Three ways substances cross cell membranes
Three ways substances cross cell membranes

A cell membrane is the thin boundary that controls what enters and leaves a cell. Particles move randomly all the time, so substances can cross membranes in predictable ways.
Step-by-step lessons covering Edexcel IGCSE Biology Movement of substances into and out of cells for IGCSE Biology. Each lesson works through exam-style questions in Paper 1 and Paper 2 format. Start with the foundational cell biology and core content before moving on to the more data-heavy ecology, genetics and practical-skills topics, which carry a large share of the exam marks.