In this series of ten blogs, various parts of the GCSE Science and IGCSE Biology specifications will be explored through the context of food. As well as assisting students revising for their GCSE and IGCSE exams, the blogs also provide an every-day context for science which all readers should find accessible, interesting and useful.
Banana, pineapple, melon and passion fruit or apple, pear, raspberry and cherry: whether you like a tropical or more home-grown fruit salad, its attraction lies in the delicious sweetness of the many fruits we can grow in our gardens or buy during the year.
All fruit grow in the same way and all owe their sweetness to the air, the rain, plenty of sunshine and a little help from the bees.
Flowers come in all shapes and sizes and they are the reproductive organs of plants. Bees collect pollen when they visit a flower. Pollen contains the male gametes (sex cells). When the bee visits another flower the pollen brushes off it onto the female stigma. The pollen grows a tube down the style (the stalk leading from the stigma to the ovary). The gamete fertilizes the flower’s ovules (eggs) which lie in the ovary at the base of the flower.
Once fertilized, the ovary starts to swell with water and form the fruit; the fertilised ovules become the seeds. Glucose also travels to the fruit making it sweet.
The glucose is made during photosynthesis in the green parts of the plant. Water absorbed by the roots of the plant reacts with carbon dioxide from the air inside structures in plant cells called chloroplasts. The products of the reaction are glucose and oxygen. Energy from sunlight is needed for the reaction to proceed. The soluble glucose travels to the fruit making it irresistible …