A functioning gene is inserted into the nucleus of one cell in an eight-cell embryo. The modified cell undergoes three rounds of division. Each of the other seven cells undergoes two rounds of division. Each division produces two daughter cells. No cells die, and only descendants of the modified cell inherit the introduced gene.
What percentage of the resulting cells contains the gene, and when should it have been inserted to give all cells the gene?
12.5%; into the original cell before the embryo's first cell division.
22.2%; into one daughter cell after the embryo's first cell division.
12.5%; into one daughter cell after the embryo's first cell division.
22.2%; into the original cell before the embryo's first cell division.
44 exam-style questions on AQA GCSE Biology 6.2 Variation and evolution, covering 6.2.1 Variation, 6.2.2 Evolution, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, and 6.2.5 Cloning. Each one has a worked solution and a mark scheme showing where the marks go.