A scientist cuts open a plasmid using restriction enzyme X. The scientist cuts out a human gene using restriction enzyme Y. Enzymes X and Y cut DNA at different base sequences. The human gene does not join into the plasmid. Which statement explains why?
Ligase can only join pieces of DNA from the same type of organism.
Enzyme Y destroys the human gene, so no gene is left to be inserted.
The sticky ends are not complementary, so their bases cannot pair.
The human gene is too large to fit into the plasmid of a bacterium.
127 exam-style questions on OCR GCSE Biology 6.2 Feeding the human race, covering 6.2.1 Biological factors affecting food security, 6.2.2 Agricultural solutions to growing demand, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, 6.2.5 Steps in genetic engineering, 6.2.6 Benefits and risks of gene technology in agriculture, and 6.2.7 Biotechnological solutions to growing demand. Each one has a worked solution and a mark scheme showing where the marks go.