Figure shows one chromosome taken from a body cell. Three of the genes on this chromosome are marked P, Q and R.
Figure: One chromosome from a body cell, with three of its genes marked P, Q and R

Give one similarity and one difference between gene P and gene Q.
The chromosome in Figure carries about 1200 genes in total. Explain what this tells you about the length of one gene compared with the length of the whole chromosome.
63 exam-style questions on AQA GCSE Biology 1.2 Cell division, covering 1.2.1 Chromosomes, 1.2.2 Mitosis and the cell cycle, and 1.2.3 Stem cells. Each one has a worked solution and a mark scheme showing where the marks go.