose uptake in intestinal and kidney tubules, and water and mineral uptake in root hair cells.

Explore biochemistry by examining carbohydrates, proteins, and lipids, and learn how carbon, hydrogen, and oxygen form these molecules—while proteins include nitrogen, phosphorus, and sulfur.

Carbohydrates form from glucose monomers into disaccharides and polysaccharides, including starch, cellulose, and glycogen. Plants store energy as starch, while animals store energy as glycogen in the liver.

Explore lipids as solid fats and liquid oils, focusing on triglycerides formed from a glycerol molecule bound to three fatty acids.

Explore how amino acids serve as the building blocks of proteins, forming peptides in varied sequences that fold into complex protein shapes.

Explore glucose detection with Benedict’s test (blue to orange/red when heated at 70°C), iodine for starch, beer test for protein, ethanol for lipids, and DC pip for vitamin C.

Explore nucleic acids and DNA as genetic material. Understand nucleotide structure and base pairing—A with T, C with G—forming the DNA double helix.

Identify glycerol and fatty acids as the basic units for oil synthesis; amino acids form proteins, while simple sugars do not serve as protein units.

Enzymes are proteins that act as biological catalysts, speeding up metabolic reactions without being changed. They are highly specific for substrates, binding at the active site in a lock-and-key fit.

Discover how enzymes break down substrates and build up molecules through binding, the formation of an enzyme-substrate complex, and product release, with incubation time defining the action.

Explore how temperature affects the rate of respiration using yeast, glucose, and methylene blue indicator; identify the optimum temperature for enzyme activity and observe denaturation at high temperatures.

Explain how the pH scale defines acidic and alkaline conditions and how stomach pH 1–2 and intestine pH 8–9 shape enzyme activity, noting denaturation outside optimum pH and pH-activity curve.

Watch amylase convert starch to maltose, shown by blue, red, and brown iodine colors as the reaction proceeds at 20 and 37 degrees Celsius, while 60 degrees Celsius halts it.

Trace water movement via xylem from roots to leaves, phloem sugar transport, and leaf anatomy with guard cells and stomata enabling photosynthesis and glucose storage as starch and oxygen release.

Glucose fuels respiration for energy and builds starch and cellulose for storage and cell walls; it forms amino acids with nitrate and moves as sucrose through the phloem.

Explore testing photosynthesis by detecting starch with iodine, removing old starch by torching, then remove chlorophyll with heat and ethanol, and study light and carbon dioxide effects on oxygen bubbles.

The plant leaf adapts for efficient diffusion and light capture with a large surface area and high chlorophyll, aided by a thin transparent epidermis, cuticle, and stomata.

Explore what a balanced diet means by including all essential food groups in the right proportions, including carbohydrates, proteins, lipids, vitamins, minerals, dietary fiber, and water.

Explore the food groups, including carbohydrates, proteins, lipids, dietary fibers, vitamins, minerals, and water, and their functions, from energy and growth to insulation and energy storage, and their common sources.

Learn how Vitamin C supports collagen formation with amino acids, boosting skin elasticity, hair, gums, and bones, and how a Vitamin C–poor diet causes scurvy.

Vitamin d from eggs, liver, fish, and sunlight enables calcium absorption, while calcium comes from milk, cheese, and eggs, and deficiencies can cause osteoporosis, rickets, or scurvy.

Discover how dietary iron from liver, meat, and greens enables hemoglobin production in red blood cells, ensuring oxygen transport from the lungs and preventing anemia.

Explore how age, lifestyle, and pregnancy influence dietary needs, highlighting calcium and iron requirements for pregnancy and breastfeeding to support energy, growth, and red blood cell production.

Explore vitamin c deficiency and scurvy with gum ulcers, tooth loss, anemia, and vitamin d deficiency causing rickets with weak bones, deformities, and the role of sunlight.

Learn the stages of food breakdown—ingest, digestion (mechanical and chemical), absorption, and assimilation—focusing on how enzymes and acids enable breakdown and how surface area to volume boosts digestion.

Explore the digestive system from mouth through intestines, detailing mechanical and chemical digestion, enzymes like amylase, pepsin, and lipase, and absorption via villi, bile, and liver functions.

Glucose and amino acids enter the blood after absorption in the ileum, while glycerol and fatty acids from triglycerides enter the lymph; minerals, vitamins, and water also enter the blood.

Explore how protease from the stomach digests egg albumin protein, requiring hydrochloric acid and suitable temperature to work efficiently; boiling denatures protease, making digestion ineffective.

Xylem carries water and minerals upward, while phloem moves sucrose and amino acids in both directions, and lecture maps vascular bundles in leaves, stems, and roots with lignin-thickened, dead-cell walls.

Learn how water moves from soil into root hairs by osmosis, travels through the cortex to the xylem, and rises to leaves, with minerals taken up by active transport.

Investigate transpiration as water loss by evaporation from stomata, driven by diffusion, with water moving from soil to leaves to maintain turgidity, cooling, and mineral transport.

Explore transpiration through a simple apparatus tracking an air bubble in a tube, comparing wind vs no wind and noting temperature, light, and humidity effects.

Explore how adhesion and cohesion drive the transpiration stream in the xylem, enabling capillary action that lifts water upward.