Practical 3: The life cycle of the apple
The life cycle of a flowering plant begins with the seed. In good conditions (moisture, warmth, air) the seed germinates and forms a young seedling. The seedling grows into a sapling and then into a perennial tree. The apple tree blooms in early spring; the flower produces a fruit, and seeds ripen inside the fruit. The fruit ripens in summer and autumn, and when a seed falls to the ground or is sown, a new cycle begins. The tree’s green leaves contain chlorophyll in their cells, and photosynthesis takes place in sunlight. A young apple is green because its cells have chloroplasts; as it ripens, chlorophyll decreases and other pigments give a yellowish or red colour. Apples contain vitamins, sugars and organic acids. Note that a tree grown from an apple seed may not look exactly like its parent, so good varieties are usually multiplied by grafting. Apple seeds usually need several weeks in the cold (the vegetable drawer of a refrigerator) before they will sprout, while mandarin, pumpkin or bean seeds sprout faster.
Practical work (at home, with a parent): line a clear glass with damp paper towel and place 3–4 bean seeds between the towel and the glass; pour a little water into the bottom so the paper stays damp. Watch how the root and shoot appear, measure the seedling with a ruler each day and record it in a 10-day table (day, height, number of leaves). Safety: do not eat the seeds; wash your hands with soap afterwards; put the glass where it cannot fall; only adults use sharp tools.