3.2 QSO spectra It only became apparent that these quasi-stellar objects were not stars when their spectra were examined. At first astronomers could not interpret their spectra because the spectral lines did not appear at appropriate wavelengths for atoms of any known chemical element. The spectrum shown in Figure 4 provided the
Introduction 3.7 Insulin Insulin is a hormone produced by the pancreas. It has many actions, but is particularly important in keeping the blood glucose level normal. Question: How does 1.3.3 Position–time graphs Tables do not give a very striking impression of how one thing varies with respect to another. A visual form of presentation, such as a graph, is usually much more effective. This is evident from Figure 7, which shows the graph obtained by plotting the data in Table 2 and then drawing a smooth curve through the resulting points. 3 Computed tomography The aim of computed tomography (CT) is to produce an image of a slice of the body. (The Greek word ‘tomos’ means slice.) This is achieved by rotating a thin, fan-shaped beam of X-rays around the patient and measuring the intensity on the opposite side of the patient with a very large number of detectors. 2.3.2 The crater Pwyll You might also have noted that there are no obvious impact craters visible in Figure 16 (see Section 2.3.1). In fact there are a few. One is a bright spot, 15 km in diameter, surrounded by a dark halo of ejecta that occurs 10 mm from the top edge and 65 mm from the left-hand edge of the figure. Another is a s Learning outcomes By the end of this unit you should be able to: discuss processes upon and within, and internal structure of, differentiated icy bodies (primarily large satellites) in comparison with the terrestrial planets; describe the conditions that may be required to originate and foster life in an icy body and discuss the likelihood of their having occurred; recognise the moral and ethical issues of landing spacecraft on potential life-bearing worlds and appre 3.5 Communication Compared with many other mammals, primates have a rich repertoire of communication skills, which I'll be looking at in more detail in this section. Identify the instances of communication that you have observed in the T 3.2 Colour vision DA stresses that colour vision is very important in primates, not only because colour is used ‘in sexual displays’ such as advertising a female's receptiveness to mating [p. 275], but also to identify ripe fruit [p.247] and to select nutritious leaves [p. 255]. This section discusses these points in more detail and explains how the visual system in primates is able to detect colour. White light is composed of light of different wavelengths, from 300–800 nanometres (nm); 1 nm is on References 4.3 Phenotypic changes that appeared without being selected As well as these behavioural changes, many of the selected foxes had unusual white markings (Figures 13c and d). The first colour change that the Russian investigators noted in their foxes was a white ‘star’ on the forehead similar to that of other domesticated mammals (Author(s): Introduction Most contemporary evolutionary biologists study evolution experimentally using laboratory organisms such as Drosophila or natural systems in the wild. However, 18th and 19th century evolutionary biologists, including Darwin, emphasised the similarities between natural evolution and artificial ‘ improvement’ of livestock under domestication. They believed that studying domesticated animals and plants could illuminate the mechanisms of natural evolution. Indeed, Chapter 1 of On th 3.1 Angular size 2 Inside the Sun To account for its brightness and activity, the Sun must contain a power source. However, the nature of that power source was a great puzzle in the nineteenth and early twentieth centuries. Fossil records and ideas about evolution were beginning to provide firm evidence that the Earth must be at least hundreds of millions of years old, rather than thousands of years as was previously thought, and the Sun must be at least as old as the Earth. The only fuels known at the time were coal, wood, o 3 Introducing the primates One group of accomplished tree dwellers are the primates – a term you perhaps think of as synonymous with monkeys and apes. Monkeys and some apes display some of the most striking adaptations to tree-living. 250 or so species of primate exist today; most taxonomists group them into 13 families. All share a lengthy list of defining features, mostly related to the following broad categories: Limbs and locomotion. The hands (and often the 2.5 Tree squirrels Coevolution also underpins the relationship between many tree squirrels and the trees that house them. The creation of food caches as a ‘winter-larder’ is mutually beneficial, partly because squirrels are sufficiently profligate in their habits to ensure that many stores are overlooked. Stealing by neighbours is so common that such over-provision may be essential – it's not through forgetfulness or lack of skill; grey squirrels appear able to detect nuts buried as deep as 30 cm below th 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 to reproduce material in this unit: The content acknowl Senses Being an effective predator requires efficient sense organs. Prey often has to be located from a considerable distance and good spatial awareness comes into play during the moments of capture. The precise mix of sensory inputs used varies a good deal, just as it does in other animal groups; many rely on good eyesight for hunting; for others, smell and/or hearing are especially important. And you'll know from the TV programme (for example, in what was said about the importance of smell in brow 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 2.1 Overview In this section, you will meet some new units, the units in which energy is measured. Nowadays, there are internationally agreed units (called SI units) that are often used in combination with a prefix to show the scale of the measurement. The SI unit for energy is the joule (pronounced ‘jool’, and with the
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Activity 4
Activity 7
