(a) Unisexual flowers: Cucumber, pumpkin, water melon, papaya, etc. Bisexual flowers: Hibiscus, rose, lily, etc. (Any one example can be written). (b) Changes in a flower after fertilisation: The outer layers of the ovule become impervious and hard and function as a seed coat. An ovule with an embryo inside is called a seed. The ovary enlarges and ripens to become a fruit. Other floral parts such as sepals, petals, stamens, styles and stigma may fall off. However, in some cases, they remain persistent in the fruit. (c) Deoxyribonucleic acid (DNA) copying is an essential part of reproduction, as it passes genetic information from parents to offspring. The reproducing cells produce a copy of their DNA through some chemical reactions and result in two copies of DNA. The copying of DNA always takes place along with the creation of additional cellular structure. This process is then followed by the division of a cell into two cells. In this way, the amount of DNA remains constant through each new generation.