Life on earth

When writing a Lewis structure we restrict a molecule s electrons to certain well defined locations either linking two atoms by a covalent bond or as unshared electrons on a sm gle atom Sometimes more than one Lewis structure can be written for a molecule espe cially those that contain multiple bonds An example often cited m introductory chem istry courses is ozone (O3) Ozone occurs naturally m large quantities m the upper atmosphere where it screens the surface of the earth from much of the sun s ultraviolet rays Were it not for this ozone layer most forms of surface life on earth would be dam aged or even destroyed by the rays of the sun The following Lewis structure for ozone satisfies fhe ocfef rule all fhree oxygens have eighf elecfrons m fheir valence shell... 

One of the principal substances obtained from archaea (one of the oldest forms of life on earth) is denved from a 40 carbon diol Given the fact that this diol is optically active is it com pound A or is it compound... 

ATP IS the mam energy storing molecule for practically every form of life on earth We often speak of ATP as a high energy compound and its P—O bonds as high energy bonds This topic is discussed m more detail m Sections 28 4 and 28 5... 

Biosolid- The resides of wastewater treatment. Formerly called sewage sludge. Biosphere- Zone incorporating all forms of life on earth. The biosphere extends from deep in sediment below the ocean to several thousand meters elevation in high mountains. 

Lovelock, J. E. (1991). GAIA, a New Look at Life on Earth. New York Oxford University Press. 

Where docs this supply of energy come from Most life on Earth depends on radiant energy from the Sun, which delivers about 13 x 10 calories to Earth each year. Living organisms take up less than 1 percent of this energy Earth absorbs or reflects most of the rest. Absorbed energy is converted to heat, while energy is... 

This system for keeping track of these important units is used as the basis for the standard geologic lime and the evolution of the animal life on earth. (See also Tables 2-26 and 2-27.) Table 2-28 gives the relationship between geologic time and important physical and evolutionary events that are used to aid in the identification of rock units in relative geologic time [26]. 

Oceans occupy 70.8% or 125 million square miles of the surface of the earth. Within or beneath this inner space are foods, fuels, and minerals. Thus interest in the sea is obvious. At least 4/5 of all life on earth exists in saltwater. It is predicted that of the oil and gas demand in future years will come from oil at 2,000 ft. depths operated by manned submarines and marine robots. All the equipment needed to collect and store oil or gas will be installed and operated on the sea floor. Underwater housing and decompression chambers will be required. The sea bottom is also reported to include trillions of tons of copper, nickel, cobalt, iron, and other important minerals. 

An allotrope of oxygen, ozone, 03 (8), is formed in the stratosphere by the effect of solar radiation on 02 molecules. Its total abundance in the atmosphere is equivalent to a layer that, at the ordinary conditions of 25°C and 1 bar, would cover the Earth to a thickness of only 3 mm, yet its presence in the stratosphere is vital to the maintenance of life on Earth (see Box 13.3). Ozone can be made in the laboratory by passing an electric discharge through oxygen. It is a blue gas that... 

Why Do We Need to Know This Material All life on Earth is based on carbon so is the fuel we burn, our food, and the clothes we wear. Therefore, to understand a major part of the everyday world, we need to be familiar with the chemistry of this extraordinary element. Compounds of carbon and hydrogen are the foundation of the petrochemical industry petroleum products are used to generate electricity and to heat our homes. They are also used to make the flexible, strong polymeric and composite materials that make modern communication and transportation possible. 

Still more confusion plagued early researches, when it was not realized that the biosynthetic routes to thiamine in prokaryotes and eukaryotes are quite different, a fact not expected at the outset. Thus, evidence collected from the study of yeast could not be transposed to bacteria, and vice-versa. For instance, formate is a most efficient precursor of one of the carbon atoms of the pyrimidine part of thiamine (pyramine), both in yeasts and enterobacteria, but incorporates at C-2 in bacteria and at C-4 in yeast. However, as is briefly covered in Section VIII, this dichotomy of pathways might have a deep significance in the perspective of biochemical evolution during primitive life on Earth. 

All living organisms require at least one mobile phase (gas or liquid) in order to exist. Life on Earth as we know it would be impossible without the involvement of the liquid phase of water. The gas phase is necessary for life forms that consume gaseous substances or that produce gaseous waste products. Hence, the very functioning of the biosphere implicitly depends on the existence of the mobile atmosphere and hydrosphere, both of which are in... 

It is significant that the earliest records of life on Earth start shortly after the period of impact frustration. Apparently life formed as soon as the conditions permitted it. Life originated from compounds produced by prebiotic organic chemistry. The source of the molecules included those produced on Earth by energetic processes such as impacts and electrical discharges as well as those that fell in from space. Whatever processes occurred, they would have had to happen either in the deep ocean or in what might have been rare regions of land and shallow water. 

Scientists do not believe that life is arising from non-life on Earth today, but, if life originated on Earth, as it apparently did, it must have developed from non-living materials. Current scientific views of when and how life might have originated and evolved are based upon imaginative chemical experiments in the laboratory, combined with studies of the fossil record and ways of dating events in the remote past. 

While the hydrosphere has long been appreciated as essential to life on Earth, only in the past couple of decades have scientists expanded their exploration of the global hydrologic cycle and its roles across the spectrum of Earth science... 

The resultant O3 layer is critically important to life on Earth as a shield against LTV radiation. It also is responsible for the thermal structure of the upper atmosphere and controls the lifetime of materials in the stratosphere. Many substances that are short-lived in the troposphere (e.g. aerosol particles) have lifetimes of a year or more in the stratosphere due to the near-zero removal by precipitation and the presence of the permanent thermal inversion and lack of vertical mixing that it causes. 

How would the nitrogen cycle change if life on Earth were suddenly absent What would be the time scale for these changes ... 

This chapter looks at the particular question of polymers and the environment. A book on the science of polymers ought to give some consideration to this issue because of the growing concern about the effect of discarded plastic on the quality of life on Earth. If we are to produce and use polymers in ways that are more environmentally responsible (and society will increasingly demand that we do) then there will be new technical challenges to face. One purpose of this chapter is to indicate what some of these challenges might be. 

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