We now turn our attention to vCJD.

## Question

If vCJD really is ‘the human form of BSE’ (as it is often described), how is it likely to have crossed the species barrier from cattle to humans?

Author(s): The Open University

A coat of profuse mammalian body hair is commonly called fur. Fur provides insulation, which is a property that one first thinks of as useful for mammals to help retain body heat. Fur is a unique and fundamental feature of mammals, though not all living species possess it.

## Question 12

Author(s): The Open University

This subsection introduces two crucially important mathematical ideas, functions and derivatives, both of which are used throughout physics.

Author(s): The Open University

Everyday experience teaches us that unconfined objects are free to move in three independent directions. I can move my hand up or down, left or right, backwards or forwards. By combining movements in these three directions I can, at least in principle, move my hand to any point in space. The fact that there are just three independent directions, and that these suffice to reach any point, shows that the space in which my hand moves is three-dimensional.

The motion of a large objec
Author(s): The Open University

The dimensions of the emerging X-ray beam can be altered by the collimator. This helps to ensure that only the region of interest is exposed to the X-rays.

Author(s): The Open University

A grainy Polaroid of the child in a mother's womb – an X-ray of a tibia fractured in a traffic accident – a report on a brain scan anxiously awaited. Very few of us have not had some connection with the techniques and practices of medical imaging. Often, these contacts are in periods of personal drama in which the medical images chart our physical status, the management of a condition and, in some cases, our future.

Imaging is a central feature of contemporary medicine. Along with c
Author(s): The Open University

• Many of the large icy bodies in the outer Solar System are internally differentiated. Thanks largely to tidal heating, some, especially Europa, are likely to have an ocean sandwiched between the icy exterior and the rocky core. Others may have had such an ocean in the past.

• Wherever water rests on warm rock, water must percolate into it and become heated. This will cause hydrothermal convection to begin. Hot, chemical-rich water will emerge
Author(s): The Open University

Now let's examine some detailed images of the region of Europa's northern hemisphere that was indicated on Figure 17 (see Section 2.3.2). A medium resolution image is shown in Figure 21, and higher resolution images from within this area are shown in Author(s): The Open University

By the end of this unit you should be able to:

• identify the charactistics of primates and explain the main differences between the two suborders, prosimians and anthropoids;

• describe the detection of colour and estimation of distance in primates and explain the advantages of stereoscopic trichromatic vision;

• discuss the various types of communication seen in anthropoids and explain how playback experiments contribute to understanding vocal communica
Author(s): The Open University

In this unit we will focus on the Anthropoidea, a suborder of primates that includes monkeys, apes and humans. We will concentrate our attention here primarily on monkeys. Colour vision, a large brain and intelligence are of great importance in the lives of anthropoids, enabling them to eat foods inaccessible to many other animals and to exploit social situations. In this unit, we will be looking at characteristics of primates that differ, or are enhanced, in anthropoids and discussing these
Author(s): The Open University

After studying this unit you should understand:

• some of the types of disease that might be treatable by gene therapy

• the basic principals of genetic manipulation

• the differences between somatic and germline gene therapy and some of the problems involved in these potential treatments

• how genetics may be used in the design of drugs.

Author(s): The Open University

Lindberg, J., Bjornerfeldt, S., Saetre, P. et al. (2005) Selection for tameness has changed brain gene expression in silver foxes, Current Biology, 15, R915–R916.
Lindblad-Toh, K., Wade, C. M., Mikkelsen, T. S. et al. (2005) Genome sequence, comparative analysis and haplotype structure of the domestic dog, Nature, 438, 803–819.

Author(s): The Open University

Since the invention of DNA sequencers in the late 20th century, measuring very small differences between the genes of different organisms has become much easier and more precise than quantifying phenotypic variation. Synonymous mutations and changes to introns are examples of genetic changes that have no consequences for the phenotype. Natural selection acts only on phenotypes, so the relationship between genotypic changes and phenotype is clearly very important to understanding evolution. Di
Author(s): The Open University

At the end of this unit you should:

• know about the electromagnetic spectrum and how it is used to infer properties of sources of radiation;

• know about the range of sizes, distances and motions of objects in the Universe and how they can be measured;

• know about the structure of, and the main processes operating in, the Sun;

• comprehend concepts lying well outside everyday experience, including those that involve very large and very smal
Author(s): The Open University

As you work through this unit you will come across boxes, like this one, which give you advice about the study skills that you will be developing as you progress through the unit. To avoid breaking up the flow of the text, they will usually appear at the start or end of the sections.

As well as the un
Author(s): The Open University

By the end of this unit you should be able to:

• explain the concept of energy transfer between trophic levels;

• outline the usefulness and limitations of food chains and food webs;

• using examples, weigh up the value of dietary specialisation and of omnivory;

• summarise the physiological changes linked with ‘hibernation’ in grizzly bears;

• give examples of variations in diet and lifestyle amongst the bear family;

Author(s): The Open University

## Activity 2

Establishing a link between endocrine disruptors and human health is complicated by the fact that experiments of the kind conducted on animals are out of the question. It would be wholly unethical to administer DDT to people, for example, to see what effects it had on them. Studies on humans are thus limited to establishing a correlation between the presence of a xenobiotic chemical in the environment and some kind of health problem.

For example, the Aamjiwnaang are a community of Nativ
Author(s): The Open University

Then he was a she…

(Lou Reed, American rock singer)

In 1996, a book called Our Stolen Future was published, bringing to public attention a debate that had been simmering among biologists for some time. Written by Theo Colborn and two colleagues at the World Wildlife Fund (WWF), this book presented the hypothesis that certain industrial chemicals, commonly found as environmental pol
Author(s): The Open University

We shall not finally defeat AIDS, tuberculosis, malaria or any of the other infectious diseases that plague the developing world until we have also won the battle for safe drinking-water, sanitation and basic health care.

(Kofi Annan, United Nations Secretary-General (2005) The International Decade for Action 2003–2015)

Freshwater is a natural resource that is vital for human survival and
Author(s): The Open University