Hint: Petals of the flower form the outermost whorl corolla of a flower. They protect the inner whorls of the plant and also help in pollination.
Complete answer:
Petals are usually brightly coloured because they attract insects. Flowers produce the sweet smell and bright coloured petals, which increases the chances of pollination. Pollination is a very important step in the sexual reproduction of higher plants. Pollen grains are produced by the male flower or by the male organs in case of hermaphrodite flowers. But the pollen does not move on its own so they require wind or animal pollinators to disperse the pollen to the stigma (receptor of the female organ) of the same or nearby flowers. However, pollinators are selective in determining the flowers they choose to pollinate which leads to a competition between flowers. To overcome this, flowers provide incentives to appeal to insects and animals. Flowers provide nectar to insects which results in insects pollinating in exchange. Petals play a major role in this part.
When the insects like butterflies or bumblebees visit a flower to collect nectar, the pollen from that flower stick to their body and get transferred to the next flower they visit for nectar.
So, the answer is ‘To attract insects’.
Note: Bright colours and sweet scents are used not only to attract insects but also, small birds like hummingbirds which feed on nectar, or small bats. They also help in pollination. Besides sweet scents, some flowers also produce foul scents to ward off predators.
