By knowing the pattern of inheritance of genes as described above, it is possible to make some predictions about the phenotypes and genotypes of each generation in breeding experiments. This section considers some examples of such predictions.

First consider whether it is possible to determine the genotype for certain characters, such as grain colour, from observing an organism's phenotype.

Author(s): The Open University

You have probably met the law of radioactive decay, which says that, given a sample of N0 similar nuclei at time tÂ =Â 0, the number remaining at time t is N(t)Â =Â N0eâˆ’Î»t, where Î», the decay constant for a particular kind of nucleus, determines the rate at which the nuclei decay. The half-life is the time needed for half of any sufficiently large sample to decay. It is related to the de
Author(s): The Open University

The procedure used to analyse scattering from a finite square step can also be applied to scattering from finite square wells or barriers, or indeed to any combination of finite square steps, wells and barriers. The general procedure is as follows:

• Divide the x-axis into the minimum possible number of regions of constant potential energy.

• Write down the general solution of the relevant time-independent SchrÃ¶dinger equation in
Author(s): The Open University

The organisers of this course are grateful for the financial support provided by the Royal Society, whose generous backing covered all aspects of the course's production and presentation.

The material acknowledged below is Proprietary and used under licence (not subject to Creative Commons licence). See terms and conditions. This content is made available under a
Author(s): The Open University

Given the function x(t) that describes some particular motion, you could plot the corresponding position-time graph, measure its gradient at a variety of times to find the instantaneous velocity at those times and then plot the velocity-time graph. If you had some time left, you might go on to measure the gradient of the velocity-time graph at various times, and then plot the acceleration-time graph for the motion. This would effectively complete the description of the motion, b
Author(s): The Open University

We end this section by reviewing some of the important features of straight-line graphs, though we do so in terms of two general variables z and y, rather than x and t, in order to emphasise their generality. If the graph of z against y is a straight line of the kind shown in Figure 22, then z and y are related by an equation of the form

<
Author(s): The Open University

Just as we may plot the position-time graph or the displacement-time graph of a particular motion, so we may plot a velocity-time graph for that motion. By convention, velocity is plotted on the vertical axis (since velocity is the dependent variable) and time (the independent variable) is plotted on the horizontal axis. In the special case of uniform motion, the velocity-time graph takes a particularly simple form - it is just a horizontal line, i.e. the gradient is zero. Examples are
Author(s): The Open University

## Activity 14

Now watch this video clip of a patients lungs being imaged, called a VQ (ventilation quotient) scan. What are the two different types of acquisitions used called? What radioactive substance is used for each acq
Author(s): The Open University

Radionuclide imaging is a very valuable way of examining the function of an organ, as opposed to the more structural images obtained by other methods such as X-ray and CT.

The basic principles of radionuclide imaging are as follows:

• a radioactive substance, usually combined with a biologically active compound, is injected into the patient;

• this targets a particular organ or tissue type;

Author(s): The Open University

You learned in Section 1.4 that geophysical data show the 'icy' outer part of Europa to be about 100 km thick, but that the information is inadequate to distinguish between the extreme possibilities of solid ice all the way down to the bedrock and a floating sheet of ice supported above a liquid ocean (Author(s): The Open University

Before the dawn of the space age, relatively little could be discovered about even the large satellites. Their orbits were well known, and from the subtle orbital perturbations caused by neighbouring satellites it was possible to deduce their masses. Measurements of their sizes enabled densities to be calculated to within about 20 per cent of the currently accepted values for the Galilean satellites, and with rather less certainty for the large satellites of the other giant planets. However,
Author(s): The Open University

Now that in vitro fertilization â€“ bringing eggs and sperm together outside the prospective mother's body â€“ is an established technology, the possibility exists that genes could be altered in eggs or sperm, or in a very early embryo. The obvious advantages of germline gene therapy are that the cells are accessible (because they are outside the body), so gene delivery is less of a problem than it tends to be with somatic cells; and the inserted gene (or genes) would be present
Author(s): The Open University

Following on from the advances made in diagnosing disorders using genetic testing, this course looks at the possibilities for genetic therapies. Two approaches to gene therapy are discussed: correcting genes involved in causing illness; and using genes to treat disorders. Before closing on a discussion of the issues around 'designer babies' somatic gene therapy and germline gene therapy are discussed.

This OpenLearn course provides a sample of Level 1 study in 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

The Sun is seen as a blindingly bright, yellow object in the sky. The part of the Sun that you normally see is called the photosphere (meaning 'sphere of light'); this is best thought of as the 'surface' of the Sun, although it is very different from the surface of a planet such as Earth. Its diameter is about 1.4 million kilometres, making the Sun's volume roughly one million times that of the Earth. The photosphere is not solid. Rather, it is a thin layer of hot gaseous material, abo
Author(s): The Open University

General relativity has a very different conceptual basis from that of Newtonian mechanics. Its success in accounting for the precession of Mercury's orbit, and the bending of light by massive objects like the Sun, gives us confidence that our picture of space and time should be Einstein's rather than Newton's. In this and the following courses, we turn our attention to the study of the large-scale structure of spacetime. We see how spacetime as a whole is curved by the gross distribution of m
Author(s): The Open University

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Author(s): The Open University

Once evidence has been found to prove the existence of an ancient ocean, is it possible to calculate its maximum width? Palaeomagnetic studies can give geologists an idea of the palaeolatitude (Nâ€“S) of the ocean but not its palaeolongitude (Eâ€“W), so depending on its orientation, an indication of how wide it was may not be possible. However, an approximate indication of how wide the former oceans were can be obtained by examining the fossil faunal assemblages that are present (e.g.
Author(s): The Open University

In the theory of plate tectonics there are three main types of plate boundary, namely: constructive, destructive and conservative plate boundaries.

Author(s): The Open University

Brain imaging and aphasic studies helped us localise the subparts of language processing within the brain. However, they have shed little light on how processing unfolds in real time. This is because contemporary brain imaging is quite poor at showing changes in activity through time in fine detail, so it is hard to pick up something that may be happening slightly before something else.