Microbe Mission Practice Tests
Free, AI-generated Microbe Mission practice tests for Science Olympiad. Choose Invitational, Regional, State, or National difficulty, import past exam PDFs, and track your scores over time.
Microbe Mission is not part of the 2027 event lineup - it ran in recent seasons, and retired events like this often return in later years. This guide and its practice tests remain open, and invitationals sometimes choose to run retired events.
What Microbe Mission Tests Cover
bacterial structure, viral replication, fungal characteristics, microbial ecology, and lab techniques. BACTERIA (Prokaryotes): - No nucleus (DNA in nucleoid region), no membrane-bound organelles - Cell wall: Peptidoglycan (unique to bacteria) - Shapes: Cocci (spheres), Bacilli (rods), Spirilla (spirals), Vibrio (comma) - Arrangements: Diplo- (pairs), Strepto- (chains), Staphylo- (clusters) - Reproduction: Binary fission (asexual), ~20 min doubling time - Genetic exchange: Conjugation (plasmid transfer), Transformation (DNA uptake), Transduction (via phage) - Structures: Flagella (movement), Pili (attachment), Capsule (protection), Endospores (survival)
- Structures: Flagella (movement), Pili (attachment), Capsule (protection), Endospores (survival)
Gram staining
1. Crystal violet (purple) - all bacteria stain purple
2. Iodine (mordant) - fixes crystal violet
3. Alcohol/acetone (decolorizer) - removes from thin cell walls
4. Safranin (counterstain) - stains decolorized cells pink
- Gram+ (purple): Thick peptidoglycan, no outer membrane (Staphylococcus, Streptococcus)
- Gram- (pink/red): Thin peptidoglycan, outer membrane with LPS (E. coli, Salmonella)
Viruses
- NOT cells, NOT alive by most definitions
- Structure: Genetic material (DNA OR RNA, never both) + Protein coat (capsid) ± Envelope
- Shapes: Helical, Icosahedral (20 faces), Complex (bacteriophages)
- Size: 20-300 nm (much smaller than bacteria)
- Must use host cell machinery to replicate
- Lytic cycle: Attachment → Entry → Replication → Assembly → Lysis (kills cell)
- Lysogenic cycle: DNA integrates into host genome (prophage), replicates with host
- Retroviruses (HIV): RNA → DNA (reverse transcriptase) → integrates into host
Fungi
- Eukaryotic (membrane-bound nucleus and organelles)
- Cell walls of CHITIN (not peptidoglycan)
- Heterotrophs (absorb nutrients externally)
- Body forms: Unicellular (yeasts) or Multicellular (molds, mushrooms)
- Multicellular structure: Hyphae (threads) → Mycelium (network)
- Reproduction: Spores (sexual and asexual)
- Examples: Yeast (Saccharomyces), Bread mold (Rhizopus), Mushrooms, Penicillium
- Symbioses: Mycorrhizae (with plants), Lichens (with algae/cyanobacteria)
Protists
- Eukaryotic, mostly unicellular, very diverse group
- Animal-like (protozoa): Heterotrophs, motile
- Amoeba (pseudopods), Paramecium (cilia), Euglena (flagella), Plasmodium (malaria)
- Plant-like (algae): Photosynthetic
- Diatoms, Dinoflagellates (red tide), Kelp, Chlamydomonas
- Fungus-like: Slime molds, Water molds
Microbial ecology
- Decomposers: Break down dead organic matter, recycle nutrients
- Nitrogen fixation: N₂ → NH₃ (Rhizobium in legume root nodules)
- Normal flora: Beneficial microbes on/in body (gut bacteria aid digestion)
- Pathogens: Disease-causing microbes
- Extremophiles: Thrive in extreme conditions (thermophiles, halophiles, acidophiles)
Lab techniques
- Aseptic technique: Prevent contamination
- Streaking for isolation: Get individual colonies
- Serial dilution: Reduce concentration for counting
- Pour plate / Spread plate: Grow colonies for counting
- Colony characteristics: Shape, color, margin, elevation
- Selective media: Favors certain organisms (MacConkey for Gram-)
- Differential media: Distinguishes organisms (Blood agar for hemolysis)
Disease & immunity
- Koch's postulates: Criteria to prove microbe causes disease
- Transmission: Direct contact, Droplet, Airborne, Fecal-oral, Vector-borne
- Antibiotics: Target bacteria (not viruses!) - cell wall, protein synthesis, DNA replication
- Antibiotic resistance: Overuse → selection for resistant strains
- Vaccines: Stimulate immune response without causing disease
Important diseases
- Bacterial: Tuberculosis (Mycobacterium), Strep throat, Food poisoning (E. coli, Salmonella), Lyme disease (Borrelia)
- Viral: Influenza, HIV/AIDS, COVID-19, Rabies, Measles, Chickenpox
- Fungal: Athlete's foot, Ringworm (not a worm!), Candidiasis, Histoplasmosis
- Protist: Malaria (Plasmodium), Amoebic dysentery, Sleeping sickness
Common mistakes
- Calling viruses "alive" or "cells"
- Confusing Gram+ (purple) vs Gram- (pink)
- Saying bacteria have a nucleus
- Confusing chitin (fungi) with peptidoglycan (bacteria)
- Thinking antibiotics work on viruses