Images Dated 25th June 2004

Germinated seed, SEM

Germinated seed. Image 4 of 4. Coloured scanning electron micrograph (SEM) of the final stage in the germination of a plant seed. The seed coat (testa) has been lost. The embryonic plant that emerged has two main parts. The radicle (white), the embryonic root, is growing downwards in a response to gravity that is called geotropism. The root hairs increase the ability of the root to obtain water and nutrients from its surroundings. The embryonic shoot (plumule) will grow upwards against gravity to the light, and its seed leaves (cotyledons, green) will photosynthesise. This is a swede (Brassica napus) seedling. For images of seed germination, see B787/394-397 and B787/398

© POWER AND SYRED/SCIENCE PHOTO LIBRARY

Food pyramid

Food pyramid showing the recommended proportions of food types for a healthy, balanced diet. The largest part of the diet should be carbohydrates from bread, cereal, rice and pasta (pyramid base), with 6-11 servings daily. The next layer of the pyramid is fruit and vegetables, with a combined amount of 6-9 servings daily. These provide many essential vitamins and minerals. The next layer is lean meat, beans, eggs and nuts (protein content), and milk, yoghurt and cheese (calcium and protein content), both groups requiring moderation (2-3 servings daily). Finally at the top of the pyramid are fats and oils, and sweets (added sugar), which should be used sparingly (0-3 servings daily)

© DAVID MUNNS/SCIENCE PHOTO LIBRARY

Geyser

Geyser erupting. A geyser is a deep natural well in a geothermal rock fissure. The water lies in a large chamber at the well's base, and is heated by surrounding rocks until it is well over its normal boiling point. The water is prevented from boiling by hydrostatic pressure, and then, at a critical temperature, the superheated water spontaneously boils, resulting in the eruption seen here. These eruptions repeat periodically. Photographed in Geysir, Iceland, the area whose name is the origin of the word geyser

© CHRIS MADELEY/SCIENCE PHOTO LIBRARY