Fill in Table 4.1 to show the differences between meiosis and mitosis. In both columns, write a tick (✓) if the statement is true and a cross (✗) if the statement is false. Every box must contain either a tick or a cross.
Compare the role of meiosis in gametogenesis when sperm cells are formed in humans with its role in gametogenesis when pollen grains are produced 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 work together to control flower colour. Fig. 4.1 shows a rosy periwinkle. Deduce the phenotypes of these rosy periwinkle genotypes: • $RR\ dd\ PP$ • $Rr\ Dd\ Pp$ • $rr\ Dd\ Pp$ • $RR\ dd\ pp$
The pigments responsible for flower colour in the rosy periwinkle are made by 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 changes the flower colour of rosy periwinkle occurs in a section of DNA that does not code for a polypeptide. Suggest what role this DNA section might have.