In Figure 25, the position x of the car depends on the time t. The graph associates a particular value of x with each value of t over the plotted range. In other circumstances we might know an equation that associates a value of x with each value of t, as in the case of the equation x = At + B that we discussed in Section 3. You can invent countless other ways in which x depends on t: for instance x =
Author(s): The Open University

Animals in the third suborder of the Artiodactlya, the pigs, peccaries and (according to most authorities) the hippopotamuses (suborder Suina), use a slight variant on the ruminant method, and are often referred to as pseudo-ruminants. You might like to add this information to your version of Table 2. These animals do have st
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 unit t
Author(s): The Open University

The panorama was collected by James B. Irwin at Station 2. David Scott is to the left of the rover. He is examining a boulder. The large hill to the left of the rover is the summit of Mt. Hadley Delta. (QuickTime, 400KB, note: this may take some time to download depending on your connection speed)

This panorama was collected by Neil Armstrong from a spot east of the landing module while Buzz Aldrin was unloading the science packages. (QuickTime, 500KB, note: this may take some time to download depending on your connection speed)

This panorama was collected by Neil Armstrong from a spot north east of the landing module at the Sea of Tranquility. (QuickTime, 500KB, note: this may take some time to download depending on your connection speed)

David A. Rothery Teach Yourself Planets, Chapter 6, pp. 66–75, Hodder Education, 2000, 2003.

The Moon's atmosphere is almost as insubstantial as Mercury's, and probably has much the same origin. The Clementine mission returned our first clear views of the lunar poles, showing sites in particular near the south pole that are permanently in shadow, and which could therefore be places where ice might accumulate (Figure 1). Clementine'
Author(s): The Open University

This section returns to bonding – the way in which atoms are joined to each other. You have already met one type of bonding involving covalent bonds, which is found in molecules. However, this is not the only bonding found in compounds. In this section you will look at ionic bonding and the ionic compounds that contain such bonding. What is the main difference between the covalent compounds you met in Author(s): The Open University

## Activity 1: Elements and compounds

0 hours 10 minutes

Click on the video clip to watch Elements and Compounds, which focuses on water and its constituent elements.

Click below to v
Author(s): The Open University

The document attached below includes the second section of Mountain building in Scotland. In this section, you will find the following subsections:

• 2.1 Introduction

• 2.2 The Lewisian Complex

• 2.2.1 The nature, age and origin of the gneiss protoliths

• 2.2.2 Deformation and high-grade metamorphism

• 2.3 Basement inliers in the Moine Supergroup

• Author(s): The Open University

Barrow, J (1988) The World Within the World, Oxford.
Berkson, W. (1974) Fields of Force, RKP.
Cassidy, D.C., (1992) Uncertainty, New York.
Cohen, I.B., (1987) The Birth of a New Physics, Penguin.
Einstein, A et al. (1952) The Principle of Relativity, New Y
Author(s): The Open University

The unique climate and topography of each desert links to the unique and characteristic flora and fauna found there. From the brief description of deserts provided in Section 1, you can appreciate that a desert provides a variety of niches for animals and plants. The term ‘niche’ applied to animals describes its role in a particular environment, and includes a number of characteristics such as habitat range, how the animal feeds, its diet, its environmental requirements and also its preda
Author(s): The Open University

If you have visited a desert you will have noticed the sparse plant cover, or in certain sandy deserts, the almost complete absence of plant life. The low productivity of deserts derives from their defining feature, which is aridity. Scarcity of water restricts the diversity and amount of plant cover, and in turn the diversity and abundance of animals. However, if you were visiting one of the American deserts after rains, you would be rewarded by the sight of the desert ‘in bloom’, as vas
Author(s): The Open University

Reactive changes in the brain are usually marked by changes in neuronal electrical activity. If these changes are to be of long duration, adjustments in neuronal electrical behaviour may be made through changes in gene expression. Rapid-response genes (sometimes called ‘immediate-early’ genes) are activated within minutes of the onset of such sustained electrical activity. These genes are master controls, acting as a gateway to a series of linked events: alteration of electrical firing pa
Author(s): The Open University

Measurements of thermoregulation, respiration and metabolic depression in the edible dormouse (Myoxus glis) during the early stages of torpor, hibernation and aestivation, indicate remarkable similarities in the profile of physiological changes for all three adaptive phenomena, suggesting that they are controlled by essentially the same mechanism. The capacity for adaptive hypothermia in animals is clearly determined genetically and is manifested in cells from many different tissues. N
Author(s): The Open University

The supply of oxygen to tissues such as the heart, liver and WAT is, under euthermic conditions, invariably linked to and dependent upon local blood flow and pulmonary function. However, as we have already seen, under conditions in which blood flow is reduced to a trickle, the control of energy supply switches to local adaptations in the capillaries and tissue cells, including the oxygen affinity of erythrocyte haemoglobin, the supply and metabolism of respiratory fuels and the rate of protei
Author(s): The Open University

Hibernation can result in the deposition of fat in adipose tissue. In tissues of finite size which are important sources of energy and sites for fuel metabolism, changes in cell structure (redistribution of organelles involved in energy metabolism and protein synthesis) are the most likely adaptation to a state of torpor. Liver hepatocytes of the hibernating dormouse (Muscardinus avellanarius), are visibly different from those of arousing and euthermic dormice when viewed in thin secti
Author(s): The Open University

Even after many years of research, the phenomenon of hibernation continues to be a mystery to scientists. Despite coming nearer to an understanding of how and why it happens, some fundamental questions remain unanswered. Is there a genetic basis underlying the evolutionary predisposition of animals to hibernate, given its occurrence in many groups of vertebrates and invertebrates? Is the problem of metabolic adaptation in cells separate from thermal regulation which occurs throughout the orga
Author(s): The Open University

Emergence can be viewed as the final step in the series of periodic arousals. Instead of re-entering hibernation, the animal maintains the euthermic condition. The cue for maintaining this final arousal is probably not temperature, as some species emerge when T a is well below zero. It is also difficult to see how arousal could be affected by daylength, since the hibernating animal is usually underground in a cavity or a burrow. Perhaps fat or food stores reach a minimum lev
Author(s): The Open University

Hibernating endotherms are not the easiest animals to study. Thus, until the late 1960s many biologists believed that mammalian hibernation was a process in which thermoregulation was simply ‘switched off’, following the receipt of a set of ‘cues’. These cues included a declining T a, a shortening daylength, the extent of body fat and a lack of food etc. With this model, the hibernator essentially becomes an ectotherm whose T b follows the T
Author(s): The Open University