Fill in Table 4.1 to show how meiosis and mitosis differ. In both columns, enter a tick if the statement is correct and a cross if it is incorrect. Every box has to contain either a tick or a cross.
Compare how meiosis functions in gametogenesis to form sperm cells in humans with how it functions in gametogenesis to form pollen grains in flowering plants.
Flower colour matters in sexual reproduction in insect-pollinated plants. In the rosy periwinkle, Catharanthus roseus, flower colour is determined by three genes, R/r, D/d and P/p, which act together to control flower colour. Work out the phenotypes of these rosy periwinkle genotypes: RR dd PP Rr Dd Pp rr Dd Pp RR dd pp.
Pigments responsible for flower colour in the rosy periwinkle are produced through a biosynthetic pathway. The R allele mutated to form the r allele. The r allele codes for a non-functional protein. Explain how the mutation that changes R to r leads to no red pigment being synthesised in the flower of rosy periwinkle.
One mutation that alters the flower colour of rosy periwinkle occurs in a stretch of DNA that does not code for a polypeptide. Suggest what role this section of DNA could have.