2.2 Interstellar space is not empty The difference between the apparent brightness of a star (as measured by its apparent magnitude), and its luminosity (represented by its absolute magnitude) is defined by the distance of the star. We can explicitly state this relationship as in Equations B and C: References 5.2 Sexually dimorphic nucleus of the preoptic area (SDN-POA) As well as affecting behaviour (Section 3.4) neonatal testosterone also affects the physical characteristics of some areas of the brain. One of these is a small area of the hypothalamus, the medial preoptic area, which, although small, is much larger in males than in females. This size difference is mediated by testosterone. 4.4 Summary of Section 4 Two important points emerge from this section. The first is the powerful effect of maternal contact on the development and later behaviour of their charges. In the Feldman study the disadvantages of prematurity were essentially overcome by early maternal contact. The second point is that some behavioural traits really do run in families, without being genetic. The Francis study clearly showed that some aspects of Open Field behaviour were the result of nursing care. 4.1 Introduction to minerals and why we need them Both vitamins and minerals are essential in the diet in small quantities and so they are often grouped together as micronutrients. Which items in the diet are classified as macronutrients? Introduction Genes are units of inheritance that contribute to a person’s behaviour and health. In this unit you will learn what genes, DNA and chromosomes are and how they combine to make the human genome. You will also learn how the principles of inheritance work, the effect that our genetic make-up has on health, and how genetic material is passed on from generation to generation. This unit is an adapted extract from the course Author(s): Learning outcomes After studying this unit you should understand: how the linear sequence of DNA within a gene is related to the linear sequence of amino acids of a protein how the information in DNA is carried via RNA to make a protein how RNA is synthesised from DNA by the process of transcription where the processes of transcription and translation occur within the cell 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: Learning outcomes After studying this unit you should understand: something of the role of a genetic counsellor and its non-directiveness the difference between pre-natal diagnosis, childhood testing and adult testing and give some examples of diseases that may be tested for the ethical and moral difficulties involved in making decisions on whether or not to carry out such tests Introduction This unit looks at three different uses of genetic testing: pre-natal diagnosis, childhood testing and adult testing. Such tests provide genetic information in the form of a predictive diagnosis, and as such are described as predictive tests. Pre-natal diagnosis uses techniques such as amniocentesis to test fetuses in the womb. For example, it is commonly offered to women over 35 to test for Down's syndrome. Childhood testing involves testing children for genetic diseases that may not 1.7.5 Theory Again, research is conducted in a context of existing ideas, evidence, and thinking. One key skill is the demonstration of cognisance of the theoretical context and of how it shapes your own research, including: understanding key theoretical strands and theoretical concepts in your discipline understanding how theory shapes your research question the ability to contribute something useful to the theoretical debate in 1.7.1 Research methods in context Any established discipline has a tradition of practice. Many disciplines have established methodologies which prescribe the selection, combination and sequencing of the methods and techniques to be employed. Others select methods and techniques less prescriptively and borrow more broadly across domain boundaries. All disciplines require an appropriate application of methods, in order to ensure rigour. Hence, one key skill is the demonstration of an appropriate knowledge and competence 1.1 Thoughts on a PhD Entering students often think of a PhD as a ‘magnum opus’, a brilliant research project culminating in a great work. This is rather a demanding model, and few students win Nobel Prizes as a result of their doctoral studies. More realistically, a PhD is research training leading to a research qualification. The PhD is a passport to a research career. There are other views of a PhD, as well. Getting a PhD can be a ‘rite of passage’, prerequisite to admission into the academic ‘t 1.10 Changing sea-level
Sedimentary rocks reveal how environmental conditions in Britain's geological past were extremely different from those of the present day (in fact ‘Britain’, like the rest of the Earth's geography is transitory when viewed in terms of the very long span of geological time). As well as evidence from sedimentary rocks, recent landforms also indicate that in the more recent geological past (within the Quaternary Period), sea-level was not the same as it is at present. 1.6 The formation of metamorphic rocks Any type of rock can become a metamorphic rock if it is heated to temperatures of several hundred degrees Celsius, and/or if subjected to high pressure (because of the weight of overlying rocks). During metamorphism, the minerals making up the rock become chemically unstable, meaning that their constituent ions are redistributed. The result is that either large crystals grow at the expense of existing smaller ones, or a new set of minerals is formed. Generally speaking, the overall chemical c 1.5.2 Sedimentary processes Sedimentary grains are formed when the rocks at the Earth's surface are slowly broken up physically by exposure to wind and frost, and decomposed (chemically) by rainwater or biological action. These processes are collectively termed weathering. Once a rock has been broken up by weathering, the small rock fragments and individual mineral grains can be eroded from their place of origin by water, wind or glaciers and transported to be deposited elsewhere as roughly horizontal layers of sediment 1.4.4 Classifying igneous rocks To classify (i.e. to name) igneous rocks, geologists use three pieces of information in combination – the grain size and the identity and proportions of the minerals present. The identification of minerals in a rock relies on recognising their particular distinguishing features. Such features include colour, lustre (the way in which light is reflected from the mineral's surface) and shape. The way in which certain minerals break apart along preferred planes, a property known as cleavage, ca 1.4.3 Chemical and mineral composition of igneous rocks As well as varying in grain size (owing to different cooling rates), igneous rocks also vary in chemical composition and hence in the identity and proportions of minerals present. For instance, the common igneous rock granite contains (as part of the strict geological definition of the term ‘granite’) between 10% and 35% by volume of the mineral quartz (chemical composition silicon dioxide – SiO2). On the other hand, the igneous rock gabbro (Author(s): 1.4.1 Igneous rocks in the landscape The rocks that erupt from volcanoes are called extrusive igneous rocks, simply because they are formed by the extrusion of magma on to the Earth's surface. Igneous rocks can also form deep underground, and these are called intrusive igneous rocks, because the magmas were intruded into pre-existing rocks and then slowly cooled. The reason that intrusive igneous rocks are now visible at the surface is that over many millions of years erosion has stripped away the overlying rocks. 4.2 Definitions of ageing The term ‘ageing’ carries a number of different meanings. It encompasses changes that occur at many levels, from the population down to the molecular. Even at a single level, ageing does not represent a single process, but many processes, which may operate independently. Therefore, the challenge of defining ageing is more complex than it might first
Activity 24
Unit Image