bio
Name the organelle responsible for synthesising ATP in aerobic respiration.
Mitochondrion
What shape and bond angle does methane have?
Tetrahedral, 109.5°
State Newton’s third law of motion.
Every action has an equal and opposite reaction.
What is the SI unit for pressure?
Pascal (Pa)
Which enzyme unwinds DNA during replication?
DNA helicase
Write the general formula of an alkene
CₙH₂ₙ
What is the unit of electric field strength in SI?
N C⁻¹ or V m⁻¹
Which element has the highest first ionisation energy?
Helium
What property of water explains how it moves up xylem against gravity?
Cohesion / adhesion creating capillarity
What is the oxidation state of chromium in K₂Cr₂O₇?
+6
Light of wavelength 500 nm falls on a photoelectric surface. If the work function is 2 eV, will electrons be emitted? (h c ≈ 1240 eV·nm)
Yes; photon energy = 1240/500 = 2.48 eV > 2 eV.
In a reversible reaction, what happens to Kc when temperature changes?
Kc changes if the reaction is exothermic/endothermic; increases in the direction favoured by heat.
In an action potential, which ion’s influx causes depolarisation of the axon membrane?
Na⁺ (sodium ions)
Explain why phenol is more acidic than ethanol.
The phenoxide ion is stabilised by delocalisation of charge into the ring.
A particle moves in a circle of radius 0.5 m at 4 m s⁻¹. Find its centripetal acceleration.
a = v²/r = 16/0.5 = 32 m s⁻²
Which branch of maths underpins quantum mechanics and modern physics?
Linear algebra / complex numbers
Describe one way in which structure of a competitive inhibitor differs from a non-competitive inhibitor.
Competitive mimics the substrate & binds to active site; non-competitive binds to allosteric site, changing enzyme shape
Name the process used industrially to obtain pure silicon from SiCl₄.
Reduction of SiCl₄ with hydrogen / the Siemens process (chemical vapour deposition).
State one difference between stationary (standing) waves and progressive waves.
Standing waves have nodes/antinodes and no net energy transfer; progressive waves transfer energy.
What is the name of the instrument used to measure very small lengths accurately (to 0.01 mm)?
Micrometer screw gauge