A mixed GCSE Science revision check

Particles move randomly, but diffusion produces an overall net movement from a region of higher concentration to a region of lower concentration.

The ion has one more negative electron than positive proton, so its overall charge is 1−.

There is only one path in a series circuit, so the same charge passes every point per second and the current is the same throughout.

A high temperature can break bonds that maintain the enzyme's shape. The active site changes, so the substrate no longer fits effectively.

80 falls to 40 after one half-life, 20 after two and 10 after three half-lives.

If more light has no effect, light is not limiting under those conditions. Carbon dioxide concentration, temperature or another factor may now limit the rate.

Work done against gravity transfers energy to the object's gravitational potential energy store.

The pH scale is logarithmic. An increase of one pH unit corresponds to a tenfold decrease in hydrogen ion concentration.