4.1 Introduction Pusztai and his team were attempting to develop suitable tests to assess the safety of GM potatoes. Typically, testing the safety of GM food involves comparing its composition and/or its effects with that of the conventionally produced food it most closely resembles. We have seen that such comparisons were at the heart of Pusztai's work. The comparison of GM and conventional crops and food has led to the so-called principle of substantial equivalence, which has been used extensiv
3.2 Communicating Pusztai's findings In mid-1998, the Rowett Institute released a succession of press releases describing Pusztai's findings. The safety, or otherwise, of GM foods was a hot issue at the time and his preliminary findings gained widespread publicity. Pusztai gave an extended interview to the World in Action TV programme ‘Eat up your genes’, broadcast in August 1998. He described some of his experiments and outlined his interpretations in ways that helped shape the general tone of the programme, which was highl
2.4.1 The second generation of GM crops Much of the present-day debate about GM plants centres around the existing range of GM crops, most of which have been engineered for herbicide tolerance or insect resistance (covered in unit S250_1 Gene manipulation in plants). One of the implications of this narrow commercial focus is that the benefit that such crops would bring, other than to those multinational companies that produce them, is by no means clear. Weighing up their value on some form of ethical scales might be unlikely
2.4 Can GM crops feed the world? The issue of global food security is at the heart of many of the ethical issues related to GM technology. United Nations population scientists estimate that the world's population will increase by 2 billion over the next 30 years, posing huge challenges for global food production. More than 842 million people are currently chronically hungry. Proponents of GM crops argue that further development of this technology is vital to meet this challenge. However, a more equal distribution of ex
4 Questions In what ways, if any, does the distance to a star influence its position on an H–R diagram? The distance to a star does not influence it 1.5 Star clusters and stellar evolution Detailed observations of star clusters suggest that they occur because the stars in them form at about the same time. Moreover, the compositions of the stars are similar. Isolated stars (including isolated binary stars) result from the later partial or complete dispersal of a cluster. The crucial points for us here are that all the stars in a cluster formed at about the same time, and all have similar compositions. 1.3 How can we explain the distribution of stars on the H–R diagram? Here is a possible explanation for the concentration of stars into certain regions on the H–R diagram. It is based on the reasonable assumptions that: Any particular star is luminous for only a finite time; There are distinct stages between the star's cradle and grave, each stage being characterized by some range of temperature and luminosity; the star thus moves around the H–R diagram as it evolves; The stars we 1.1 Constructing the H–R diagram Three properties which are suitable for comparing stars are temperature, luminosity and radius. However, we don't need all three. Why not? 3.4 Integration of anatomical features and biochemical and physiological strategies in endurers The endurers, large animals with a relatively low surface area: volume ratio, have problems in losing heat from the body when exposed to high T
a. Certain large lizard species behave like endurers, but they are evaders and evaporators too, a salutary reminder that we should not apply classification criteria too rigidly.
Dipsosaurus dorsalis, the desert iguana, lives in the Sonoran desert and is found most commonly in dry sandy areas where creosote bushes grow ( 2.2 How animals interact with the environment is affected by their body size Willmer et al. (2000) classify desert animals in terms of the range of body sizes and the rate of evaporation (Figure 8). Acknowledgements The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: Figure 2 Michael and Diane Porter, American Goldfinch, Ideaform Inc.; Figure 3 Tom and Cathy Saxton, Hummingbird, Saxton.org.; Fig References 3.5 Arousal (continued)
What alternatives to shivering might act as a source of heat? BMR is maintained mainly by a number of tissues with high metabolic activity. One of Learning outcomes By the end of this unit you should be able to: define and use, or recognize definitions and applications of, each of the bold terms; give definitions of the terms ‘hibernation’, ‘torpor’ and ‘adaptive hypothermia’, and the three physiological processes that underlie them; give examples of the diversity of the major groups of mammals and birds that contain hibernating species; describe the physiological changes occur 4.1 Insulation in terrestrial endotherms For organisms of similar size and shape in a similar thermal gradient, the rate of heat loss from convection is up to 90 times as fast in water as in air, so in temperate climates, aquatic endotherms need much more efficient insulation than terrestrial species. Since seawater freezes at −1.9° C, but the temperature of the air around the Poles can fall below −50° C, the insulation requirements of aquatic and terrestrial polar animals are not very different. Nonetheless, there are impor 4.5.4 Phosphorus Phosphorus is recognised as a potential poison for automotive catalysts. The phosphorus level in fuel is generally very low (2×10−5 g l−1), but it is present in higher concentrations in engine oils (1.2 g l−1). Phosphorus derived from the engine oil is believed to react with the alumina support, and also to reduce the activity of the noble metal component. This deactivation is particularly important for Pd, with which phosphorus may form an all 4.5.3 The effect of poisons The use of catalytic converters was one of the major contributors to the phasing-in of unleaded petrol. Lead in petrol is a severe poison for the catalyst, and there have been many stories, particularly in the early days of the converter, of people disabling the catalyst by misfuelling. Figure 25 shows how the activity 4.4.1 Introduction Since its development, the three-way catalyst has been exposed to the full spectrum of techniques available for the characterisation of catalytic materials. The data provided can be correlated with the results of activity tests and kinetic measurements, which provide information on the performance of the catalyst. This reveals that although the catalyst functions as a composite material, it can be divided into distinct groups of catalytic centres that provide several different types of site, Introduction Ensuring good quality air is essential for the protection of public health. Governments worldwide have adopted a range of increasingly demanding measures to curb air pollution with a particular focus on the emissions from motor vehicles. An important part of this strategy has been the development of the three-way catalytic converter to remove exhaust pollutants such as carbon monoxide, unburnt hydrocarbons and nitrogen oxides. This unit takes an in-depth look at the construction of this conve 9.1 The psychological arena The examples in the previous section followed the traditional medical approach, namely that there is a disease, it can be diagnosed (identified), and the cause of the disease, be it viruses, bacteria, pathogens, genes or poisons, can be sought. This section moves away from the medical arena and into the psychological arena, where the symptoms are behavioural. In this case, the symptoms are socially unacceptable behaviour and to the list of causes just mentioned is added family circumstances a
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