Acknowledgements Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: The material acknowledged below is Proprietary and used under licence (not subject to Creative Commons Licence). See Terms and Conditions.
Acknowledgements
4.4 The marine carbon cycle The ocean stores much more carbon than the terrestrial system (Figure 1.9). How is this marine carbon fixed into organic carbon within the sediments, and what are the main reasons for marine carbon fluxes? Author(s):
2 How should we think of monotremes? This section contains the first of the activities, Activity 1. If possible, you should do each activity as you come to it; the text that follows Introduction Mammals come in a bewildering variety of shapes and sizes and yet all of the 4700 or so species have some characteristics in common. Indeed, it's the existence of these common features that justifies the inclusion of all such diverse types within the single taxonomic group (or class) called the Mammalia. This is the first in a series of units about studying mammals. To get the most from these units, you will need access to a copy of The Life of Mammals (2002) by David Attenboroug 1.5.7 The signed area under a general velocity–time graph We have already seen (in Section 3.6) that in the context of uniform motion, the signed area under a particle's velocity–time graph, between two given times, represents the change in the particle's position during that time interval, with a positive area corresponding to displacement in the positive direction. In the 8 Multiple plate collisions and the end of the Iapetus Ocean The document attached below includes the eighth section of Mountain building in Scotland. In this section, you will find the following subsections: 8.1 Introduction 8.2 Palaeocontinental reconstructions 8.2.1 The global view 8.2.2 A model for the closure of the Iapetus Ocean 8.2.3 Summary of Section 8.2 8.3 Tectonics of the Northe 6.6.2 Hibernation-induction trigger Researchers have devoted much effort to the search for a possible blood-borne chemical messenger that might communicate a signal within the brain and to other body tissues, causing entry to hibernation. Serum from hibernating animals such as the woodchuck (Marmota monax;
Figure 8), when injected into active animals, can induce torpor. Partly purified serum extracts are also able to induce hibernation-like behavioural changes in a variety of mammalian species. Chemical analysis of the s 6.6.1 Melatonin Syrian hamsters, which display pronounced circadian temperature fluctuations before hibernation, lose these circadian cycles on entry to hibernation, and start to regain them shortly before arousal. Cycles are distorted during the early recovery period, suggesting that the SON oscillator has either been switched off or de-synchronized in hibernation. Another monoamine, melatonin, is involved in making these adjustments. A hormone rather than a neurotransmitter, melatonin is secreted by the pi 6.5 The neurotransmitters histamine and serotonin: a role for chemical signalling between neurons of As in all other regions of the brain, the integration of physiological change in the hypothalamus, conducted by the dialogue between many thousands of nerve cells, is the result of transmissions across chemical synapses. The functions of the hypothalamus are therefore dependent upon neurotransmission by a number of different chemical mediators and are critically dependent on the balance between their respective activities. Monoamine neurotransmitters (histamine and serotonin) operate in subgr 6 Conclusion There is much more to living in polar regions than insulation against the cold. Food may be very scattered both in space and in time and breeding must be tightly synchronized to seasons and food availability. Some of the most spectacular examples of natural obesity and efficient regulation of appetite are found among polar animals. The study of such species not only demonstrates that it is possible to remain healthy and active when very obese and during prolonged fasting, it also helps us to 3.2 Small babies Development continues in the womb until birth, which, in humans, is about 38 weeks after conception. (The often quoted duration of pregnancy of 40 weeks is based on pregnancy beginning on the first day of the last menstrual period.) The duration of the period of development before birth, called gestation, is highly variable. It is not possible to determine its full range in the UK, because medical intervention usually prevents pregnancies going beyond about two weeks after the due date, or te 2.2 Vitamin A Look back at Table 1 and identify the foods that contain vitamin A. On the basis of this information, try to predict where vitamin A is stored in the human body. 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 All other materials included in this unit are derived from content originated at the Open University. 1. Join the 200,000 studen 1.4.2 The functional group approach It is the classification of functional groups that simplifies the study of organic chemistry (the chemistry of compounds that contain carbon). With many millions of known organic compounds, and more being added by the day, it would be hopeless if their properties could not be systematised in some way. It turns out that a given functional group usually has the same chemical properties whatever carbon chain it is bonded to, so once the general properties of each functional group are known, all 1.4.1 Salicylic acid The structural formula of salicylic acid, 2.1, looks quite complicated. However, it becomes less daunting if you unpack it a bit. One of the first things to do when confronted with an unfamiliar structure is to check that all the valencies are correct (four for carbon, two for oxygen and one for hydrogen). If any atoms have the wrong valency, it follows that there is a mistake somewhere and the molecule does not exist as drawn. It looks OK for the structure of salicylic acid. You proba 1.2.4 Fertilization Now that we have considered the production of gamete cells, including the process of meiosis, we can examine the next stage of reproduction, the process of fertilization, which occurs inside the female's reproductive tract. As fertilization occurs, the successful sperm stops swimming and a change takes place in the egg cell membrane, which prevents any other sperm from fusing with it. The nucleus of the sperm cell is injected into the cytoplasm of the egg cell. The chromosomes of the fertiliz 2.2 Persistent currents lead to constant magnetic flux An important consequence of the persistent currents that flow in materials with zero resistance is that the magnetic flux that passes through a continuous loop of such a material remains constant. To see how this comes about, consider a ring of metal, enclosing a fixed area A, as shown in Figure 6a. An initial magnetic field B0 is applied perpendicular to the plane of the ring when the temperature is above the critical temperature of the material from which the rin 2.1 Zero electrical resistance In this section we shall discuss some of the most important electrical properties of superconductors, with discussion of magnetic properties to follow in the next section. The most obvious characteristic of a superconductor is the complete disappearance of its electrical resistance below a temperature that is known as its critical temperature. Experiments have been carried out to attempt to detect whether there is any small residual resistance in the superconducting state. A sensitive t Optional reading Debates about the relationship between science, citizenship and democracy continue to influence public policies related to science communication and public engagement in science. In part, these debates involve discussions about scientific and other ways of knowing. For an introduction to these issues, see Irwin (1999). This premise, of exchanging information and learning from others, is also relevant to your communication with other expert scientists. As a research student you will lear 5: Other forms of potential energy It is worth emphasising that the gravitational energy (or gravitational potential energy, to give it the full name) of an object increases when it moves in the opposite direction to the gravitational force (i.e. when it moves upwards). This relationship between energy and force does not apply only to gravity. For many forces, motion against the force (that is, in the opposite direction to the force) allows energy to be stored, and this energy can be reclaimed when the obj
Activity 4
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