In thinking about the sizes of things, it is sometimes useful to do so in quite rough terms, just to the nearest power of ten. For example, 200 is nearer to 100 than it is to 1000, but 850 is nearer to 1000 than it is to 100. So if we were approximating to the nearest power of ten we could say 200 was roughly 102, but 850 was roughly 103. This process is called reducing the numbers to the nearest order of magnitude.

Author(s): The Open University

This extract is taken from S809 Â© 2005 The Open University.

Course image: Liz West in Flickr made available under Creative Commons Attribution 2.0 Licence.

All written material contained within this course originated at the Open University.

Don't miss out:
Author(s): The Open University

## Activity 17

Perhaps you are asking yourself why there are so many different imaging modalities. Is there not one that will do everything that is required? The answer, at the moment, is â€˜Noâ€™. With most of the imaging te
Author(s): The Open University

The visible photons are collected by an array of photomultiplier tubes behind the crystal. These convert each visible photon to an electron and then multiply the number of electrons sufficiently to give a voltage pulse. Because the number of visible photons is proportional to the energy of the incoming gamma ray, the height of the pulse depends on this energy. This gives a method of counting the numbers of gamma photons at different energies that reach the crystal.

A resistive network c
Author(s): The Open University

X-rays are produced when energetic electrons strike a metal target. The X-ray source consists of an evacuated tube containing a cathode, from which the electrons are emitted, and an anode, which supports the target material where the X-rays are produced. Only about 1 per cent of the energy used is emitted as X-rays â€“ the remainder is dissipated as heat in the anode. In most systems the anode is rotated so that the electrons strike only a small portion at any one time and the rest of the ano
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There are currently no scheduled missions to Jupiter's moons, since NASA's Jupiter Icy Moons Orbiter (JIMO) was cancelled in 2005, but Europa remains a high priority target for both NASA and ESA, so a mission with simlar objectives to JIMO seems likely by about 2020. On arrival at Jupiter, JIMO would have gone into orbit first round Callisto, then Ganymede and finally Europa.

The main objectives of JIMO at Europa would have been to:

1. Determine the
Author(s): The Open University

It was a long time before the Voyager missions were followed up by more detailed surveys of the outer planet satellites. No Uranus or Neptune missions are planned, but a mission to Saturn called Cassini-Huygens was launched in 1997 for arrival at Saturn in 2004. However, the Jupiter system received a similar visitor first. This was Galileo, launched in 1989, which became the first spacecraft to orbit Jupiter in December 1995. It continued to function through 2002, and was destroyed by plungin
Author(s): The Open University

In order to be able to state that animals are communicating vocally with one another, scientists need to demonstrate that particular sounds made by one individual can be understood and acted upon by others.

## Activity 5

Author(s): The Open University

There is a distinction between somatic cells, those making up almost all of the body, and germline cells, which are the eggs and sperm and the cells that produce them. Somatic gene therapy is the transfer of genes into the somatic cells of the patient, such as cells of the bone marrow, and hence the new DNA does not enter the eggs or sperm. The genes transferred are usually normal alleles that could â€˜correctâ€™ the mutant or disease alleles of the recipient (see Study Note 2: The
Author(s): The Open University

7 Conclusions

Throughout this course, numerous examples of science promotion have been given, from the individual level of Pro-Ams to the supranational level of the EU Action Plan. Is there an appropriate political level for initiating science promotion or might a multi-level approach be more fruitful?

Certainly there is evidence that local or sub-national initiatives can engage people â€“ from Science CafÃ©s and Cities of Science, to the Pub Understanding of Science beer mats with scientific questio
Author(s): The Open University

Learning outcomes

After studying this course, you should be able to:

• demonstrate an awareness of the issues surrounding public understanding of science

• engage with some of the debates surrounding this topic.

Author(s): The Open University

1.2 Artificial selection

Selection acts on phenotypic characters whatever their origin, and can retain or eliminate the characters' genetic basis. Artificial selection is any selective breeding intentionally practiced by humans leading to the evolution of domesticated organisms. Artificial selection may oppose or amplify or be neutral in relation to natural selection. Most livestock, including dogs, cats, goats, pigs, cattle, sheep, guinea pigs, horses, geese and poultry and scores of crop plants were d
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2.6 End-of-course questions

## Question 1

What is the approximate wavelength range (in metres) of microwaves?

The range is from about 1 m down to a little less than
Author(s): The Open University

During the twentieth century, astronomers extended their capabilities by developing telescopes and detectors that were sensitive to radio waves, microwaves, infrared and ultraviolet radiation, X-rays and gamma rays. All these forms of electromagnetic radiation, along with visible light, are emitted by the Sun.

Author(s): The Open University

Most of the activities that you have done so far are based on your understanding of single sections that you have just read. Activity 8 which follows, is different. It requires you to assemble and integrate information over the whole 'Life in the trees' topic and is likely to require some extra effort and thought. Integrating information from different sections of the course; is an important element in building your study skills. You're asked here to assemble evidence in support of a particul
Author(s): The Open University

## Activity 7

Watch the video sequence below, which focuses on just three lemur species - the ring-tailed (in a very brief sequence, leaping from one tree to another), the golden bamboo lemur, already mentioned, and the s
Author(s): The Open University

Wildebeest are only one of the species of plant predator that live in herds. Many others do too.

## Activity 7

Watch the the TV programme from 30.48-47.32 and read LoM p. 109. Identify and write down (a) a couple of
Author(s): The Open University

The odd-toed ungulates (comprising the order Perissodactyla), the horses, tapirs and rhinoceroses, are hindgut fermenters, as are elephants. Update Table 2 with this information. These animals have a relatively simple, small undivided stomach, but this time an even larger caecum and colon where the microbes are housed and whe
Author(s): The Open University

Darwin summarised his theory of natural selection in the introduction to The Origin of Species as follows:

As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life
Author(s): The Open University