Life Sciences
This polysaccharide provides structural support in plant cell walls and consists of β-1,4-linked glucose units.
What is cellulose?
This atmospheric circulation cell dominates tropical latitudes and drives trade winds.
What is the Hadley cell?
This periodic trend generally increases across a period and decreases down a group, reflecting an atom’s attraction to electrons.
What is electronegativity?
This vector quantity represents the rate of change of momentum with respect to time.
What is force?
Estimate the number of heartbeats in an average human lifetime.
What is ~2–3 billion heartbeats?
This checkpoint ensures that all chromosomes are properly attached to spindle fibers before anaphase proceeds.
What is spindle assembly checkpoint (or metaphase checkpoint)?
This mineral property describes the tendency to break along specific crystallographic planes.
What is cleavage?
This type of intermolecular force arises from temporary dipoles induced in nonpolar molecules.
What is London dispersion forces?
This conservation law follows directly from spatial translational symmetry via Noether’s theorem.
What is conservation of momentum?
Estimate the number of plastic water bottles used in the United States per day.
What is ~100–200 million bottles per day?
This enzyme synthesizes RNA in the 5′→3′ direction while proofreading via a backtracking mechanism.
What is RNA polymerase?
This isotope system is commonly used to date recent (<50,000 years old) organic material.
What is carbon-14 dating (or radiocarbon dating)?
This thermodynamic quantity determines whether a reaction is spontaneous under constant temperature and pressure.
What is Gibbs free energy (ΔG)?
This equation relates electric field, magnetic field, and electromagnetic wave propagation in free space.
What is Maxwell’s equations?
Estimate the total number of neurons in the human brain.
What is ~8 × 10¹⁰ (80 billion) neurons?
This evolutionary mechanism increases genetic variation by reshuffling alleles without changing allele frequencies.
What is genetic recombination (or independent assortment)?
This orbital phenomenon explains why Earth’s seasons vary in intensity over ~23,000-year cycles.
What is axial precession?
This approximation allows weak acids and bases to be treated as partially dissociated when calculating equilibrium concentrations.
What is the ICE table approximation (or small-x approximation)?
This relativistic effect causes clocks moving at high speeds relative to an observer to run slower.
What is time dilation?
Estimate the number of air molecules in a standard classroom (≈8 m × 10 m × 3 m).
What is ~10²⁸ molecules?
This transcription factor complex is activated by calcium signaling and is essential for T-cell activation and immune response regulation.
What is NFAT (Nuclear Factor of Activated T-cells)?
This discontinuity marks the transition between Earth’s upper and lower mantle and is associated with phase changes in olivine.
What is the 410 km discontinuity?
This spectroscopic technique exploits transitions between nuclear spin states in a magnetic field to determine molecular structure.
What is NMR spectroscopy (Nuclear Magnetic Resonance)?
This principle states that certain pairs of physical properties cannot both be known with arbitrary precision simultaneously.
What is the Heisenberg uncertainty principle?
Estimate the number of piano tuners in Los Angeles using population-based assumptions.
What is ~100–300 piano tuners?