7 The threat of extinction DA ends his book by writing eloquently of the dangers of extinction faced by mammals, from habitat loss as we exploit our environment to produce more and more food, for our growing population. However bleak the picture, there is still time and opportunity to save mammal species from extinction. Although bison in the USA and Canada were reduced to barely 1000 individuals in 1900, their numbers have now risen to well over 150 000 thanks to the efforts of First Nation indigenous peoples, and ran
2.2 Energy flow in ecosystems You are about to meet some very large numbers, expressed in scientific notation, and some new units. The new units are those that are used to measure the amount of solar energy received by a part of the Earth's surface. Since plants are dependent on light for photosynthesis, the amount of plant material that ca 10 Living in herds Wildebeest are only one of the species of plant predator that live in herds. Many others do too. Watch the the TV programme from 30.48–47.32 and read LoM p. 109. Identify and write down (a) a couple of advantages and 5.1 Monogamy and polygamy You've seen plenty of evidence that reproduction in rodents – more precisely what I've called their reproductive strategies – are versatile and varied. You'll appreciate that ‘versatile and varied’ describes the range of sexual habits seen in the rodents as a group, not the behaviour within a single species. As DA says, some are monogamous, which means that individuals mate exclusively with one partner, over at least a single breeding cycle or season. The marmots are an example of a g 6.2.2 The Earth's motion relative to the 3 K radiation Radiation has energy and momentum, so we can use the molecules of a fluid such as air as an analogy for the photons of radiation. A detector pointing forwards along the direction of our motion (if any) will encounter a greater number of photons than a detector pointing backwards; in other words, it will record a higher intensity of 3 K radiation. (If the detector is tuned to a narrow band of frequencies one would also have to take account of the change in observed spectrum, but the principle 3.2 Some general properties of galaxies Firstly, we note that galaxies tend to occur in clusters rather than singly. The mutual gravitational attraction of galaxies naturally tends to hold them on paths that remain close to each other. Typically a cluster contains tens or hundreds of galaxies. There are, however, large clusters with thousands of galaxies, and there are some solitary galaxies. Our own Galaxy is a member of a smallish cluster of about 36 galaxies called the Local Group (see Author(s): 5.2 The energy of electromagnetic waves The energy density of an electric field E is Although we will not prove it in this unit, a very similar result applies to magnetic fields. The energy density of a magnetic field B is 5.1.2 Getting agreement with Gauss's law Substituting the assumed form of the electric field (Equation 7.20) into the empty-space version of Gauss's law (Equation 7.16) gives The first two partial derivatives are equal to zero because f does not depend on x or y. So we obtain 4.2 DDT: a classic case in ecotoxicology DDT is very effective in controlling pests, being very toxic to insects, and is cheap to produce. Its effectiveness is enhanced because it is very persistent, remaining active in the environment for a long time. This increases its value as an insecticide to farmers because one application lasts a long time, but is also a major reason why it poses a threat to wildlife and to human health. Although the agricultural use of DDT was banned in most developed countries 30 years ago, it can still be Acknowledgements Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence Grateful acknowledgement is made to the following sources for permission: 3.1 Graphs Information is everywhere these days – in the form of images, written records, tables and graphs. In this part of the unit we want you to realise how useful graphs can be to analyse numerical information, and to show you some techniques that can help you decide how reliable this numerical information is. It's often difficult to spot a trend or a relationship in a long list of numbers. Because the human mind is highly adapted to recognising visual patterns, it is often much easier to u 1.4.1 Study Note 2 An important point to remember when writing down measurements from a scale is never to quote more decimal places than you can reliably read from the measuring device you are using. 6 Unit summary A discrete exotic terrane refers to a large crustal fragment that can be recognised by its distinct sedimentary, igneous, metamorphic and structural history compared with that of its eventual neighbours, and has been juxtaposed into position by major strike–slip faults. Nine discrete exotic terranes make up the Basement in the British Isles. These consist primarily of Precambrian metamorphosed rocks but also contain some unmetamorphosed sedi 5.5 Variscan Orogenic Belt Unlike the Caledonian Orogenic Belt, outcrops of the Variscan Orogenic Belt are limited to the south-west of England, southern Wales and the south of Ireland (see Figure 9 and Author(s): 3.10 Moon42: Apollo 15 station 10 James B. Irwin took this pan moments after he and Dave Scott arrived at Station 10. (QuickTime, 500KB, note: this may take some time to download depending on your connection speed) 3.9 Moon41: Apollo 15 station 2 The panorama was collected by James B. Irwin at Station 2. David Scott is to the left of the rover. He is examining a boulder. The large hill to the left of the rover is the summit of Mt. Hadley Delta. (QuickTime, 400KB, note: this may take some time to download depending on your connection speed) 6.2 Chemical symbols So far, atoms have been represented as labelled spheres or circles and the bonds that link atoms in molecules have been represented as lines. This is a rather cumbersome method of writing down molecules. Chemists have developed their own shorthand language for the names of the elements. It involves giving each element a symbol consisting of one or two letters. You can guess some of them, because they start with the first letter of the element's name. Thus oxygen is designated by 3 What are compounds? Click on the video clip to watch Elements and Compounds, which focuses on water and its constituent elements. Click below to v 2.2 Generativity and duality of patterning Let us now reconsider the sentence you heard in the imaginary scenario at the beginning of this unit. Here it is again. (1)  My dad's tutor's no joker, and he told me the TMA's going to hit home with a bang. 7 Sedimentation and tectonics at a mid-Ordovician to Silurian active margin The document attached below includes the seventh section of Mountain building in Scotland. In this section, you will find the following subsections: 7.1 Introduction 7.2 Mid-Ordovician to Silurian sedimentation in the Midland Valley Terrane 7.2.1 Ordivician sedimentation 7.2.2 Silurian sedimentiation 7.2.3 Summary of Section 7.2 7
Activity 7
Illustrat
Activity 1: Elements and compounds
Activity 2
