🧬 Biology Essentials

What you’ll learn

1. Cells: The Unit of LifeExplain cell theory, distinguish prokaryotes from eukaryotes, identify key organelles, and describe cell division and energy processes.Every living thing is made of cells, the smallest unit of life. Cells are either prokaryotic (no nucleus) or eukaryotic (nucleus and organelles). Organelles like mitochondria and ribosomes divide the work. Cells reproduce by mitosis and meiosis, and life runs on the paired energy processes of photosynthesis and cellular respiration.
2. DNA to ProteinDescribe DNA's structure and base pairing, define genes and the genome, explain the DNA-to-RNA-to-protein pathway, and understand mutations.DNA is a double helix whose four bases (A-T, C-G) spell genetic instructions. A gene codes for a protein; all genes together form the genome. The central dogma runs DNA to RNA to protein, with ribosomes building proteins from RNA. Mutations change DNA and are the ultimate source of genetic variation for evolution.
3. Heredity and GeneticsExplain Mendel's discoveries, dominant and recessive alleles, how to use Punnett squares, and more complex patterns of inheritance.Mendel showed traits pass in discrete units (genes) with predictable ratios. Organisms carry two alleles per gene; dominant alleles mask recessive ones. Punnett squares predict offspring odds, giving a 1-in-4 chance of a recessive trait from two carriers. Real inheritance also includes polygenic, codominant, and sex-linked traits shaped by environment.
4. Evolution and Natural SelectionExplain evolution and natural selection, how selection changes populations, and the multiple lines of evidence supporting evolution.Evolution is heritable change in populations over generations. Darwin's natural selection works because individuals vary, more are born than survive, and better-suited traits are passed on, shifting populations over time. Evidence comes from fossils, shared DNA, comparative anatomy like homologous limbs, and observed cases such as antibiotic resistance.
5. Body Systems OverviewDescribe the levels of biological organization and the major body systems and how they cooperate to maintain homeostasis.Life is organized from cells to tissues to organs to systems to organism. The respiratory and circulatory systems supply oxygen; the digestive system extracts energy; the nervous system controls and senses; the immune system defends. About a dozen systems cooperate constantly to keep the body in a stable balance called homeostasis.
6. Ecosystems and Energy FlowDefine ecosystems, explain food chains and energy flow with the 10 percent rule, and describe how matter cycles and ecosystems stay balanced.An ecosystem is a community of organisms interacting with their environment through producers, consumers, and decomposers. Energy flows from sunlight up food chains, losing about 90 percent at each level. Unlike energy, matter such as carbon and water is recycled. Ecosystems are delicately balanced webs vulnerable to disruption.
7. The Microbial WorldDescribe the diversity and importance of microbes, the strange status of viruses, and the role of microbes in human health and disease.Microbes, mostly bacteria, are Earth's most abundant and ancient life, running essential jobs like producing oxygen and cycling nutrients. Viruses sit at the edge of life, unable to reproduce without hijacking a host cell. Your microbiome mostly helps you, while antibiotics and vaccines fight harmful microbes, though antibiotic overuse breeds resistance.

Questions this course answers

Grounded in trusted sources

• National Human Genome Research Institute
• Encyclopaedia Britannica
• Khan Academy Biology
• Smithsonian National Museum of Natural History

Every Wunder lesson is built from real, reputable sources — never invented.

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