Answer: Spores and crystals.
- A Flagella, used for bacterial motility
- B Plasmids, small circular DNA molecules
- C Spores and crystals
- D Capsules, the protective outer layer
Correct answer: C. Spores and crystals
Explanation: Cry proteins (delta endotoxins) are stored as spore-crystal complexes in Bacillus thuringiensis. The crystalline inclusions are released and activated in the insect gut.
Sewage passes through physical removal (primary), then aerobic biological treatment where microbes form flocs that consume organic matter (secondary); the settled activated sludge is then digested anaerobically to produce biogas - a deliberate switch from aerobic to anaerobic conditions between stages.
Concept context
Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers